00:00:00 --> 00:00:02 Happy first day of spring, everyone. At
00:00:02 --> 00:00:04 least if you're in the northern
00:00:04 --> 00:00:06 hemisphere. I'm Anna.
00:00:06 --> 00:00:08 >> And I'm Avery. And what a day for the
00:00:08 --> 00:00:11 cosmos to celebrate with us. Because
00:00:11 --> 00:00:13 right now, as we're recording, the sun
00:00:13 --> 00:00:15 has fired three enormous blasts of
00:00:16 --> 00:00:19 charged particles straight at Earth. A 7
00:00:19 --> 00:00:21 ton space rock just lit up the skies
00:00:21 --> 00:00:24 over Ohio. A satellite that went silent
00:00:24 --> 00:00:26 for a full month has finally phoned
00:00:26 --> 00:00:29 home. And astronomers have found a star
00:00:29 --> 00:00:31 so old it carries the direct
00:00:31 --> 00:00:33 fingerprints of the very first stars
00:00:33 --> 00:00:35 that ever existed.
00:00:35 --> 00:00:37 >> Plus, we're going to explain exactly why
00:00:38 --> 00:00:40 the equinox and those solar storms are
00:00:40 --> 00:00:42 connected. It's one of the most
00:00:42 --> 00:00:44 fascinating quirks of Earth's orbit
00:00:44 --> 00:00:46 around the sun. And today is literally
00:00:46 --> 00:00:48 the best day of the year to talk about
00:00:48 --> 00:00:49 it.
00:00:49 --> 00:00:51 >> This is Astronomy Daily, season 5,
00:00:52 --> 00:00:54 episode 68. Let's get into it. Okay,
00:00:54 --> 00:00:56 Avery, before we even get into the
00:00:56 --> 00:00:59 equinox itself, we have to talk about
00:00:59 --> 00:01:01 what the sun has been doing this week
00:01:01 --> 00:01:03 because it has been busy.
00:01:03 --> 00:01:06 >> Extremely busy. So, here's a situation.
00:01:06 --> 00:01:09 As of today, Friday the 20th of March.
00:01:09 --> 00:01:11 Earth is being targeted by not one, not
00:01:11 --> 00:01:14 two, but three separate coronal mass
00:01:14 --> 00:01:17 ejections, CMEs, all fired off within
00:01:17 --> 00:01:20 the last few days. So, for anyone who
00:01:20 --> 00:01:22 needs a quick refresher, a CME is
00:01:22 --> 00:01:25 essentially a massive eruption of plasma
00:01:25 --> 00:01:27 and magnetic field from the sun. When
00:01:27 --> 00:01:29 these hit Earth's magnetic fields, they
00:01:29 --> 00:01:32 compress it, cause geomagnetic storms,
00:01:32 --> 00:01:34 and most visibly for us down here, they
00:01:34 --> 00:01:36 trigger auroras.
00:01:36 --> 00:01:38 >> The first of the three CMEs was expected
00:01:38 --> 00:01:41 to arrive today. Forecasters at Noah's
00:01:41 --> 00:01:43 Space Weather Prediction Center have
00:01:43 --> 00:01:45 issued a geomagnetic storm watch with
00:01:46 --> 00:01:48 conditions potentially reaching G2.
00:01:48 --> 00:01:51 That's moderate with a chance of G3 or
00:01:51 --> 00:01:55 strong. And that second level, G3, is
00:01:55 --> 00:01:56 where things get really interesting
00:01:56 --> 00:01:59 >> because G3 conditions could push aurora
00:02:00 --> 00:02:02 visibility well into mid latitudes as
00:02:02 --> 00:02:05 far south as Illinois, Oregon,
00:02:05 --> 00:02:07 potentially even lower under the right
00:02:07 --> 00:02:09 conditions. So, if you're in the
00:02:09 --> 00:02:11 northern US, northern Europe, Canada,
00:02:12 --> 00:02:14 tonight is a night to keep an eye on the
00:02:14 --> 00:02:14 sky.
00:02:14 --> 00:02:17 >> And there's more to come. A second CME
00:02:17 --> 00:02:19 is expected to deliver a glancing blow.
00:02:19 --> 00:02:22 And the third, triggered by an M2.75
00:02:22 --> 00:02:27 flare from sunspot region AR4392
00:02:27 --> 00:02:30 is expected to arrive around March 21st.
