Himalayan Sprite Lightning, Mars’ Shocking Spherules, Asteroid Belt Mapping

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Kind: captions
Language: en

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this is spacetime series 28 episode 41


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for broadcast on the 4th of April


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2025 coming up on SpaceTime mysterious


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red sprite lightning seen over the


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Himalayas shocking spheral on Mars and a


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new geological map for the asteroid belt


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all that and more coming up on


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SpaceTime welcome to SpaceTime with


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Stuart Gary


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scientists have captured rare images of


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red sprite lightning high above thunder


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storms in the Himalayas the mesmerizing


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display of more than a 100 of these red


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Sprites were photographed by Chinese


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asttr photographers Angel an and chuch


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Chang dong over the world's highest


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mountain range at an observational site


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located in the southern Tibetan plateau


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in one of the Region's three sacred


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Lakes the breathtaking Celestial event


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included dancing Sprites rarely seen


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secondary Jets and the first ever


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recorded case in Asia of green Afterglow


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at the base of the nighttime ionosphere


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a new study reported in the journal


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advances in atmospheric sciences sheds


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light on the driving force behind this


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Grand Sprite display by analyzing the


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parent lightning discharges the authors


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discovered that the Sprites were being


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triggered by high peak current positive


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CL Cloud to Cloud lightning strikes


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within a massive misos scale convective


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system this suggest that the


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thunderstorms in the Himalayan region


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have the potential to produce some of


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the most complex and intense upper


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atmosphere electrical discharges on


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Earth lacking precise timestamps for


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detail analysis the authors developed an


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Innovative method to synchronize video


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timing using satellite trajectories and


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Starfield analyses this allowed them to


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determine the exact occurrence times of


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the Sprites and Link that to their


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parent lightning discharges the study


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revealed that the parent lightning


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discharges occurred within Strat


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precipitation regions of Mescal


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convective complexes stretching from the


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Ganges Plaine to the southern foothills


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of the Tibetan Plateau the events


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recorded the highest number of Sprites


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during a single thunderstorm in South


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Asia suggesting that thunderstorms in


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this region possess upper atmospheric


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discharge capabilities comparable with


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those on the United States great ples


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and offshore European storms moreover


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the findings indicate the storms may


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generate even more complex discharge


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structures potentially influencing


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atmospheric coupling processes with


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significant physical and chemical


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effects Sprites belong to a colorful


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group of transient luminous phenoma with


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fairy tale names such as Sprites blue


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jets and elves their transient vertical


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column-like plasma flashes high in


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Earth's atmosphere often resembling a


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glowing reddish jellyfish with tentacle


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streaming down they're thought to be


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large scale electrical discharges at


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altitudes of between 50 and 100 km above


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the ground triggered by Rare positive


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lightning that originates in the Anvil


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head of a thunderstorm Cloud where


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positive charges tend to accumulate now


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positive lightning is about five times


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as hot and Powerful as the regular type


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of lightning we normally see which is


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technically known as negative lightning


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positive lightning also lasts about 10


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times longer allowing it to strike many


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kilometers from the storm in fact that's


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the feature which is led to the famous


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expression a bolt out of the blue unlike


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negative lightning which occurs either


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inside the storm cloud or from the base


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of the thunderstorm Cloud to the ground


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positive lightning travels outside the


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cloud striking the ground directly


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Sprites sometimes preceded by a red halo


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emission lighting up a millisecond


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before the Sprite about 70 km above the


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initiating lightning strike then there


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are sprite Halos they look like 50 km


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wide discs and are thought to be


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produced by a weaker version of the same


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ionization processes which produce the


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Sprites next we have blue Jets blue jets


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are very bright narrow cones of plasma


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seen above thunderstorms propagating


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upwards into the stratosphere from the


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cloud tops often reaching Heights of 80


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km or more they're thought to be


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associated with strong hail activity


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during thunderstorms and their colors


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beli to be caused by Blue and near


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infrared emissions from neutral and


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ionized molecular nitrogen another


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closely related phenomena are blue


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starters which are thought to be shorter


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brighter versions of blue jets only


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reaching to about 20 km in height and


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then there's a third type known as


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gigantic Jets which are thought to be


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bigger versions of blue jets and finally


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we have the elves they flattened


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expanding reddish concentric rings that


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often appear is dim expanding 400 km


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wide glows lasting for just a


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millisecond they've been seen at


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altitudes of 100 km above thunderstorms


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and are thought to be generated by the


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excitation of nitrogen molecules due to


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collisions between electrons energized


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by lightning from the underlying


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thunderstorm Sprites elves and jets are


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all very little understood seldom scen


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but a fascinating part of our upper


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atmosphere this is spacetime still to


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come shocking spheral discovered on Mars


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and scientists develop a new geologic


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map of the main asteroid build all that


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and more still to come on SpaceTime


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ness's Mars perseverance Rover has


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discovered a strange Rock composed of


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hundreds of millimeters size spheres the


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finder shocked scientists were now


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working overtime to try and understand


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their origin it's now been 2 weeks since


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the perseverance Rover arrived at broom


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Point situated at the lower slopes of


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the witch hazel Hill area on the rim of


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jezzro crater here a series of light and


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dark toned bands of rock were visible


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from orbit now last week the six wheel


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car-sized Rover successfully abided and


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sampled one of these light toned beds


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and it was from this sampling workspace


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that perseverance spied a very strange


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texture in a nearby Rock The Rock which


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is now being named St Paul's B appeared


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to be comprised of hundreds of


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millimeter siiz dark gray spheres some


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of these occurred as more elongated


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elliptical shapes While others possessed


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angular edges perhaps representing


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broken spheral fragments and some


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spheres even possess tiny pin holes it's


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all raising questions about the type of


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geology that could produce these strange


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shapes of course this isn't the first


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time strange spheres have been spotted


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on Mars you may recall back in 2004


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NASA's Mars exploration Rover


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opportunity spotted so-called Martian


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blueberries in the meridiani plum and


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since then curiosity observes spheral in


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the rocks of Yellow Knife Bay in gal


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crater in fact just a few months ago


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perseverance itself also spied


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popcorn-like Textures in sedimentary


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rocks which had been exposed in the gzro


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crater Inlet Channel near Riva valys now


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in each of these cases the spheral have


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been interpreted as being concretions


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features that were formed through the


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interaction with groundwater circulating


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through poor spaces in rock however not


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all spheral form this way here are Earth


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that can also be formed by the rapid


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cooling of molten rock droplets from


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volcanic eruptions or through the


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condensation of rock which is vaporized


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during a meteor impact each of these


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formation mechanisms would have vastly


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different implications for the evolution


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of these rocks so scientists need to


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work hard to try and determine their


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context and origin however the simpul


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bay was a float Rock that's a term used


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by geologists to describe something


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that's not in place scientists are now


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working to try and Link the spheral rich


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texture observed at some's Bay with the


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widest strateg graphy at witch hazel


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Hill initial observations have provided


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tantalizing indications that could be


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linked to one of the dark toned layers


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identified from orbit placing these


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features in geological context is


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crucial for understanding their origin


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and determining their significance for


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the geological history not just of jez


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Creator's Rim but also for the red


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planet Beyond this is spacetime still to


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come a new geological map of the main


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asteroid built between Mars and Jupiter


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and the splendas of the Southern Cross


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and its two pointer Stars Alpha and beta


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sentor the blue super giant canopus and


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the ly's meteor shower are all among the


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highlights of the April night skies on


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Skywatch


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scientists have put together a new


00:08:43.159 --> 00:08:45.110
geological map of the main asteroid


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built between Mars and Jupiter knowing


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from what asteroid built debris field


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and meteorites hitting the Earth


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originate from is important for


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planetary defense efforts the new


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findings reported in the journal


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meteoritics and planetary science traces


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the impact orbits of a number of


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observed meteorite Falls including


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several the previously unidentified


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Source regions in the main asteroid belt


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the studies lead Author Peter jisin from


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NASA's as Research Center and the SEI


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Institute describes the report as a


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decades long detective story with each


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meteorite impact providing a new clue 10


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years ago jesin teamed up with hadrien


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diloy and astronomist from curtain


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University to develop the first outlines


00:09:25.680 --> 00:09:28.750
of a geologic map of the asteroid build


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by then had already developed its now


00:09:30.880 --> 00:09:32.910
famous Outback Fireball network of


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cameras and they assisted jesin and


00:09:35.360 --> 00:09:37.069
colleagues in North America to build a


00:09:37.079 --> 00:09:39.310
similar network of all Sky cameras in


00:09:39.320 --> 00:09:41.750
California and Nevada these are designed


00:09:41.760 --> 00:09:43.350
to capture and track the bright lights


00:09:43.360 --> 00:09:45.310
of meteors as they hit the Earth's


00:09:45.320 --> 00:09:47.710
atmosphere many other institutions as


00:09:47.720 --> 00:09:49.389
well as citizen scientists have


00:09:49.399 --> 00:09:51.030
participated in these efforts over the


00:09:51.040 --> 00:09:53.389
years and eventually created a global


00:09:53.399 --> 00:09:54.670
fball


00:09:54.680 --> 00:09:56.790
Observatory initially Dilo and


00:09:56.800 --> 00:09:58.750
colleagues tracked the path of 17


00:09:58.760 --> 00:10:01.470
recovered meteorite Falls and many more


00:10:01.480 --> 00:10:03.350
Fireballs were tracked using doorbell


00:10:03.360 --> 00:10:05.389
and dash cam video cameras by citizen


00:10:05.399 --> 00:10:07.750
scientists as well as by other dedicated


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networks now altoe the effort has now


