Anna: Picture a black hole two and a half billion
times the mass of our sun. Now stop
picturing it as a drain, because the one
we're opening with today isn't just
swallowing, it's blowing. And the
blast it drives reaches across
300,000 light years,
stirring an entire cluster of galaxies.
Avery: 300,000 light years.
That's roughly three times the width of the
Milky Way. The reach of a single single black
hole.
Anna: That's our lead. Then, dead stars
that hide their meals. A, uh, Metal World
mission using Mars as a rehearsal studio.
And the growing problem of traffic on the
road to the Moon.
Avery: And, uh, because it's the 30th, there are two
meteor showers peeking over your head.
Tonight. We'll tell you exactly where to
look. North and South.
Anna: It's Thursday, the 30th of July,
2026. I'm Anna.
Avery: And I'm Avery. This is Astronomy Daily.
Anna: So let's start with a question that sounds
simple and isn't. What does a black
hole actually do to the space around it?
Avery: The cartoon answer is it eats
anything that gets too close, falls in, and
never comes back.
Anna: Right? And that part's true, but it's only
half the story. When a supermassive black
hole is feeding hard, it doesn't swallow
everything cleanly. It's a messy eater.
Enormous amounts of energy pour out of the
region around it. Radiation and powerful
outflowing winds of gas. And
astronomers have a name for the way those
winds push back on the wider universe.
They call it feedback.
Avery: Feedback, as in, um, the black hole feeds and
the galaxy gets a response?
Anna: Exactly. And it matters
enormously because feedback is one of the
ways galaxies keep themselves in check.
Here's the puzzle. It at the center of a big
galaxy cluster, there's a huge reservoir of
hot gas, millions of degrees glowing in
X rays. By all rights, that gas should be
cooling, sinking to the center and collapsing
into vast numbers of new stars.
Avery: And it doesn't.
Anna: And it doesn't. These cluster cores are far
quieter than the simple physics predicts.
Something is reheating that gas, keeping it
stirred up, stopping the runaway cooling.
For years, the leading suspect has been the
central black hole. That its outbursts
dump energy back into the gas and hold
the whole system in balance. But there's been
a stubborn gap in the evidence, which is
we could see black holes driving winds on the
scale of their own galaxy. What we couldn't
show was those winds reaching much beyond the
galaxy, out into the space between
galaxies. On the scale of the whole cluster.
That's the part that stayed Theoretical until
this study.
Avery: So who did it and, um, how?
Anna: A team led by Satoshi Yamada at
Tohoku University in Japan with colleagues
from Kanazawa, Tokyo Metropolitan and
Kyoto Universities. It's published in
Nature Astronomy this week on the 28th.
And their target is a genuinely special
object, a quasar called
H1821
643.
Avery: Quasar, meaning a black hole that's feeding
so ferociously it outshines its entire
galaxy.
Anna: That's it. Some of the most luminous
single objects in the universe. This one sits
in the Constellation Draco, about
3.4 billion light years away. And
its black hole weighs in around 2.6
billion solar masses. But here's what makes
it the perfect laboratory. It's the nearest
quasar that lives right at the heart of a
galaxy cluster. So you've got a raging black
hole and a giant reservoir of hot
cluster gas in the same place, close enough
to study in detail. That almost never
happens.
Avery: And to study it, uh, they used xrism, which
longtime listeners will remember.
Anna: We've talked about it before. Yes,
Xrism M, the X Ray Imaging and
Spectroscopy mission is the Japanese led
X Ray Observatory with NASA and the European
Space Agency aboard. Uh, and its superpower
is a kind of spectroscopy so precise
it can read the motion of hot gas from the
light it gives off.
Avery: Explain how that works, because this is the
clever bit.
Anna: It is the hot gas in a cluster
contains iron atoms. And those iron atoms
emit X rays at very specific
sharp energies, like a particular note.
Now, if that gas is churning and swirling,
some of it moves towards us and some away.
And just like a siren changes pitch as it
passes you, the motion smears that sharp
X ray note out, it broadens the line.
Measure how broad the line is and you've
measured how violently the gas is moving.
Avery: So the iron lines become a speedometer for
gas you can't otherwise see.
Anna: A speedometer for turbulence. And when they
pointed xrism
m@h1821
643 and read those lines,
the gas was full of far more turbulent than
anyone expected. Compared with a calm,
well behaved cluster like Perseus, the motion
here is dramatically more violent. And
it's violent across a huge span of space.
Avery: How huge?
Anna: The disturbance reaches out to something like
300,000 light years from the black
hole, well beyond the host galaxy, out
into the cluster itself. And the energy tied
up in that turbulence is on the order of a
hundred times greater than earlier estimates.
Avery: Hundred times. So this isn't A tweak to the
model. It's a different order of magnitude.
Anna: It really is. What they've shown is that this
black hole is pumping something like a few
to 10% of its radiative energy
straight into the surrounding cluster. Gas on
scales of tens to 100
kiloparsecs. That's the missing link.
