Avery: One of the most famous stars in the whole
night sky has been keeping a secret for about
100 years.
Anna: And this week, a telescope in the Chilean
desert finally caught it red handed.
Betelgeuse, it turns out, is not alone.
Avery: Also ahead, a black hole caught wandering the
lonely outskirts of a galaxy dreading a
star tens of thousands of light years from
where any black hole has a right to be.
Anna: NASA's next great observatory gets its tank
filled and a date on the calendar.
Avery: And the little spacecraft sent to rescue an
aging telescope suddenly needs rescuing
itself. G', day, and welcome to Astronomy
Daily, your daily dose of space and astronomy
news. I'm Avery.
Anna: And I'm, um, anna. It's Wednesday, the 29th
of July, four stories and a look at the sky
from both hemispheres. Let's get into it.
If you've ever looked up at Orion, and from
Sydney or Seattle, just about everyone has,
you've seen tonight's star Betelgeuse,
that deep orange point marking the hunter's
shoulder. It's a red supergiant, roughly
650 light years away, and it is
enormous. Drop it where our sun sits and it
would swallow the orbit of Jupiter.
Avery: And it's famous for misbehaving. It
flickers.
Anna: It does. Betelgeuse brightens and dims on
a whole set of overlapping cycles. And people
have been writing that down for more than a
thousand years. But there's one rhythm, um,
in particular, a slow beat about six years
long that astronomers have never been able to
fully explain. And for almost a century,
one idea kept coming back. What if
Betelgeuse has a companion, a second star,
orbiting close, tugging on it?
Avery: The famous Betel Buddy.
Anna: That's the affectionate nickname, yes. The
trouble is nobody had ever seen it. And you
can see why. Imagine trying to spot a
candle sitting right next to a lighthouse.
Betelgeuse is so blindingly bright and so
physically huge that any little companion
tucked in beside it just drowns in the glare.
For a hundred years, it stayed a hypothesis.
Avery: So what changed?
Anna: A team led by Miguel Montargis at the Paris
Observatory in Chile, the vlt,
and an instrument called Sphere that's built
for exactly this job. Blocking out a bright
star to hunt for faint things right beside
it. And crucially, they picked their moment.
They observed in December 2024, at the
point in the orbit when the companion was
predicted to swing out as far from Betelgeuse
as it ever gets from seen from Earth. Best
possible chance to split the two apart. And
there it was. A faint little source right
Where a companion should be. Their paper
landed yesterday, 28th July in the journal
Astronomy and Astrophysics. And Montargis
called it the end of a century long quest.
After a hundred years of arguing about it, we
have a direct image of what is very likely
Betelgeuse B.
Avery: That gives me chills, honestly. A star that
people have watched since antiquity and we're
still learning brand new things about it.
Anna: And here's the lovely twist. The reason they
could see it at all is that it surprised
them. The companion was predicted to be
roughly the mass of our Sun. But the data
say it's bigger than that, something like two
to three times the Sun's mass. Montargis put
it beautifully, because it's more massive
than we expected, it's brighter than we
expected, and that's the only reason it
peeked out of the glare. If it had been as
small as the textbook said, they might have
missed it entirely.
Avery: So the companion did us a favor by being
chunkier than advertised. What is it though?
Another supergiant?
Anna: No, nothing like Betelgeuse. Think of it as
a young, hot, fairly ordinary star,
but locked in a very awkward orbit.
It appears to circle so close that it's
essentially skimming through the outer puffed
up layers of the supergiant. And that has
consequences. That orbit is almost
certainly what paces that mysterious M6
year brightness cycle. But it's also most
likely a death sentence for the companion.
Avery: Ooh, M. Go on.
Anna: Plowing through a supergiant's outer
atmosphere means constant drag. Every
orbit, the little star loses a bit of energy.
And models suggest it's slowly spiraling
inward on astronomical timescales.
Betelgeuse is very likely to swallow its
own companion. Not tomorrow. We're talking
thousands of years. But the relationship is,
let's say, not built to last.
Avery: The lighthouse eats the candle.
Anna: Eventually, yes. And this matters for the big
question everyone actually wants answered
about Betelgeuse. When is it going to
explode? Because it will. It's an old
massive star, near the end of its life, and
one day it will go supernova and briefly
outshine everything in the night sky. Now,
before anyone emails us, that's expected on a
timescale of up to 100,000 years.
