Equinox Auroras, Ancient Stars, and a Satellite Resurrection

Happy first day of spring everyone, at least if you're in the northern hemisphere. I'm Anna and I'm Avery, And what a day for the cosmos to celebrate with us, because right now, as we're recording, the Sun has fired three enormous blasts of charged particles straight at Earth. A seven ton space rock just lit up the skies over Ohio, a satellite that went silent for a full month has finally phoned home, and astronomers have found a star so old it carries the direct fingerprints of the very first stars that ever existed. Plus, we're going to explain exactly why the equinox and those solar storms are connected. It's one of the most fascinating quirks of Earth's orbit around the Sun, and today is literally the best day of the year to talk about it. This is Astronomy Daily, Season five, episode sixty eight. Let's get into. It, okay, Avery, Before we even get into the equinox itself, we have to talk about what the Sun has been doing this week, because it has been. Busy, extremely busy. So here's a situation. As of today, Friday, the twentieth of March, Earth is being targeted by not one, not two, but three separate coronal mass ejections CMEs all fired off within the last few days. So for anyone who needs a quick refresher, A CME is essentially a massive eruption of plasma and magnetic field from the Sun. When these hit Earth's magnetic field, they compress it cause geomagnetic storms, and most visibly for us down here, they trigger auroras. The first of the three CMEs was expected to arrive today. Forecasters at Noah's Space Weather Prediction Center have issued a geomagnetic storm watch with conditions potentially reaching G two that's moderate with a chance of G three or strong, and that second level G three is where things get really interesting. Because G three conditions could push aurora of ability well into mid latitudes as far south as Illinois, Oregon, potentially even lower under the right conditions. So if you're in the northern US, northern Europe, Canada, tonight is a night to keep an eye on the sky. And there's more to come. A second CME is expected to deliver a glancing blow, and the third, triggered by an M two point seventy five flare from sunspot region AR four three nine two, is expected to arrive around March twenty first, so this isn't a one day event. The Space Weather picture remains active through the weekend. We should also mention we're currently near solar maximum, the peak of the Sun's eleven year cycle, which is part of why we're seeing this kind of activity. Peak activity is expected to continue through the second half of twenty twenty six, so get used to these kinds of alerts. Worth bookmarking Noah's Space Weather Prediction Center spaceweather dot gov for live Aurora forecasts, and on our website at ostrowna medaily dot io, we'll link to some recommended Aurora apps for your phone. Okay, so let's talk about the actual astronomical event that is happening today, the vernal equinox. The twenty twenty six March equinox falls at fourteen forty six UTC this afternoon. At that moment, the Sun crosses the celestial equator, the imaginary line in the sky directly above Earth's equator, moving from south to north, and at that precise moment, every point on Earth receives roughly equal amounts of daylight and darkness. The word equinox comes from the Latin for equal night I equos nooakes. It's the astronomical beginning of spring in the northern hemisphere and autumn in the southern. So if you're listening from Australia or New Zealand, happy autumn to you. And here's the thing that connects this equinox directly to the aurora story we just told. There's a phenomenon called the Russell Macphear in effect, named after the two scientists who identified it, and it specifically amplifies aurora activity around the equinoxes. Right basically around the equinoxes, Earth's magnetic field orientation is particularly favorable for coupling with the solar wind. The geometry of our planet's tilt relative to the Sun means incoming charged particles from CMEs interact more efficiently with our magnetosphere. So what this means in practice is the equinoxes are historically the best times of year to see auroras, even when the Sun isn't being especially active. When you combine a natural peak and aurora probability with three incoming CMEs on the same day, well, today is genuinely a special aurora opportunity. And there's a lovely bonus for skywatchers this evening. After sunset today, look to the west southwest and you'll be able to spot a thin, five percent lit, waxing crescent moon glowing just above Venus. Spring evenings don't get much more beautiful than. That equinox Aurora's crescent moon Venus, and I feel like the Universe planned this episode. I am starting to think so too. Check Astronomy Daily dot io for skywatching links for tonight. Okay, shifting from things you need to look up for to something that came down from above rather dramatically. On Tuesday, Saint Patrick's Day, thousands of people across the American Midwest experienced quite the green tinged morning, and not just from the holiday. At around eight fifty seven in the morning, a seven ton asteroid roughly six feet in diameter, entered the atmosphere above Lake Erie near