That's direct evidence of a black hole
heating and stirring its cluster from the
inside. Exactly the process theorists
needed to explain why all that gas
isn't collapsing into stars.
Avery: Yamada had a nice way of putting it, didn't?
Anna: Hm, he, he did. He said black holes
are famous for sucking matter in, but they
also eject gas in powerful winds.
And this study says those winds are immensely
stronger than we understood. For the first
time, he says, we've shown a black hole
influencing the broader cosmos through a
shockwave of astonishing power.
Avery: And the reason to care beyond wow, big
number is that this is really a story about
how galaxies grow up.
Anna: That's the heart of it. Black holes and their
galaxies grow together and feedback is the
thermostat. Too little and the gas cools and
the galaxy makes far too many stars. Too
much and it blows the fuel away and star
formation shuts down. Get it right and you
build the galaxies we actually see. What
Yamada's team has done is catch that
thermostat in the act, working on a scale we
could only assume before moving energy
and eventually the chemical elements forged
in stars out across the cluster.
Avery: A black hole redecorating a whole
neighborhood it never touches directly.
Anna: More than three times the width of the Milky
Way from a single point at the center. And
this is really just the opening chapter.
Xrism is still young and objects
like
H1821,643
are, uh, rare and precious. Expect more of
these hot cluster cores to get the same
treatment. And expect our picture of how
black holes shape the universe to keep
getting bigger. Which is a lovely irony,
isn't it? The more we look at the objects
famous for pulling everything in, the more we
find them reaching out.
Avery: Reaching out. Good place to leave the giant.
Let's bring it right down to a single dead
star and a, uh, mystery about what it's been
eating. So story two, A white
dwarf is what our sun will become billions of
years from now. The burnt out Earth sized
core left behind when a star like ours runs
out of fuel. And for a long time we've known
these dead stars are a bit macabre. They're
surrounded by the shredded remains of their
old Planetary systems, asteroids, and even
planets torn apart and pulled in.
Anna: The star literally raining its old
planets down onto itself.
Avery: Beautifully grim. Yes, we can tell, because
we see the metals from that debris polluting
the star's atmosphere. But new research says
we've been undercounting the meal, that white
dwarfs are eating far more planetary material
than we thought. And the reason we missed it
is magnetism.
Anna: Magnetic fields hiding the evidence.
Avery: Exactly. Some white dwarfs are strongly
magnetic. And when debris falls in, those
magnetic field lines funnel the infalling
material down to the star's magnetic poles,
concentrating it into small patches instead
of spreading it evenly. And patches at the
poles are much easier to miss.
Anna: And here's the part I love. The researchers
point out it's essentially the same physics
as an aurora.
Avery: It is. Think about how our own auroras
work. The sun throws charged particles at
Earth. They follow our magnetic field lines
down to the poles, and they light up a
glowing patch in the atmosphere on a magnetic
white dwarf. Swap the solar particles for the
debris of a dead planetary system, and you
get the same choreography material guided
along field lines to a bright spot at the
pole.
Anna: An aurora made of ground up, uh,
Avery: planets on the corpse of a star.
And the practical upshot's real. If this
magnetic funneling is common, then a lot of
white dwarfs we've written down as clean may
actually be feeding just quietly in a way
our surveys don't catch. Which changes how we
estimate what these old planetary systems
were made of.
Anna: A window into the guts of dead solar
systems, including, one day, our own.
Speaking of dress rehearsals for the future,
let's go to Mars. Story 3.
NASA's Psyche spacecraft is on its way to one
of the strangest targets in the solar the
asteroid 16 Psyche. A world that
may be the exposed metal core of a shattered
baby planet. Mostly metal, not rock or
ice. We've never visited anything like it.
Avery: And it doesn't get there until 2029.
Anna: Not until 2029. That's right. But on the
way back in May, it swung past Mars for a
gravity assist, using the planet's pole to
bend its path and pick up speed for free.
And NASA's just shared with the team did with
that flyby, which is the fun part. They
treated Mars as a rehearsal studio.
Avery: A chance to switch everything on and check.
It works. Far from home.
Anna: Exactly. They put the cameras, the
magnetometer, and the particle instruments
through their paces against a real world
instead of empty space. They captured a
striking time lapse of Mars sliding by.
They even picked up neutrons coming off the
planet. But the detail that jumped out at me.
The imager managed to pick out Phoos and
Deimos, the two tiny moons of Mars from a
great distance, the little Martian moons.
Avery: And that wasn't just for a nice photo.
Anna: No, that was the whole point. Spotting two
small faint moons against the glare is
exactly the kind of needle in a haystack test
they'll need when they arrive at asteroid
Psyche and go looking for any little moonlets
orbiting it. So Mars became a practice run
for a search they'll do for real in a few
years time, rehearsing the hardshot
Avery: on a target you already know, so you're ready
for the one you don't.
Anna: Precisely. Every instrument checked,
calibrated and confident three years before
it matters. From one careful mission to a
much messier problem closer to home.
Avery the traffic on the road to the Moon.
