Aug. 27, 2026

Microbial Hitchhikers: Contamination Risks on the Moon and Mars

Microbial Hitchhikers: Contamination Risks on the Moon and Mars
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Season 29
SpaceTime Series 29 Episode 103 *Warnings that some Earth microbes could contaminate the Moon NASA says some of Earth's microbes hitching a ride to space with human explorers could survive in the shaded nooks and crannies of the Moon's South Pole contaminating the otherwise pristine environment. *China’s first reusable rocket China has finally landed a reusable rocket in one piece. *Russia develops a nuclear rocket motor Russia has developed a prototype nuclear plasma engine which could cut journey times to Mars from 6 months to just 30 days. *September Skywatch The September equinox, and the constellations Capricorn, Pegasus, and Cygnus are among the highlights of the September night skies on SkyWatch. Our regular guests: Alex Zaharov-Reutt from techadvice.life Tim Mendham from Australian Skeptics And Senior science writer and Sky and Telescope magazine contributor Jonathan Nally

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The Astronomy, Space, Technology & Science News Podcast.

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This is Space Time, Series 29, Episode 103, for broadcast

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on the 28th of August, 2026. Coming up on Space Time.

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Warnings that some Earth microbes could contaminate the Moon, maybe

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even Mars. Finally, success for China and its first reusable rocket.

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And Russia eyeing off the Red Planet as it develops

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its own nuclear rocket engine. All that and more coming

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up on Space Time.

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Welcome to Space Time with Stuart Gary.

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NASA says some of Earth's microbes hitching a ride into

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space with human explorers could survive in shaded nooks and

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crannies at the moon's south pole, contaminating the otherwise pristine environment.

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The findings, reported in the journal Science Advances, highlight the

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need to better understand microbial persistence in extreme lunar environments.

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Scientists are warning that as humans build a permanent presence

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on the moon through the Artemis program, and similar projects

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by other nations such as China and Russia, it may

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become difficult to distinguish ancient lunar chemistry from the contamination

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delivered by visiting astronauts. And that concern extends well beyond

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the moon to the red planet Mars. The study's lead author,

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Prebill Saxner, from NASA's Goddard Space Flight Center in Greenbelt, Maryland,

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says humans are natural explorers, and with them come their voices,

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their memories, and also their microbes. And for some scientists,

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that is unsettling. You see, people bringing microbes with them

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when they travel into space is unavoidable. The average human has,

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on average, a million bacteria living on each patch of

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skin the size of a pencil eraser. So these bacteria

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vent from spacesuits and habitats. Though the authors are worried

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about contamination interfering with the search for chemical clues to

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ancient geology and biology, they also argue that the moon

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should be used as a natural laboratory.

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In shaded areas.

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Around the South Pole, scientists could carefully test the real-life

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limitations of microbial survival in an environment that can't be

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easily reproduced in the lab here on Earth. But before

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any surface science can happen, scientists need a baseline measurement

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of what contaminants humans bring. They'll need to understand what

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was there beforehand, because when they go to Mars to

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search for signs of life beyond Earth, they want to

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make sure it doesn't turn out being stuff they brought

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with them. And even with the strictest sterilization procedures, some

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organisms are stubbornly resilient. One good example is Aspergillus niger,

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a fungus that thrives in warm, damp places, like household

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bathrooms and heating, ventilation and air conditioning systems. Astronauts have

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sampled this bug inside the International Space Station, and experiments

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demonstrate the fungus can even survive outside the station as well.

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Aspergillus negeri is one of five microbes, including bacteria and fungi,

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selected for this study because they're known for their toughness

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in spaceflight environments. The very fact these microbes have survived

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in a vacuum of space was surprising. That's because these

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species are not considered to be extremophiles, which can survive

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in the harsh conditions in the vacuum of space. NASA

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geomicrobiologist Adam Regberg from the Johnson Space Center in Houston, Texas,

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says he would have expected the microbes to have dried out.

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He says NASA often bakes robotic spacecraft at temperatures above

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200 degrees Celsius in order to reduce the number of

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living organisms on the items. But of course, that's not

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possible with astronauts. So contamination concerns take on a new

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meaning in manned missions to explore the moon's south pole environment.

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A clearer picture of where microbes might survive comes from

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understanding how sunlight behaves at the lunar poles. Now, survival

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for this study means the microbe can stay alive for

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at least one Earth day, which doesn't mean that it

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can grow and reproduce. Because the moon has a very

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small tilt on its axis, the view from its poles

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is of a sun that appears just above the horizon,

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skimming the surface like a flashlight lying on a table.

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As a result, elevated parts of the surface, including crater ridges, mountains,

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and even small bumps, block light from reaching the lower-lying terrain.

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And this produces pockets of shattered areas that can remain

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cold and preserve water, as well as shielding fragile molecules

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and possible microorganisms from lethal radiation. With that scientific context

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in mind, the authors set out to test which Earth

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microbes could survive extreme polar conditions. They focused on the

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sorts of organisms commonly found in spaceflight environments and those

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common on human skin. Besides Aspergillus negeri, these included Bacillus subtilis,

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Stephylococcus aureus, Deinococcus radioduranus, and several species of Fusarium. Based

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on previous studies, the authors noted the maximum amount of

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heat and ultraviolet radiation each organism can withstand. Then the

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organisms were tested in simulations of three regions near the

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lunar south pole, Nerval Rim, Connecting Ridge, and Djalaki Rim.

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These simulations used detailed environmental maps built up from elevation

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and temperature data collected by instruments aboard NASA's Lunar Reconnaissance Orbiter,

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combined with models of how radiation strikes the Earth's surface.

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The models showed maps of survivable niches that range in

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size from a kilometer-wide crater floor to an astronaut's boot print.

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Aspergillus negeri, which was most resistant to ultraviolet radiation, was

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able to survive even in areas with some sunlight exposure.

