Equinox Auroras, Ancient Stars, and a Satellite Resurrection

0:00 Speaker 1: Happy first day of spring everyone, at least if you're

0:03 Speaker 1: in the northern hemisphere.

0:05 Speaker 2: I'm Anna and I'm Avery, And what a day for

0:08 Speaker 2: the cosmos to celebrate with us, because right now, as

0:11 Speaker 2: we're recording, the Sun has fired three enormous blasts of

0:16 Speaker 2: charged particles straight at Earth. A seven ton space rock

0:20 Speaker 2: just lit up the skies over Ohio, a satellite that

0:23 Speaker 2: went silent for a full month has finally phoned home,

0:27 Speaker 2: and astronomers have found a star so old it carries

0:30 Speaker 2: the direct fingerprints of the very first stars that ever existed.

0:35 Speaker 1: Plus, we're going to explain exactly why the equinox and

0:38 Speaker 1: those solar storms are connected. It's one of the most

0:42 Speaker 1: fascinating quirks of Earth's orbit around the Sun, and today

0:45 Speaker 1: is literally the best day of the year to talk

0:48 Speaker 1: about it.

0:49 Speaker 2: This is Astronomy Daily, Season five, episode sixty eight. Let's

0:53 Speaker 2: get into.

0:54 Speaker 1: It, okay, Avery, Before we even get into the equinox itself,

0:58 Speaker 1: we have to talk about what the Sun has been

1:00 Speaker 1: doing this week, because it has been.

1:02 Speaker 2: Busy, extremely busy. So here's a situation. As of today, Friday,

1:07 Speaker 2: the twentieth of March, Earth is being targeted by not one,

1:11 Speaker 2: not two, but three separate coronal mass ejections CMEs all

1:16 Speaker 2: fired off within the last few days.

1:18 Speaker 1: So for anyone who needs a quick refresher, A CME

1:22 Speaker 1: is essentially a massive eruption of plasma and magnetic field

1:26 Speaker 1: from the Sun. When these hit Earth's magnetic field, they

1:29 Speaker 1: compress it cause geomagnetic storms, and most visibly for us

1:33 Speaker 1: down here, they trigger auroras.

1:36 Speaker 2: The first of the three CMEs was expected to arrive today.

1:40 Speaker 2: Forecasters at Noah's Space Weather Prediction Center have issued a

1:43 Speaker 2: geomagnetic storm watch with conditions potentially reaching G two that's

1:48 Speaker 2: moderate with a chance of G three or strong, and

1:52 Speaker 2: that second level G three is where things get really interesting.

1:56 Speaker 1: Because G three conditions could push aurora of ability well

2:01 Speaker 1: into mid latitudes as far south as Illinois, Oregon, potentially

2:06 Speaker 1: even lower under the right conditions. So if you're in

2:08 Speaker 1: the northern US, northern Europe, Canada, tonight is a night

2:13 Speaker 1: to keep an eye on the sky.

2:14 Speaker 2: And there's more to come. A second CME is expected

2:17 Speaker 2: to deliver a glancing blow, and the third, triggered by

2:20 Speaker 2: an M two point seventy five flare from sunspot region

2:25 Speaker 2: AR four three nine two, is expected to arrive around

2:28 Speaker 2: March twenty first, so this isn't a one day event.

2:32 Speaker 2: The Space Weather picture remains active through the weekend.

2:35 Speaker 1: We should also mention we're currently near solar maximum, the

2:39 Speaker 1: peak of the Sun's eleven year cycle, which is part

2:42 Speaker 1: of why we're seeing this kind of activity. Peak activity

2:45 Speaker 1: is expected to continue through the second half of twenty

2:48 Speaker 1: twenty six, so get used to these kinds of alerts.

2:51 Speaker 2: Worth bookmarking Noah's Space Weather Prediction Center spaceweather dot gov

2:56 Speaker 2: for live Aurora forecasts, and on our website at ostrowna

3:00 Speaker 2: medaily dot io, we'll link to some recommended Aurora apps

3:03 Speaker 2: for your phone.

3:04 Speaker 1: Okay, so let's talk about the actual astronomical event that

3:08 Speaker 1: is happening today, the vernal equinox. The twenty twenty six

3:14 Speaker 1: March equinox falls at fourteen forty six UTC this afternoon.

