A Hundred and Nine Flashes

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Anna: Hello and welcome to Astronomy daily. It's

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Thursday the 10th of September 2026.

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This is series five, episode 190.

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And I'm Anna.

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Avery: And I'm Avery. Anna, I want to start with a

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number. 109.

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Anna: Ah, 109 radio flashes.

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Each one lasting about a thousandth of a

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second. Each one from a different galaxy.

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And together they have just been used to

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weigh the ordinary matter of the universe and

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to work out how badly galaxies have been

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throwing it around.

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Avery: A hundred and nine. That's not a lot of

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anything.

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Anna: It's not. And yet the answer they give is

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already as good as what you get from an X ray

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survey of the entire sky. Or a microwave

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telescope that's been running a decade on the

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problem currently standing between cosmology

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and a straight answer about dark energy,

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dark matter and the mass of the neutrino.

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That's our lead.

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Avery: After that, 84 objects that have been sitting

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in the Chandra archive for years, glowing

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in a part of the X ray spectrum nobody was

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really looking at. And which may turn out to

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be the missing ancestors of the exploding

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stars we used to measure the universe.

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Anna: A serious worked out plan to fly a spacecraft

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alongside Hallie's Comet in 2060,

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not past it in a blur alongside it for

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for months, using nothing that hasn't already

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flown.

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Avery: And the US military manoeuvring real

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satellites across three orbital regimes

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in the first exercise of its kind.

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Anna: Plus the sky for both hemispheres. New moon

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tomorrow afternoon. So tonight is about as

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dark as September gets and there's a run of

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solar storms arriving that could put aurora

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at both ends of the planet.

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Let's start with the flashes before the

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result.

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Avery: Set it up for me. What is a fast radio burst?

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Anna: Actually, a pulse of radio energy that

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arrives, does its business in about a

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millisecond and is gone in that

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thousandth of a second. It can release as

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much energy as the sun puts out in a couple

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of days. The first one was found in

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2007 in archived data from the Parkes

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dish in New South Wales. Murrayang by

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Dunkley Lorimer and a student going back

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through observations from 2001. For

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a while, nobody believed it. Reasonably

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enough, one burst, one telescope, no

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repeat.

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Avery: And now.

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Anna: Now we know of thousands. And we know at

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least some come from magnetars, neutron stars

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with absurd magnetic fields. Because in

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2020, one went off inside our own

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galaxy. But that's not today's storey. And

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this is the interesting turn the field has

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taken. What a fast radio burst is, has

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become less important than what it does on

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the way here, which is what it gets

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stretched. That millisecond pulse contains a

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range of radio frequencies, all leaving at

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the same instant. But space between galaxies

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isn't, uh, empty. There's a thin haze of free

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electrons in it. And free electrons, slow,

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low radio frequencies, slightly more than

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high ones.

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Avery: Like a prism.

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Anna: Exactly like a prism. And that's Caltech's

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own comparison. The burst leaves

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its galaxy as one clean pulse

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and arrives here smeared out in time. High

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frequencies first, low frequencies trailing

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behind. You can measure that smear

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precisely. And it has a name, the

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dispersion measure. The size of the delay

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tells you how many free electrons the pulse

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went through, not how far it travelled, how

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much stuff it travelled through. Every burst

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is a core sample of the universe along one

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line of sight.

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Avery: And that solved something.

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Anna: It solved a real embarrassment first time

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out. Ordinary matter, baryons,

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the stuff of atoms. We knew from the cosmic

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microwave background how much of it the

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universe was made with. And when you added up

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everything we could actually see, roughly a

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third was missing. The suspicion was always

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that it sat between the galaxies, spread

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impossibly thin and too cool to glow in X

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rays, which is exactly what a dispersion

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measure is sensitive to, glowing or not.

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Avery: And that's where Australia comes in.

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Anna: That's where Australia comes in. In 2020,

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a team led by Jean Pierre Macquart at the

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Curtain node of ICRAR used ASCAP in

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Western Australia to localise a handful of

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bursts to their host galaxies, compared

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dispersion against distance. And there was

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the missing matter. It's called the Macart

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relation. Now, Makartt himself died that same

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year at 45 months after the paper.

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And it's the foundation everything today is

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built on.

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Avery: So we found the missing matter.

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Anna: What's left to argue about where it is

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in detail? And that's the whole problem,

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because galaxies don't sit quietly and hold

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onto their gas, they throw it out.

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Supernovae. And more importantly,

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supermassive black holes, switching on and

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driving enormous outflows. Gas that

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started concentrated around galaxies gets

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pushed into the space between them, sometimes

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millions of light years out.

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Avery: Feedback.

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Anna: Feedback. And Vikram Ravi at Caltech

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puts the consequence better than I can. The

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process thins the gas around galaxies,

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redistributing matter across vast distances.