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Now usually ultraviolet radiation is so deadly to most microbes

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that it's used for sterilization in hospitals. When we think

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of the Moon, we don't typically think of biology. But

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it turns out the Moon is a place where a

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cell can survive, so a first exploration of these sites

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should pay extra attention to our microbial hitchhikers. and we

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need to work hard to characterize lunar chemistry before our

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visits change.

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What we find there. This is space time.

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Still to come, China finally succeeds in landing a reusable rocket,

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and Russia develops a nuclear-powered rocket engine. All that and

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more still to come on Space Time. China has finally

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landed a reusable rocket in one piece. The XUQ3Y2 is

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a Chinese copy of SpaceX's Falcon 9, adopting as much

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of the American reusable first-stage booster's designs as possible. The

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Chinese mission was launched from the Dongfeng Commercial Space Innovation

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Pilot Zone in northwestern China. The facility serves as a

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key technology test site and launch complex, used primarily by

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China's ever-expanding commercial aerospace industry.

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Following its launch, the.

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Zhukui 3Y2 first stage separation happened as planned 137 seconds

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into the flight, with the upper stage and payload then

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continuing to orbit and successfully deploying the Honghu 03 satellite. Meanwhile,

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the launch vehicle's first stage booster returned to Earth and

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successfully landed at the Landspace Landing Site No. 1 in

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Gansu Province six minutes after its launch. However, after touchdown,

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leftover liquid methane and oxygen propellant suddenly ignited, triggering a

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fire which weakened one of the carbon fiber landing legs,

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causing the stainless steel booster to topple over, crashing to

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the ground. A less than auspicious end for what had

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been a successful mission. This is space time. Still to come,

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Russia develops a nuclear rocket motor. and the September equinox.

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And the constellations Capricorn, Pegasus and Cygnus are among the

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highlights of the September night skies on Skywatch. Russia has

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developed a prototype nuclear plasma engine which could cut journey

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times to the red planet Mars from six months to

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just 30 days. And they hope to have a full-scale

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version of the system operational by 2030. Rather than using

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conventional chemical rocket engines, scientists at the Rosatom-affiliated Trzysk Institute

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near Moscow claim their experimental propulsion system ionizes hydrogen into

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a plasma that accelerates these charged particles using powerful magnets.

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They say their 300-kilowatt prototype successfully accelerated plasma to 100

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kilometers per second. Now, if successfully upscaled and integrated into

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a spacecraft, this continuous thrust mechanism could reduce one-way travel

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from the Earth to Mars to between 30 and 60 days.

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Such a dramatic speed-up would greatly cut astronauts' exposure to

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hazardous cosmic radiation and also reduce the amount of fuel

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and other supplies needed for the journey. With existing technologies,

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a manned mission to the red planet is likely to

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take two years, six months to get there, a year

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on the surface waiting for Mars to be in the

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right orbital position compared to the Earth for the return,

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and then six months to return to Earth. However, the

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Russian scientists behind the project admit there's still some major

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engineering challenges needed to be overcome before the system could

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be turned into a viable option for spaceflight. These include

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things like thermal control, long-term durability, and the generation of

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immense electrical power in deep space. The news comes as

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NASA is continuing to develop its own high-powered electric propulsion

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nuclear system, including a pulsed plasma rocket, which aims to

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cut travel times to Mars down to just a couple

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of months. Needless to say, we'll keep you informed. This

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is Space Time. And time now to turn our eyes

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to the skies and check out the night skies for

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September on Skywatch. September was the 7th month of the

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year in the old Roman calendar which had just 10 months.

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That's before the addition of January and February. That 10-month

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year is still reflected today in the name September or

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Septum being Latin for 7, October or Octo meaning 8,

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November or Novem 9, and December or Deci meaning 10.

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It really wasn't until the Gregorian calendar that January the

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1st marked the start of the new year, but in

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the beginning it was mostly only Catholic countries that adopted it.

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Protestant nations only gradually moved across, with the British, for example,

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not adopting the reformed calendar until 1752. Prior to that date,

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the British Empire and its American colonies still celebrated the

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new year on March the 25th, marking the Feast of

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the Annunciation and Easter. The earliest recordings of a New

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Year celebration are believed to have taken place in Mesopotamia

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around 2000 BCE, around the time of the northern hemisphere

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vernal equinox in mid-March. A variety of other dates tied

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to the seasons are also used by various ancient cultures.

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The Egyptians, Phoenicians and Persians began their new year off

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with the fall equinox, and the Greeks celebrated it on

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the winter solstice. While the Jewish new year, or Rosh Hashanah,

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the festival of trumpets, occurs in September, where it marks

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the beginning of the northern hemisphere's cycle of sowing, growth

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and harvest, and apparently the creation of Adam and Eve,

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according to the Jewish Bible, the Old Testament. The September

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equinox will take place at 10.05 in the morning of Wednesday,

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September 23rd, Australian Eastern Standard Time. That's 8.05 in the

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evening of Tuesday, the 22nd of September, US Eastern Daylight Time,

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and five minutes past midnight on the morning of Wednesday,

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September 23rd, Greenwich Mean Time. The day marks the point

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in Earth's orbit around the Sun when the planet's rotational

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axial tilt means the Sun will appear to rise exactly

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due east to someone standing on the equator. It means

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almost equal hours of darkness and light. In fact, the

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word equinox is derived from the Latin, meaning Aquinas or equal,

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and nox meaning night. It all comes about because Earth's

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rotational axis is tilted at an angle of around 23.4

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degrees in relation to the ecliptic, the plane created by

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Earth's orbit around the Sun. And Earth's axial tilt is

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pointed in the same direction in the sky, regardless of

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Earth's orbital position.

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Around the Sun.