So don't cancel your weekend. But whether a
star has a close binary companion
changes the whole picture. How it sheds mass,
the shape of the gas around it, even the
choreography of the explosion when it finally
comes. Knowing Betelgeuse is a pear
rewrites part of that story.
Avery: And this was direct imaging. An actual
Picture not just an inference from wobbles in
the light.
Anna: That's what makes it land. There had been
circumstantial hints for years, but this is a
direct detection light caught from the
companion itself in the right place at the
right time. It's the difference between the
data suggest a second star and here
it is.
Avery: So if you want to go and look at the star at
the center of all this, Betelgeuse itself.
Where are we? Both hemispheres right now?
Anna: Orion is a pre dawn act. It's climbing
back into the morning sky after being lost in
the sun's glare. For our Southern hemisphere
listeners, Orion rides high in the northern
part of the early morning sky. And it's
upside down compared to the northern view.
Look for Betelgeuse as the bright orange star
from North America and mid northern
latitudes. It's lower in the east southeast
before dawn, climbing higher each week. As we
head towards the northern winter, we'll come
back to it properly in the sky watch. But
next time you find it, just remember it's not
one star. It never was.
Avery: Now from a star that's hiding a companion to
a black hole that was hiding full stop.
Anna, picture, uh, a supermassive black hole.
Where is it?
Anna: Dead center of a galaxy. That's the rule. The
big ones sit in the core.
Avery: That's the rule. And this week, NASA's Swift
observatory helped break it. Astronomers
announced a tidal disruption event. That's
the technical name for a black hole tearing a
star apart and eating it. And the flare it
produced was blazing briefly outshining its
entire host galaxy in ultraviolet. Like
10 billion suns switched on at once. But
here's the thing. It didn't happen in the
middle of the galaxy. It went off about
30,000 light years out from the core.
Anna: 30,000. That's not a rounding error.
That's further from the center than the sun
is from the middle of the Milky Way. That
black hole is out in the suburbs.
Avery: Way out in the suburbs. The event's called
TDE 2025 ABCR
in a Galaxy about 750 million light
years away. And the teams one led out of
NASA and the University of Maryland, another
from UNC Chapel Hill, published it on
27 July in the Astrophysical Journal
Letters. It's the most off center tidal
disruption ever seen. And what it reveals is
a wandering black hole, a around a million
times the mass of the sun, just roaming
through its galaxy, nowhere near the core.
Anna: How does a black hole end up out there? They
don't exactly stroll.
Avery: Best guess is a, uh, galaxy merger. When two
galaxies collide and their central black
holes get thrown together, one can get kicked
out of the middle and left drifting.
Theorists have predicted these wanderers for
years. The problem is they're invisible. A
black hole sitting quietly in the dark emits
no light. You only ever attach one if it does
something dramatic.
Anna: Like grabbing a passing star and lighting up.
Avery: Exactly. The star is the flashbulb. It
wanders too close, gets shredded, and for a
few weeks, the wreckage glows and gives the
whole thing away. That's the only reason we
know this black hole is there at all.
Anna: And there's a lovely modern wrinkle to how
they found it isn't there. This wasn't a
human squinting at plates.
Avery: Not a chance. The sky is too big for that
now. The initial flare was picked up back in
November 2025 by a survey at Palo are
in California that scans the whole northern
sky every couple of nights. It throws up
something like half a million flashes every
single night. So the team trained an AI to
sift that fire hose and flag the ones that
look like a tidal disruption. And it caught
this one precisely because it was in a weird
place off in the outskirts where nobody would
have thought to look. Swift followed up to
nail down the details.
Anna: And that's the taste of what's coming, right?
Once the big new survey telescopes are
running.
Avery: That's the real headline. Under the headline,
with observatories like the Vera Rubin
Observatory and UNC's Argus array coming
online, we go from finding a handful of these
a year to potentially hundreds or thousands.
And suddenly all those invisible wandering
black holes become findable. We're about to
start taking a census of the galaxy's hidden
monsters. And keep swip in mind, by the
Anna: way, because it's going to come back to bite
us later in the show.
Avery: It is. Hold that thought.
Anna: Speaking of survey telescopes about to change
the game, let's talk about one that's now
genuinely nearly on the
NASA's Nancy Grace Roman Space
Telescope, because as of this week, it is
fueled and counting down.
Avery: Fueled. That's a real milestone. That's not a
slide in a presentation. That's propellant in
the tank.