00:02:30 --> 00:02:32 So, this isn't a one-day event. The
00:02:32 --> 00:02:34 space weather picture remains active
00:02:34 --> 00:02:35 through the weekend.
00:02:35 --> 00:02:37 >> We should also mention we're currently
00:02:37 --> 00:02:40 near solar maximum, the peak of the
00:02:40 --> 00:02:42 sun's 11-year cycle, which is part of
00:02:42 --> 00:02:44 why we're seeing this kind of activity.
00:02:44 --> 00:02:47 Peak activity is expected to continue
00:02:47 --> 00:02:50 through the second half of 2026. So get
00:02:50 --> 00:02:51 used to these kinds of alerts.
00:02:51 --> 00:02:53 >> Worth bookmarking Noah's space weather
00:02:54 --> 00:02:56 prediction center, spaceweather.gov,
00:02:56 --> 00:02:59 for live aurora forecasts. And on our
00:02:59 --> 00:03:01 website at astronomydaily.io,
00:03:01 --> 00:03:03 we'll link to some recommended aurora
00:03:03 --> 00:03:04 apps for your phone.
00:03:04 --> 00:03:07 >> Okay, so let's talk about the actual
00:03:07 --> 00:03:09 astronomical event that is happening
00:03:09 --> 00:03:13 today, the vernal equinox. The 2026
00:03:14 --> 00:03:17 March equinox falls at 14:46
00:03:17 --> 00:03:20 UTC this afternoon.
00:03:20 --> 00:03:22 >> At that moment, the sun crosses the
00:03:22 --> 00:03:25 celestial equator, the imaginary line in
00:03:25 --> 00:03:28 the sky directly above Earth's equator,
00:03:28 --> 00:03:30 moving from south to north. And at that
00:03:30 --> 00:03:33 precise moment, every point on Earth
00:03:33 --> 00:03:35 receives roughly equal amounts of
00:03:35 --> 00:03:36 daylight and darkness.
00:03:36 --> 00:03:39 >> The word equinox comes from the Latin
00:03:39 --> 00:03:41 for equal night.
00:03:41 --> 00:03:43 It's the astronomical beginning of
00:03:43 --> 00:03:45 spring in the northern hemisphere and
00:03:45 --> 00:03:47 autumn in the southern. So if you're
00:03:47 --> 00:03:50 listening from Australia or New Zealand,
00:03:50 --> 00:03:51 happy autumn to you.
00:03:51 --> 00:03:53 >> And here's the thing that connects this
00:03:53 --> 00:03:56 equinox directly to the aurora story we
00:03:56 --> 00:03:58 just told. There's a phenomenon called
00:03:58 --> 00:04:00 the Russell McFaran effect named after
00:04:00 --> 00:04:02 the two scientists who identified it.
00:04:02 --> 00:04:05 And it specifically amplifies aurora
00:04:05 --> 00:04:07 activity around the equinoxes.
00:04:07 --> 00:04:10 >> Right? Basically around the equinoxes,
00:04:10 --> 00:04:12 Earth's magnetic field orientation is
00:04:12 --> 00:04:14 particularly favorable for coupling with
00:04:14 --> 00:04:16 the solar wind. The geometry of our
00:04:16 --> 00:04:19 planet's tilt relative to the sun means
00:04:19 --> 00:04:22 incoming charged particles from CMEs
00:04:22 --> 00:04:23 interact more efficiently with our
00:04:24 --> 00:04:26 magnetosphere. So what this means in
00:04:26 --> 00:04:28 practice is the equinoxes are
00:04:28 --> 00:04:30 historically the best times of year to
00:04:30 --> 00:04:33 see auroras even when the sun isn't
00:04:33 --> 00:04:35 being especially active. When you
00:04:35 --> 00:04:37 combine a natural peak in aurora
00:04:37 --> 00:04:39 probability with three incoming CMEs on
00:04:39 --> 00:04:43 the same day, well, today is genuinely a
00:04:43 --> 00:04:46 special aurora opportunity. And there's
00:04:46 --> 00:04:48 a lovely bonus for sky watchers this
00:04:48 --> 00:04:51 evening. After sunset today, look to the
00:04:51 --> 00:04:53 west southwest and you'll be able to
00:04:53 --> 00:04:57 spot a thin 5% lit waxing crescent moon
00:04:57 --> 00:05:00 glowing just above Venus. Spring
00:05:00 --> 00:05:02 evenings don't get much more beautiful
00:05:02 --> 00:05:05 than that. Equinox, auroras, crescent
00:05:05 --> 00:05:08 moon, Venus. Anna, I feel like the
00:05:08 --> 00:05:11 universe planned this episode.