Lorraine, Ohio, and moved southeast at around forty thousand miles per hour before fragmenting about thirty miles above Valley City. The explosion had the energy equivalent of two hundred and fifty tons of TNT, and it produced multiple sonic booms that were heard and felt across northeast Ohio and into Pennsylvania, New York and beyond. Some reports came in as far as Ontario and Canada. People were flooding nine to one one lines thinking it was an earthquake or an explosion or actually there was quite a creative range of theories on social media. But NASA's Meteoroid Environment's Office confirmed the medior quickly and tracked its trajectory precisely. And here's the exciting follow up that's still unfolding. NASA confirmed meteorites, actual fragments that survived the journey to the ground landed in the vicinity of Medina County, Ohio, and the meteorite hunting community has mobilized in a spectacular fashion. Within days, hunters from Connecticut, South Carolina, and multiple other states were converging on a small town called Sharon Center. At least one hunter found a twelve point two gram fragment found pieces in a parking lot, and the hunt is still very much on. Daytime. Fireballs this bright are genuinely rare. An amateur astronomer in the area sets something along the lines of to see a fireball in the daytime, it has to be extraordinarily bright, and the fact that it created multiple signing booms over a populated area is something that happens, perhaps once in a lifetime. If you're in the Medina County area and you spot a dark rock with a shiny exterior or a gray interior that looks slightly out of place, it might be worth a closer look. NASA's guidance is to photograph it without disturbing it and contact a local university geology department, and absolutely do not pick it up without checking the rules. Meteorites have real scientific value. Happy hunting, Ohio, All right. From things falling to Earth to a star so old it predates almost everything we can see in the modern universe. This week in the journal Nature Astronomy, a team led by anarud Cheaty of Stanford University published a discovery that is being called, and I love this phrase, cosmic archaeology. So let's set the scene. In the very early universe. The first stars were enormous and formed from just three elements hydrogen, helium, and a tiny bit of lithium. That was it. Those were the only elements that existed. No carbon, no iron, no oxygen, none of the building blocks of chemistry. As we know it. These first stars, called Population three stars burned fast and hot, and when they exploded as supernovae, they scattered the first heavy elements into the surrounding gas clouds. The next generation of stars, population two, formed from that enriched material. And that's what makes this week's discovery so extraordinary. Astronomers have found a star called Picked two Dash five zero three sitting in a tiny ancient dwarf galaxy called Picter two, located about one hundred and fifty thousand light years from Earth. And this star contains virtually no iron, less than one forty thousandth of the iron in our Sun. To put that in perspective, our Sun is a third generation star. Picked two five oh three is second generation. It formed from the direct debris of the universe's very first stars. It is quite literally carrying the chemical fingerprints of stars that no longer exist anywhere in the observable universe. The star also has an extraordinary overabundance of carbon, about fifteen hundred times more carbon relative to iron than our Sun, and this is the key to unlocking a mystery that astronomers have puzzled over for years. There's a whole class of stars in the outer halo of our Milky Way called carbon enhanced metal poor stars that show this same bizarre signature high carbon almost no iron. Scientists knew they were ancient, but they couldn't explain where they originally formed because our galaxy has been cannibalizing smaller galaxies for billions of years, scattering stars far from their birthplaces. Picked two five oh three is the missing link. It shows that these mysterious halo stars were born in tiny, primitive dwarf galaxies like picture two, galaxies that formed early in cosmic history and haven't changed much since. The discovery was made possible by the Magic Survey that stands for decam mapping the ancient galaxy in cachk, a fifty four to night observing program using the Dark Energy Camera in Chile, combined with the follow up from the Very Large telescopes and the Magellan telescopes. The lead researcher described it as being at the edge of what we thought possible, and I think that phrase captures it perfect because this star isn't just old. It's a direct record of chemical processes that happened when the universe was less than a billion years old. It's a time capsule. The paper is in Nature Astronomy this week. We'll link to the nor Lab press release on the website. They have some spectacular images of picture two. Now. This one is a follow up to a story we covered a few weeks ago, and it is very much a good news update. You'll remember that Europe's Proba three mission, issa's ingenious two satellite formation flying solar science mission, ran into serious trouble in mid February when the Coronagraph spacecraft went completely