The Reach of a Giant | A Black Hole Story

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Anna: Picture a black hole two and a half billion

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times the mass of our sun. Now stop

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picturing it as a drain, because the one

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we're opening with today isn't just

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swallowing, it's blowing. And the

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blast it drives reaches across

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300,000 light years,

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stirring an entire cluster of galaxies.

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Avery: 300,000 light years.

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That's roughly three times the width of the

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Milky Way. The reach of a single single black

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hole.

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Anna: That's our lead. Then, dead stars

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that hide their meals. A, uh, Metal World

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mission using Mars as a rehearsal studio.

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And the growing problem of traffic on the

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road to the Moon.

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Avery: And, uh, because it's the 30th, there are two

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meteor showers peeking over your head.

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Tonight. We'll tell you exactly where to

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look. North and South.

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Anna: It's Thursday, the 30th of July,

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2026. I'm Anna.

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Avery: And I'm Avery. This is Astronomy Daily.

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Anna: So let's start with a question that sounds

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simple and isn't. What does a black

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hole actually do to the space around it?

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Avery: The cartoon answer is it eats

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anything that gets too close, falls in, and

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never comes back.

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Anna: Right? And that part's true, but it's only

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half the story. When a supermassive black

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hole is feeding hard, it doesn't swallow

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everything cleanly. It's a messy eater.

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Enormous amounts of energy pour out of the

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region around it. Radiation and powerful

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outflowing winds of gas. And

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astronomers have a name for the way those

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winds push back on the wider universe.

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They call it feedback.

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Avery: Feedback, as in, um, the black hole feeds and

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the galaxy gets a response?

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Anna: Exactly. And it matters

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enormously because feedback is one of the

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ways galaxies keep themselves in check.

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Here's the puzzle. It at the center of a big

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galaxy cluster, there's a huge reservoir of

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hot gas, millions of degrees glowing in

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X rays. By all rights, that gas should be

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cooling, sinking to the center and collapsing

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into vast numbers of new stars.

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Avery: And it doesn't.

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Anna: And it doesn't. These cluster cores are far

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quieter than the simple physics predicts.

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Something is reheating that gas, keeping it

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stirred up, stopping the runaway cooling.

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For years, the leading suspect has been the

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central black hole. That its outbursts

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dump energy back into the gas and hold

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the whole system in balance. But there's been

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a stubborn gap in the evidence, which is

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we could see black holes driving winds on the

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scale of their own galaxy. What we couldn't

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show was those winds reaching much beyond the

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galaxy, out into the space between

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galaxies. On the scale of the whole cluster.

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That's the part that stayed Theoretical until

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this study.

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Avery: So who did it and, um, how?

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Anna: A team led by Satoshi Yamada at

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Tohoku University in Japan with colleagues

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from Kanazawa, Tokyo Metropolitan and

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Kyoto Universities. It's published in

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Nature Astronomy this week on the 28th.

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And their target is a genuinely special

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object, a quasar called

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H1821

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643.

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Avery: Quasar, meaning a black hole that's feeding

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so ferociously it outshines its entire

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galaxy.

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Anna: That's it. Some of the most luminous

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single objects in the universe. This one sits

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in the Constellation Draco, about

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3.4 billion light years away. And

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its black hole weighs in around 2.6

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billion solar masses. But here's what makes

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it the perfect laboratory. It's the nearest

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quasar that lives right at the heart of a

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galaxy cluster. So you've got a raging black

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hole and a giant reservoir of hot

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cluster gas in the same place, close enough

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to study in detail. That almost never

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happens.

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Avery: And to study it, uh, they used xrism, which

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longtime listeners will remember.

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Anna: We've talked about it before. Yes,

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Xrism M, the X Ray Imaging and

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Spectroscopy mission is the Japanese led

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X Ray Observatory with NASA and the European

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Space Agency aboard. Uh, and its superpower

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is a kind of spectroscopy so precise

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it can read the motion of hot gas from the

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light it gives off.

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Avery: Explain how that works, because this is the

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clever bit.

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Anna: It is the hot gas in a cluster

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contains iron atoms. And those iron atoms

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emit X rays at very specific

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sharp energies, like a particular note.