Anna: Precisely. On the 25th of July,
teams at, uh, Kennedy loaded around
290 gallons of hydrazine into
the observatory. That's the fuel it'll use to
hold its position and point with real
precision once it's out there. And NASA is
holding its big mission preview briefing
today, exactly one month out from launch.
The date to circle is the 30th of August
and remarkably, that's about eight months
ahead of the original schedule.
Avery: A NASA flagship running early and as
I understand it, on budget. Let the record
show it can be done.
Anna: It can. And here's why Roman is worth
the excitement. Think of it as a telescope
with Hubble quality sharpness, but a jaw
droppingly wide field of view. Something like
a hundred times the patch of sky Hubble sees
in a single shot. Bass estimate is that in
its first five years, it could image more
than 50 times as much sky as Hubble has
in 30. It's built to survey fast and
wide.
Avery: And what's that actually hunting?
Anna: Two headline jobs. One, dark Energy,
the mystery. Pushing the universe apart
faster and faster. Roman will map how
cosmic structure has grown over billions of
years to pin down what Dark Energy is
actually doing. And two, this is the one
I love. It's an exoplanet machine.
Using a trick called microlensing, Roman
is expected to find more than 100,000
new planets and to catch hundreds of others
in the very act of finding forming around
young stars.
Avery: 100,000. We do a story
most weeks about one interesting new planet
and Roman's going to hand us 100,000.
Anna: It really might reset the whole field.
And this is genuinely for everyone listening
wherever you are. It's a space telescope,
though there's no hemisphere that misses out.
The whole planet shares this one. One
month to go.
Avery: Fingers crossed for the 30th of August.
Right? I told you Swift would come back
around. In story two, Swift was the hero,
the observatory that helped us catch that
wandering black hole. Well, here's the
thing in the tale, Swift itself is in
trouble and the spacecraft sent to save it
is now in trouble too.
Anna: Set it up. Why does Swift need saving in
the first place?
Avery: Because Swift is falling. It's a fantastic
gamma ray and X ray observatory that's been
working since 2004. But it has no
engine of its own, no way to boost its own
orbit, and its orbit has been decaying faster
than expected, partly because heightened
solar activity puffs up the upper atmosphere
and increases the drag. Left alone,
Swift is looking at an uncontrolled re entry
by around the end of this year.
Anna: So it burns up unless someone
goes up and gives it a push.
Avery: Which is exactly the plan. A company called
Catalyst Space Technologies built a
robotics servicing spacecraft named Link.
And NASA hired them for what its own mission
director called a fast, high risk, high
reward rescue. Link launched on 3
July, and the goal is genuinely a first
to fly up, grab hold of Swift, a
satellite that was never designed to be
docked with or serviced and physically
boosted into a higher, safer orbit.
Nobody has ever commercially docked with a
government spacecraft that wasn't built for
it.
Anna: That's ambitious. So what's gone wrong?
Avery: Over the weekend, Link ran into an attitude
control problem and started spinning with its
communications dropping in and out. According
to NASA's update, and I want to be precise
here because this is developing, the
preliminary finding is that two of Link's
three reaction wheels are no longer working
and, and there's some loss of function in its
cold gas thruster system as well.
Anna: Reaction wheels, Those are the spinning
wheels inside a spacecraft that let it turn
and hold steady without using fuel.
Lose those and you lose fine control of which
way you're pointing.
Avery: That's the one. And losing two of three is
serious, especially because there was already
a wobble with one Wheel earlier in
commissioning that they patched in software.
The good news, Link is not lost. It's still
powered, still in contact, and its other
major systems are behaving. The team's plan
is to use Link's electric thrusters, its
xenon propulsion, to stop the spin over the
next few days, then re establish stable
pointing, update the spacecraft's guidance
and navigation to work around the dead
hardware, and only then sit, uh, down with
NASA and decide whether it's still safe to
attempt the approach and capture of Swift.
Anna: So the rescue isn't canceled, it's on
hold while they figure out if the rescuer can
still do the job.
Avery: That's exactly it. And I'll flag for
everyone. This is a life situation as of when
we're recording. By the time you hear this,
the team may already have stopped a spin or
the picture may have changed again. But step
back and look at the shape of it. The same
little observatory that just helped us find
an invisible black hole halfway across the
universe is now clinging on in low Earth
orbit, waiting to see if its own lifeboat can
limp over and give it a shovel. Space is
hard. Even the rescue missions need rescuing.
Anna: We'll keep you posted as that one develops.
And that brings us to the sky over the next
few nights. And there's one thing you cannot
miss, because it's going to be lighting up
the whole night. The moon.
