Speaker 1: Welcome to Astronomy Daily.
Speaker 2: I'm Anna and I'm Avery. It is Thursday, the nineteenth
of February twenty twenty six, and we are recording this
episode while NASA is literally fueling a rocket at this
very moment, and we cannot wait to tell you about it.
Speaker 1: That's right. This is one of those days where space
news isn't just something that happened somewhere out there in
the universe. It is happening right now on a launchpad
in Florida. But that's not all today. We're also asking
what lurks in the darkness between us and our nearest
cosmic neighbors. Could there be a cosmic clock ticking next
to the most extreme object in our galaxy? And brace yourselves?
Is the universe actually going to end?
Speaker 2: Plus, we have a story that will make you want
to check the sky tonight, a warning from NASA that
is genuinely a little unsettling, and we're going to space
with a music video. All of that is coming up
on Astronomy Daily.
Speaker 1: Let's start with the big one, and I mean big
in every sense of the word. As we speak, NASA's
Space Launch System, the most powerful rocket ever built, is
being loaded with more than seven hundred thousand gallons of
cryogenic propellant at Launch Complex thirty nine B at Kennedy's
Space Center in Florida.
Speaker 2: This is the second wet dress rehearsal for Artemis two,
the mission that will carry four astronauts on a loop
around the Moon, the first time humans have ventured to
lunar distance since Apollo seventeen back in nineteen seventy two.
The crew are Commander Reidwiseman, pilot Victor Glover, mission specialist
Christina Cokes from NASA, and Jeremy Hansen from the Canadian
Space Agency.
Speaker 1: Now. The reason they're doing this rehearsal and the reason
there have been so many eyes on it today, is
that the first attempt, back on the second and third
of February, did not go as planned. Engineers detected a
liquid hydrogen leak during fueling, which forced them to halt
the test before they could complete the full countdown sequence.
Speaker 2: In the week, sense technicians have replaced seals around two
fueling lines, swapped out a filter in the ground support equipment,
and added an extra hour of buffer time into the
countdown to allow more room for troubleshooting. It's the kind
of painstaking, unglamorous engineering work that rarely makes headlines, but
it's exactly what keeps astronauts alive.
Speaker 1: Today's rehearsal targets a simulated launch window opening at eight
thirty this evening Eastern Time. The test is expected to
run until around twelve thirty Friday morning, and the stakes
are high. NASA has said it won't set a formal
launch date until after a successful wet dress rehearsal campaign.
March sixth remains the earliest possible crude launch date.
Speaker 2: NASA Administrator Jared Isaacman put it well when he said,
we anticipated encountering challenges. That is precisely why we conduct
a wet dress rehearsal. These tests are designed to surface
issues before flight. This safety of the crew comes first.
So tonight we watch and we wait.
Speaker 1: We will be keeping a close eye on this one,
and we'll bring you the results intomorrow's episode. Fingers crossed
for a clean test, no leaks, and a March launch
that puts humans back in the vicinity of the Moon
for the first time in over fifty years.
Speaker 2: All right from a rocket at Kennedy Space Center to
the absolute heart of our galaxy, and this story is
one of those discoveries that, if it's confirmed, could fundamentally
change how we understand the universe.
Speaker 1: Researchers from Columbia University, working with the Breakthrough Listen initiative,
which is best known for searching for signs of intelligent
life beyond Earth, have announced the detection of a candidate
millisecond pulsar very close to Sagittarius, a star that's the
super massive black hole sitting at the center of the
Milky Way, roughly four million times the mass of our
own Sun.
Speaker 2: So let's unpack what a pulsar is, because it's one
of the most extraordinary objects in the universe. When a
massive star reaches the end of its life and explodes
as a supernova, what's left behind is an incredibly dense
core called a neutron star. Some of those neutron stars
spin rapidly and emit beams of radio waves like a
cosmic lighthouse sweeping through space. When those beams sweep past Earth,
we detect them as regular pulses, hence pulsar.
Speaker 1: And what makes millisecond pulsar special is their extraordinary precision.
They spin hundreds of times per second with almost perfect
regularitydientists have called them the most accurate clocks in the universe,
more stable than atomic clocks here on Earth. This candidate,
nicknamed BLPSR, completes one full rotation every eight point one
nine milliseconds.
Speaker 2: Now here's why finding one near Sagittarius a star is
such a big deal. A pulsar next to a four
million solar mass black hole would be operating in one
of the most extreme gravitational environments imaginable, and Einstein's general
theory of relativity makes very specific predictions about what happens
to space and time in such extreme environments, predictions that
have never been tested at this level of precision.
Speaker 1: And if a pulsar is orbiting close to Sagittarius astar,
the black hole's gravity would warp space time so severely
that those precise pulsar pulses would arrive at our telescopes
with tiny but measurable distortions. As researcher Slovko Bogdanov from
Columbia put it, any external influence on a pulsar would
introduce anomalies in the steady arrival of pulses, which can
be measured and modeled.