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Now, if that gas is churning and swirling,

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some of it moves towards us and some away.

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And just like a siren changes pitch as it

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passes you, the motion smears that sharp

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X ray note out, it broadens the line.

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Measure how broad the line is and you've

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measured how violently the gas is moving.

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Avery: So the iron lines become a speedometer for

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gas you can't otherwise see.

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Anna: A speedometer for turbulence. And when they

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pointed xrism

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m@h1821

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643 and read those lines,

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the gas was full of far more turbulent than

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anyone expected. Compared with a calm,

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well behaved cluster like Perseus, the motion

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here is dramatically more violent. And

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it's violent across a huge span of space.

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Avery: How huge?

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Anna: The disturbance reaches out to something like

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300,000 light years from the black

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hole, well beyond the host galaxy, out

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into the cluster itself. And the energy tied

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up in that turbulence is on the order of a

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hundred times greater than earlier estimates.

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Avery: Hundred times. So this isn't A tweak to the

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model. It's a different order of magnitude.

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Anna: It really is. What they've shown is that this

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black hole is pumping something like a few

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to 10% of its radiative energy

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straight into the surrounding cluster. Gas on

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scales of tens to 100

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kiloparsecs. That's the missing link.

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That's direct evidence of a black hole

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heating and stirring its cluster from the

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inside. Exactly the process theorists

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needed to explain why all that gas

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isn't collapsing into stars.

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Avery: Yamada had a nice way of putting it, didn't?

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Anna: Hm, he, he did. He said black holes

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are famous for sucking matter in, but they

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also eject gas in powerful winds.

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And this study says those winds are immensely

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stronger than we understood. For the first

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time, he says, we've shown a black hole

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influencing the broader cosmos through a

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shockwave of astonishing power.

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Avery: And the reason to care beyond wow, big

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number is that this is really a story about

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how galaxies grow up.

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Anna: That's the heart of it. Black holes and their

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galaxies grow together and feedback is the

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thermostat. Too little and the gas cools and

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the galaxy makes far too many stars. Too

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much and it blows the fuel away and star

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formation shuts down. Get it right and you

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build the galaxies we actually see. What

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Yamada's team has done is catch that

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thermostat in the act, working on a scale we

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could only assume before moving energy

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and eventually the chemical elements forged

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in stars out across the cluster.

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Avery: A black hole redecorating a whole

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neighborhood it never touches directly.

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Anna: More than three times the width of the Milky

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Way from a single point at the center. And

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this is really just the opening chapter.

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Xrism is still young and objects

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like

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H1821,643

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are, uh, rare and precious. Expect more of

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these hot cluster cores to get the same

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treatment. And expect our picture of how

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black holes shape the universe to keep

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getting bigger. Which is a lovely irony,

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isn't it? The more we look at the objects

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famous for pulling everything in, the more we

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find them reaching out.

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Avery: Reaching out. Good place to leave the giant.

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Let's bring it right down to a single dead

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star and a, uh, mystery about what it's been

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eating. So story two, A white

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dwarf is what our sun will become billions of

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years from now. The burnt out Earth sized

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core left behind when a star like ours runs

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out of fuel. And for a long time we've known

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these dead stars are a bit macabre. They're

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surrounded by the shredded remains of their

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old Planetary systems, asteroids, and even

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planets torn apart and pulled in.

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Anna: The star literally raining its old

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planets down onto itself.

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Avery: Beautifully grim. Yes, we can tell, because

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we see the metals from that debris polluting

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the star's atmosphere. But new research says

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we've been undercounting the meal, that white

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dwarfs are eating far more planetary material

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than we thought. And the reason we missed it

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is magnetism.

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Anna: Magnetic fields hiding the evidence.

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Avery: Exactly. Some white dwarfs are strongly

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magnetic. And when debris falls in, those

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magnetic field lines funnel the infalling

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material down to the star's magnetic poles,

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concentrating it into small patches instead

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of spreading it evenly. And patches at the

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poles are much easier to miss.

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Anna: And here's the part I love. The researchers

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point out it's essentially the same physics

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as an aurora.

