Equinox Auroras, Ancient Stars, and a Satellite Resurrection

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Language: en

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Happy first day of spring, everyone. At


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least if you're in the northern


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hemisphere. I'm Anna.


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>> And I'm Avery. And what a day for the


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cosmos to celebrate with us. Because


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right now, as we're recording, the sun


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has fired three enormous blasts of


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charged particles straight at Earth. A 7


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ton space rock just lit up the skies


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over Ohio. A satellite that went silent


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for a full month has finally phoned


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home. And astronomers have found a star


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so old it carries the direct


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fingerprints of the very first stars


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that ever existed.


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>> Plus, we're going to explain exactly why


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the equinox and those solar storms are


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connected. It's one of the most


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fascinating quirks of Earth's orbit


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around the sun. And today is literally


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the best day of the year to talk about


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it.


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>> This is Astronomy Daily, season 5,


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episode 68. Let's get into it. Okay,


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Avery, before we even get into the


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equinox itself, we have to talk about


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what the sun has been doing this week


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because it has been busy.


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>> Extremely busy. So, here's a situation.


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As of today, Friday the 20th of March.


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Earth is being targeted by not one, not


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two, but three separate coronal mass


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ejections, CMEs, all fired off within


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the last few days. So, for anyone who


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needs a quick refresher, a CME is


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essentially a massive eruption of plasma


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and magnetic field from the sun. When


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these hit Earth's magnetic fields, they


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compress it, cause geomagnetic storms,


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and most visibly for us down here, they


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trigger auroras.


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>> The first of the three CMEs was expected


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to arrive today. Forecasters at Noah's


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Space Weather Prediction Center have


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issued a geomagnetic storm watch with


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conditions potentially reaching G2.


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That's moderate with a chance of G3 or


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strong. And that second level, G3, is


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where things get really interesting


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>> because G3 conditions could push aurora


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visibility well into mid latitudes as


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far south as Illinois, Oregon,


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potentially even lower under the right


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conditions. So, if you're in the


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northern US, northern Europe, Canada,


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tonight is a night to keep an eye on the


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sky.


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>> And there's more to come. A second CME


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is expected to deliver a glancing blow.


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And the third, triggered by an M2.75


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flare from sunspot region AR4392


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is expected to arrive around March 21st.


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So, this isn't a one-day event. The


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space weather picture remains active


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through the weekend.


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>> We should also mention we're currently


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near solar maximum, the peak of the


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sun's 11-year cycle, which is part of


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why we're seeing this kind of activity.


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Peak activity is expected to continue


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through the second half of 2026. So get


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used to these kinds of alerts.


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>> Worth bookmarking Noah's space weather


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prediction center, spaceweather.gov,


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for live aurora forecasts. And on our


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website at astronomydaily.io,


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we'll link to some recommended aurora


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apps for your phone.


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>> Okay, so let's talk about the actual


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astronomical event that is happening


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today, the vernal equinox. The 2026


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March equinox falls at 14:46


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UTC this afternoon.


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>> At that moment, the sun crosses the


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celestial equator, the imaginary line in


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the sky directly above Earth's equator,


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moving from south to north. And at that


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precise moment, every point on Earth


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receives roughly equal amounts of


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daylight and darkness.


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>> The word equinox comes from the Latin


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for equal night.


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It's the astronomical beginning of


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spring in the northern hemisphere and


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autumn in the southern. So if you're


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listening from Australia or New Zealand,


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happy autumn to you.


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>> And here's the thing that connects this


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equinox directly to the aurora story we


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just told. There's a phenomenon called


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the Russell McFaran effect named after


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the two scientists who identified it.


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And it specifically amplifies aurora


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activity around the equinoxes.