3:20 Speaker 2: At that moment, the Sun crosses the celestial equator, the

3:23 Speaker 2: imaginary line in the sky directly above Earth's equator, moving

3:28 Speaker 2: from south to north, and at that precise moment, every

3:32 Speaker 2: point on Earth receives roughly equal amounts of daylight and darkness.

3:36 Speaker 1: The word equinox comes from the Latin for equal night

3:40 Speaker 1: I equos nooakes. It's the astronomical beginning of spring in

3:44 Speaker 1: the northern hemisphere and autumn in the southern. So if

3:47 Speaker 1: you're listening from Australia or New Zealand, happy autumn to you.

3:51 Speaker 2: And here's the thing that connects this equinox directly to

3:54 Speaker 2: the aurora story we just told. There's a phenomenon called

3:58 Speaker 2: the Russell Macphear in effect, named after the two scientists

4:01 Speaker 2: who identified it, and it specifically amplifies aurora activity around

4:06 Speaker 2: the equinoxes.

4:07 Speaker 1: Right basically around the equinoxes, Earth's magnetic field orientation is

4:12 Speaker 1: particularly favorable for coupling with the solar wind. The geometry

4:16 Speaker 1: of our planet's tilt relative to the Sun means incoming

4:20 Speaker 1: charged particles from CMEs interact more efficiently with our magnetosphere.

4:25 Speaker 2: So what this means in practice is the equinoxes are

4:28 Speaker 2: historically the best times of year to see auroras, even

4:32 Speaker 2: when the Sun isn't being especially active. When you combine

4:35 Speaker 2: a natural peak and aurora probability with three incoming CMEs

4:39 Speaker 2: on the same day, well, today is genuinely a special

4:43 Speaker 2: aurora opportunity.

4:45 Speaker 1: And there's a lovely bonus for skywatchers this evening. After

4:49 Speaker 1: sunset today, look to the west southwest and you'll be

4:52 Speaker 1: able to spot a thin, five percent lit, waxing crescent

4:57 Speaker 1: moon glowing just above Venus. Spring evenings don't get much

5:01 Speaker 1: more beautiful than.

5:02 Speaker 2: That equinox Aurora's crescent moon Venus, and I feel like

5:08 Speaker 2: the Universe planned this episode.

5:11 Speaker 1: I am starting to think so too. Check Astronomy Daily

5:14 Speaker 1: dot io for skywatching links for tonight.

5:17 Speaker 2: Okay, shifting from things you need to look up for

5:21 Speaker 2: to something that came down from above rather dramatically. On Tuesday,

5:25 Speaker 2: Saint Patrick's Day, thousands of people across the American Midwest

5:29 Speaker 2: experienced quite the green tinged morning, and not just from

5:33 Speaker 2: the holiday.

5:34 Speaker 1: At around eight fifty seven in the morning, a seven

5:38 Speaker 1: ton asteroid roughly six feet in diameter, entered the atmosphere

5:42 Speaker 1: above Lake Erie near Lorraine, Ohio, and moved southeast at

5:47 Speaker 1: around forty thousand miles per hour before fragmenting about thirty

5:52 Speaker 1: miles above Valley City.

5:54 Speaker 2: The explosion had the energy equivalent of two hundred and

5:58 Speaker 2: fifty tons of TNT, and it produced multiple sonic booms

6:02 Speaker 2: that were heard and felt across northeast Ohio and into Pennsylvania,

6:07 Speaker 2: New York and beyond. Some reports came in as far

6:10 Speaker 2: as Ontario and Canada.

6:12 Speaker 1: People were flooding nine to one one lines thinking it

6:15 Speaker 1: was an earthquake or an explosion or actually there was

6:19 Speaker 1: quite a creative range of theories on social media. But

6:23 Speaker 1: NASA's Meteoroid Environment's Office confirmed the medior quickly and tracked

6:28 Speaker 1: its trajectory precisely.

6:30 Speaker 2: And here's the exciting follow up that's still unfolding. NASA

6:34 Speaker 2: confirmed meteorites, actual fragments that survived the journey to the

6:38 Speaker 2: ground landed in the vicinity of Medina County, Ohio, and

6:42 Speaker 2: the meteorite hunting community has mobilized in a spectacular fashion.

6:47 Speaker 1: Within days, hunters from Connecticut, South Carolina, and multiple other

6:51 Speaker 1: states were converging on a small town called Sharon Center.