00:10:10.399 --> 00:10:13.430
yielded some 75 laboratory classified


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meteorites each with an impact orbit


00:10:15.920 --> 00:10:17.790
tracked by video and photographic


00:10:17.800 --> 00:10:19.870
cameras jisin says that this is


00:10:19.880 --> 00:10:21.590
providing enough material to start to


00:10:21.600 --> 00:10:23.590
see some patterns in the direction from


00:10:23.600 --> 00:10:26.110
which meteors approach the Earth most


00:10:26.120 --> 00:10:27.790
meteorites originate from the main


00:10:27.800 --> 00:10:29.829
asteroid built between Mars and Jupiter


00:10:29.839 --> 00:10:31.509
were over a million asteroids larger


00:10:31.519 --> 00:10:34.269
than a kilometer orbit the sun now this


00:10:34.279 --> 00:10:36.269
massive collection of space rocks all


00:10:36.279 --> 00:10:38.269
originate from much smaller number of


00:10:38.279 --> 00:10:40.150
larger asteroids which have been broken


00:10:40.160 --> 00:10:41.949
apart in collisions creating debris


00:10:41.959 --> 00:10:44.509
fields which litter much of the region


00:10:44.519 --> 00:10:46.190
even today asteroids are colliding


00:10:46.200 --> 00:10:48.110
creating new debris fields or clusters


00:10:48.120 --> 00:10:50.550
Within These asteroid families during


00:10:50.560 --> 00:10:52.069
their studies the authors have found


00:10:52.079 --> 00:10:54.590
that 12 of the iron rich ordinary htype


00:10:54.600 --> 00:10:56.710
condite meteorites originated from a


00:10:56.720 --> 00:11:00.110
single debris field now called Coronas


00:11:00.120 --> 00:11:02.790
it's located in the pristine main belt


00:11:02.800 --> 00:11:04.990
jesin says that these meteorites arrived


00:11:05.000 --> 00:11:06.990
at lwi inclined orbits on orbital


00:11:07.000 --> 00:11:08.750
periods consistent with this debris


00:11:08.760 --> 00:11:11.190
field astronomers can measure how long


00:11:11.200 --> 00:11:13.110
ago these rocks were dug up from below


00:11:13.120 --> 00:11:14.949
an asteroid Surface by measuring the


00:11:14.959 --> 00:11:16.990
level of radioactive elements created by


00:11:17.000 --> 00:11:19.750
exposure to cosmic rays and this cosmic


00:11:19.760 --> 00:11:21.949
ray exposure ede in meteorites can be


00:11:21.959 --> 00:11:23.990
used to match the dynamical age of some


00:11:24.000 --> 00:11:26.590
of the asteroid debris Fields scientists


00:11:26.600 --> 00:11:28.150
can determine the dynamical age of an


00:11:28.160 --> 00:11:30.190
asteroid debris field by measuring how


00:11:30.200 --> 00:11:32.389
far the asteroids of different sizes


00:11:32.399 --> 00:11:35.389
have spread over time by measuring the


00:11:35.399 --> 00:11:37.509
cosmic rare exposure age of meteorites


00:11:37.519 --> 00:11:38.910
they could determine that three of these


00:11:38.920 --> 00:11:41.470
12 meteorites originated from the kiring


00:11:41.480 --> 00:11:44.150
cluster of the coronus field and the


00:11:44.160 --> 00:11:47.190
coronus field has a dynamical age of 5.8


00:11:47.200 --> 00:11:49.829
million years and a further two came


00:11:49.839 --> 00:11:51.870
from the coronus 2 cluster which has a


00:11:51.880 --> 00:11:54.949
dynamical age of 10 to 15 million years


00:11:54.959 --> 00:11:56.550
another meteorite from this group May


00:11:56.560 --> 00:11:58.310
well be measuring the age of the coronus


00:11:58.320 --> 00:12:00.350
3 cluster resulting in a figure of


00:12:00.360 --> 00:12:04.509
around 83 million years jisin and Dil


00:12:04.519 --> 00:12:07.230
Ploy also found a group of hondes on


00:12:07.240 --> 00:12:09.829
steep orbits they appear to originate


00:12:09.839 --> 00:12:11.710
from the Neil asteroid family in the


00:12:11.720 --> 00:12:13.790
Central Main asteroid belt and it's been


00:12:13.800 --> 00:12:15.670
shown to have a dynamical age of around


00:12:15.680 --> 00:12:17.310
6 million


00:12:17.320 --> 00:12:19.910
years a third group of H condres that


00:12:19.920 --> 00:12:22.389
have exposure ages of around 35 million


00:12:22.399 --> 00:12:24.269
years originated from the inner main


00:12:24.279 --> 00:12:25.990
belt these are all thought to have


00:12:26.000 --> 00:12:27.790
originated from the mallar asteroid


00:12:27.800 --> 00:12:29.949
family low in the inner Main built


00:12:29.959 --> 00:12:31.829
jenkinson says that the asteroid which


00:12:31.839 --> 00:12:34.509
created that cluster 20 Melia is also an


00:12:34.519 --> 00:12:38.230
AG condite parent body type jenkinson


00:12:38.240 --> 00:12:40.790
nilo find that the low iron L Type


00:12:40.800 --> 00:12:43.350
condres and very low iron LL condite


00:12:43.360 --> 00:12:45.590
meteorites also primarily come from the


00:12:45.600 --> 00:12:48.470
inner main belt CST have long link the


00:12:48.480 --> 00:12:50.910
LL condres to the Flora asteroid family


00:12:50.920 --> 00:12:52.629
on the inner side of the main asteroid


00:12:52.639 --> 00:12:54.990
belt and this new work has now confirmed


00:12:55.000 --> 00:12:55.990
that is


00:12:56.000 --> 00:12:58.670
correct jenkinson proposes that the old


00:12:58.680 --> 00:13:00.350
condr originated from the hether


00:13:00.360 --> 00:13:02.310
asteroid family located just above the


00:13:02.320 --> 00:13:05.069
mallia group but asteroid Heria doesn't


00:13:05.079 --> 00:13:07.430
look anything like its debris it's


00:13:07.440 --> 00:13:08.910
covered in dark rocks that were all


00:13:08.920 --> 00:13:10.829
shock blackened indicative of an


00:13:10.839 --> 00:13:13.189
unusually violent Collision the El


00:13:13.199 --> 00:13:14.790
condres experienced a very violent


00:13:14.800 --> 00:13:17.670
origin 468 million years ago and since


00:13:17.680 --> 00:13:19.189
then these meteorites have showered the


00:13:19.199 --> 00:13:20.910
Earth in such numbers that they can be


00:13:20.920 --> 00:13:22.949
found throughout the geological


00:13:22.959 --> 00:13:25.590
record knowing from which debris field


00:13:25.600 --> 00:13:27.829
an asteroid built meteorite originates


00:13:27.839 --> 00:13:29.590
from is important for Planet your


00:13:29.600 --> 00:13:31.269
defense efforts against near Earth


00:13:31.279 --> 00:13:33.949
asteroids an approaching asteroids orbit


00:13:33.959 --> 00:13:35.870
can provide clues about its origins in


00:13:35.880 --> 00:13:37.710
the main asteroid built in the same way


00:13:37.720 --> 00:13:40.310
as a meteorite orbit does but Neo


00:13:40.320 --> 00:13:41.750
asteroids don't arrive on the same


00:13:41.760 --> 00:13:44.230
orbits as meteorites that's because they


00:13:44.240 --> 00:13:46.110
take longer for these to evolve into


00:13:46.120 --> 00:13:48.230
Earth Crossing orbits but they


00:13:48.240 --> 00:13:50.069
nevertheless come from some of the same


00:13:50.079 --> 00:14:09.870
asteroid families this is spacetime


00:14:09.880 --> 00:14:11.350
and time now to check out the night


00:14:11.360 --> 00:14:14.590
skies of April on Skywatch April is the


00:14:14.600 --> 00:14:16.350
fourth month of the year in the gorian


00:14:16.360 --> 00:14:18.269
calendar and the fifth in the early


00:14:18.279 --> 00:14:20.990
Julian calendar the Romans gave this


00:14:21.000 --> 00:14:23.670
month the Latin name ailis although the


00:14:23.680 --> 00:14:25.509
name's Origins aren't certain


00:14:25.519 --> 00:14:27.509
traditional entomology suggested from


00:14:27.519 --> 00:14:30.550
the verb aara to open as in it being the


00:14:30.560 --> 00:14:32.829
season when the trees and flowers begin


00:14:32.839 --> 00:14:35.110
to open as the Northern Hemisphere moves


00:14:35.120 --> 00:14:38.230
into spring April is also Prevention of


00:14:38.240 --> 00:14:40.470
Cruelty to animals month and so it's a


00:14:40.480 --> 00:14:42.710
good time to consider adopting a shelter


00:14:42.720 --> 00:14:45.590
pit or donating to an animal welfare