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>> Right? Basically around the equinoxes,


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Earth's magnetic field orientation is


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particularly favorable for coupling with


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the solar wind. The geometry of our


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planet's tilt relative to the sun means


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incoming charged particles from CMEs


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interact more efficiently with our


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magnetosphere. So what this means in


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practice is the equinoxes are


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historically the best times of year to


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see auroras even when the sun isn't


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being especially active. When you


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combine a natural peak in aurora


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probability with three incoming CMEs on


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the same day, well, today is genuinely a


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special aurora opportunity. And there's


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a lovely bonus for sky watchers this


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evening. After sunset today, look to the


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west southwest and you'll be able to


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spot a thin 5% lit waxing crescent moon


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glowing just above Venus. Spring


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evenings don't get much more beautiful


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than that. Equinox, auroras, crescent


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moon, Venus. Anna, I feel like the


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universe planned this episode.


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>> I am starting to think so, too. Check


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astronomyaily.io


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for skywatching links for tonight.


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>> Okay, shifting from things you need to


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look up for to something that came down


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from above rather dramatically on


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Tuesday, St. Patrick's Day. Thousands of


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people across the American Midwest


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experienced quite the green tinged


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morning. And not just from the holiday.


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>> At around 8:57 in the morning, a 7 ton


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asteroid roughly 6 feet in diameter


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entered the atmosphere above Lake Erie


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near Lraine, Ohio, and moved southeast


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at around 40,000 mph before fragmenting


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about 30 m above Valley City. The


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explosion had the energy equivalent of


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250 tons of TNT, and it produced


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multiple sonic booms that were heard and


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felt across northeast Ohio, and into


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Pennsylvania, New York, and beyond. Some


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reports came in as far as Ontario and


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Canada.


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>> People were flooding 911 lines thinking


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it was an earthquake or an explosion, or


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actually, there was quite a creative


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range of theories on social media. But


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NASA's Meteoroid Environments Office


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confirmed the meteor quickly and tracked


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its trajectory precisely.


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>> And here's the exciting follow-up that's


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still unfolding. NASA confirmed


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meteorites, actual fragments that


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survived the journey to the ground,


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landed in the vicinity of Medina County,


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Ohio. And the meteorite hunting


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community has mobilized in a spectacular


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fashion. Within days, hunters from


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Connecticut, South Carolina, and


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multiple other states were converging on


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a small town called Sharon Center. At


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least one hunter found a 12.2 g


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fragment. Another found pieces in a


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parking lot, and the hunt is still very


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much on. Daytime fireballs this bright


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are genuinely rare. An amateur


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astronomer in the area said something


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along the lines of, "To see a fireball


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in the daytime, it has to be


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extraordinarily bright." And the fact


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that it created multiple sonic booms


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over a populated area is something that


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happens perhaps once in a lifetime. If


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you're in the Medina County area and you


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spot a dark rock with a shiny exterior


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or a gray interior that looks slightly


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out of place, it might be worth a closer


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look. NASA's guidance is to photograph


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it without disturbing it and contact a


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local university geology department and


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absolutely do not pick it up without


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checking the rules. Meteorites have real


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scientific value.


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>> Happy hunting, Ohio.


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>> All right. From things falling to Earth


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to a star so old it predates almost


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everything we can see in the modern


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universe. This week in the journal


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Nature Astronomy, a team led by Anna


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Rude Chitty of Stanford University


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published a discovery that is being


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called, and I love this phrase, cosmic


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archaeology.


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>> So, let's set the scene. In the very


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early universe, the first stars were


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enormous and formed from just three


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elements: hydrogen, helium, and a tiny


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bit of lithium. That was it. Those were


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the only elements that existed. No


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carbon, no iron, no oxygen, none of the


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building blocks of chemistry as we know


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it.


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>> These first stars, called population 3


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stars, burned fast and hot. And when


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they exploded as supernova, they


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scattered the first heavy elements into


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the surrounding gas clouds. The next


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generation of stars, population 2,


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formed from that enriched material.


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>> And that's what makes this week's


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discovery so extraordinary. Astronomers


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have found a star called PIC 2-503


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sitting in a tiny ancient dwarf galaxy


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called Pictor 2, located about 150,000


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light years from Earth. And this star


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contains virtually no iron, less than


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140,000th of the iron in our sun.