6:55 Speaker 1: At least one hunter found a twelve point two gram

6:58 Speaker 1: fragment found pieces in a parking lot, and the hunt

7:03 Speaker 1: is still very much on.

7:05 Speaker 2: Daytime. Fireballs this bright are genuinely rare. An amateur astronomer

7:09 Speaker 2: in the area sets something along the lines of to

7:12 Speaker 2: see a fireball in the daytime, it has to be

7:15 Speaker 2: extraordinarily bright, and the fact that it created multiple signing

7:19 Speaker 2: booms over a populated area is something that happens, perhaps

7:22 Speaker 2: once in a lifetime.

7:24 Speaker 1: If you're in the Medina County area and you spot

7:27 Speaker 1: a dark rock with a shiny exterior or a gray

7:30 Speaker 1: interior that looks slightly out of place, it might be

7:33 Speaker 1: worth a closer look. NASA's guidance is to photograph it

7:37 Speaker 1: without disturbing it and contact a local university geology department,

7:42 Speaker 1: and absolutely do not pick it up without checking the rules.

7:46 Speaker 1: Meteorites have real scientific value.

7:49 Speaker 2: Happy hunting, Ohio, All right.

7:52 Speaker 1: From things falling to Earth to a star so old

7:55 Speaker 1: it predates almost everything we can see in the modern universe.

8:00 Speaker 1: This week in the journal Nature Astronomy, a team led

8:03 Speaker 1: by anarud Cheaty of Stanford University published a discovery that

8:08 Speaker 1: is being called, and I love this phrase, cosmic archaeology.

8:13 Speaker 2: So let's set the scene. In the very early universe.

8:16 Speaker 2: The first stars were enormous and formed from just three

8:20 Speaker 2: elements hydrogen, helium, and a tiny bit of lithium. That

8:24 Speaker 2: was it. Those were the only elements that existed. No carbon,

8:28 Speaker 2: no iron, no oxygen, none of the building blocks of chemistry.

8:32 Speaker 2: As we know it.

8:33 Speaker 1: These first stars, called Population three stars burned fast and hot,

8:39 Speaker 1: and when they exploded as supernovae, they scattered the first

8:43 Speaker 1: heavy elements into the surrounding gas clouds. The next generation

8:47 Speaker 1: of stars, population two, formed from that enriched material.

8:52 Speaker 2: And that's what makes this week's discovery so extraordinary. Astronomers

8:57 Speaker 2: have found a star called Picked two Dash five zero

9:00 Speaker 2: three sitting in a tiny ancient dwarf galaxy called Picter two,

9:06 Speaker 2: located about one hundred and fifty thousand light years from Earth.

9:10 Speaker 2: And this star contains virtually no iron, less than one

9:15 Speaker 2: forty thousandth of the iron in our Sun.

9:18 Speaker 1: To put that in perspective, our Sun is a third

9:21 Speaker 1: generation star. Picked two five oh three is second generation.

9:26 Speaker 1: It formed from the direct debris of the universe's very

9:29 Speaker 1: first stars. It is quite literally carrying the chemical fingerprints

9:34 Speaker 1: of stars that no longer exist anywhere in the observable universe.

9:39 Speaker 2: The star also has an extraordinary overabundance of carbon, about

9:44 Speaker 2: fifteen hundred times more carbon relative to iron than our Sun,

9:48 Speaker 2: and this is the key to unlocking a mystery that

9:51 Speaker 2: astronomers have puzzled over for years.

9:54 Speaker 1: There's a whole class of stars in the outer halo

9:57 Speaker 1: of our Milky Way called carbon enhanced metal poor stars

10:01 Speaker 1: that show this same bizarre signature high carbon almost no iron.

10:06 Speaker 1: Scientists knew they were ancient, but they couldn't explain where

10:10 Speaker 1: they originally formed because our galaxy has been cannibalizing smaller

10:14 Speaker 1: galaxies for billions of years, scattering stars far from their birthplaces.