00:05:11 --> 00:05:13 >> I am starting to think so, too. Check
00:05:13 --> 00:05:15 astronomyaily.io
00:05:15 --> 00:05:18 for skywatching links for tonight.
00:05:18 --> 00:05:20 >> Okay, shifting from things you need to
00:05:20 --> 00:05:22 look up for to something that came down
00:05:22 --> 00:05:25 from above rather dramatically on
00:05:25 --> 00:05:27 Tuesday, St. Patrick's Day. Thousands of
00:05:28 --> 00:05:29 people across the American Midwest
00:05:30 --> 00:05:32 experienced quite the green tinged
00:05:32 --> 00:05:34 morning. And not just from the holiday.
00:05:34 --> 00:05:38 >> At around 8:57 in the morning, a 7 ton
00:05:38 --> 00:05:41 asteroid roughly 6 feet in diameter
00:05:41 --> 00:05:44 entered the atmosphere above Lake Erie
00:05:44 --> 00:05:47 near Lraine, Ohio, and moved southeast
00:05:47 --> 00:05:51 at around 40 mph before fragmenting
00:05:51 --> 00:05:55 about 30 m above Valley City. The
00:05:55 --> 00:05:57 explosion had the energy equivalent of
00:05:57 --> 00:06:01 250 tons of TNT, and it produced
00:06:01 --> 00:06:03 multiple sonic booms that were heard and
00:06:03 --> 00:06:06 felt across northeast Ohio, and into
00:06:06 --> 00:06:09 Pennsylvania, New York, and beyond. Some
00:06:09 --> 00:06:12 reports came in as far as Ontario and
00:06:12 --> 00:06:13 Canada.
00:06:13 --> 00:06:15 >> People were flooding 911 lines thinking
00:06:15 --> 00:06:18 it was an earthquake or an explosion, or
00:06:18 --> 00:06:20 actually, there was quite a creative
00:06:20 --> 00:06:23 range of theories on social media. But
00:06:23 --> 00:06:25 NASA's Meteoroid Environments Office
00:06:25 --> 00:06:28 confirmed the meteor quickly and tracked
00:06:28 --> 00:06:30 its trajectory precisely.
00:06:30 --> 00:06:32 >> And here's the exciting follow-up that's
00:06:32 --> 00:06:34 still unfolding. NASA confirmed
00:06:34 --> 00:06:37 meteorites, actual fragments that
00:06:37 --> 00:06:39 survived the journey to the ground,
00:06:39 --> 00:06:41 landed in the vicinity of Medina County,
00:06:41 --> 00:06:43 Ohio. And the meteorite hunting
00:06:43 --> 00:06:46 community has mobilized in a spectacular
00:06:46 --> 00:06:48 fashion. Within days, hunters from
00:06:48 --> 00:06:50 Connecticut, South Carolina, and
00:06:50 --> 00:06:53 multiple other states were converging on
00:06:53 --> 00:06:55 a small town called Sharon Center. At
00:06:55 --> 00:06:58 least one hunter found a 12.2 g
00:06:58 --> 00:07:01 fragment. Another found pieces in a
00:07:01 --> 00:07:03 parking lot, and the hunt is still very
00:07:04 --> 00:07:07 much on. Daytime fireballs this bright
00:07:07 --> 00:07:09 are genuinely rare. An amateur
00:07:09 --> 00:07:11 astronomer in the area said something
00:07:11 --> 00:07:13 along the lines of, "To see a fireball
00:07:13 --> 00:07:15 in the daytime, it has to be
00:07:15 --> 00:07:17 extraordinarily bright." And the fact
00:07:17 --> 00:07:19 that it created multiple sonic booms
00:07:19 --> 00:07:21 over a populated area is something that
00:07:21 --> 00:07:24 happens perhaps once in a lifetime. If
00:07:24 --> 00:07:26 you're in the Medina County area and you
00:07:26 --> 00:07:29 spot a dark rock with a shiny exterior
00:07:29 --> 00:07:32 or a gray interior that looks slightly
00:07:32 --> 00:07:34 out of place, it might be worth a closer
00:07:34 --> 00:07:37 look. NASA's guidance is to photograph
00:07:37 --> 00:07:39 it without disturbing it and contact a
00:07:40 --> 00:07:43 local university geology department and
00:07:43 --> 00:07:45 absolutely do not pick it up without
00:07:45 --> 00:07:48 checking the rules. Meteorites have real
00:07:48 --> 00:07:49 scientific value.