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Avery: It is. Think about how our own auroras

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work. The sun throws charged particles at

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Earth. They follow our magnetic field lines

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down to the poles, and they light up a

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glowing patch in the atmosphere on a magnetic

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white dwarf. Swap the solar particles for the

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debris of a dead planetary system, and you

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get the same choreography material guided

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along field lines to a bright spot at the

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pole.

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Anna: An aurora made of ground up, uh,

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Avery: planets on the corpse of a star.

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And the practical upshot's real. If this

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magnetic funneling is common, then a lot of

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white dwarfs we've written down as clean may

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actually be feeding just quietly in a way

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our surveys don't catch. Which changes how we

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estimate what these old planetary systems

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were made of.

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Anna: A window into the guts of dead solar

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systems, including, one day, our own.

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Speaking of dress rehearsals for the future,

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let's go to Mars. Story 3.

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NASA's Psyche spacecraft is on its way to one

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of the strangest targets in the solar the

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asteroid 16 Psyche. A world that

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may be the exposed metal core of a shattered

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baby planet. Mostly metal, not rock or

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ice. We've never visited anything like it.

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Avery: And it doesn't get there until 2029.

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Anna: Not until 2029. That's right. But on the

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way back in May, it swung past Mars for a

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gravity assist, using the planet's pole to

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bend its path and pick up speed for free.

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And NASA's just shared with the team did with

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that flyby, which is the fun part. They

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treated Mars as a rehearsal studio.

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Avery: A chance to switch everything on and check.

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It works. Far from home.

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Anna: Exactly. They put the cameras, the

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magnetometer, and the particle instruments

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through their paces against a real world

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instead of empty space. They captured a

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striking time lapse of Mars sliding by.

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They even picked up neutrons coming off the

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planet. But the detail that jumped out at me.

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The imager managed to pick out Phoos and

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Deimos, the two tiny moons of Mars from a

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great distance, the little Martian moons.

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Avery: And that wasn't just for a nice photo.

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Anna: No, that was the whole point. Spotting two

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small faint moons against the glare is

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exactly the kind of needle in a haystack test

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they'll need when they arrive at asteroid

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Psyche and go looking for any little moonlets

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orbiting it. So Mars became a practice run

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for a search they'll do for real in a few

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years time, rehearsing the hardshot

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Avery: on a target you already know, so you're ready

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for the one you don't.

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Anna: Precisely. Every instrument checked,

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calibrated and confident three years before

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it matters. From one careful mission to a

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much messier problem closer to home.

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Avery the traffic on the road to the Moon.

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Avery: We spend a lot of time on this show talking

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about who's going to the moon now. NASA's

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Artemis program, China and Russia's planned

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research station, Europe's Argonaut landers,

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and the growing crowd of commercial missions.

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The next decade could see dozens of flights

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into what's called cislunar space. The whole

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region between Earth and the moon.

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Anna: And everywhere we've ever gone in space,

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we've left junk behind.

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Avery: That's the worry. We've made low Earth

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orbit crowded and cluttered. The question

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this new study asks is, are we about to do

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the same thing to the road to the Moon before

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we've even properly moved in? It's from a

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team at the Chinese Academy of Sciences, and

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they've looked at a specific clever kind of

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orbit out there, a, uh, distant retrograde

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orbit, which

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Anna: is one of those very stable parking spots in

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the Earth Moon system.

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Avery: Um, right. A wide stable loop

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that's attractive precisely because

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spacecraft can sit in it for a long time

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without much fuel. The catch is if a

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spacecraft in one of those orbits breaks up,

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an explosion, a, ah, collision, the debris

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doesn't just fall away and disappear the way

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it might near Earth. The team modeled how

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those debris clouds spread. And out there,

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the fragments can linger and drift in ways

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that are genuinely hard to predict.

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Anna: And unlike low Earth orbit, there's no

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friendly atmosphere out there to eventually

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drag the rubbish down and burn it up.