10:19 Speaker 2: Picked two five oh three is the missing link. It

10:23 Speaker 2: shows that these mysterious halo stars were born in tiny,

10:27 Speaker 2: primitive dwarf galaxies like picture two, galaxies that formed early

10:32 Speaker 2: in cosmic history and haven't changed much since. The discovery

10:36 Speaker 2: was made possible by the Magic Survey that stands for

10:39 Speaker 2: decam mapping the ancient galaxy in cachk, a fifty four

10:44 Speaker 2: to night observing program using the Dark Energy Camera in Chile,

10:48 Speaker 2: combined with the follow up from the Very Large telescopes

10:51 Speaker 2: and the Magellan telescopes.

10:53 Speaker 1: The lead researcher described it as being at the edge

10:56 Speaker 1: of what we thought possible, and I think that phrase

10:58 Speaker 1: captures it perfect because this star isn't just old. It's

11:02 Speaker 1: a direct record of chemical processes that happened when the

11:06 Speaker 1: universe was less than a billion years old. It's a

11:09 Speaker 1: time capsule.

11:10 Speaker 2: The paper is in Nature Astronomy this week. We'll link

11:13 Speaker 2: to the nor Lab press release on the website. They

11:16 Speaker 2: have some spectacular images of picture two.

11:19 Speaker 1: Now. This one is a follow up to a story

11:21 Speaker 1: we covered a few weeks ago, and it is very

11:24 Speaker 1: much a good news update. You'll remember that Europe's Proba

11:28 Speaker 1: three mission, issa's ingenious two satellite formation flying solar science mission,

11:34 Speaker 1: ran into serious trouble in mid February when the Coronagraph

11:38 Speaker 1: spacecraft went completely silent.

11:41 Speaker 2: For those who need the refresher, Proba three consists of

11:45 Speaker 2: two small satellites flying in exquisitely precise formation about one

11:49 Speaker 2: hundred and fifty meters apart, with positioning accuracy of one millimeter.

11:55 Speaker 2: The oculture spacecraft blocks out the bright disc of the Sun,

11:59 Speaker 2: while the Corona gramp photographs the Sun's outer atmosphere, the Corona.

12:04 Speaker 1: It's basically a spacecraft that manufactures artificial solar eclipses on

12:09 Speaker 1: demand in orbit. The sience potential is enormous because the

12:13 Speaker 1: corona is normally invisible from Earth except during the few

12:17 Speaker 1: minutes of a total solar eclipse.

12:20 Speaker 2: But in mid February, an anomaly on the corona graph

12:23 Speaker 2: triggered a cascade of failures. It lost its attitude, its

12:27 Speaker 2: orientation in space, and failed to enter safe mode as expected.

12:32 Speaker 2: ESA spent weeks attempting to regain contact, working through ground

12:36 Speaker 2: stations around the world.

12:38 Speaker 1: And the great news confirmed on March nineteenth, issa's ground

12:42 Speaker 1: station in Via Franca, Spain, received a data packet from

12:46 Speaker 1: the coronagraph. The satellite is alive. It's in safe mode.

12:50 Speaker 1: Its solar panel is facing the sun, powering the electronics

12:54 Speaker 1: and charging the battery.

12:55 Speaker 2: Proba IIE mission manager Damian Galano said, and this is

12:59 Speaker 2: a direct quote from the ESA statement, hearing back from

13:02 Speaker 2: the Corona graph is amazing news and a great relief.

13:06 Speaker 1: Now we should be clear the mission team isn't popping

13:09 Speaker 1: champagne just yet. The satellite has spent a month floating

13:13 Speaker 1: in space, exposed to the deep cold of orbital night,

13:18 Speaker 1: and its systems need time to warm up before any

13:21 Speaker 1: major actions are taken. Health checks are underway to assess

13:25 Speaker 1: whether any damage occurred, but.

13:27 Speaker 2: The spacecraft is stable, the hardware is powered, and if

13:31 Speaker 2: those health checks come back clean, PROBA three could resume

13:34 Speaker 2: its artificial eclipse science program. We'll be following this one

13:37 Speaker 2: closely what.

13:39 Speaker 1: A relief is. Right. We'll link to the full ESA

13:42 Speaker 1: update at Astronomy Daily dot io.

13:44 Speaker 2: And finally, a story that is both a scientific mystery

13:48 Speaker 2: solved and a lovely reminder for why sample return missions

13:51 Speaker 2: matter so much. You'll remember NASA's Osiris REX spacecraft collected

13:56 Speaker 2: samples from asteroid Benin back in twenty twenty, and those

13:59 Speaker 2: samples ared on Earth in twenty twenty three. Well, this week,

14:03 Speaker 2: scientists published results in Nature Communications that finally solve one

14:07 Speaker 2: of Benu's most puzzling features.