00:14:45.600 --> 00:14:48.269
charity high in the southern sky during


00:14:48.279 --> 00:14:50.749
April you'll find the Southern Cross and


00:14:50.759 --> 00:14:53.189
its two pointer Stars Alpha and beta


00:14:53.199 --> 00:14:55.470
centor the more distant of the two


00:14:55.480 --> 00:14:57.509
pointer stars from The Southern Cross is


00:14:57.519 --> 00:15:00.030
Alpha centu which also happens to be the


00:15:00.040 --> 00:15:03.189
nearest star system to our own located


00:15:03.199 --> 00:15:06.269
some 4.3 light years away Alpha centor


00:15:06.279 --> 00:15:08.990
actually consists of three stars there's


00:15:09.000 --> 00:15:11.310
Alpha centor A and B which orbit each


00:15:11.320 --> 00:15:13.790
other and Proxima centor which orbits


00:15:13.800 --> 00:15:17.470
the pair and at 4.25 lie distant is


00:15:17.480 --> 00:15:19.269
currently the nearest St of the earth


00:15:19.279 --> 00:15:22.069
other than the Sun a lightyear is about


00:15:22.079 --> 00:15:25.030
10 trillion kilm the distance of photon


00:15:25.040 --> 00:15:28.550
can travel in a year at 300,000 km/s the


00:15:28.560 --> 00:15:30.590
speed of of light in a vacuum and the


00:15:30.600 --> 00:15:33.230
ultimate speed limit of the universe


00:15:33.240 --> 00:15:36.309
like the sun Alpha centu a is a spectr


00:15:36.319 --> 00:15:39.829
type G yellow dwarf star it's slightly


00:15:39.839 --> 00:15:41.749
bigger having about a tenth more mass


00:15:41.759 --> 00:15:45.030
than the Sun and has about 50% more


00:15:45.040 --> 00:15:48.030
Luminosity astronomers describe stars in


00:15:48.040 --> 00:15:50.710
terms of spectral types A classification


00:15:50.720 --> 00:15:52.749
system based on temperature and


00:15:52.759 --> 00:15:55.069
characteristics the hottest most massive


00:15:55.079 --> 00:15:57.189
and most luminous stars are known as


00:15:57.199 --> 00:15:59.749
spectr type O blue stars


00:15:59.759 --> 00:16:01.870
they're followed by spectr type B blue


00:16:01.880 --> 00:16:04.550
white stars then spectr type a white


00:16:04.560 --> 00:16:08.150
stars spectr type f whitish yellow stars


00:16:08.160 --> 00:16:10.629
spectr type G yellow stars that's where


00:16:10.639 --> 00:16:13.350
our sun fits in spectr type K orange


00:16:13.360 --> 00:16:15.829
stars and the coolest and least massive


00:16:15.839 --> 00:16:18.509
stars of all are spectral type M red


00:16:18.519 --> 00:16:21.509
dwarf stars each spectral classification


00:16:21.519 --> 00:16:23.910
is further subdivided using a numeric


00:16:23.920 --> 00:16:26.269
digit to represent temperature with zero


00:16:26.279 --> 00:16:28.590
being the hottest and nine the coolest


00:16:28.600 --> 00:16:31.269
and then a Roman numeral to represent


00:16:31.279 --> 00:16:35.030
Luminosity so our sun is a spectr type


00:16:35.040 --> 00:16:39.790
g2v or G25 yellow dwarf star also


00:16:39.800 --> 00:16:41.710
included in the Stellar classification


00:16:41.720 --> 00:16:44.949
system are special types LT and Y which


00:16:44.959 --> 00:16:46.910
are assigned to failed Stars called


00:16:46.920 --> 00:16:50.069
Brown dwarves these are sometimes born


00:16:50.079 --> 00:16:52.710
as spectr typm red dwarf stars but


00:16:52.720 --> 00:16:54.829
become Brown dwarves after losing some


00:16:54.839 --> 00:16:57.749
of their Mass Brown dwarves fit into a


00:16:57.759 --> 00:16:59.790
category between the largest planets


00:16:59.800 --> 00:17:01.389
which are about 13 times the mass of


00:17:01.399 --> 00:17:03.829
Jupiter and the smallest spectr type M


00:17:03.839 --> 00:17:06.590
red dwarf stars which are around 75 to


00:17:06.600 --> 00:17:09.470
80 times the mass of Jupiter or about


00:17:09.480 --> 00:17:11.470
0.08 solar


00:17:11.480 --> 00:17:14.189
masses orbiting in a binary system with


00:17:14.199 --> 00:17:17.669
Alpha centori a is Alpha centor B A


00:17:17.679 --> 00:17:20.510
spectr type K orange dwarf star a little


00:17:20.520 --> 00:17:22.470
smaller and cooler than the sun with


00:17:22.480 --> 00:17:25.710
about 0.9 times the Sun's mass and about


00:17:25.720 --> 00:17:29.110
half its Luminosity Alpha centor a in


00:17:29.120 --> 00:17:30.950
orbit each other around a common center


00:17:30.960 --> 00:17:32.590
of gravity every


00:17:32.600 --> 00:17:35.870
79.9 earth years the distance between


00:17:35.880 --> 00:17:38.310
the two stars varies between roughly


00:17:38.320 --> 00:17:40.310
that of Pluto in the Sun and that of


00:17:40.320 --> 00:17:42.830
Saturn in the Sun the third star in the


00:17:42.840 --> 00:17:45.190
system Proxima centor sometimes called


00:17:45.200 --> 00:17:47.990
Alpha centor C is a spectral type M Red


00:17:48.000 --> 00:17:50.190
Dwarf star with roughly a seventh the


00:17:50.200 --> 00:17:52.150
diameter and about an eighth the mass of


00:17:52.160 --> 00:17:55.710
the Sun it takes around 550,000 earth


00:17:55.720 --> 00:17:59.470
years to orbit Alpha centu A and B


00:17:59.480 --> 00:18:01.470
the nearer of the two pointer stars to


00:18:01.480 --> 00:18:04.390
the Southern Cross is beta centor also a


00:18:04.400 --> 00:18:06.630
triple star system but this one located


00:18:06.640 --> 00:18:10.029
a far more distant 390 light years away


00:18:10.039 --> 00:18:13.350
all three are massive young blue stars


00:18:13.360 --> 00:18:15.149
far larger and more luminous than the


00:18:15.159 --> 00:18:19.029
sun two of the stars named beta centu AA


00:18:19.039 --> 00:18:22.190
and beta centor a orbit each other while


00:18:22.200 --> 00:18:24.830
the third star bentor B orbits the


00:18:24.840 --> 00:18:27.990
primary pair every 1500 Earth years


00:18:28.000 --> 00:18:30.710
bentor AA and ab are known as a


00:18:30.720 --> 00:18:33.310
spectroscopic binary orbiting each other


00:18:33.320 --> 00:18:36.830
every 357 Earth days spectroscopic


00:18:36.840 --> 00:18:38.549
binaries are double star systems


00:18:38.559 --> 00:18:40.310
orbiting each other so closely and at


00:18:40.320 --> 00:18:42.270
such an angle that they can only be


00:18:42.280 --> 00:18:44.230
visually separated from our point of


00:18:44.240 --> 00:18:46.029
view here on Earth at least by their


00:18:46.039 --> 00:18:48.669
spectroscopic signatures both these


00:18:48.679 --> 00:18:50.390
stars are now reaching the end of their


00:18:50.400 --> 00:18:52.750
time on the main sequence and will soon


00:18:52.760 --> 00:18:54.909
run out of the core hydrogen they Ed for


00:18:54.919 --> 00:18:57.230
Fusion the process which makes stars


00:18:57.240 --> 00:19:00.270
like the sun shine the two pointer Stars


00:19:00.280 --> 00:19:02.750
Alfred and be centori are named after


00:19:02.760 --> 00:19:05.510
siron the centur a mythological Greek


00:19:05.520 --> 00:19:08.870
being half man half horse siron taught


00:19:08.880 --> 00:19:10.830
many of the Great gods and heroes but


00:19:10.840 --> 00:19:12.590
was placed Among the Stars after


00:19:12.600 --> 00:19:14.390
accidentally being shot with a poison


00:19:14.400 --> 00:19:15.710
arrow by


00:19:15.720 --> 00:19:18.470
Hercules next to the point of stars is


00:19:18.480 --> 00:19:21.430
the spectacular Southern Cross or Crux


00:19:21.440 --> 00:19:23.430
the smallest but one of the best known


00:19:23.440 --> 00:19:26.710
of the 88 constellations in the sky the


00:19:26.720 --> 00:19:28.310
Southern Cross is considered an


00:19:28.320 --> 00:19:30.549
important constellation for navigation


00:19:30.559 --> 00:19:32.070
and he's featured on the flags of


00:19:32.080 --> 00:19:34.470
several Nations including Australia


00:19:34.480 --> 00:19:37.350
Brazil New Zealand Papa New Guinea and


00:19:37.360 --> 00:19:40.270
Samoa in April the Southern Cross lies


00:19:40.280 --> 00:19:42.230
on its side in the early evening but


00:19:42.240 --> 00:19:44.029
becomes more and more upright as the


00:19:44.039 --> 00:19:45.149