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>> To put that in perspective, our sun is a


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third generation star. Picked 25503 is


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second generation. It formed from the


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direct debris of the universe's very


00:09:29.440 --> 00:09:32.389
first stars. It is quite literally


00:09:32.399 --> 00:09:34.470
carrying the chemical fingerprints of


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stars that no longer exist anywhere in


00:09:37.279 --> 00:09:40.470
the observable universe. The star also


00:09:40.480 --> 00:09:42.870
has an extraordinary overabundance of


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carbon, about 1,500 times more carbon


00:09:46.480 --> 00:09:49.430
relative to iron than our sun. And this


00:09:49.440 --> 00:09:51.509
is the key to unlocking a mystery that


00:09:51.519 --> 00:09:54.230
astronomers have puzzled over for years.


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There's a whole class of stars in the


00:09:56.480 --> 00:09:58.870
outer halo of our Milky Way called


00:09:58.880 --> 00:10:01.670
carbon-enhanced metal pore stars that


00:10:01.680 --> 00:10:04.470
show this same bizarre signature. High


00:10:04.480 --> 00:10:07.829
carbon, almost no iron. Scientists knew


00:10:07.839 --> 00:10:09.750
they were ancient, but they couldn't


00:10:09.760 --> 00:10:11.990
explain where they originally formed.


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Because our galaxy has been


00:10:13.360 --> 00:10:15.750
cannibalizing smaller galaxies for


00:10:15.760 --> 00:10:18.389
billions of years, scattering stars far


00:10:18.399 --> 00:10:19.829
from their birthplaces.


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>> Picked 25503 is the missing link. It


00:10:23.680 --> 00:10:25.990
shows that these mysterious halo stars


00:10:26.000 --> 00:10:28.389
were born in tiny primitive dwarf


00:10:28.399 --> 00:10:31.190
galaxies like picture 2. Galaxies that


00:10:31.200 --> 00:10:33.590
formed early in cosmic history and


00:10:33.600 --> 00:10:35.509
haven't changed much since. The


00:10:35.519 --> 00:10:37.829
discovery was made possible by the magic


00:10:37.839 --> 00:10:40.790
survey. That stands for DAM mapping the


00:10:40.800 --> 00:10:44.630
ancient galaxy in CHK. A 54night


00:10:44.640 --> 00:10:46.870
observing program using the dark energy


00:10:46.880 --> 00:10:49.509
camera in Chile combined with a followup


00:10:49.519 --> 00:10:51.670
from the very large telescopes and the


00:10:51.680 --> 00:10:53.350
Mellan telescopes.


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>> The lead researcher described it as


00:10:55.279 --> 00:10:56.949
being at the edge of what we thought


00:10:56.959 --> 00:10:58.949
possible. And I think that phrase


00:10:58.959 --> 00:11:01.430
captures it perfectly because this star


00:11:01.440 --> 00:11:04.150
isn't just old. It's a direct record of


00:11:04.160 --> 00:11:05.910
chemical processes that happened when


00:11:05.920 --> 00:11:07.910
the universe was less than a billion


00:11:07.920 --> 00:11:10.470
years old. It's a time capsule.


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>> The paper is in Nature Astronomy this


00:11:12.560 --> 00:11:14.710
week. We'll link to the Nor lab press


00:11:14.720 --> 00:11:16.630
release on the website. They have some


00:11:16.640 --> 00:11:19.030
spectacular images of Pictor 2.