14:10 Speaker 1: So here's the mystery. Back in two thousand and seven,

14:13 Speaker 1: NASA's Spitzer space telescope measured what's called low thermal inertia

14:18 Speaker 1: on Benu, meaning the asteroid's surface heats up and cools

14:22 Speaker 1: down rapidly as it rotates on Earth. That's what sand does,

14:26 Speaker 1: which led astronomers to expect Benu's surface would be sandy

14:30 Speaker 1: and smooth, a bit like a beach.

14:32 Speaker 2: And then Osiris Rex arrived in twenty eighteen and found

14:36 Speaker 2: the opposite. The surface was covered in enormous boulders, rough, rocky,

14:41 Speaker 2: definitely not sandy, and these boulders should behave like blocks

14:45 Speaker 2: of concrete, thermally holding heat for hours after the sun

14:48 Speaker 2: goes down, but they weren't. They were losing heat rapidly,

14:52 Speaker 2: just like the original observation suggested.

14:55 Speaker 1: Scientists scratched their heads for years. The boulders were porous.

14:59 Speaker 1: That explained some of the heat loss, but not all

15:02 Speaker 1: of it. The numbers still didn't add.

15:04 Speaker 2: Up, and then they put the actual return samples into

15:08 Speaker 2: an X ray CT scanner, and that's when everything clicked

15:11 Speaker 2: into place. The boulders aren't just porous. They're riddled with

15:14 Speaker 2: an extensive internal network of fine cracks, like a shattered

15:18 Speaker 2: windshield that's still in one piece. The cracks dramatically alter

15:22 Speaker 2: how heat moves through the rock.

15:24 Speaker 1: When scientists ran computer simulations scaling those cracked boulder properties

15:29 Speaker 1: up to the full size of Venu's actual surface, the

15:32 Speaker 1: numbers matched perfectly, right down to what the spacecraft had

15:36 Speaker 1: measured from orbit.

15:37 Speaker 2: The lead researcher, Andrew Ryan from the University of Arizona

15:41 Speaker 2: put it simply, it turns out they're really cracked too,

15:44 Speaker 2: and that was the missing piece of the puzzle. The

15:46 Speaker 2: full citation is in the show notes, and.

15:49 Speaker 1: The implications go way beyond Benu. This work means scientists

15:53 Speaker 1: can now use the thermal properties of an asteroid measured

15:57 Speaker 1: from a telescope on Earth to make much more acuiate

16:00 Speaker 1: at inferences about its internal structure. You no longer need

16:03 Speaker 1: to go there and pick it up to understand it.

16:06 Speaker 2: Which matters enormously for planetary defense. The more accurately we

16:10 Speaker 2: can model asteroid composition and structure from a distance, the

16:13 Speaker 2: better we can predict trajectories, deflection responses, and potential impact hazards.

16:18 Speaker 2: Osyrus Rex keeps on delivering.

16:21 Speaker 1: What an episode to celebrate the first day of spring

16:24 Speaker 1: in the Northern Hemisphere and autumn in the Southern Hemisphere.

16:28 Speaker 1: We had solar storms, an Aurora opportunity, a meteorite hunt

16:32 Speaker 1: in Ohio, one of the oldest stars ever discovered, a

16:36 Speaker 1: satellite that came back from the dead, and an asteroid

16:39 Speaker 1: mystery finally cracked. Not bad for a Friday.

16:42 Speaker 2: If you're an Aurora territory, tonight, get outside, find a

16:46 Speaker 2: dark spot, look north. The sky may reward you.

16:49 Speaker 1: You can find show notes, source links, and skywatching guides

16:53 Speaker 1: at Astronomy Daily dot io. Follow us on x, Instagram, TikTok, YouTube,

16:59 Speaker 1: and tumbler all at astro Daily Pod.

17:02 Speaker 2: If you're enjoying the show, Please leave us a review

17:04 Speaker 2: wherever you get your podcasts. It genuinely helps new listeners

17:08 Speaker 2: find us.

17:09 Speaker 1: Until next time, keep looking up.

17:11 Speaker 2: I'm Anna and I'm Avery. Happy Equinox everyone, Sunday Stars

17:26 Speaker 2: start