night


00:19:45.159 --> 00:19:47.630
progresses the bottom and brightest star


00:19:47.640 --> 00:19:50.029
in the Southern Cross is Alpha cruus or


00:19:50.039 --> 00:19:52.669
AC which is actually a multiple star


00:19:52.679 --> 00:19:56.350
system located 321 light years away it


00:19:56.360 --> 00:19:59.270
consists of three stars a one cruises


00:19:59.280 --> 00:20:02.070
which is a spectroscopic binary and A2


00:20:02.080 --> 00:20:05.310
crues A2 crues and the primary staring


00:20:05.320 --> 00:20:08.510
A1 cruises are both spectral type B blue


00:20:08.520 --> 00:20:10.630
stars with surface temperatures of


00:20:10.640 --> 00:20:14.430
26,000 and 28,000 Kelvin respectively


00:20:14.440 --> 00:20:16.310
the two components orbit each other


00:20:16.320 --> 00:20:18.909
every 1500 Earth years at an average


00:20:18.919 --> 00:20:21.870
distance of around 430 astronomical


00:20:21.880 --> 00:20:24.270
units an astronomical unit is the


00:20:24.280 --> 00:20:25.990
average distance between the Earth and


00:20:26.000 --> 00:20:29.909
the Sun roughly 150 million kilm or 8.3


00:20:29.919 --> 00:20:33.310
L minutes the spectroscopic binary A1


00:20:33.320 --> 00:20:36.669
Cruis is thought to comprise two stars


00:20:36.679 --> 00:20:38.990
with about 10 and 14 times the mass of


00:20:39.000 --> 00:20:41.710
the Sun respectively the pair orbit each


00:20:41.720 --> 00:20:44.270
other every 76 Earth days at a distance


00:20:44.280 --> 00:20:47.230
of around 150 million kilm in other


00:20:47.240 --> 00:20:49.950
words one astronomical unit the masses


00:20:49.960 --> 00:20:52.630
of A2 crues and the larger component of


00:20:52.640 --> 00:20:55.029
A1 crues are expected to eventually


00:20:55.039 --> 00:20:57.390
explode as core collapse Supernova


00:20:57.400 --> 00:20:59.950
ending up as Neutron St Stars while the


00:20:59.960 --> 00:21:02.190
smaller component of A1 crues could


00:21:02.200 --> 00:21:03.830
survive as a white


00:21:03.840 --> 00:21:06.350
dwarf the left hand and second brightest


00:21:06.360 --> 00:21:08.070
star in the Southern Cross is called


00:21:08.080 --> 00:21:10.750
beta cruus and it's also a spectroscopic


00:21:10.760 --> 00:21:13.230
binary consisting of two stars orbiting


00:21:13.240 --> 00:21:15.390
each other every five Earth years at an


00:21:15.400 --> 00:21:17.269
average distance which varies between


00:21:17.279 --> 00:21:21.390
5.4 and 12 astronomical units beta cruus


00:21:21.400 --> 00:21:24.950
is located some 280 L years away the


00:21:24.960 --> 00:21:27.669
primary star beta cruus a is a spectral


00:21:27.679 --> 00:21:30.510
type B B a sephy variable blue star


00:21:30.520 --> 00:21:32.390
which changes in brightness over a


00:21:32.400 --> 00:21:35.750
period of around 4 to 4 1/2 hours it has


00:21:35.760 --> 00:21:38.470
about 16 times the Sun's mass about 8


00:21:38.480 --> 00:21:40.549
times its diameter and a surface


00:21:40.559 --> 00:21:43.990
temperature of some 27,000 Kelvin by


00:21:44.000 --> 00:21:45.950
comparison our sun has a surface


00:21:45.960 --> 00:21:48.549
temperature of just 6,000 the second


00:21:48.559 --> 00:21:50.669
star in the system betac cruus B has


00:21:50.679 --> 00:21:53.710
about 10 solar masses a third companion


00:21:53.720 --> 00:21:56.310
has also been detected in the system


00:21:56.320 --> 00:21:58.750
however it appears to be a low mass pre


00:21:58.760 --> 00:22:01.149
sequence star which hasn't yet commenced


00:22:01.159 --> 00:22:04.470
nuclear fusion NE beta cruus is the


00:22:04.480 --> 00:22:06.830
spectacular young open star cluster


00:22:06.840 --> 00:22:11.190
known as the Capac crusis cluster or NGC


00:22:11.200 --> 00:22:14.149
4755 and more commonly referred to as


00:22:14.159 --> 00:22:17.070
the jewelbox the name given to it by


00:22:17.080 --> 00:22:19.110
famous 18th century astronomer John


00:22:19.120 --> 00:22:22.070
hersel open star clusters are groups of


00:22:22.080 --> 00:22:23.950
stars which were originally all born at


00:22:23.960 --> 00:22:26.310
the same time out of the same collapsing


00:22:26.320 --> 00:22:29.029
molecular gas and dust cloud although


00:22:29.039 --> 00:22:31.070
somewhat still gravitationally bound to


00:22:31.080 --> 00:22:33.470
each other stars in open clusters


00:22:33.480 --> 00:22:35.630
eventually separate moving to other


00:22:35.640 --> 00:22:38.590
parts of the Galaxy as the name suggests


00:22:38.600 --> 00:22:40.470
the jewel box is a stunning collection


00:22:40.480 --> 00:22:43.310
of more than 100 bright colorful stars


00:22:43.320 --> 00:22:46.630
located some 6,440 light years away


00:22:46.640 --> 00:22:48.669
although its exact distance is somewhat


00:22:48.679 --> 00:22:50.110
difficult to determine because of the


00:22:50.120 --> 00:22:52.669
nearby ksac nebula which obscures some


00:22:52.679 --> 00:22:55.789
of the light the corac is a dark nebula


00:22:55.799 --> 00:22:58.190
containing lots of gas and dust blocking


00:22:58.200 --> 00:23:01.110
out background stars in Australian


00:23:01.120 --> 00:23:03.549
Aboriginal dream time Legend the K saac


00:23:03.559 --> 00:23:05.909
forms the head of the Emu constellation


00:23:05.919 --> 00:23:08.269
with a dark dust Lanes of the Milky Way


00:23:08.279 --> 00:23:11.070
forming the emu's body and legs the


00:23:11.080 --> 00:23:13.230
central parts of the jawbox are framed


00:23:13.240 --> 00:23:16.310
by Bright Stars making up an a-shaped


00:23:16.320 --> 00:23:18.750
asterism these are among the brightest


00:23:18.760 --> 00:23:21.750
known blue white and red super Giants in


00:23:21.760 --> 00:23:22.870
the Milky


00:23:22.880 --> 00:23:25.789
Way gamma cruus which is located at the


00:23:25.799 --> 00:23:27.710
top of the Southern Cross is the third


00:23:27.720 --> 00:23:30.029
brightest star in the the constellation


00:23:30.039 --> 00:23:31.870
it's also one of the nearest red giants


00:23:31.880 --> 00:23:34.750
to our solar system located just 88.6


00:23:34.760 --> 00:23:37.909
light years away although any 30% more


00:23:37.919 --> 00:23:40.549
massive than the sun its expanded outer


00:23:40.559 --> 00:23:43.269
envelope is bloated out to some 84 times


00:23:43.279 --> 00:23:46.070
the sun's radius and is radiating some


00:23:46.080 --> 00:23:49.430
1500 times more Luminosity than the sun


00:23:49.440 --> 00:23:51.590
as a red giant no longer on the main


00:23:51.600 --> 00:23:53.990
sequence gamic Cruis is nearing the end


00:23:54.000 --> 00:23:56.830
of its life its surface temperature is


00:23:56.840 --> 00:24:00.470
some 3,6 26 Kelvin and it has a


00:24:00.480 --> 00:24:02.350
prominent reddish orange


00:24:02.360 --> 00:24:04.710
appearance the star on the right hand


00:24:04.720 --> 00:24:06.630
side of the Southern Cross is delac


00:24:06.640 --> 00:24:09.590
cruus a massive hot and rapidly rotating


00:24:09.600 --> 00:24:11.630
star that's in the process of evolving


00:24:11.640 --> 00:24:14.029
into a red giant and will eventually end


00:24:14.039 --> 00:24:16.310
up as a white dwarf the Stellar corpse


00:24:16.320 --> 00:24:19.710
of sunlike stars Delta cruus is located


00:24:19.720 --> 00:24:22.789
some 345 light years away and has about


00:24:22.799 --> 00:24:25.389
nine times the Sun's mass and 8 times


00:24:25.399 --> 00:24:28.029
its radius it's presently radiating at


00:24:28.039 --> 00:24:30.230
around 10,000 times the Luminosity of


00:24:30.240 --> 00:24:33.110
the Sun at an effective temperature of


00:24:33.120 --> 00:24:35.870
22570 kelv causing it to Glow with a


00:24:35.880 --> 00:24:38.830
blue white Hue the smallest star in the


00:24:38.840 --> 00:24:41.230
Southern Cross is Epsilon crues which is


00:24:41.240 --> 00:24:43.389
located in the space between Delta and


00:24:43.399 --> 00:24:47.669
Alpha crues it's a red giant some 228


00:24:47.679 --> 00:24:51.230