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Avery: That's the crux of it. Near Earth, the

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atmosphere slowly cleans up after us. In

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deep cislunar space, there's no such

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janitor. Debris can stay a hazard far

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longer. So the value of work like this is

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that it's preventative if we can map where

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the risky orbits and the lingering debris

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clouds are before the traffic arrives. We can

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design missions to steer clear and maybe keep

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the highway to the moon open for everyone who

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wants to use it.

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Anna: Cleaning up before we make the mess for once.

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Now let's get you outside because tonight the

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sky is putting on a show. And this one is

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genuinely for tonight, wherever you're

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listening. Two meteor showers are peaking at

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the same time, the night of the 30th into the

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early hours of the 31st. The southern delta

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aquariids and the alpha

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Avery: capricornids, two at once,

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tell us the difference between them.

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Anna: They've got very different personalities. The

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Southern Delta Aquariids are the steady

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workhorses. More meteors, a bit fainter,

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radiating from the constellation Aquarius.

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Their parent is thought to be a comet called

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96PMachholz. The alpha

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Capricornids are the opposite. Not many, but

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the ones you get are slow bright fireballs,

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real showstoppers coming from the direction

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of Capricornus from a comet called

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16.9pmeet.

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Avery: So quality versus quantity sharing

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the same night.

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Anna: Exactly. Now the honest catch this year,

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the moon. We had the full buck moon just last

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night, so tonight it's still around 98%

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lit. And that glare will wash out the fainter

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meteors. But, and this is the saving grace,

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those bright Capricornid fireballs can punch

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right through moonlight. As one astronomer

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put it, one bright one is worth 20 faint

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ones.

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Avery: So how do people actually watch? And um, this

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is where north and south really difference.

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Anna: It does. So let's do both properly. First,

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the good news for us here in the Southern

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hemisphere, this is our show. Both

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radiants ride high overhead from southern

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latitudes, so we get the best seats. The

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Southern Delta Aquarids can deliver something

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like 10 to 20 an hour from a dark site under

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a better moon. And even tonight with the moon

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bright, the south still comes out ahead

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Cygny

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Avery: and um, the east coast. When and where head

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out after the

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Anna: moon and sky settle late evening onward. But

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the best window is the small hours local

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time, roughly 1 to 4am when the

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radiance are highest. Look towards the north

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and east. Get as far from city lights as you

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can and give your eyes a solid 20 to 30

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minutes to adapt. Lie back and take in a

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wide patch of sky rather than staring at one

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spot.

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Avery: And for our North American listeners, our

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biggest audience who don't get the radiant

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Anna: as high, you can still absolutely

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catch this. You just work with lower numbers

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and lean on the fireballs. Your best time

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is Also the pre dawn hours. Think

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2 to 4am local, whether that's

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Eastern Central Mountain or Pacific time.

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Once the radiants have climbed as high as

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they'll get the pro tip for the moonlight

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Position yourself facing away from the moon

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with it at your back or blocked behind a

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building or a hill so its glare isn't in your

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eyes. Then watch a broad stretch

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of sky and wait for those slow Capricorned

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fireballs.

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Avery: No telescope, no binoculars.

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Anna: Done it all meteors are a naked eye

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whole sky event. Just you, a

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reclining chair, something warm and patience.

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And if tonight clouds you out, both showers

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stayed active for another week or two, so

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you'll get more chances as the moon thins out

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and conditions improve.

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Avery: Two comets worth of dust burning up over your

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head. Not a bad way to end the day.

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Anna: Not bad at all. Look up if you can.

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Avery: That's the lot for today. Every story with

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links and sources is over at astronomydaily

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00:17:29.720 --> 00:17:32.320
IO. The new site has the full back

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00:17:32.320 --> 00:17:34.600
catalog, a rolling news feed, and you can

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00:17:34.600 --> 00:17:36.840
sign up for the newsletter or drop us a line

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right there.

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Anna: We love hearing from you. Tell us if you

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catch a Capricorned fireball tonight. Find us

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00:17:43.270 --> 00:17:45.390
at astrodaily pod and on the

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bytes.com podcast network for

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Anna and for me.

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Avery: Thanks for listening.

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Anna: Until tomorrow. Clear skies.

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Avery: Mhm.

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Anna: You

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stories we told.