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So on other days of the year, either the northern

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or southern hemisphere are tilted more towards the sun. But

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on the two equinoxes, around March the 21st and September 23rd,

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the tilt of Earth's axis is directly perpendicular to the

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sun's rays. For those in the northern hemisphere, it means

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the start of fall or autumn, while those of us

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south of the equator are moving into spring. It's also

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worth noting that the solstices and equinoxes change, and they're

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impacted by what's known as precession. That causes Earth's spin

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axis to wobble ever so slightly, sort of like the

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axle of a spinning top. Now, the rate of precession

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is only very slight, just half a degree per century,

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so you don't notice it on normal human timescales. But

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because the direction of Earth's axis of rotation determines at

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which point in Earth's orbit around the Sun the seasons occur,

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precession will cause a particular season, for example the southern

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hemisphere summer, to occur at a slightly different place on

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the calendar from year to year over a 26,000 year

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cycle relative to the planet's orbital position. At the same time,

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obliquity causes the angle of the axial tilt to change

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with respect to the ecliptic, that is Earth's orbital plane

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around the Sun. Earth's obliquity, that is the tilt of

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the axis, is currently 23.5 degrees. And it's what's actually

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responsible for the seasons, and that varies over a cycle

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of roughly 41,000 years, between approximately 22.1 and 24.5 degrees.

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This axial tilt or obliquity changes due to the gravitational

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pull of the Sun, the Moon, and other planets. A

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higher obliquity leads to more extreme seasons. while a lower

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tilt results in milder seasons and can contribute to glacial periods.

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Then there's eccentricity. This involves changes in the actual shape

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of Earth's orbit around the Sun, sometimes making it more

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circular and other times more elliptical. This gradually shifts the

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point of perihelion, which is Earth's closest orbital position to

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the Sun. Now, these three effects, precession, obliquity and eccentricity,

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are collectively known as Milakovich cycles, and they affect the

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amount of solar energy reaching the planet and have a

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major influence on climatic patterns. Okay, let's start our tour

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of the September night skies by looking towards the east

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and the constellation of Capricornus the goat. The name comes

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from the ancient Greek tale about the demon Typhon emerging

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from a fissure in the earth and attacking Zeus, the

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king of gods, during a banquet. The sudden appearance of

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Typhon scared Pan, the flute-playing goat boy, who tried to

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escape by turning into a fish and swimming away. However,

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he realized his cowardice before completing the transformation, and so

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distracted the demon by playing his flute instead. and this

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gave Zeus enough time to use the thunderbolt from the

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heavens to frighten Typhon away. Because of his actions, both

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cowardly and brave, Zeus placed Pan in the sky forevermore,

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still in his half-goat, half-fished eyes. The brightest star in

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Capricornus is Delta Capricorni, also known as Denebal Jetty, or

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the tail of the goat. It's a near neighbor, located

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just 39 light-years away. A light year is about 10

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trillion kilometers. The distance a photon can travel in a

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year at the speed of light, which is about 300,000

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kilometers per second in a vacuum, and the ultimate speed

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00:15:54.720 --> 00:15:58.899
limit across the universe. Denebile Jetty is a spectral type

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A white beta Lyra variable eclipsing binary. It's comprised of

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two stars closely orbiting each other. Now, astronomers describe stars

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00:16:09.070 --> 00:16:13.129
in terms of spectral types, a classification system based on

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temperature and characteristics. The hottest, most massive, and most luminous

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stars are known as spectral type O blue stars. They're

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00:16:21.750 --> 00:16:25.600
followed by spectral type B blue-white stars, then spectral type

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00:16:25.659 --> 00:16:30.600
A white stars, spectral type F whitish-yellow stars, spectral type

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G yellow stars. That's where our sun fits in. Then

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00:16:33.919 --> 00:16:37.529
there's spectral type K orange stars. And the coolest and

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00:16:37.590 --> 00:16:41.090
least massive stars are known as spectral type M red

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00:16:41.149 --> 00:16:45.870
dwarf stars. Each spectral classification can also be subdivided using

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a numeric digit to represent temperature, with zero being the

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hottest and nine the coolest, and a Roman numeral to

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represent luminosity. Now put all that together and our Sun

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is officially classified as a spectral type G2V or G25

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yellow dwarf star. Also included in the stellar classification system

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00:17:07.210 --> 00:17:10.880
are spectrotypes LT and Y, which are assigned to failed

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00:17:10.920 --> 00:17:14.259
stars known as brown dwarfs, some of which were born

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00:17:14.319 --> 00:17:17.849
as spectrotype M red dwarf stars, but became brown dwarfs

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after losing some of their mass. Brown dwarfs fit into

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a category between the largest planets, which are about 13

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00:17:24.529 --> 00:17:27.410
times the mass of Jupiter, and the smallest spectra type

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M red dwarf stars, which are usually about 75 to

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80 times the mass of Jupiter, or about 0.08 solar masses.

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As we mentioned earlier, Denebel Jetty is a beta Lyra

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variable eclipsing binary system. It's made up of two stars

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closely orbiting each other. the total brightness of the system

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changes because the two component stars periodically pass in front

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of each other as seen from Earth, thereby blocking out

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the light from the other star in the system. The

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two component stars of Beta Lyra are massive giants or

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00:18:00.700 --> 00:18:04.299
even supergiants, so close to each other that their shapes

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00:18:04.380 --> 00:18:08.700
are heavily distorted by their mutual gravitational forces. This gives

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each of the stars in the system an ellipsoidal shape

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with extensive mass flows from one component to the other.

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Just below Capricornus on the eastern horizon, you'll see the

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constellation Aquarius, the water carrier to the gods. Greek mythology

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00:18:24.160 --> 00:18:28.069
describes Aquarius as the most beautiful-looking boy that ever lived,

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00:18:28.740 --> 00:18:31.210
and so was carried from Earth up to Mount Olympus

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00:18:31.269 --> 00:18:33.730
by Zeus in the guise of Aquila the Eagle to

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00:18:33.769 --> 00:18:37.869
become the water carrier. The two brightest stars in Aquarius

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00:18:38.049 --> 00:18:41.230
are Alpha and Beta Aquarii, a pair of luminous yellow

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00:18:41.269 --> 00:18:46.430
supergiants that were once spectrotype B blue-white stars. the pair

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00:18:46.509 --> 00:18:49.470
are moving through space perpendicular to the plane of the

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00:18:49.509 --> 00:18:53.690
Milky Way galaxy. Beta-accurately the brightest of the pair is