light years away it is about 1.42 time


00:24:51.240 --> 00:24:53.750
the mass of the Sun and about 32 times


00:24:53.760 --> 00:24:56.990
its radius its surface temperature of


00:24:57.000 --> 00:25:00.070
4,148 kin means it sometimes referred to


00:25:00.080 --> 00:25:01.750
as an orange


00:25:01.760 --> 00:25:04.110
giant the Southern Cross is at its


00:25:04.120 --> 00:25:05.789
highest point in the southern sky this


00:25:05.799 --> 00:25:08.029
time of year and is pointing directly at


00:25:08.039 --> 00:25:10.750
the southern Celestial pole it's within


00:25:10.760 --> 00:25:13.230
the constellation Centaurus the centur


00:25:13.240 --> 00:25:15.110
the half man half horse of Greek


00:25:15.120 --> 00:25:17.549
mythology we mentioned earlier the


00:25:17.559 --> 00:25:19.750
creature is holding a bow loaded with an


00:25:19.760 --> 00:25:22.710
arrow the centaur's front leg is marked


00:25:22.720 --> 00:25:25.310
by the two pointer Stars Alpha and beta


00:25:25.320 --> 00:25:28.070
curus his back arches over the southern


00:25:28.080 --> 00:25:30.789
C Ross and just above this is Amiga


00:25:30.799 --> 00:25:33.830
centori a spectacular globular cluster


00:25:33.840 --> 00:25:36.350
visible with the uned eye from dark


00:25:36.360 --> 00:25:39.149
locations unlike open star clusters


00:25:39.159 --> 00:25:41.350
globular clusters are tightly packed


00:25:41.360 --> 00:25:43.470
spheres containing thousands to millions


00:25:43.480 --> 00:25:45.710
of stars which were originally all


00:25:45.720 --> 00:25:47.389
thought to have been born at the same


00:25:47.399 --> 00:25:49.590
time from the same molecular gas and


00:25:49.600 --> 00:25:52.750
dust cloud Amigas centori is about


00:25:52.760 --> 00:25:55.950
16,000 light years away it's one of the


00:25:55.960 --> 00:25:58.269
largest and brightest of the hundreds of


00:25:58.279 --> 00:26:00.389
po clusters known to orbit around the


00:26:00.399 --> 00:26:03.750
Milky Way galaxy curus was included


00:26:03.760 --> 00:26:06.149
among the 48 constellations listed by


00:26:06.159 --> 00:26:08.870
the second century astronomer té and it


00:26:08.880 --> 00:26:11.990
remains one of the 88 modern day


00:26:12.000 --> 00:26:14.149
constellations the constellation Aryan


00:26:14.159 --> 00:26:15.990
the hunter is still clearly visible in


00:26:16.000 --> 00:26:18.389
the Northwestern sky this time of year


00:26:18.399 --> 00:26:20.430
with its rectangle of four stars


00:26:20.440 --> 00:26:22.789
surrounded by a central Trio of stars


00:26:22.799 --> 00:26:25.990
which form aion's build to the right or


00:26:26.000 --> 00:26:28.950
east of Aion is the constellation Gemini


00:26:28.960 --> 00:26:32.549
and its two brighter Stars Pax and cter


00:26:32.559 --> 00:26:34.710
this time of year the Gemini twins are


00:26:34.720 --> 00:26:36.750
almost directly due north for southern


00:26:36.760 --> 00:26:39.310
hemisphere Sky Watchers the higher of


00:26:39.320 --> 00:26:42.269
the two stars paax is a red giant some


00:26:42.279 --> 00:26:44.470
11 times the diameter of the Sun and


00:26:44.480 --> 00:26:47.269
located just 34 light years away the


00:26:47.279 --> 00:26:49.950
other star Caster is much further away


00:26:49.960 --> 00:26:53.630
some 51 light years look to the East and


00:26:53.640 --> 00:26:55.549
you'll see the star regulars the


00:26:55.559 --> 00:26:57.269
brightest star in the constellation of


00:26:57.279 --> 00:26:58.789
Leo the Lion


00:26:58.799 --> 00:27:00.630
regulus which means little King is


00:27:00.640 --> 00:27:03.070
located 77 light years away and it's


00:27:03.080 --> 00:27:05.149
about 3 and 1/2 times as massive as the


00:27:05.159 --> 00:27:08.430
sun and about 140 times as luminous


00:27:08.440 --> 00:27:11.110
regulus is a binary companion star which


00:27:11.120 --> 00:27:14.310
takes 130,000 years to orbit the


00:27:14.320 --> 00:27:16.990
primary to the right of regulus and


00:27:17.000 --> 00:27:19.549
virtually due east in the sky right now


00:27:19.559 --> 00:27:22.669
is the star Spiker located directly


00:27:22.679 --> 00:27:24.110
below the four stars in the


00:27:24.120 --> 00:27:26.630
constellation corvis the crow Spiker is


00:27:26.640 --> 00:27:28.590
the brightest star in the constellation


00:27:28.600 --> 00:27:31.470
Virgo also known as Alpha virgines it's


00:27:31.480 --> 00:27:34.310
the 16th brightest star in the night sky


00:27:34.320 --> 00:27:36.950
and is another spectroscopic binary


00:27:36.960 --> 00:27:39.350
comprising two stars closely orbiting


00:27:39.360 --> 00:27:42.149
each other every four Earth days in fact


00:27:42.159 --> 00:27:44.269
the two stars in Spiker are orbiting so


00:27:44.279 --> 00:27:46.149
close together that the gravitational


00:27:46.159 --> 00:27:48.110
interaction between them has caused them


00:27:48.120 --> 00:27:50.430
to become rotating epsol loidal


00:27:50.440 --> 00:27:52.669
variables distorting them into the shape


00:27:52.679 --> 00:27:55.509
of a rugby league or GD iron football


00:27:55.519 --> 00:27:57.430
light from the Spiner changes in


00:27:57.440 --> 00:27:59.470
brightness as the two stars orbit each


00:27:59.480 --> 00:28:01.310
other exposing their elongated


00:28:01.320 --> 00:28:04.509
hemispheres to us Spiker is located some


00:28:04.519 --> 00:28:07.710
260 light years away it is some 2,000


00:28:07.720 --> 00:28:10.630
times as luminous as the sun Spiker


00:28:10.640 --> 00:28:12.990
means ear of wheat which Virgo is


00:28:13.000 --> 00:28:15.830
holding in her hand it's so named


00:28:15.840 --> 00:28:17.269
because it marks the start of the


00:28:17.279 --> 00:28:19.269
harvest season in the northern


00:28:19.279 --> 00:28:22.269
hemisphere the primary is a blue giant


00:28:22.279 --> 00:28:25.070
variable beted which undergoes small


00:28:25.080 --> 00:28:27.190
rapid variations in brightness because


00:28:27.200 --> 00:28:29.470
of pulsations in the star surface


00:28:29.480 --> 00:28:30.990
thought to be caused by the unusual


00:28:31.000 --> 00:28:32.909
properties of iron at temperatures of


00:28:32.919 --> 00:28:36.190
200,000 de in the Stellar interior it is


00:28:36.200 --> 00:28:38.389
about 10 times the Sun's mass and about


00:28:38.399 --> 00:28:41.509
7 and 1/2 times its diameter once a


00:28:41.519 --> 00:28:43.870
spectr type B blue white main sequence


00:28:43.880 --> 00:28:46.870
star it's now pulsating rapidly rotating


00:28:46.880 --> 00:28:50.909
at more than 199 km/s over


00:28:50.919 --> 00:28:54.149
01738 Earth day period it's one of the


00:28:54.159 --> 00:28:56.110
nearest stars to the Earth which is


00:28:56.120 --> 00:28:58.630
expected to end its life as a type 2


00:28:58.640 --> 00:29:01.470
core collapse Supernova the second star


00:29:01.480 --> 00:29:03.549
in the system is also thought to be a


00:29:03.559 --> 00:29:06.149
spectal Type e blue white giant about


00:29:06.159 --> 00:29:08.909
seven solar masses and 3.6 times the


00:29:08.919 --> 00:29:10.070
Sun's


00:29:10.080 --> 00:29:12.470
diameter okay going back to the Southern


00:29:12.480 --> 00:29:14.789
Cross and looking to the right or west


00:29:14.799 --> 00:29:17.070
you'll see the star kopus it's the


00:29:17.080 --> 00:29:18.909
second brightest star in the night sky


00:29:18.919 --> 00:29:22.389
after Sirius even though kopus is 32


00:29:22.399 --> 00:29:24.430
light years away it looks incredibly


00:29:24.440 --> 00:29:27.110
bright because it's huge 100 times the


00:29:27.120 --> 00:29:30.430
diameter of the Sun and 10,000 times as


00:29:30.440 --> 00:29:32.950
luminous this year's second major meteor


00:29:32.960 --> 00:29:35.190
shower the lids will Peak on April the


00:29:35.200 --> 00:29:38.669
22nd and 23rd the liid appear to radiate


00:29:38.679 --> 00:29:41.149
out from the constellation Lyra close to


00:29:41.159 --> 00:29:43.269