00:07:49 --> 00:07:51 >> Happy hunting, Ohio.
00:07:51 --> 00:07:53 >> All right. From things falling to Earth
00:07:53 --> 00:07:57 to a star so old it predates almost
00:07:57 --> 00:07:59 everything we can see in the modern
00:07:59 --> 00:08:01 universe. This week in the journal
00:08:01 --> 00:08:04 Nature Astronomy, a team led by Anna
00:08:04 --> 00:08:07 Rude Chitty of Stanford University
00:08:07 --> 00:08:09 published a discovery that is being
00:08:09 --> 00:08:11 called, and I love this phrase, cosmic
00:08:11 --> 00:08:13 archaeology.
00:08:13 --> 00:08:15 >> So, let's set the scene. In the very
00:08:15 --> 00:08:18 early universe, the first stars were
00:08:18 --> 00:08:20 enormous and formed from just three
00:08:20 --> 00:08:23 elements: hydrogen, helium, and a tiny
00:08:23 --> 00:08:25 bit of lithium. That was it. Those were
00:08:25 --> 00:08:28 the only elements that existed. No
00:08:28 --> 00:08:31 carbon, no iron, no oxygen, none of the
00:08:31 --> 00:08:33 building blocks of chemistry as we know
00:08:33 --> 00:08:33 it.
00:08:33 --> 00:08:37 >> These first stars, called population 3
00:08:37 --> 00:08:40 stars, burned fast and hot. And when
00:08:40 --> 00:08:42 they exploded as supernova, they
00:08:42 --> 00:08:44 scattered the first heavy elements into
00:08:44 --> 00:08:47 the surrounding gas clouds. The next
00:08:47 --> 00:08:49 generation of stars, population 2,
00:08:49 --> 00:08:52 formed from that enriched material.
00:08:52 --> 00:08:54 >> And that's what makes this week's
00:08:54 --> 00:08:57 discovery so extraordinary. Astronomers
00:08:57 --> 00:09:01 have found a star called PIC 2-503
00:09:01 --> 00:09:04 sitting in a tiny ancient dwarf galaxy
00:09:04 --> 00:09:09 called Pictor 2, located about 150
00:09:09 --> 00:09:11 light years from Earth. And this star
00:09:11 --> 00:09:15 contains virtually no iron, less than
00:09:15 --> 00:09:18 140th of the iron in our sun.
00:09:18 --> 00:09:20 >> To put that in perspective, our sun is a
00:09:20 --> 00:09:24 third generation star. Picked 25503 is
00:09:24 --> 00:09:27 second generation. It formed from the
00:09:27 --> 00:09:29 direct debris of the universe's very
00:09:29 --> 00:09:32 first stars. It is quite literally
00:09:32 --> 00:09:34 carrying the chemical fingerprints of
00:09:34 --> 00:09:37 stars that no longer exist anywhere in
00:09:37 --> 00:09:40 the observable universe. The star also
00:09:40 --> 00:09:42 has an extraordinary overabundance of
00:09:42 --> 00:09:46 carbon, about 1 times more carbon
00:09:46 --> 00:09:49 relative to iron than our sun. And this
00:09:49 --> 00:09:51 is the key to unlocking a mystery that
00:09:51 --> 00:09:54 astronomers have puzzled over for years.
00:09:54 --> 00:09:56 There's a whole class of stars in the
00:09:56 --> 00:09:58 outer halo of our Milky Way called
00:09:58 --> 00:10:01 carbon-enhanced metal pore stars that
00:10:01 --> 00:10:04 show this same bizarre signature. High
00:10:04 --> 00:10:07 carbon, almost no iron. Scientists knew
00:10:07 --> 00:10:09 they were ancient, but they couldn't
00:10:09 --> 00:10:11 explain where they originally formed.