Speaker 2: In other words, a confirmed pulsar next to a super
massive black hole would be a natural laboratory for testing
Einstein's series in the most extreme conditions possible. It could
also help us understand things like the massive Sagittarius astar,
the geometry of space time near a supermassive black hole,
and potentially even offer clues about dark matter.
Speaker 1: Now it's important to be clear this is still a candidate.
The team published their findings in the Astrophysical Journal, and
Breakthrough Listen has released all the observational data publicly, so
researchers around the world can do independent analyses. Confirmation will
require extensive follow up observations, but the scientific community is buzzing.
This is the kind of discovery that reshapes entire research programs.
Speaker 2: If it holds up, keep watching the skies and the
galactic center. This story is far from over.
Speaker 1: So we've talked about what's happening in Florida tonight and
what might be happening at the center of our galaxy.
Now let's zoom all the way out farther than you've
probably ever thought about, and ask how does the universe end?
Speaker 2: For most of the past few decades, the scientific consensus
has been pretty clear the universe expands forever. Dark energy,
that mysterious force making up roughly sixty eight percent of
the mass and energy in the cosmos, was thought to
be a constant, relentlessly pushing everything apart. Eventually, galaxies would
drift so far from each other that the night sky
would go dark, stars would burn out, everything would fade
into a cold, silent void. Scientists call this the Big
Freeze or heat.
Speaker 1: Death, but new data is challenging that picture in a
dramatic way. Physicist Henry Tie at Cornell University has published
new calculations using data from two of the world's most
powerful dark energy observatories, the Dark Energy Survey in Chile
and the Dark Energy Spectroscopic Instrument in Arizona, and his
conclusion is striking. The universe may be heading not for
a frieze, but for a crunch.
Speaker 2: Here's how it works. Both surveys are finding evidence that
dark energy isn't actually constant. It appears to be weakening
over time. If that's true, then the force pushing the
universe apart is gradually fading, and at some point gravity
takes over. The expansion slows, stops, and then reverses Everything
that has been flying apart for billions of years, begins
falling back together.
Speaker 1: A TIES model introduces a hypothetical particle called an ultra
light axion, combined with what's known as a negative cosmological
constant to explain how dark energy could behave this way.
The math suggests the universe is currently about thirteen point
eight billion years old and approaching the halfway point of
its total lifespan. It would continue expanding for roughly another
eleven billion years, reach its maximum size, and then begin
to contract, ultimately collapsing into a single point of unimaginable density.
The Big crunch total elapsed time approximately thirty three billion years.
Speaker 2: Now before anyone starts updating their bucket lists, this is
one model. It's not yet scientific senses. There's healthy debate
about how to interpret the dark energy data, and upcoming
messions from the European Space Agency's EUCLID Telescope, NASA SPHEREx
project and the Veraice Reuben Observatory will provide much better
measurements over the coming years.
Speaker 1: But the very fact that two independent observatories, one in
the southern hemisphere one in the northern are converging on
similar results about dark energy evolving. That's significant. As TI
himself put it, for the last twenty years, people believed
the universe would expand forever. The new data may be
telling us something very different.
Speaker 2: The universe might be mortal after all. Quite the thought
to sit with on a Thursday evening.
Speaker 1: And now, because apparently one existential revelation isn't enough for
one episode, let's talk about City Killer asteroids.
Speaker 2: Those two words together are doing a lot of work.
Speaker 1: They really are so. At the American Association for the
Advancement of Science conference in Arizona this week, NASA's Planetary
Defense Officer, and yes, that is a real job title,
Doctor Kelly Fast, gave a presentation that's been making headlines
ever since, and for good reason.
Speaker 2: Doctor Fast explained that when it comes to asteroids, there
are essentially three categories of concern. At the small end,
things are hitting Earth all the time, meteors burning up
in the atmosphere, the occasional fireball, We're not particularly worried
about those. At the large end, the extinction level rocks
the movie asteroid kind. Scientists are actually fairly confident about
where those are. We track them, we know their orbits.
Speaker 1: It's the middle ground that keeps doctor fast up at night.
Asteroids in the range of one hundred and forty meters
and larger, large enough to devastate an entire city or
a wide region, but small enough to be difficult to
detect with current telescopes. Her estimate there are around twenty
five thousand of these objects in the vicinity of Earth's orbit.
Speaker 2: And how many have we found about forty percent, meaning
there are potentially fifteen thousand city killing space rocks out
there right now that we simply do not know about.
Speaker 1: To add some context to that and to the challenge
of actually doing something about it if we did spot one.
Doctor Nancy Shabbitt, the planetary scientist who led NASA's Dart mission,
the spacecraft that successfully changed the orbit of an asteroid
back in twenty twenty two, was also at the conference.