Avery: We spend a lot of time on this show talking
about who's going to the moon now. NASA's
Artemis program, China and Russia's planned
research station, Europe's Argonaut landers,
and the growing crowd of commercial missions.
The next decade could see dozens of flights
into what's called cislunar space. The whole
region between Earth and the moon.
Anna: And everywhere we've ever gone in space,
we've left junk behind.
Avery: That's the worry. We've made low Earth
orbit crowded and cluttered. The question
this new study asks is, are we about to do
the same thing to the road to the Moon before
we've even properly moved in? It's from a
team at the Chinese Academy of Sciences, and
they've looked at a specific clever kind of
orbit out there, a, uh, distant retrograde
orbit, which
Anna: is one of those very stable parking spots in
the Earth Moon system.
Avery: Um, right. A wide stable loop
that's attractive precisely because
spacecraft can sit in it for a long time
without much fuel. The catch is if a
spacecraft in one of those orbits breaks up,
an explosion, a, ah, collision, the debris
doesn't just fall away and disappear the way
it might near Earth. The team modeled how
those debris clouds spread. And out there,
the fragments can linger and drift in ways
that are genuinely hard to predict.
Anna: And unlike low Earth orbit, there's no
friendly atmosphere out there to eventually
drag the rubbish down and burn it up.
Avery: That's the crux of it. Near Earth, the
atmosphere slowly cleans up after us. In
deep cislunar space, there's no such
janitor. Debris can stay a hazard far
longer. So the value of work like this is
that it's preventative if we can map where
the risky orbits and the lingering debris
clouds are before the traffic arrives. We can
design missions to steer clear and maybe keep
the highway to the moon open for everyone who
wants to use it.
Anna: Cleaning up before we make the mess for once.
Now let's get you outside because tonight the
sky is putting on a show. And this one is
genuinely for tonight, wherever you're
listening. Two meteor showers are peaking at
the same time, the night of the 30th into the
early hours of the 31st. The southern delta
aquariids and the alpha
Avery: capricornids, two at once,
tell us the difference between them.
Anna: They've got very different personalities. The
Southern Delta Aquariids are the steady
workhorses. More meteors, a bit fainter,
radiating from the constellation Aquarius.
Their parent is thought to be a comet called
96PMachholz. The alpha
Capricornids are the opposite. Not many, but
the ones you get are slow bright fireballs,
real showstoppers coming from the direction
of Capricornus from a comet called
16.9pmeet.
Avery: So quality versus quantity sharing
the same night.
Anna: Exactly. Now the honest catch this year,
the moon. We had the full buck moon just last
night, so tonight it's still around 98%
lit. And that glare will wash out the fainter
meteors. But, and this is the saving grace,
those bright Capricornid fireballs can punch
right through moonlight. As one astronomer
put it, one bright one is worth 20 faint
ones.
Avery: So how do people actually watch? And um, this
is where north and south really difference.
Anna: It does. So let's do both properly. First,
the good news for us here in the Southern
hemisphere, this is our show. Both
radiants ride high overhead from southern
latitudes, so we get the best seats. The
Southern Delta Aquarids can deliver something
like 10 to 20 an hour from a dark site under
a better moon. And even tonight with the moon
bright, the south still comes out ahead
Cygny
Avery: and um, the east coast. When and where head
out after the
Anna: moon and sky settle late evening onward. But
the best window is the small hours local
time, roughly 1 to 4am when the
radiance are highest. Look towards the north
and east. Get as far from city lights as you
can and give your eyes a solid 20 to 30
minutes to adapt. Lie back and take in a
wide patch of sky rather than staring at one
spot.
Avery: And for our North American listeners, our
biggest audience who don't get the radiant
Anna: as high, you can still absolutely
catch this. You just work with lower numbers
and lean on the fireballs. Your best time
is Also the pre dawn hours. Think
2 to 4am local, whether that's
Eastern Central Mountain or Pacific time.
Once the radiants have climbed as high as
they'll get the pro tip for the moonlight
Position yourself facing away from the moon
with it at your back or blocked behind a
building or a hill so its glare isn't in your
eyes. Then watch a broad stretch
of sky and wait for those slow Capricorned
fireballs.
Avery: No telescope, no binoculars.
Anna: Done it all meteors are a naked eye
whole sky event. Just you, a
reclining chair, something warm and patience.
And if tonight clouds you out, both showers
stayed active for another week or two, so
you'll get more chances as the moon thins out
and conditions improve.
Avery: Two comets worth of dust burning up over your
head. Not a bad way to end the day.
Anna: Not bad at all. Look up if you can.
Avery: That's the lot for today. Every story with
links and sources is over at astronomydaily
IO. The new site has the full back
catalog, a rolling news feed, and you can
sign up for the newsletter or drop us a line
right there.
Anna: We love hearing from you. Tell us if you
catch a Capricorned fireball tonight. Find us
at astrodaily pod and on the
bytes.com podcast network for
Anna and for me.
Avery: Thanks for listening.
Anna: Until tomorrow. Clear skies.
Avery: Mhm.
Anna: You
stories we told.