00:11:19.040 --> 00:11:21.430
>> Now, this one is a followup to a story


00:11:21.440 --> 00:11:23.990
we covered a few weeks ago, and it is


00:11:24.000 --> 00:11:26.790
very much a good news update. You'll


00:11:26.800 --> 00:11:29.670
remember that Europe's proba 3 mission,


00:11:29.680 --> 00:11:32.710
issa's ingenious two satellite formation


00:11:32.720 --> 00:11:35.590
flying solar science mission ran into


00:11:35.600 --> 00:11:38.150
serious trouble in midFebruary when the


00:11:38.160 --> 00:11:40.710
coronagraph spacecraft went completely


00:11:40.720 --> 00:11:42.630
silent. For those who need the


00:11:42.640 --> 00:11:45.750
refresher, proba 3 consists of two small


00:11:45.760 --> 00:11:48.389
satellites flying in exquisitly precise


00:11:48.399 --> 00:11:51.990
formation about 150 m apart with


00:11:52.000 --> 00:11:55.430
positioning accuracy of 1 mm. The


00:11:55.440 --> 00:11:57.829
oultter spacecraft blocks out the bright


00:11:57.839 --> 00:12:00.389
disc of the sun, while the coronagraph


00:12:00.399 --> 00:12:02.949
photographs the sun's outer atmosphere,


00:12:02.959 --> 00:12:05.910
the corona. It's basically a spacecraft


00:12:05.920 --> 00:12:08.310
that manufactures artificial solar


00:12:08.320 --> 00:12:11.430
eclipses on demand in orbit. The science


00:12:11.440 --> 00:12:14.069
potential is enormous because the corona


00:12:14.079 --> 00:12:16.710
is normally invisible from Earth except


00:12:16.720 --> 00:12:19.110
during the few minutes of a total solar


00:12:19.120 --> 00:12:22.470
eclipse. But in midFebruary, an anomaly


00:12:22.480 --> 00:12:24.790
on the coronagraph triggered a cascade


00:12:24.800 --> 00:12:27.750
of failures. It lost its attitude, its


00:12:27.760 --> 00:12:29.990
orientation in space, and failed to


00:12:30.000 --> 00:12:33.269
enter safe mode as expected. ESA spent


00:12:33.279 --> 00:12:35.670
weeks attempting to regain contact,


00:12:35.680 --> 00:12:37.590
working through ground stations around


00:12:37.600 --> 00:12:40.629
the world. And the great news confirmed


00:12:40.639 --> 00:12:43.590
on March 19th, issa's ground station in


00:12:43.600 --> 00:12:46.150
Vafrana, Spain, received a data packet


00:12:46.160 --> 00:12:48.629
from the coronagraph. The satellite is


00:12:48.639 --> 00:12:51.269
alive. It's in safe mode. Its solar


00:12:51.279 --> 00:12:53.590
panel is facing the sun, powering the


00:12:53.600 --> 00:12:55.910
electronics and charging the battery.


00:12:55.920 --> 00:12:58.629
>> Proba 3 mission manager Damian Galano


00:12:58.639 --> 00:13:00.389
said, and this is a direct quote from


00:13:00.399 --> 00:13:03.110
the ESA statement. Hearing back from the


00:13:03.120 --> 00:13:05.829
coronagraph is amazing news and a great


00:13:05.839 --> 00:13:06.550
relief.


00:13:06.560 --> 00:13:08.790
>> Now, we should be clear, the mission


00:13:08.800 --> 00:13:11.590
team isn't popping champagne just yet.


00:13:11.600 --> 00:13:13.910
The satellite has spent a month floating


00:13:13.920 --> 00:13:17.030
in space, exposed to the deep cold of


00:13:17.040 --> 00:13:19.750
orbital night, and its systems need time


00:13:19.760 --> 00:13:22.550
to warm up before any major actions are


00:13:22.560 --> 00:13:24.949
taken. Health checks are underway to


00:13:24.959 --> 00:13:27.269
assess whether any damage occurred.


00:13:27.279 --> 00:13:29.430
>> But the spacecraft is stable. The


00:13:29.440 --> 00:13:31.590
hardware is powered, and if those health


00:13:31.600 --> 00:13:33.910
checks come back clean, Proba 3 could


00:13:33.920 --> 00:13:35.990
resume its artificial eclipse science


00:13:36.000 --> 00:13:37.829
program. We'll be following this one


00:13:37.839 --> 00:13:38.870
closely.