00:10:12 --> 00:10:13 Because our galaxy has been
00:10:13 --> 00:10:15 cannibalizing smaller galaxies for
00:10:15 --> 00:10:18 billions of years, scattering stars far
00:10:18 --> 00:10:19 from their birthplaces.
00:10:19 --> 00:10:23 >> Picked 25503 is the missing link. It
00:10:23 --> 00:10:25 shows that these mysterious halo stars
00:10:26 --> 00:10:28 were born in tiny primitive dwarf
00:10:28 --> 00:10:31 galaxies like picture 2. Galaxies that
00:10:31 --> 00:10:33 formed early in cosmic history and
00:10:33 --> 00:10:35 haven't changed much since. The
00:10:35 --> 00:10:37 discovery was made possible by the magic
00:10:37 --> 00:10:40 survey. That stands for DAM mapping the
00:10:40 --> 00:10:44 ancient galaxy in CHK. A 54night
00:10:44 --> 00:10:46 observing program using the dark energy
00:10:46 --> 00:10:49 camera in Chile combined with a followup
00:10:49 --> 00:10:51 from the very large telescopes and the
00:10:51 --> 00:10:53 Mellan telescopes.
00:10:53 --> 00:10:55 >> The lead researcher described it as
00:10:55 --> 00:10:56 being at the edge of what we thought
00:10:56 --> 00:10:58 possible. And I think that phrase
00:10:58 --> 00:11:01 captures it perfectly because this star
00:11:01 --> 00:11:04 isn't just old. It's a direct record of
00:11:04 --> 00:11:05 chemical processes that happened when
00:11:05 --> 00:11:07 the universe was less than a billion
00:11:07 --> 00:11:10 years old. It's a time capsule.
00:11:10 --> 00:11:12 >> The paper is in Nature Astronomy this
00:11:12 --> 00:11:14 week. We'll link to the Nor lab press
00:11:14 --> 00:11:16 release on the website. They have some
00:11:16 --> 00:11:19 spectacular images of Pictor 2.
00:11:19 --> 00:11:21 >> Now, this one is a followup to a story
00:11:21 --> 00:11:23 we covered a few weeks ago, and it is
00:11:24 --> 00:11:26 very much a good news update. You'll
00:11:26 --> 00:11:29 remember that Europe's proba 3 mission,
00:11:29 --> 00:11:32 issa's ingenious two satellite formation
00:11:32 --> 00:11:35 flying solar science mission ran into
00:11:35 --> 00:11:38 serious trouble in midFebruary when the
00:11:38 --> 00:11:40 coronagraph spacecraft went completely
00:11:40 --> 00:11:42 silent. For those who need the
00:11:42 --> 00:11:45 refresher, proba 3 consists of two small
00:11:45 --> 00:11:48 satellites flying in exquisitly precise
00:11:48 --> 00:11:51 formation about 150 m apart with
00:11:52 --> 00:11:55 positioning accuracy of 1 mm. The
00:11:55 --> 00:11:57 oultter spacecraft blocks out the bright
00:11:57 --> 00:12:00 disc of the sun, while the coronagraph
00:12:00 --> 00:12:02 photographs the sun's outer atmosphere,
00:12:02 --> 00:12:05 the corona. It's basically a spacecraft
00:12:05 --> 00:12:08 that manufactures artificial solar
00:12:08 --> 00:12:11 eclipses on demand in orbit. The science
00:12:11 --> 00:12:14 potential is enormous because the corona
00:12:14 --> 00:12:16 is normally invisible from Earth except
00:12:16 --> 00:12:19 during the few minutes of a total solar
00:12:19 --> 00:12:22 eclipse. But in midFebruary, an anomaly
00:12:22 --> 00:12:24 on the coronagraph triggered a cascade
00:12:24 --> 00:12:27 of failures. It lost its attitude, its
00:12:27 --> 00:12:29 orientation in space, and failed to
00:12:30 --> 00:12:33 enter safe mode as expected. ESA spent
00:12:33 --> 00:12:35 weeks attempting to regain contact,
00:12:35 --> 00:12:37 working through ground stations around
00:12:37 --> 00:12:40 the world. And the great news confirmed
00:12:40 --> 00:12:43 on March 19th, issa's ground station in
00:12:43 --> 00:12:46 Vafrana, Spain, received a data packet
00:12:46 --> 00:12:48 from the coronagraph. The satellite is
00:12:48 --> 00:12:51 alive. It's in safe mode. Its solar
00:12:51 --> 00:12:53 panel is facing the sun, powering the
00:12:53 --> 00:12:55 electronics and charging the battery.