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00:18:53.789 --> 00:18:58.539
also known as Sedal-Sud. It's a multiple star system, located

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00:18:58.579 --> 00:19:02.900
about 540 light-years away. The primary star is about 6

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00:19:02.900 --> 00:19:05.660
times the mass of the Sun, but emits roughly 2,300

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00:19:05.660 --> 00:19:09.849
times the Sun's luminosity, implying a radius at least 50

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00:19:09.849 --> 00:19:13.049
times that of our Sun. Beta Aquarii appears to have

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00:19:13.089 --> 00:19:16.250
at least two faint companion stars, but you'll need a

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00:19:16.309 --> 00:19:20.809
decent-sized telescope to see them. The second brightest star in

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00:19:20.849 --> 00:19:25.410
Aquarius is Alpha Aquarii, also known as Sedalmelech. It's about

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00:19:25.410 --> 00:19:29.930
520 light-years away, around 6.5 times as massive as the Sun,

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00:19:30.190 --> 00:19:34.599
and some 3,000 times as luminous. Next, we move to

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00:19:34.640 --> 00:19:38.799
the southern constellation of Pisces Astrinus, the Southern Fish. The

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00:19:38.839 --> 00:19:42.089
brightest star in the constellation is Fomalhaut, the mouth of

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00:19:42.119 --> 00:19:44.650
the southern fish, and the 18th brightest star in the

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00:19:44.710 --> 00:19:48.950
night sky. Interestingly, thousands of years ago, it was used

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00:19:48.970 --> 00:19:51.680
to mark the position of the winter solstice, the sun's

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most southerly position as seen from the northern hemisphere. But

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the precession of the equinoxes, which we talked about earlier,

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00:19:58.750 --> 00:20:01.529
has now moved the northern winter solstice to its new

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00:20:01.569 --> 00:20:06.220
position in December. Located only 25 light years away, Formalhaut

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00:20:06.319 --> 00:20:09.900
is a spectral type A white-yellow star, about twice the

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00:20:09.940 --> 00:20:13.079
mass of the Sun and around 16 times as luminous.

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00:20:13.759 --> 00:20:16.509
It's also a really young star, only about 400 million

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00:20:16.529 --> 00:20:20.369
years old. By comparison, our own star, the Sun, is

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00:20:20.410 --> 00:20:24.849
some 4.6 billion years of age. Formalhaut exhibits an excess

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00:20:24.890 --> 00:20:29.480
of infrared radiation, indicating that it's surrounded by a circumstellar disk.

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00:20:30.220 --> 00:20:33.059
It's also part of a triple star system, together with

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00:20:33.119 --> 00:20:37.230
a spectrotype K orange dwarf star T.W. Pisces-Astrini and a

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00:20:37.269 --> 00:20:40.369
spectrotype M red dwarf star L.P.

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00:20:40.390 --> 00:20:43.450
876-10. Turning to the.

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00:20:43.410 --> 00:20:46.950
North now, there you'll see the constellation Pegasus, the winged

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00:20:47.009 --> 00:20:50.690
horse of Greek mythology. Pegasus is the one who delivered

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00:20:50.730 --> 00:20:54.150
Medusa's head to Polydectes, after which he travelled to Mount

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00:20:54.170 --> 00:20:56.869
Olympus in order to become the bearer of thunder and

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00:20:56.890 --> 00:21:00.720
lightning bolts for Zeus. The brightest star in Pegasus is

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00:21:00.759 --> 00:21:05.000
the orange supergiant Epsilon Pegasi, which marks the horse's muzzle.

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00:21:05.640 --> 00:21:08.059
Almost 12 times the mass of the Sun, it's a

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00:21:08.140 --> 00:21:11.500
blurted-out or spectrotype K supergiant nearing.

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00:21:11.200 --> 00:21:12.180
The end of its life.

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00:21:12.880 --> 00:21:15.240
Astronomers are still debating as to whether it will end

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00:21:15.279 --> 00:21:19.619
its days as a core-collapse supernova or a rare neon-oxygen

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00:21:19.700 --> 00:21:24.220
white dwarf. Also in the north is the constellation Cygnus

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00:21:24.259 --> 00:21:26.680
the Swan, which lies on the planet of the Milky

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00:21:26.720 --> 00:21:30.710
Way galaxy. Cygnus contains the star Deneb, one of the

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00:21:30.750 --> 00:21:32.890
brightest stars in the night sky, and one of the

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00:21:32.990 --> 00:21:36.380
corners of the Summer Triangle. It's also home to the

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00:21:36.420 --> 00:21:40.480
giant Cygnus OB2 Stellar Association, which includes one of the

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00:21:40.519 --> 00:21:44.259
largest known stars in the universe, MNL Cygni, a red

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00:21:44.359 --> 00:21:46.630
hypergiant about 1,183 times the radius and 50 times the

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00:21:46.650 --> 00:21:53.210
mass of our Sun. In fact, were it placed at

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the center of our solar system where the Sun is,

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00:21:55.920 --> 00:21:59.059
its surface would extend out beyond the orbit of Jupiter.

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00:21:59.700 --> 00:22:04.980
It's so big, it contains a volume approximately 1.6 billion times.

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That of the Sun.

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00:22:06.299 --> 00:22:12.380
NML Cygni is located about 5,300 light-years away. Now, Cygnus

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00:22:12.420 --> 00:22:16.769
is also home to Cygnus X-1, a powerful galactic X-ray

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00:22:16.809 --> 00:22:21.240
source which became the first widely accepted black hole. It

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00:22:21.279 --> 00:22:25.019
was discovered back in 1964, and even today it remains

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00:22:25.059 --> 00:22:28.039
one of the most studied astronomical objects in the sky.

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00:22:28.839 --> 00:22:31.900
The black hole is estimated to have about 14.8 times

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00:22:31.940 --> 00:22:34.569
the mass of our Sun, all crammed into an event

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00:22:34.609 --> 00:22:39.269
horizon with a radius of just 44 kilometres. Little wonder

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black holes are the densest objects in the universe. Located

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just above the northern horizon this time of the year

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00:22:46.470 --> 00:22:49.490
is the star Vega. It's the brightest star in the

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00:22:49.529 --> 00:22:53.170
constellation Lyra and the fifth brightest star in the night sky.