00:13:38.880 --> 00:13:41.190
>> What a relief is right. We'll link to


00:13:41.200 --> 00:13:42.790
the full ESA update at


00:13:42.800 --> 00:13:45.030
astronomydaily.io.


00:13:45.040 --> 00:13:47.269
>> And finally, a story that is both a


00:13:47.279 --> 00:13:49.750
scientific mystery solved and a lovely


00:13:49.760 --> 00:13:51.829
reminder for why sample return missions


00:13:51.839 --> 00:13:54.310
matter so much. You'll remember NASA's


00:13:54.320 --> 00:13:56.710
Osiris Rex spacecraft collected samples


00:13:56.720 --> 00:13:59.269
from asteroid Bennon back in 2020, and


00:13:59.279 --> 00:14:02.470
those samples arrived on Earth in 2023.


00:14:02.480 --> 00:14:04.310
Well, this week, scientists published


00:14:04.320 --> 00:14:06.870
results in Nature Communications that


00:14:06.880 --> 00:14:08.870
finally solve one of Bennu's most


00:14:08.880 --> 00:14:11.269
puzzling features. So, here's the


00:14:11.279 --> 00:14:14.629
mystery. Back in 2007, NASA's Spitzer


00:14:14.639 --> 00:14:16.710
Space Telescope measured what's called


00:14:16.720 --> 00:14:19.509
low thermal inertia on Bennu, meaning


00:14:19.519 --> 00:14:22.069
the asteroid surface heats up and cools


00:14:22.079 --> 00:14:24.870
down rapidly as it rotates. on Earth.


00:14:24.880 --> 00:14:27.030
That's what sand does, which led


00:14:27.040 --> 00:14:29.269
astronomers to expect Bennu's surface


00:14:29.279 --> 00:14:31.590
would be sandy and smooth, a bit like a


00:14:31.600 --> 00:14:32.470
beach.


00:14:32.480 --> 00:14:35.670
>> And then Osiris Rex arrived in 2018 and


00:14:35.680 --> 00:14:38.230
found the opposite. The surface was


00:14:38.240 --> 00:14:40.949
covered in enormous boulders, rough,


00:14:40.959 --> 00:14:43.750
rocky, definitely not sandy. And these


00:14:43.760 --> 00:14:45.590
boulders should behave like blocks of


00:14:45.600 --> 00:14:47.829
concrete thermally, holding heat for


00:14:47.839 --> 00:14:49.990
hours after the sun goes down. But they


00:14:50.000 --> 00:14:52.389
weren't. They were losing heat rapidly,


00:14:52.399 --> 00:14:54.150
just like the original observation


00:14:54.160 --> 00:14:55.269
suggested.


00:14:55.279 --> 00:14:57.350
>> Scientists scratched their heads for


00:14:57.360 --> 00:15:00.069
years. The boulders were porous. That


00:15:00.079 --> 00:15:02.389
explained some of the heat loss, but not


00:15:02.399 --> 00:15:04.470
all of it. The numbers still didn't add


00:15:04.480 --> 00:15:05.269
up.


00:15:05.279 --> 00:15:07.430
>> And then they put the actual return


00:15:07.440 --> 00:15:09.990
samples into an X-ray CT scanner. And


00:15:10.000 --> 00:15:11.350
that's when everything clicked into


00:15:11.360 --> 00:15:13.910
place. The boulders aren't just porous.


00:15:13.920 --> 00:15:15.509
They're riddled with an extensive


00:15:15.519 --> 00:15:18.230
internal network of fine cracks, like a


00:15:18.240 --> 00:15:20.150
shattered windshield that's still in one


00:15:20.160 --> 00:15:22.790
piece. The cracks dramatically alter how


00:15:22.800 --> 00:15:24.949
heat moves through the rock. When


00:15:24.959 --> 00:15:27.269
scientists ran computer simulations


00:15:27.279 --> 00:15:29.509
scaling those cracked boulder properties


00:15:29.519 --> 00:15:31.910
up to the full size of Bennu's actual


00:15:31.920 --> 00:15:34.629
surface, the numbers matched perfectly,


00:15:34.639 --> 00:15:36.310
right down to what the spacecraft had


00:15:36.320 --> 00:15:37.670
measured from orbit.