00:12:55 --> 00:12:58 >> Proba 3 mission manager Damian Galano
00:12:58 --> 00:13:00 said, and this is a direct quote from
00:13:00 --> 00:13:03 the ESA statement. Hearing back from the
00:13:03 --> 00:13:05 coronagraph is amazing news and a great
00:13:05 --> 00:13:06 relief.
00:13:06 --> 00:13:08 >> Now, we should be clear, the mission
00:13:08 --> 00:13:11 team isn't popping champagne just yet.
00:13:11 --> 00:13:13 The satellite has spent a month floating
00:13:13 --> 00:13:17 in space, exposed to the deep cold of
00:13:17 --> 00:13:19 orbital night, and its systems need time
00:13:19 --> 00:13:22 to warm up before any major actions are
00:13:22 --> 00:13:24 taken. Health checks are underway to
00:13:24 --> 00:13:27 assess whether any damage occurred.
00:13:27 --> 00:13:29 >> But the spacecraft is stable. The
00:13:29 --> 00:13:31 hardware is powered, and if those health
00:13:31 --> 00:13:33 checks come back clean, Proba 3 could
00:13:33 --> 00:13:35 resume its artificial eclipse science
00:13:36 --> 00:13:37 program. We'll be following this one
00:13:37 --> 00:13:38 closely.
00:13:38 --> 00:13:41 >> What a relief is right. We'll link to
00:13:41 --> 00:13:42 the full ESA update at
00:13:42 --> 00:13:45 astronomydaily.io.
00:13:45 --> 00:13:47 >> And finally, a story that is both a
00:13:47 --> 00:13:49 scientific mystery solved and a lovely
00:13:49 --> 00:13:51 reminder for why sample return missions
00:13:51 --> 00:13:54 matter so much. You'll remember NASA's
00:13:54 --> 00:13:56 Osiris Rex spacecraft collected samples
00:13:56 --> 00:13:59 from asteroid Bennon back in 2020, and
00:13:59 --> 00:14:02 those samples arrived on Earth in 2023.
00:14:02 --> 00:14:04 Well, this week, scientists published
00:14:04 --> 00:14:06 results in Nature Communications that
00:14:06 --> 00:14:08 finally solve one of Bennu's most
00:14:08 --> 00:14:11 puzzling features. So, here's the
00:14:11 --> 00:14:14 mystery. Back in 2007, NASA's Spitzer
00:14:14 --> 00:14:16 Space Telescope measured what's called
00:14:16 --> 00:14:19 low thermal inertia on Bennu, meaning
00:14:19 --> 00:14:22 the asteroid surface heats up and cools
00:14:22 --> 00:14:24 down rapidly as it rotates. on Earth.
00:14:24 --> 00:14:27 That's what sand does, which led
00:14:27 --> 00:14:29 astronomers to expect Bennu's surface
00:14:29 --> 00:14:31 would be sandy and smooth, a bit like a
00:14:31 --> 00:14:32 beach.
00:14:32 --> 00:14:35 >> And then Osiris Rex arrived in 2018 and
00:14:35 --> 00:14:38 found the opposite. The surface was
00:14:38 --> 00:14:40 covered in enormous boulders, rough,
00:14:40 --> 00:14:43 rocky, definitely not sandy. And these
00:14:43 --> 00:14:45 boulders should behave like blocks of
00:14:45 --> 00:14:47 concrete thermally, holding heat for
00:14:47 --> 00:14:49 hours after the sun goes down. But they
00:14:50 --> 00:14:52 weren't. They were losing heat rapidly,
00:14:52 --> 00:14:54 just like the original observation
00:14:54 --> 00:14:55 suggested.
00:14:55 --> 00:14:57 >> Scientists scratched their heads for
00:14:57 --> 00:15:00 years. The boulders were porous. That
00:15:00 --> 00:15:02 explained some of the heat loss, but not
00:15:02 --> 00:15:04 all of it. The numbers still didn't add
00:15:04 --> 00:15:05 up.