She pointed out that Dart was a breakthrough demonstration, but
there isn't another one sitting on a launch pad ready
to go.
Speaker 2: She specifically referenced the asteroid why Are four, which caused
some anxiety earlier this year, with a small but not
zero probability of a lunar impact in twenty thirty two.
She said, if something like Why R four had been
headed towards the Earth, we would not have any way
to go and deflect it actively.
Speaker 1: Right now, the hope on the horizon is the Near
Earth Object survey or telescope, which is planned for launch
next year. Unlike conventional optical telescopes, it uses thermal infrared
signatures to detect darker asteroids that are essentially invisible to
conventional instruments, potentially a game changer for the detection side
of the problem.
Speaker 2: But doctor Schabbot's point stands. Detection is one thing, having
an active, ready to deploy deflection capability is another, and
that investment, she says, is simply not being made at
the level that needs to be something worth thinking about.
Given that planetary defense is probably the one area of
space science that is quite literally about survival.
Speaker 1: Sobering stuff. Let's come back down to Earth for a moment,
or rather, let's look up from it.
Speaker 2: Here's something wonderful and wonderfully timely, because this one is
happening right now to night as you listen.
Speaker 1: To this, Mercury, the innermost planet of our Solar system
and the one most people have never actually seen with
their own eyes, is tonight reaching what astronomers call its
greatest eastern elongation. That's the point in its orbit where
it's at its maximum angular distance from the Sun as
seen from Earth, meaning it appears as far from the
Sun in our sky as it ever gets.
Speaker 2: And why does that matter for observers because Mercury is
normally incredibly difficult to spot. It's always close to the
Sun in the sky, so you're either trying to catch
it just before sunrise or just after sunset, with very
little time before it follows the Sun below the horizon.
But at greatest elongation you get the best window.
Speaker 1: Tonight, look to the western horizon shortly after sunset. Mercury
will be visible as a moderately bright point of light,
shining steadily rather than twinkling like a star. You won't
need any special equipment, though binoculars will give you a
much nicer view. This is Mercury's first greatest elongation of
twenty twenty six, and the best evening viewing opportunity will
get for the year so far.
Speaker 2: There's also a bonus tonight, the crescent moon, Saturn, and
Neptune are all gathering in the same part of the sky,
with Saturn and Neptune very close together near the western horizon. Now,
Neptune will need a telescope and you'll need to wait
until the sun is fully set. Do not point any
optical instrument toward the horizon until the sun has cleared
it completely. But the overall scene is really quite beautiful
this evening.
Speaker 1: And for those of you keeping track of the upcoming
six planet parade on the twenty eighth of February, Mercury
reaching greatest elongation tonight is actually a key milestone in
that build up. By the twenty eighth, Mercury will have
improved its position enough to join Venus, Saturn, Jupiter, Uranus,
and Neptune, all visible in the same sky. We'll have
a full guide to that event closer to the date,
but tonight is your previous go look west.
Speaker 2: And now to close out the episode, we have something
that we absolutely love, a reminder that even on a
space station in orbit, humans will find a way to celebrate.
Speaker 1: The crew of China's shen Zoo twenty one mission, currently
living and working aboard the Tionggong space station, have released
a music video to mark the lunar New Year, the
Year of the Horse, and honestly it is delightful.
Speaker 2: Filming a music video in microgravity is, as you might imagine,
a unique creative challenge. Everything floats, hair floats, props float,
but the crew apparently embraced all of it, and the
result is one of those lovely, warm, deeply human moments
that cuts right through all the geopolitical complexity of the
space race and reminds you that the people up there
are just people celebrating a holiday with their families watching
from below.
Speaker 1: Tionggong, which means Heavenly Palace, currently has a crew of
three aboard. Following the shen Zu twenty one mission, has
been steadily expanding its space station program, and moments like
this one shared with the world are a reminder of
why humans go to space in the first place, not
just for science or national prestige, but for the sheer
joy of being up there.
Speaker 2: Don sifa chai to all of our listeners celebrating the
lunar new Year. May the Year of the Horse bring
you good fortune and hopefully fewer hydrogen leaks.
Speaker 1: And on that note, that's your Astronomy Daily for Thursday,
February nineteenth, twenty twenty six. What a lineup today? A
live rocket fueling test a cosmic clock near a black hole,
the possible end of the universe, city killing asteroids, mercury
in the evening sky, and a music video from Orbit.
Speaker 2: If you want to follow along with the Artemis two
fueling test tonight, NASA has a live stream at NASA
dot gov. We'll link everything in the show notes, and
if you spot mercury tonight, tag us on social media
at hame stro Daily Pod. We would love to see
your photos.
Speaker 1: Subscribe, leave a review if you're enjoying the show, and
we will be back tomorrow with the results of tonight's
fueling test. Until then, keep looking up clear skies everyone, Sunny.
Speaker 2: Day star ist so starst