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00:22:53.569 --> 00:22:56.369
Vega has about twice the mass of our Sun. And

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00:22:56.410 --> 00:22:59.569
it's a relatively young star, less than 500 million years old.

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00:23:00.009 --> 00:23:03.289
And it's also fairly close, just 25 light years away.

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00:23:03.309 --> 00:23:07.579
Now once again, due to the precession of Earth's rotational axis,

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00:23:07.950 --> 00:23:11.619
Vega used to be the northern pole star around 14,000

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00:23:11.619 --> 00:23:14.640
years ago. And it will do so again in another 12,000

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00:23:14.640 --> 00:23:20.380
years time. Just above Vega is Alpha Aquila or Altair,

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00:23:20.680 --> 00:23:24.160
the brightest star of the constellation Aquila. It's a spectral

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00:23:24.200 --> 00:23:27.420
type A white-yellow star with about twice the mass of

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00:23:27.500 --> 00:23:33.059
our Sun. Altair is located really nearby, just 16.7 light-years away,

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00:23:33.259 --> 00:23:36.599
and it rotates very rapidly, with an equatorial velocity of

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00:23:36.660 --> 00:23:40.839
about 286 km per second, and that's a significant fraction

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of the star's estimated break-up speed of around 400 km

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00:23:43.700 --> 00:23:49.079
per second. Now this high rotation rate means Altair isn't spherical,

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00:23:49.240 --> 00:23:52.799
but highly flattened at the poles. Altair is the eye

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00:23:52.819 --> 00:23:55.589
of the eagle that carried Aquarius up to Mount Olympus

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00:23:55.630 --> 00:23:59.170
to become the water bearer for the gods. Looking to

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00:23:59.190 --> 00:24:02.549
the southeast now, and you'll see the bright star Achenar.

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00:24:02.829 --> 00:24:05.730
It's the brightest star of the constellation Eridanus the river.

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00:24:06.410 --> 00:24:10.240
Located around 140 light years away, Achenar has 7 times

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00:24:10.299 --> 00:24:13.700
the mass and 3,000 times the luminosity of our sun.

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00:24:14.519 --> 00:24:17.700
The star rotates so rapidly it's elliptical in shape, with

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00:24:17.759 --> 00:24:22.420
its equatorial diameter being about 56% wider than its polar diameter.

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00:24:23.619 --> 00:24:27.099
September also sees the bulk of the origin's meteor shower,

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00:24:27.319 --> 00:24:29.700
which is produced as the Earth passes through the debris

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00:24:29.740 --> 00:24:34.670
trail left by the comet KESS C1911N1. KESS is a

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00:24:34.690 --> 00:24:38.029
long-period comet, only reaching the inner solar system every 1800

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00:24:38.029 --> 00:24:43.180
to 2000 years. Its meteor shower runs between August the

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00:24:43.240 --> 00:24:46.839
28th and September the 5th. The Oridgids provide up to

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00:24:46.960 --> 00:24:49.920
five swift and bright meteors an hour, with its peak

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00:24:49.980 --> 00:24:53.640
just before dawn on September the 1st. It's best viewed

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00:24:53.660 --> 00:24:56.680
from the northern hemisphere as its radiant, that is the

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00:24:56.700 --> 00:24:59.460
direction the meteors appear to be coming from, lies in

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00:24:59.500 --> 00:25:04.569
the northern sky constellation of central Oridgia. A second meteor

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00:25:04.609 --> 00:25:07.710
shower in the month of September is the Epsilon Perseids,

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00:25:07.990 --> 00:25:11.470
which run from September the 5th to the 21st. Although

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00:25:11.490 --> 00:25:14.890
they're called the Epsilon Perseids, the radiant actually lies closer

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00:25:14.910 --> 00:25:18.329
to the star Beta Perseus or Algol. Now the Epsilon

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00:25:18.369 --> 00:25:22.059
Perseids shouldn't be confused with last month's Perseids meteor shower.

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00:25:22.630 --> 00:25:25.079
That's because while both appear to have their radiant in

401
00:25:25.119 --> 00:25:28.720
the constellation Perseus, they're caused by debris trails from two

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00:25:28.799 --> 00:25:32.339
very different comets. And joining us now for the rest

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00:25:32.380 --> 00:25:35.200
of our tour of the September night skies, senior science

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00:25:35.220 --> 00:25:37.460
writer and Sky & Telescope magazine contributor.

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00:25:37.579 --> 00:25:38.359
Jonathan Alley.

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00:25:38.460 --> 00:25:40.369
G'day, Stuart. Well, this is actually a great time of

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00:25:40.410 --> 00:25:43.349
year for stargazing. I really do love this season, especially

408
00:25:43.390 --> 00:25:45.529
for us south of the equator, because we have the

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00:25:45.589 --> 00:25:48.890
fantastic constellation Sagittarius. We've got the centre of our galaxy

410
00:25:49.009 --> 00:25:51.730
overhead in the evening, best time for stargazing. And we've

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00:25:51.750 --> 00:25:54.450
got the summer constellations beginning to appear in the morning sky.

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00:25:54.579 --> 00:25:56.339
So we're getting a good mix of both winter and

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00:25:56.380 --> 00:25:58.720
summer viewing. So let's start as usual with the Milky

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00:25:58.740 --> 00:26:01.279
Way and the constellations. So at mid-evening, we've got the

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00:26:01.319 --> 00:26:04.000
Milky Way, which is our home galaxy seen from the inside.

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00:26:04.140 --> 00:26:06.400
It's stretching right across the sky from north to south. Now,

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00:26:06.440 --> 00:26:08.099
you do need dark skies to see it. If you're

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00:26:08.119 --> 00:26:09.829
in the city, you're probably not going to see the

419
00:26:09.849 --> 00:26:12.829
Milky Way, unfortunately, because it's quite pale. But if you're

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00:26:12.950 --> 00:26:14.890
out of the city, in the country, or you get

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00:26:14.910 --> 00:26:16.750
away from light, then you might be able to see it. Certainly,

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00:26:16.769 --> 00:26:18.529
you'll see it in the country. So for those of us...