the star Vega one of the brightest stars


00:29:43.279 --> 00:29:45.630
in the sky this time of year the source


00:29:45.640 --> 00:29:47.750
of the meteor shower are particles of


00:29:47.760 --> 00:29:50.310
dust and debris shed by the long period


00:29:50.320 --> 00:29:54.750
Comet C1 1861 G1 Thatcher Sky Watchers


00:29:54.760 --> 00:29:56.470
in the northern hemisphere get the best


00:29:56.480 --> 00:29:59.190
view of the lieds however listeners at


00:29:59.200 --> 00:30:01.029
mids southern hemisphere latitudes can


00:30:01.039 --> 00:30:03.190
also see the shower between midnight and


00:30:03.200 --> 00:30:06.110
Dawn patient observers will be rewarded


00:30:06.120 --> 00:30:08.430
with around 18 meteors per hour before


00:30:08.440 --> 00:30:10.909
Dawn from dark sky


00:30:10.919 --> 00:30:12.789
locations and now with a look at what


00:30:12.799 --> 00:30:14.190
else is happening in the April night


00:30:14.200 --> 00:30:16.029
skies we're joined by science writer


00:30:16.039 --> 00:30:18.029
Jonathan alley good day Stuart well


00:30:18.039 --> 00:30:20.070
we're now under Autumn here where I live


00:30:20.080 --> 00:30:21.190
which will be spring in the northern


00:30:21.200 --> 00:30:22.430
half of the Planet of the course and for


00:30:22.440 --> 00:30:24.149
me the Sun is setting earlier and the


00:30:24.159 --> 00:30:25.669
night's becoming longer which means it's


00:30:25.679 --> 00:30:27.470
perfect conditions for starga so we'll


00:30:27.480 --> 00:30:29.350
start with a old Southern Cross which we


00:30:29.360 --> 00:30:31.630
can find in the Southeast about a third


00:30:31.640 --> 00:30:33.909
to halfway up from the Horizon sort of


00:30:33.919 --> 00:30:35.830
after Sunset an hour or two after Sunset


00:30:35.840 --> 00:30:37.590
it's lying on its left hand side at the


00:30:37.600 --> 00:30:40.029
moment so it looks like a kite that's on


00:30:40.039 --> 00:30:42.149
its left hand side but as the night goes


00:30:42.159 --> 00:30:43.630
on and the Earth turns a bit more on its


00:30:43.640 --> 00:30:45.029
axis you'll see that it becomes more


00:30:45.039 --> 00:30:46.470
upright we'll just talk about the cross


00:30:46.480 --> 00:30:48.430
for a sec the Southern Cross appears to


00:30:48.440 --> 00:30:50.269
have four main stars and they make up


00:30:50.279 --> 00:30:52.389
the shape of this kite two of those


00:30:52.399 --> 00:30:55.149
stars are Solo stars but the third of


00:30:55.159 --> 00:30:56.950
them is made up of either two or three


00:30:56.960 --> 00:30:58.669
stars it's either abinding star system


00:30:58.679 --> 00:31:00.509
or a trinary star system they're so


00:31:00.519 --> 00:31:02.629
close together that to the uned eye they


00:31:02.639 --> 00:31:04.149
just look like one star of course but


00:31:04.159 --> 00:31:05.750
the fourth star it's the brightest of


00:31:05.760 --> 00:31:08.110
the four stars is actually a six star


00:31:08.120 --> 00:31:10.190
system and six stars all sort of


00:31:10.200 --> 00:31:11.870
circling each other in this star which


00:31:11.880 --> 00:31:13.710
is called acux it's really amazing that


00:31:13.720 --> 00:31:15.909
how many stars out there are part of


00:31:15.919 --> 00:31:19.029
binary or trinary or prary systems it's


00:31:19.039 --> 00:31:21.070
the norm really to be in a binary star


00:31:21.080 --> 00:31:22.350
system or Triple Star system or


00:31:22.360 --> 00:31:24.629
something so our sun is a bit of an


00:31:24.639 --> 00:31:27.070
odity being on its own but you don't see


00:31:27.080 --> 00:31:28.190
this you don't think about this when you


00:31:28.200 --> 00:31:29.629
look up and look at some of the stars in


00:31:29.639 --> 00:31:31.230
the night sky don't no that one's part


00:31:31.240 --> 00:31:32.789
of a six-star system or that one's part


00:31:32.799 --> 00:31:34.470
of a four star system but a lot of them


00:31:34.480 --> 00:31:36.430
are now right next to the Southern Cross


00:31:36.440 --> 00:31:38.389
there's a dark patch that's known as the


00:31:38.399 --> 00:31:40.710
coal sack this was once thought to be a


00:31:40.720 --> 00:31:43.149
gap or a hole in the Milky Way long time


00:31:43.159 --> 00:31:45.549
ago but really it's just a huge region


00:31:45.559 --> 00:31:47.870
of gas and dust that's very thick and it


00:31:47.880 --> 00:31:49.950
blocks our view of the stars behind it


00:31:49.960 --> 00:31:51.990
so we can't see the background stars now


00:31:52.000 --> 00:31:53.789
in order to see the co sack you do need


00:31:53.799 --> 00:31:57.110
to have some clear Dark Skies citt skies


00:31:57.120 --> 00:31:58.789
probably don't cut it because all the


00:31:58.799 --> 00:32:00.310
light pollution just drowned stuff out


00:32:00.320 --> 00:32:01.990
anyway so the thing is that the Southern


00:32:02.000 --> 00:32:03.430
Cross for instance that there is a fifth


00:32:03.440 --> 00:32:05.389
star in a Southern Cross but a lot of


00:32:05.399 --> 00:32:07.310
people in cities can't see it this light


00:32:07.320 --> 00:32:09.509
pollution is now so bad that in fact I


00:32:09.519 --> 00:32:10.870
think from where I am I can't even see


00:32:10.880 --> 00:32:13.870
the fifth far sad isn't it it is really


00:32:13.880 --> 00:32:15.149
sad you know it's one of the funny


00:32:15.159 --> 00:32:16.710
things is that here in Australia there's


00:32:16.720 --> 00:32:18.590
a uh piece of from one of the government


00:32:18.600 --> 00:32:20.230
departments they have a a software


00:32:20.240 --> 00:32:22.629
service that's used for um navigation


00:32:22.639 --> 00:32:24.750
systems and surveying systems and it's


00:32:24.760 --> 00:32:26.830
named after this fit star and the the


00:32:26.840 --> 00:32:28.789
irony of course is that used to be used


00:32:28.799 --> 00:32:30.629
for finding your position and navigating


00:32:30.639 --> 00:32:32.430
but most people now can't see it because


00:32:32.440 --> 00:32:34.029
they live in cities that are so light


00:32:34.039 --> 00:32:36.230
polluted that the star is invisible


00:32:36.240 --> 00:32:37.750
that's the way it goes I'm afraid and


00:32:37.760 --> 00:32:38.990
speaking of brightnesses and not being


00:32:39.000 --> 00:32:40.710
able to see things know you might think


00:32:40.720 --> 00:32:42.230
that stars when you look up you see


00:32:42.240 --> 00:32:43.870
stars and they all look much the same


00:32:43.880 --> 00:32:45.310
brightness and you think that because


00:32:45.320 --> 00:32:46.470
they're of similar brightness they'll


00:32:46.480 --> 00:32:47.870
all be roughly the same distance from


00:32:47.880 --> 00:32:49.389
the Earth but that's not the case we've


00:32:49.399 --> 00:32:51.310
got some stars that are intrinsically


00:32:51.320 --> 00:32:53.430
very bright but they might be very far


00:32:53.440 --> 00:32:55.590
away and that that therefore they seem


00:32:55.600 --> 00:32:57.509
dim but then you have other stars that


00:32:57.519 --> 00:32:59.909
are dim but they're very close so they


00:32:59.919 --> 00:33:01.870
seem brighter than the bright ones are


00:33:01.880 --> 00:33:03.629
so the four stars of Southern Cross for


00:33:03.639 --> 00:33:05.269
instance they range in distance from us


00:33:05.279 --> 00:33:07.830
from about 90 light years to about 340


00:33:07.840 --> 00:33:10.710
light years so you can't really tell the


00:33:10.720 --> 00:33:12.830
distance of a star from the earth just


00:33:12.840 --> 00:33:14.470
based on its brightness you got to think


00:33:14.480 --> 00:33:16.149
a bit deeper than that so brightness


00:33:16.159 --> 00:33:18.070
does not equate with distance now


00:33:18.080 --> 00:33:19.950
speaking of a bright star up really high


00:33:19.960 --> 00:33:21.029
in the south at the moment there's a


00:33:21.039 --> 00:33:23.149
bright star called kopus This is the


00:33:23.159 --> 00:33:24.950