00:15:05 --> 00:15:07 >> And then they put the actual return
00:15:07 --> 00:15:09 samples into an X-ray CT scanner. And
00:15:10 --> 00:15:11 that's when everything clicked into
00:15:11 --> 00:15:13 place. The boulders aren't just porous.
00:15:13 --> 00:15:15 They're riddled with an extensive
00:15:15 --> 00:15:18 internal network of fine cracks, like a
00:15:18 --> 00:15:20 shattered windshield that's still in one
00:15:20 --> 00:15:22 piece. The cracks dramatically alter how
00:15:22 --> 00:15:24 heat moves through the rock. When
00:15:24 --> 00:15:27 scientists ran computer simulations
00:15:27 --> 00:15:29 scaling those cracked boulder properties
00:15:29 --> 00:15:31 up to the full size of Bennu's actual
00:15:31 --> 00:15:34 surface, the numbers matched perfectly,
00:15:34 --> 00:15:36 right down to what the spacecraft had
00:15:36 --> 00:15:37 measured from orbit.
00:15:37 --> 00:15:39 >> The lead researcher, Andrew Ryan, from
00:15:39 --> 00:15:42 the University of Arizona put it simply.
00:15:42 --> 00:15:43 It turns out they're really cracked,
00:15:44 --> 00:15:45 too. And that was the missing piece of
00:15:46 --> 00:15:48 the puzzle. The full citation is in the
00:15:48 --> 00:15:49 show notes.
00:15:49 --> 00:15:51 >> And the implications go way beyond
00:15:51 --> 00:15:53 Bennu. This work means scientists can
00:15:54 --> 00:15:55 now use the thermal properties of an
00:15:55 --> 00:15:58 asteroid measured from a telescope on
00:15:58 --> 00:16:00 Earth to make much more accurate
00:16:00 --> 00:16:02 inferences about its internal structure.
00:16:02 --> 00:16:04 You no longer need to go there and pick
00:16:04 --> 00:16:06 it up to understand it,
00:16:06 --> 00:16:08 >> which matters enormously for planetary
00:16:08 --> 00:16:10 defense. The more accurately we can
00:16:10 --> 00:16:12 model asteroid composition and structure
00:16:12 --> 00:16:14 from a distance, the better we can
00:16:14 --> 00:16:16 predict trajectories, deflection
00:16:16 --> 00:16:18 responses, and potential impact hazards.
00:16:18 --> 00:16:22 Osiris Rex keeps on delivering. What an
00:16:22 --> 00:16:24 episode to celebrate the first day of
00:16:24 --> 00:16:26 spring in the northern hemisphere and
00:16:26 --> 00:16:28 autumn in the southern hemisphere. We
00:16:28 --> 00:16:31 had solar storms, an aurora opportunity,
00:16:31 --> 00:16:33 a meteorite hunt in Ohio, one of the
00:16:33 --> 00:16:36 oldest stars ever discovered, a
00:16:36 --> 00:16:38 satellite that came back from the dead,
00:16:38 --> 00:16:41 and an asteroid mystery finally cracked.
00:16:41 --> 00:16:43 Not bad for a Friday.
00:16:43 --> 00:16:45 >> If you're in aurora territory tonight,
00:16:45 --> 00:16:47 get outside, find a dark spot, look
00:16:47 --> 00:16:49 north. The sky may reward you.
00:16:49 --> 00:16:52 >> You can find show notes, source links,
00:16:52 --> 00:16:53 and skywatching guides at
00:16:53 --> 00:16:55 astronomyaily.io.
00:16:55 --> 00:16:58 Follow us on X, Instagram, Tik Tok,
00:16:58 --> 00:17:01 YouTube, and Tumblr, all at Astro Daily
00:17:01 --> 00:17:02 Pod.
00:17:02 --> 00:17:04 >> If you're enjoying the show, please
00:17:04 --> 00:17:05 leave us a review wherever you get your
00:17:05 --> 00:17:07 podcasts. It genuinely helps new
00:17:07 --> 00:17:09 listeners find us.
00:17:09 --> 00:17:11 >> Until next time, keep looking up. I'm
00:17:11 --> 00:17:12 Anna
00:17:12 --> 00:17:26 >> and I'm Avery. Happy Equinox, everyone.
00:17:26 --> 00:17:29 Stories told.