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00:26:18.849 --> 00:26:21.599
at temperate latitudes, sort of mid-latitudes in the southern hemisphere,

424
00:26:21.630 --> 00:26:23.960
the centre of the galaxy and the star fields of

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00:26:23.980 --> 00:26:27.740
the constellations Scorpius and Sagittarius are more or less directly overhead,

426
00:26:27.819 --> 00:26:30.220
at least they are from where I live. And Scorpius, incidentally,

427
00:26:30.240 --> 00:26:31.900
is one of the few constellations that looks like the

428
00:26:31.940 --> 00:26:34.869
thing it's supposed to represent, Scorpius. Someone showed me a

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00:26:34.890 --> 00:26:36.430
picture they took on their phone the other night and

430
00:26:36.450 --> 00:26:37.490
they just said, oh, I just took a picture of

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00:26:37.819 --> 00:26:39.440
of the sky, first time taking a picture of the sky,

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00:26:39.500 --> 00:26:41.220
and I said, oh, there's Scorpius. And she said, where?

433
00:26:41.279 --> 00:26:43.450
And I said, I just traced out the line. She said, oh, yeah,

434
00:26:43.460 --> 00:26:46.009
I can see the Scorpion there. So it's big, and

435
00:26:46.029 --> 00:26:48.210
it's a huge constellation. It's not a tiny little thing.

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00:26:48.450 --> 00:26:51.490
So no wonder people perhaps don't see it at first.

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00:26:51.630 --> 00:26:53.279
But once you see it, you can't unsee it. You

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00:26:53.299 --> 00:26:56.279
will always... know how to recognise Scorpius. And the whole

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00:26:56.359 --> 00:26:58.980
region around there is really great to explore. You can

440
00:26:59.000 --> 00:27:02.029
spend hours over multiple nights just sweeping back and forth

441
00:27:02.049 --> 00:27:05.130
through this area with a pair of binoculars or a telescope,

442
00:27:05.170 --> 00:27:07.099
particularly a telescope that's got a wide field of view.

443
00:27:07.319 --> 00:27:10.059
There's so much to see, an endless list of famous,

444
00:27:10.279 --> 00:27:13.700
what astronomers call deep sky objects. You've got the Lagoon Nebula,

445
00:27:13.839 --> 00:27:16.160
you've got the Triffid Nebula, you've got the Eagle Nebula,

446
00:27:16.220 --> 00:27:18.589
the Hubble Telescope, the famous picture of the Eagle Nebula.

447
00:27:18.700 --> 00:27:21.750
You've got star clusters like Ptolemy's star clusters and the

448
00:27:21.849 --> 00:27:24.210
Wild Duck star cluster because it looks like a flock

449
00:27:24.230 --> 00:27:26.349
of ducks. All sorts of things. Do try to get

450
00:27:26.390 --> 00:27:28.190
away from any sources of light pollution if you can.

451
00:27:28.269 --> 00:27:30.910
It always helps when you're doing stargazing. Way down south,

452
00:27:30.930 --> 00:27:33.099
we've got the Southern Cross lying on its right-hand side.

453
00:27:33.259 --> 00:27:35.759
The two bright pointer stars are above it. If you

454
00:27:35.799 --> 00:27:38.059
have really dark skies and you let your eyes adapt

455
00:27:38.079 --> 00:27:39.940
to the dark, see if you can see spot a

456
00:27:39.980 --> 00:27:42.400
dark patch just next to the Southern Cross. This is

457
00:27:42.440 --> 00:27:45.519
a huge cloud of dark dust and gas floating in

458
00:27:45.619 --> 00:27:49.299
space called the Coalsack Nebula. And it really does stand out.

459
00:27:49.680 --> 00:27:51.539
If you're out in the middle of nowhere and you've

460
00:27:51.579 --> 00:27:53.880
got really dark skies and you let your eyes adapt

461
00:27:53.900 --> 00:27:56.539
to the dark, then you'll definitely see the Coalsack. It's

462
00:27:56.559 --> 00:27:59.069
like this big black patch next to the Southern Cross.

463
00:27:59.089 --> 00:28:00.980
And you get a telescope onto that and sweep through

464
00:28:01.009 --> 00:28:03.089
this nebula, you'll see that there are some stars there

465
00:28:03.210 --> 00:28:06.609
between us. and this huge nebula and the nebula's blocking

466
00:28:06.650 --> 00:28:08.710
all the stars that are behind. In the old days,

467
00:28:08.730 --> 00:28:11.150
we'll call it the old days, when astronomers were still

468
00:28:11.170 --> 00:28:14.150
investigating these things, no one really knew whether this big

469
00:28:14.190 --> 00:28:17.150
dark patch next to Southern Cross was a hole. We're

470
00:28:17.170 --> 00:28:19.460
looking all the way through this hole out through a

471
00:28:19.539 --> 00:28:22.279
gap in the galaxy out beyond or whether it was

472
00:28:22.539 --> 00:28:24.259
what it has been found to be, a big floating

473
00:28:24.299 --> 00:28:26.599
nebula that's blocking the stars from behind but a few

474
00:28:26.619 --> 00:28:29.339
little stars in the foreground. Anyway, that's the Coalsack. And

475
00:28:29.380 --> 00:28:31.980
just near the left-hand star of the Southern Cross, that's

476
00:28:32.099 --> 00:28:34.200
at the moment, that's the one that's uppermost in the sky,

477
00:28:34.400 --> 00:28:36.730
there's a little cluster of stars called the Jewel Box.

478
00:28:36.910 --> 00:28:39.130
And even a pair of binoculars will show it really well.