brightest light in the constellation of


00:33:24.960 --> 00:33:26.389
Karina and it's actually the second


00:33:26.399 --> 00:33:28.110
brightest star in the night sky and it's


00:33:28.120 --> 00:33:29.830
no wonder talking about brightness


00:33:29.840 --> 00:33:31.430
because even though it's more than 300


00:33:31.440 --> 00:33:33.629
light years away intrinsically it's more


00:33:33.639 --> 00:33:37.789
than 10,000 times brighter than our sun


00:33:37.799 --> 00:33:40.710
and it's 70 times as big now that's


00:33:40.720 --> 00:33:43.230
that's really big imagine that 10,000


00:33:43.240 --> 00:33:45.190
times brighter that's why it's the


00:33:45.200 --> 00:33:46.750
second brightest star in the night sky


00:33:46.760 --> 00:33:48.509
even though it's 300 light years away


00:33:48.519 --> 00:33:50.990
the night Sky's brightest star Sirius is


00:33:51.000 --> 00:33:53.029
also very easily visible at the moment


00:33:53.039 --> 00:33:54.669
it's practically overhead in the early


00:33:54.679 --> 00:33:56.070
evening if you live at the latitude of


00:33:56.080 --> 00:33:57.830
Sydney in the southern hemisphere


00:33:57.840 --> 00:34:00.470
comparing Sirius to canopus that canopus


00:34:00.480 --> 00:34:02.750
being that really big one Sirius is only


00:34:02.760 --> 00:34:05.070
25 times brighter than the sun but it's


00:34:05.080 --> 00:34:06.789
only 8 and a half light years away


00:34:06.799 --> 00:34:09.550
compared to 300 so that's why it seems a


00:34:09.560 --> 00:34:11.869
bit brighter to our eyes now not far


00:34:11.879 --> 00:34:13.230
from Sirus you've got the constellation


00:34:13.240 --> 00:34:15.710
of Ry with its two bright stars rul and


00:34:15.720 --> 00:34:17.550
Beetle Juice and there are three stars


00:34:17.560 --> 00:34:19.589
in a row known as Orion's Belt now if


00:34:19.599 --> 00:34:21.829
you thought canopus is impressive being


00:34:21.839 --> 00:34:23.950
10,000 times brighter than the sun well


00:34:23.960 --> 00:34:26.430
Riel beats that easily scus not quite


00:34:26.440 --> 00:34:27.790
sure the number for some technical


00:34:27.800 --> 00:34:29.149
reasons is a that of a range of


00:34:29.159 --> 00:34:31.190
estimates of how bright it intrinsically


00:34:31.200 --> 00:34:33.950
is and that ranges from 60,000 times


00:34:33.960 --> 00:34:37.310
brighter than our sun to 360,000 times


00:34:37.320 --> 00:34:39.270
brighter than our sun I mean that's just


00:34:39.280 --> 00:34:41.069
berserk and the other star I mentioned


00:34:41.079 --> 00:34:42.750
Beetle Juice it's no slouch either it's


00:34:42.760 --> 00:34:44.909
about 60,000 times brighter than the sun


00:34:44.919 --> 00:34:46.790
but with Beetle Juice it's the size that


00:34:46.800 --> 00:34:48.710
really impresses it's somewhere between


00:34:48.720 --> 00:34:51.389
about 640 and


00:34:51.399 --> 00:34:54.829
76 times as big as our star which is


00:34:54.839 --> 00:34:56.629
just crazy it's hard to imagine isn't it


00:34:56.639 --> 00:34:59.109
if you put it center of our solar system


00:34:59.119 --> 00:35:01.349
its outer limb would be roughly where


00:35:01.359 --> 00:35:03.910
Jupiter is yeah basically yeah it would


00:35:03.920 --> 00:35:05.950
gobble up Mercury Venus Earth Mars the


00:35:05.960 --> 00:35:07.589
asteroid Bel pretty much all the way out


00:35:07.599 --> 00:35:09.589
to Jupiter that's how big it would be


00:35:09.599 --> 00:35:11.430
it's just unimaginable there are some


00:35:11.440 --> 00:35:13.430
big big stars out there now let's look


00:35:13.440 --> 00:35:15.430
at the planets if we take a look to the


00:35:15.440 --> 00:35:16.710
north at least from here in the southern


00:35:16.720 --> 00:35:18.230
hemisphere about a third of the way up


00:35:18.240 --> 00:35:20.150
from the Horizon you'll find what


00:35:20.160 --> 00:35:22.230
appears to be three stars in a row the


00:35:22.240 --> 00:35:24.910
two whitish ones are actually Stars they


00:35:24.920 --> 00:35:27.150
the Stars Castor and Pollock but the


00:35:27.160 --> 00:35:30.150
orangey looking one is the planet Mars


00:35:30.160 --> 00:35:32.069
okay now you hear this thing quite often


00:35:32.079 --> 00:35:33.710
that when you look up with the night sky


00:35:33.720 --> 00:35:36.030
night sky stars twinkle and planets


00:35:36.040 --> 00:35:37.990
don't and the explanation usually given


00:35:38.000 --> 00:35:40.190
for that is that stars are so far away


00:35:40.200 --> 00:35:42.230
that they are effectively Point sources


00:35:42.240 --> 00:35:43.910
like tiny pinpoint of light and that


00:35:43.920 --> 00:35:45.109
when the light comes through the Earth's


00:35:45.119 --> 00:35:47.670
atmosphere it gets interfered with by


00:35:47.680 --> 00:35:49.069
air currents and things so that makes


00:35:49.079 --> 00:35:51.030
that's what makes stars twinkle whereas


00:35:51.040 --> 00:35:53.270
planets even though you can't make out


00:35:53.280 --> 00:35:55.710
their size with the uned eye they do


00:35:55.720 --> 00:35:57.790
have a bit of a size and therefore that


00:35:57.800 --> 00:35:59.510
doesn't get interfere with quite so much


00:35:59.520 --> 00:36:01.069
so that's that's the explanation usually


00:36:01.079 --> 00:36:03.510
given but when stars and even planets


00:36:03.520 --> 00:36:05.670
are low down towards the horizon even a


00:36:05.680 --> 00:36:07.030
planet will twinkle I remember getting a


00:36:07.040 --> 00:36:09.309
phone call one what night from mamine


00:36:09.319 --> 00:36:11.349
and he said every night out there he Liv


00:36:11.359 --> 00:36:12.910
in the water every night out over the


00:36:12.920 --> 00:36:15.030
water there's this red star but it


00:36:15.040 --> 00:36:17.390
changes color and it goes red and green


00:36:17.400 --> 00:36:19.390
and white and and it's there every night


00:36:19.400 --> 00:36:21.270
and is it the Air Force doing something


00:36:21.280 --> 00:36:22.950
what could it be and I looked it up and


00:36:22.960 --> 00:36:24.510
it was just miles but because it was


00:36:24.520 --> 00:36:26.630
down low on the horizon the the light


00:36:26.640 --> 00:36:28.390
coming through our


00:36:28.400 --> 00:36:30.630
the the Earth's atmospheric currents


00:36:30.640 --> 00:36:32.510
were distorting the light basically and


00:36:32.520 --> 00:36:35.550
making it flicker so even planets can


00:36:35.560 --> 00:36:37.910
twinkle if you like is that why the Moon


00:36:37.920 --> 00:36:40.150
looks bigger on the horizon than it does


00:36:40.160 --> 00:36:41.990
when it's high up in the sky oh this is


00:36:42.000 --> 00:36:43.750
the Moon Illusion and I don't know


00:36:43.760 --> 00:36:45.270
anyone's ever really got to the bottom


00:36:45.280 --> 00:36:47.150
of this there are all sorts of ideas


00:36:47.160 --> 00:36:49.829
about why the moon appears to be bigger


00:36:49.839 --> 00:36:52.030
because it's you know you can compare it


00:36:52.040 --> 00:36:54.510
against houses or trees or the horizon


00:36:54.520 --> 00:36:56.670
or whatever so it seems to have a


00:36:56.680 --> 00:36:58.390
discernable you know not a discernable


00:36:58.400 --> 00:36:59.550
size but you know something you can


00:36:59.560 --> 00:37:01.430
compare it against whereas when it's up


00:37:01.440 --> 00:37:03.190
there high in the night sky it's just an


00:37:03.200 --> 00:37:05.349
empty empty sky so you can't really get


00:37:05.359 --> 00:37:07.230
a good good comparison against anything


00:37:07.240 --> 00:37:08.550
else I mean the moon's only half a


00:37:08.560 --> 00:37:10.950
degree across I mean from Horizon to


00:37:10.960 --> 00:37:13.190
Horizon you drew a line from The Horizon


00:37:13.200 --> 00:37:14.750
up overhead down to the other Horizon


00:37:14.760 --> 00:37:17.069
that of course is 180° so you could


00:37:17.079 --> 00:37:19.550
stack 360 moons all the way from one


00:37:19.560 --> 00:37:20.710