silent. For those who need the refresher, Proba three consists of two small satellites flying in exquisitely precise formation about one hundred and fifty meters apart, with positioning accuracy of one millimeter. The oculture spacecraft blocks out the bright disc of the Sun, while the Corona gramp photographs the Sun's outer atmosphere, the Corona. It's basically a spacecraft that manufactures artificial solar eclipses on demand in orbit. The sience potential is enormous because the corona is normally invisible from Earth except during the few minutes of a total solar eclipse. But in mid February, an anomaly on the corona graph triggered a cascade of failures. It lost its attitude, its orientation in space, and failed to enter safe mode as expected. ESA spent weeks attempting to regain contact, working through ground stations around the world. And the great news confirmed on March nineteenth, issa's ground station in Via Franca, Spain, received a data packet from the coronagraph. The satellite is alive. It's in safe mode. Its solar panel is facing the sun, powering the electronics and charging the battery. Proba IIE mission manager Damian Galano said, and this is a direct quote from the ESA statement, hearing back from the Corona graph is amazing news and a great relief. Now we should be clear the mission team isn't popping champagne just yet. The satellite has spent a month floating in space, exposed to the deep cold of orbital night, and its systems need time to warm up before any major actions are taken. Health checks are underway to assess whether any damage occurred, but. The spacecraft is stable, the hardware is powered, and if those health checks come back clean, PROBA three could resume its artificial eclipse science program. We'll be following this one closely what. A relief is. Right. We'll link to the full ESA update at Astronomy Daily dot io. And finally, a story that is both a scientific mystery solved and a lovely reminder for why sample return missions matter so much. You'll remember NASA's Osiris REX spacecraft collected samples from asteroid Benin back in twenty twenty, and those samples ared on Earth in twenty twenty three. Well, this week, scientists published results in Nature Communications that finally solve one of Benu's most puzzling features. So here's the mystery. Back in two thousand and seven, NASA's Spitzer space telescope measured what's called low thermal inertia on Benu, meaning the asteroid's surface heats up and cools down rapidly as it rotates on Earth. That's what sand does, which led astronomers to expect Benu's surface would be sandy and smooth, a bit like a beach. And then Osiris Rex arrived in twenty eighteen and found the opposite. The surface was covered in enormous boulders, rough, rocky, definitely not sandy, and these boulders should behave like blocks of concrete, thermally holding heat for hours after the sun goes down, but they weren't. They were losing heat rapidly, just like the original observation suggested. Scientists scratched their heads for years. The boulders were porous. That explained some of the heat loss, but not all of it. The numbers still didn't add. Up, and then they put the actual return samples into an X ray CT scanner, and that's when everything clicked into place. The boulders aren't just porous. They're riddled with an extensive internal network of fine cracks, like a shattered windshield that's still in one piece. The cracks dramatically alter how heat moves through the rock. When scientists ran computer simulations scaling those cracked boulder properties up to the full size of Venu's actual surface, the numbers matched perfectly, right down to what the spacecraft had measured from orbit. The lead researcher, Andrew Ryan from the University of Arizona put it simply, it turns out they're really cracked too, and that was the missing piece of the puzzle. The full citation is in the show notes, and. The implications go way beyond Benu. This work means scientists can now use the thermal properties of an asteroid measured from a telescope on Earth to make much more acuiate at inferences about its internal structure. You no longer need to go there and pick it up to understand it. Which matters enormously for planetary defense. The more accurately we can model asteroid composition and structure from a distance, the better we can predict trajectories, deflection responses, and potential impact hazards. Osyrus Rex keeps on delivering. What an episode to celebrate the first day of spring in the Northern Hemisphere and autumn in the Southern Hemisphere. We had solar storms, an Aurora opportunity, a meteorite hunt in Ohio, one of the oldest stars ever discovered, a satellite that came back from the dead, and an asteroid mystery finally cracked. Not bad for a Friday. If you're an Aurora territory, tonight, get outside, find a dark spot, look north. The sky may reward you. You can find show notes, source links, and skywatching guides at Astronomy Daily dot io. Follow us on x, Instagram, TikTok, YouTube, and tumbler all at astro Daily Pod. If you're enjoying the show, Please leave us a review wherever you get your podcasts. It genuinely helps new listeners find us. Until next time, keep looking up. I'm Anna and I'm Avery. Happy Equinox everyone, Sunday Stars start