479
00:28:39.150 --> 00:28:41.329
It has a really pretty collection of stars of a

480
00:28:41.390 --> 00:28:44.049
variety of different sort of colours. Most star clusters, they

481
00:28:44.309 --> 00:28:47.009
generally just have white stars or blue stars, but this

482
00:28:47.069 --> 00:28:49.650
one's got a whole collection of really nicely coloured stars. Now,

483
00:28:49.670 --> 00:28:52.150
as the night goes on and the Earth turns, the

484
00:28:52.170 --> 00:28:55.019
stars will appear to move towards the west, some going

485
00:28:55.039 --> 00:28:57.619
below the western horizon and others coming up in the east.

486
00:28:57.740 --> 00:29:00.599
By midnight, the Milky Way is now low in the west.

487
00:29:00.759 --> 00:29:03.079
It was north-south, sort of straight across the middle of

488
00:29:03.099 --> 00:29:05.829
the sky, north-south in the early evening. But by midnight

489
00:29:05.869 --> 00:29:07.930
or so, the Milky Way is now low down in

490
00:29:07.950 --> 00:29:09.930
the west, because the Earth is turning in the other direction,

491
00:29:10.049 --> 00:29:12.230
and the Milky Way will dip below the horizon. But

492
00:29:12.269 --> 00:29:14.390
the eastern part of the sky, even though it will

493
00:29:14.410 --> 00:29:16.210
seem a bit bare through till about one o'clock in

494
00:29:16.230 --> 00:29:18.470
the morning, then some other constellations are going to start

495
00:29:18.490 --> 00:29:21.619
to rise, including the fabulous Orion constellation that we talk

496
00:29:21.650 --> 00:29:23.759
about a lot. And when you see Orion start to

497
00:29:23.799 --> 00:29:25.359
come up in the night sky, you know that the

498
00:29:25.400 --> 00:29:27.740
seasons are changing. So for us in the southern hemisphere,

499
00:29:27.799 --> 00:29:30.119
seeing Orion means that summer months are on their way.

500
00:29:30.440 --> 00:29:32.819
and not too far away. And for our friends north

501
00:29:32.839 --> 00:29:34.740
of the equator, it means that winter is on its

502
00:29:34.809 --> 00:29:38.089
way as well. And in the hours before dawn, you'll see,

503
00:29:38.170 --> 00:29:39.859
if you're up that early or up that late, you'll

504
00:29:39.880 --> 00:29:43.099
see the constellations Taurus and Gemini there, very close to

505
00:29:43.160 --> 00:29:46.680
Orion too. Taurus has got this wedge-shaped cluster of stars

506
00:29:46.779 --> 00:29:50.160
called the Hyades, and Gemini has a very small but

507
00:29:50.240 --> 00:29:52.980
very prominent star cluster called the Pleiades, which is the

508
00:29:53.019 --> 00:29:55.319
seven sisters. And I have a really soft spot for

509
00:29:55.339 --> 00:29:57.789
both these constellations as they were some of the first

510
00:29:57.809 --> 00:30:00.309
I identified and studied when I was a teenager using

511
00:30:00.329 --> 00:30:01.910
just a pair of binoculars. All I had was a

512
00:30:01.910 --> 00:30:03.930
pair of binoculars. I had my mum's binoculars. I think

513
00:30:03.950 --> 00:30:07.509
they were 8x30. Binoculars are very small. And I had

514
00:30:07.549 --> 00:30:09.549
the old star chart that came out of an issue

515
00:30:09.589 --> 00:30:12.089
of National Geographic in the 70s. It was a famous

516
00:30:12.109 --> 00:30:15.420
star chart. Not really intended for use in stargazing because

517
00:30:15.460 --> 00:30:18.539
of the way it's drawn, but I managed to figure

518
00:30:18.660 --> 00:30:21.440
out some of the constellations just using this old star chart.

519
00:30:21.460 --> 00:30:22.559
I wish I still had it. It'd be worth a

520
00:30:22.940 --> 00:30:24.980
mint now, I reckon, an original one of those. Anyway,

521
00:30:25.000 --> 00:30:27.630
that's the stars and constellations thing. Let's have a look

522
00:30:27.690 --> 00:30:29.210
now at where and when we can see the planets

523
00:30:29.289 --> 00:30:31.190
this month. And the month actually starts with a bang

524
00:30:31.230 --> 00:30:34.269
because they've got Venus appearing very close to a bright

525
00:30:34.309 --> 00:30:37.369
star called Spica. They'll only be about three moon widths

526
00:30:37.450 --> 00:30:40.619
apart in the evening, just in the first couple of

527
00:30:40.660 --> 00:30:43.400
days in September. You'll see them about halfway up from

528
00:30:43.440 --> 00:30:45.539
the western horizon. I mean, you won't miss Venus. It's

529
00:30:45.839 --> 00:30:47.839
big and bright, and the star that's right next to

530
00:30:47.900 --> 00:30:50.809
it is called Spica. And as each night passes, Venus

531
00:30:50.869 --> 00:30:53.609
will gradually separate from that star and climb a bit

532
00:30:53.650 --> 00:30:55.589
higher in the sky, or the star might be getting

533
00:30:55.609 --> 00:30:58.609
a little bit lower, or both, and Venus will be

534
00:30:58.730 --> 00:31:01.730
joined by the Moon on the 15th, very close to

535
00:31:01.769 --> 00:31:04.150
the Moon. That should be another very pleasant sight. And

536
00:31:04.170 --> 00:31:06.299
in the second week of September, you've got the innermost

537
00:31:06.380 --> 00:31:08.720
planet Mercury. You'll be able to see that low above

538
00:31:08.759 --> 00:31:12.660
the western horizon after sunset, little bright star-like thing, climbing

539
00:31:12.740 --> 00:31:16.160
higher each night. So by the 19th, of September, it'll

540
00:31:16.200 --> 00:31:19.549
form a nice straight equal even line with that star

541
00:31:19.569 --> 00:31:22.509
I mentioned, Spica and Venus. So we've got Mercury, Spica,

542
00:31:22.589 --> 00:31:25.910
Venus going up from the horizon. And on the 26th, Mercury,

543
00:31:26.069 --> 00:31:28.470
because it's moving through the night sky, and that star

544
00:31:28.490 --> 00:31:31.589
Spica will appear even closer together than the Venus and

545
00:31:31.630 --> 00:31:34.640
Spica appearing a few weeks earlier, only about two moon

546
00:31:34.660 --> 00:31:37.720
weeks apart. And then as the month ends, we've got Spica,

547
00:31:37.740 --> 00:31:39.319
Mercury and Venus will all be the same part of

548
00:31:39.339 --> 00:31:42.339
the sky forming a nice little triangle above the western horizon.