Avery: The full buck moon.
Anna: The full buck moon. Full tonight, the
29th, and near enough to 100%
lit for a couple of nights either side.
Gorgeous to look at as it climbs the eastern
sky after sunset. But it is a
floodlight and that shapes everything else we
can and can't
Avery: do this week, starting with the meteors,
because there are three showers on the go at
once.
Anna: There are. And this is where our two
hemispheres genuinely differ. The headline
shower right now is the Southern Delta
Aquarius, peaking over the next couple of
nights. And the clue is in the name of. For
our Southern Hemisphere listeners, this one's
yours. The radiant over near the bright star
Fomalhaut rides high almost
overhead in the pre dawn hours. So from
Australia, New Zealand and southern Africa,
you're in the best seats on Earth for it.
And for the north, from North America,
it's lower and stingier, though observers
in the southern United States still get a
fair look. Best window everywhere is
the couple of hours before dawn. But
big caveat, this year, that brilliant
moon is going to wash out most of the faint
Delta Aquarids. So temper expectations.
Avery: If the faint ones are drowned out, what's
worth staying up for?
Anna: The fireballs. The Alpha Capricornids
are active at the same time. They're sparse,
only a handful an hour. But they specialize
in slow, brilliant fireballs bright enough
to punch through moonlight. And unlike the
Delta Aquarids, the Capricornids play
fair. They're just as good from either
hemisphere. So the tip for everyone this
week, don't chase quantity. Get
comfortable, be patient and wait for
one big slow fireball to make your
night.
Avery: And the shower, everyone's really waiting for
the Perseids.
Anna: And here's the good news to hold onto.
They're building now, but they peak on the
night of the 12th into the 13th of August.
And this year the timing is close to perfect.
The peak lands right on the New Moon.
Dark skies, no moonlight.
Potentially the best Perseids in years.
They favor the northern Hemisphere, but mid
southern latitudes will catch some too. Mark
it. The night of 12 August is the one to
keep clear.
Avery: And that same date is a big one for another
reason.
Anna: It is a, uh, total solar eclipse on
12 August, with the path of totality
crossing Greenland, Iceland and slice of
Spain, and a partial eclipse visible across
much of Europe and parts of North America.
We'll have full timings closer to the day.
And the one rule that never changes
wherever you are, never look at the
partial phases of a solar eclipse. Without
certified eclipse glasses, ISO
123122
or a properly filtered telescope.
Ordinary sunglasses will not protect your
eyes. That safety line stays in.
No exceptions.
Avery: One quick planet note before we wrap the sky.
Anna: Yes, say goodbye to Jupiter for a
little while. Today the 29th
Jupiter reaches solar conjunction. It's
passing almost directly behind the sun from
our point of view, so it's lost in the glare
and out of action for the next few weeks.
It'll creep back as a pre dawn object
later in August. And for early risers,
Mercury is putting on its best morning
showing of the season, low in the pre dawn
east,
Avery: and we have to close the loop on our lead
story.
Anna: We do. If you're up before dawn chasing
those meteors, look for Orion climbing in
the east and find Betelgeuse, that bright
orange shoulder from the southern hemisphere.
It's high in the northern sky and flipped
over from the north. It's lower in the east
before sunrise. Either way, give it a nod.
You now know something about that star that
nobody knew for a hundred years.
It's got a companion before we go,
Avery: a bit of proper news from our end. We've just
launched the brand new home for the show
astronomydaily.
Anna: Uh, IO same
address you already know, but it's had a
complete makeover and there's a lot there.
Now you can stream the entire back catalog
every episode. There's a news feed that
updates continuously through the day so you
can keep up with the latest space and
astronomy headlines between episodes. You can
read listener reviews and leave one of your
own. And you can sign up for uh, our daily
Space News newsletter to get it all straight
to your inbox.
Avery: And there's a spot to drop us a line,
questions, suggestions, a story you think
we've missed, or just to say good day, we
read them.
Anna: It's brand new, so we genuinely love your
feedback on it. Head to astronomydaily
IO have a wander around and tell us what you
think, what you love, what you change. Help
us make it yours.
Avery: That's astronomy daily for Wednesday, 29th of
July. Betelgeuse's Hundred Year Secret
A black hole in the wrong part of town, Roman
on the clock and a rescue mission holding its
breath.
Anna: Thanks for spending part of your day with us.
Look after each other and whichever
hemisphere you're in.
Avery: Clear skies.