horizon to the other it's actually


00:37:20.720 --> 00:37:22.550
really small as for the Moon Illusion


00:37:22.560 --> 00:37:24.270
the so-call Moon Illusion why the moon


00:37:24.280 --> 00:37:26.430
appears bigger on the horizon I don't I


00:37:26.440 --> 00:37:27.670
really don't know the answer there all


00:37:27.680 --> 00:37:28.950
sorts of things with those but might


00:37:28.960 --> 00:37:30.510
have more to do with our brains and the


00:37:30.520 --> 00:37:34.069
way our brains perceive things than the


00:37:34.079 --> 00:37:36.230
a lot of that yeah yeah I mean you can


00:37:36.240 --> 00:37:37.630
do a test if the moon's down near the


00:37:37.640 --> 00:37:39.190
Horizon have a look and see how big it


00:37:39.200 --> 00:37:41.470
is and then get a cardboard tube and


00:37:41.480 --> 00:37:42.670
look at the Moon through the cardboard


00:37:42.680 --> 00:37:44.510
tube so you can't see anything else


00:37:44.520 --> 00:37:46.109
around it no houses and trees and things


00:37:46.119 --> 00:37:47.950
and see whether it seems quite as big


00:37:47.960 --> 00:37:49.710
I've actually measured it on the horizon


00:37:49.720 --> 00:37:51.030
compared to when it's high in the sky


00:37:51.040 --> 00:37:53.230
and it it's exactly the same size but it


00:37:53.240 --> 00:37:54.829
just doesn't look it it's weird that's


00:37:54.839 --> 00:37:55.829
right yeah there's something in our


00:37:55.839 --> 00:37:58.230
brains that that does it so anyway yeah


00:37:58.240 --> 00:37:59.630
that's the moon now over to the


00:37:59.640 --> 00:38:01.750
Northwest again looking this is from


00:38:01.760 --> 00:38:03.150
looking from the southern hemisphere so


00:38:03.160 --> 00:38:04.910
the Southwest if you're in the northern


00:38:04.920 --> 00:38:07.190
hemisphere there appears to be a bright


00:38:07.200 --> 00:38:09.670
white star but it is in fact the planet


00:38:09.680 --> 00:38:11.670
Jupiter now if you have even just a pair


00:38:11.680 --> 00:38:13.550
of binoculars take a look at Jupiter you


00:38:13.560 --> 00:38:15.230
won't be able to make out anything on


00:38:15.240 --> 00:38:16.630
the planet itself it'll just look like a


00:38:16.640 --> 00:38:18.470
bright star but you should be able to


00:38:18.480 --> 00:38:21.309
see up to four tiny pin Pricks of light


00:38:21.319 --> 00:38:23.510
either to its left or right or both it


00:38:23.520 --> 00:38:24.990
might be you know three on one side and


00:38:25.000 --> 00:38:26.750
one on the other or two on one side and


00:38:26.760 --> 00:38:28.750
two on the other whatever now these are


00:38:28.760 --> 00:38:31.109
the four moons discovered by Galileo and


00:38:31.119 --> 00:38:32.470
by looking through a pair of binoculars


00:38:32.480 --> 00:38:34.430
you've got about the same Optical power


00:38:34.440 --> 00:38:37.030
as Galileo had with his first little


00:38:37.040 --> 00:38:38.630
telescope in fact your binoculars would


00:38:38.640 --> 00:38:41.150
be far better quality W than Galileo's


00:38:41.160 --> 00:38:42.589
telescope was but youd have about the


00:38:42.599 --> 00:38:44.470
same magnifying power so yeah have a


00:38:44.480 --> 00:38:45.670
look at Jupiter even through a pair of


00:38:45.680 --> 00:38:47.270
binoculars and you'll see these tiny pin


00:38:47.280 --> 00:38:48.790
picks of light they're very noticeable


00:38:48.800 --> 00:38:50.510
they're very very noticeable you go out


00:38:50.520 --> 00:38:52.349
and do it every night night after night


00:38:52.359 --> 00:38:54.069
for a while you'll see that these little


00:38:54.079 --> 00:38:56.349
p light will have moved because they're


00:38:56.359 --> 00:38:58.190
orbiting around Jupiter and a lot of


00:38:58.200 --> 00:38:59.430
astronomers like to do this of course


00:38:59.440 --> 00:39:00.990
with their telescopes and and what you


00:39:01.000 --> 00:39:03.230
can see is for instance sometimes when


00:39:03.240 --> 00:39:05.390
one of these moons goes around behind


00:39:05.400 --> 00:39:06.870
Jupiter and goes into its shadow it just


00:39:06.880 --> 00:39:09.030
Winks out it just disappears because


00:39:09.040 --> 00:39:11.309
it's CL into the the shadow behind


00:39:11.319 --> 00:39:13.990
Jupiter and just vanishes and then it'll


00:39:14.000 --> 00:39:15.790
reappear sometime later on the other


00:39:15.800 --> 00:39:16.829
side when it comes back into the


00:39:16.839 --> 00:39:18.510
sunlight again so that's fun to watch


00:39:18.520 --> 00:39:20.109
but it does take a little while so you


00:39:20.119 --> 00:39:22.390
need to allow some time now to see the


00:39:22.400 --> 00:39:23.990
other bright planets the other three


00:39:24.000 --> 00:39:25.270
bright planets you'll need to be up


00:39:25.280 --> 00:39:27.430
before Dawn this month and looking to


00:39:27.440 --> 00:39:29.750
East Saturn is the first of them to rise


00:39:29.760 --> 00:39:32.790
at about 5:30 a.m. daylight sing time at


00:39:32.800 --> 00:39:34.790
least here in Australia followed around


00:39:34.800 --> 00:39:36.870
about 20 minutes later by both Mercury


00:39:36.880 --> 00:39:39.230
and Venus now Saturn's fairly bright and


00:39:39.240 --> 00:39:41.069
it has a slightly yellowish teen so it


00:39:41.079 --> 00:39:42.790
should be pretty easy to identify


00:39:42.800 --> 00:39:45.309
Mercury is quite small and dim Venus on


00:39:45.319 --> 00:39:48.270
the other hand is big and bright now if


00:39:48.280 --> 00:39:50.270
you're up early enough to spot these


00:39:50.280 --> 00:39:52.230
you'll see that they're going to be in


00:39:52.240 --> 00:39:54.510
the beginning of the Dawn glow as the


00:39:54.520 --> 00:39:56.430
Sunrise approaches and the sky is


00:39:56.440 --> 00:39:58.030
starting to lighten and as it gets


00:39:58.040 --> 00:39:59.510
lighter and lighter Mercury and Saturn


00:39:59.520 --> 00:40:01.309
will quickly fade into that Dawn glow


00:40:01.319 --> 00:40:02.990
but Venus will linger a bit longer


00:40:03.000 --> 00:40:04.550
because it is really quite bright and


00:40:04.560 --> 00:40:06.069
then the sun will come up of course and


00:40:06.079 --> 00:40:07.710
they all drowned out although you can


00:40:07.720 --> 00:40:09.349
actually see Venus during the daytime


00:40:09.359 --> 00:40:10.710
I've seeing Venus during the daytime


00:40:10.720 --> 00:40:12.470
when it's up high in the sky and in a


00:40:12.480 --> 00:40:15.550
crystal clear bright blue sky Venus is


00:40:15.560 --> 00:40:17.030
actually bright enough to be seen with


00:40:17.040 --> 00:40:18.550
the uned eye but you've got to know


00:40:18.560 --> 00:40:20.230
exactly where to look so if you've got a


00:40:20.240 --> 00:40:22.109
way to pinpoint exactly where it is you


00:40:22.119 --> 00:40:23.870
look up and you think oh goodness yes


00:40:23.880 --> 00:40:25.630
there is a tiny thing that looks like a


00:40:25.640 --> 00:40:27.349
star up there when you look directly at


00:40:27.359 --> 00:40:29.030
at it you know it's there you can see it


00:40:29.040 --> 00:40:32.030
you think wow that is Venus but because


00:40:32.040 --> 00:40:35.270
it's usually closest to the Sun people


00:40:35.280 --> 00:40:37.109
of course don't bother looking up don't


00:40:37.119 --> 00:40:38.630
go looking up with a pair of binoculars


00:40:38.640 --> 00:40:40.309
or telescope during daytime if the sun's


00:40:40.319 --> 00:40:41.750
anywhere near please don't do that


00:40:41.760 --> 00:40:43.309
because just one wrong move and you


00:40:43.319 --> 00:40:44.950
might blind yourself so on that happy


00:40:44.960 --> 00:40:47.750
note St that's the um sky for a that's


00:40:47.760 --> 00:40:50.349
science writer Jonathan alley and this


00:40:50.359 --> 00:41:06.990
is spacetime


00:41:07.000 --> 00:41:09.870
and that's the show for now SpaceTime is


00:41:09.880 --> 00:41:11.750
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