549
00:31:42.579 --> 00:31:45.220
The next planet is Saturn, which will rise above the

550
00:31:45.279 --> 00:31:48.250
eastern horizon about 8.30pm local time at the start of

551
00:31:48.269 --> 00:31:50.329
the month. And it'll just get higher and higher each

552
00:31:50.390 --> 00:31:53.430
night as the weeks go by up above the eastern horizon.

553
00:31:53.529 --> 00:31:56.089
The other two bright planets, Mars and Jupiter, can only

554
00:31:56.130 --> 00:31:58.690
be seen in the morning sky before sunrise. So you've

555
00:31:58.710 --> 00:32:00.720
either got to be an early riser or very late

556
00:32:00.740 --> 00:32:03.039
getting to bed. Mars is rising about 3am in the

557
00:32:03.079 --> 00:32:05.859
northeast with Jupiter following about an hour later. And it's

558
00:32:05.880 --> 00:32:08.880
interesting to compare the two because Mars looks really small

559
00:32:08.920 --> 00:32:11.619
and dim compared to Jupiter. So to the untrained eye,

560
00:32:11.660 --> 00:32:13.390
you'd think that while it looks smaller and dimmer, It

561
00:32:13.430 --> 00:32:15.750
must be further away, but it's not. At the moment,

562
00:32:15.789 --> 00:32:19.710
Mars is about 251 million kilometers from Earth, whereas Jupiter

563
00:32:19.890 --> 00:32:23.690
is about 890 million kilometers away. So that's more than

564
00:32:23.710 --> 00:32:26.210
three times, three and a half times further away. But

565
00:32:26.259 --> 00:32:28.500
the reason Jupiter looks so much bigger and brighter, even

566
00:32:28.519 --> 00:32:30.880
though it's further away than Mars, is that Jupiter is

567
00:32:30.940 --> 00:32:33.700
bigger and brighter. It's a huge planet. It's a gas giant,

568
00:32:33.720 --> 00:32:35.819
whereas Mars is just a tiny little ball of rock,

569
00:32:35.920 --> 00:32:38.799
even smaller than the Earth. And finally, down here on Earth,

570
00:32:38.920 --> 00:32:41.970
we're going to reach the equinox on September the 23rd.

571
00:32:42.210 --> 00:32:44.710
So in some parts of the world, this date is

572
00:32:44.769 --> 00:32:47.210
considered to be the beginning of the relevant season, so

573
00:32:47.309 --> 00:32:49.509
either autumn or spring, depending on which hemisphere you're in.

574
00:32:49.730 --> 00:32:51.450
And in other parts of the world, it's considered to

575
00:32:51.470 --> 00:32:54.640
be roughly the midpoint of the season. So September 23rd

576
00:32:54.680 --> 00:32:57.920
this year, so our friends in most countries in the

577
00:32:57.940 --> 00:33:01.220
Northern Hemisphere will consider September 23rd to be the start

578
00:33:01.440 --> 00:33:05.119
of their autumn. For us, September 23rd, we consider it

579
00:33:05.140 --> 00:33:07.609
to be the rough, it's not really the midpoint, but

580
00:33:07.710 --> 00:33:10.170
rough midpoint of spring. That's just the way we decide

581
00:33:10.190 --> 00:33:12.339
to do it because we base it more on meteorology

582
00:33:12.380 --> 00:33:15.019
than the actual dates. In other parts of the world,

583
00:33:15.039 --> 00:33:17.579
of course, such as the parts of the tropics, those

584
00:33:17.599 --> 00:33:19.890
sort of seasons, autumn and spring, they don't have much relevance,

585
00:33:19.950 --> 00:33:21.490
of course, because a lot of the tropics.

586
00:33:21.509 --> 00:33:22.430
It's wet or dry.

587
00:33:22.509 --> 00:33:26.970
It's that simple. You've got the dry season which is

588
00:33:27.109 --> 00:33:28.859
not really very dry and then you've got the wet

589
00:33:28.880 --> 00:33:31.519
season which is like monsoon. It's really, really wet. So

590
00:33:31.680 --> 00:33:34.279
equinoxes don't really come into play much. I mean, it's

591
00:33:34.299 --> 00:33:37.079
still the equinox. It's when the sun's crossing the equator

592
00:33:37.099 --> 00:33:39.910
but in terms of meteorology it doesn't quite apply to

593
00:33:39.930 --> 00:33:45.059
about 50% wet or dry, a bit like sandpaper. But anyway, Stuart,

594
00:33:45.099 --> 00:33:46.960
that's the night sky for September.

595
00:33:47.019 --> 00:33:51.160
That's senior science writer and Sky Telescope magazine contributor Jonathan Alley,

596
00:33:51.500 --> 00:33:52.900
and this is Space Time.

597
00:34:08.469 --> 00:34:09.829
And that's the show for now.

598
00:34:10.610 --> 00:34:16.769
Spacetime is available every Monday, Wednesday, and Friday through Bytes.com, SoundCloud, YouTube,

599
00:34:16.909 --> 00:34:23.460
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600
00:34:23.539 --> 00:34:27.019
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601
00:34:27.360 --> 00:34:30.900
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00:34:30.940 --> 00:34:33.699
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00:34:37.489 --> 00:34:41.190
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609
00:34:54.909 --> 00:34:58.320
You've been listening to Spacetime with Stuart Gary. This has

610
00:34:58.360 --> 00:35:01.380
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