00:15:37.680 --> 00:15:39.750
>> The lead researcher, Andrew Ryan, from


00:15:39.760 --> 00:15:42.150
the University of Arizona put it simply.


00:15:42.160 --> 00:15:43.990
It turns out they're really cracked,


00:15:44.000 --> 00:15:45.990
too. And that was the missing piece of


00:15:46.000 --> 00:15:48.069
the puzzle. The full citation is in the


00:15:48.079 --> 00:15:49.189
show notes.


00:15:49.199 --> 00:15:51.509
>> And the implications go way beyond


00:15:51.519 --> 00:15:53.990
Bennu. This work means scientists can


00:15:54.000 --> 00:15:55.910
now use the thermal properties of an


00:15:55.920 --> 00:15:58.230
asteroid measured from a telescope on


00:15:58.240 --> 00:16:00.230
Earth to make much more accurate


00:16:00.240 --> 00:16:02.710
inferences about its internal structure.


00:16:02.720 --> 00:16:04.629
You no longer need to go there and pick


00:16:04.639 --> 00:16:06.310
it up to understand it,


00:16:06.320 --> 00:16:08.550
>> which matters enormously for planetary


00:16:08.560 --> 00:16:10.550
defense. The more accurately we can


00:16:10.560 --> 00:16:12.629
model asteroid composition and structure


00:16:12.639 --> 00:16:14.550
from a distance, the better we can


00:16:14.560 --> 00:16:16.310
predict trajectories, deflection


00:16:16.320 --> 00:16:18.870
responses, and potential impact hazards.


00:16:18.880 --> 00:16:22.230
Osiris Rex keeps on delivering. What an


00:16:22.240 --> 00:16:24.310
episode to celebrate the first day of


00:16:24.320 --> 00:16:26.150
spring in the northern hemisphere and


00:16:26.160 --> 00:16:28.310
autumn in the southern hemisphere. We


00:16:28.320 --> 00:16:31.110
had solar storms, an aurora opportunity,


00:16:31.120 --> 00:16:33.829
a meteorite hunt in Ohio, one of the


00:16:33.839 --> 00:16:36.310
oldest stars ever discovered, a


00:16:36.320 --> 00:16:38.629
satellite that came back from the dead,


00:16:38.639 --> 00:16:41.350
and an asteroid mystery finally cracked.


00:16:41.360 --> 00:16:43.030
Not bad for a Friday.


00:16:43.040 --> 00:16:45.110
>> If you're in aurora territory tonight,


00:16:45.120 --> 00:16:47.430
get outside, find a dark spot, look


00:16:47.440 --> 00:16:49.910
north. The sky may reward you.


00:16:49.920 --> 00:16:52.069
>> You can find show notes, source links,


00:16:52.079 --> 00:16:53.590
and skywatching guides at


00:16:53.600 --> 00:16:55.749
astronomyaily.io.


00:16:55.759 --> 00:16:58.629
Follow us on X, Instagram, Tik Tok,


00:16:58.639 --> 00:17:01.749
YouTube, and Tumblr, all at Astro Daily


00:17:01.759 --> 00:17:02.470
Pod.


00:17:02.480 --> 00:17:04.069
>> If you're enjoying the show, please


00:17:04.079 --> 00:17:05.750
leave us a review wherever you get your


00:17:05.760 --> 00:17:07.669
podcasts. It genuinely helps new


00:17:07.679 --> 00:17:09.029
listeners find us.


00:17:09.039 --> 00:17:11.429
>> Until next time, keep looking up. I'm


00:17:11.439 --> 00:17:12.230
Anna


00:17:12.240 --> 00:17:26.150
>> and I'm Avery. Happy Equinox, everyone.


00:17:26.160 --> 00:17:29.880
Stories told.