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And it smooths out the clumps in a way, he

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says, that looks astonishingly similar to

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what massive neutrinos do or what dark energy

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or dark matter theories predict. Unless you

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can independently measure the feedback, you

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can't tell those effects apart.

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Avery: Explain why clumpiness is the thing being

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Anna: measured, because how lumpy the universe is,

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how strongly matter clusters on different

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scales, is one of the sharpest tests we have

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of what it's made of. Massive neutrinos

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wash out small scale structure. Certain

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dark energy behaviours change the clustering.

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Dark matter that isn't quite cold and inert.

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Same thing. And so does gas being blown about

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by a black hole.

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Avery: So it's a confound.

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Anna: It's the confound and it has a name.

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This sits at the heart of the S8 tension,

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the long running disagreement between how

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lumpy the early universe says things should

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be and how lumpy the late universe actually

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looks. Either that gap is new physics,

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which would be enormous, or we simply

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don't understand how much gas galaxies throw

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around, which is deflating but entirely

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plausible. And nobody could settle it because

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nobody could measure the diffuse gas

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properly. X ray telescopes see the hot

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gas and miss the cool. The microwave

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technique, the kinetic Sunyaev Zeldovich

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effect works, but it's statistical and

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hard. You want something that counts

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electrons and doesn't care what temperature

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they are.

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Avery: A dispersion measure.

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Anna: A dispersion measure. So the new

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work published Tuesday 8 September in Nature

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Astronomy, led by Kriti Sharma at Caltech,

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with Vikram Ravi, Liam Connor and

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Elizabeth Kraus at the University of Arizona.

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Among The CO authors, 109

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fast radio bursts, each localised to a

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host galaxy, so it has a redshift as well as

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a dispersion measure out to a redshift of

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about 0.3, relatively local,

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deliberately, because that's where feedback

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effects are most measurable. Most of the

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bursts come from the Deep synoptic array, the

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DSA110, a Caltech instrument

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at Owens Valley in California built to catch

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these things and pin them to a galaxy in real

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time.

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Avery: And what did the hundred and nine tell them?

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Anna: Two things. First, they measured how much

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feedback has suppressed the clustering of

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matter across the range from galaxy group

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structures down to individual galaxy halos.

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And how much gas is actually sitting in

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groups and clusters between 10 to the 13

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and 10 to the 15 solar masses.

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And there's more of it there than the other

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methods we're finding. The gas fractions come

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out about 1.9 Sigma higher than

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stacking. Erosita's X ray observations of the

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same kinds of systems, and a little above

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what the Atacama Cosmology Telescope gives

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the team reads that the obvious. The bursts

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are counting cool gas the X rays can't see

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because it isn't hot. Enough to shine.

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Avery: So feedback has smoothed things less than we

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thought.

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Anna: Less than the X ray picture implied. And the

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second result is precision Using the bursts

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cut the uncertainty on the clustering at

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those scales by roughly a factor of eight.

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And the constraint is competitive with E.

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Rosita and with the Atacama Cosmology

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Telescope. Those are enormous experiments.

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This is 109 Flashes. Kraus

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Line. This is amazing considering we only had

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about a hundred FRBs in our sample. It's only

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the beginning.

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Avery: Caveats?

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Anna: Three honest ones. One M hundred nine

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is a small sample and the tension with

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Erosita at 1.9 Sigma is

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interesting, not established. Second

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part of every dispersion measure comes from

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the host galaxy itself and has to be

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modelled. They get an average host

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contribution of about 129

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in the units the field uses, give or take

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nearly 20.

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That's the weakest joint in the chain. And

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third, it's a low redshift sample. A

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lot about the recent universe, much less

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about the deep past.

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Avery: And the fix is more bursts.

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Anna: Many more. And it's being built.

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Caltech's next machine, the full Deep

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Synoptic Array is planned for a valley in

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Nevada with construction targeted around

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2029. And should find these in the tens

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of thousands. Ravi's assessment is blunt.

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It'll be a game changer. Sharma's is that

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they've established fast radio bursts as a

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leading probe of the distribution of matter

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in the universe. And that the data can now

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sharpen experiments asking about dark matter,

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dark energy and the mass of the neutrino.

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For something that was a single unexplained

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blip in an Australian archive 19 years ago.

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That's quite a promotion.

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Avery: And that's the thread back home.

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Anna: That's the thread. The technique is southern

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in origin and still substantially southern in

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practise. The first burst came out of parks.

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The McCourt relation came out of Azcap on

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Wajari country at Inyarimana Il Ghari

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Bundara. And ASCAP is still one of the most

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productive burst localising instruments on

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the planet. Its Krako upgrade exists

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specifically to catch them live and hand a

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position to other telescopes fast enough to

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chase. Meerkat works the same field.

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Both sites are the foundations of the Square

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Kilometre Array which we talked about

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Avery: five days ago for a completely different

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reason.

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Anna: The MeerKAT 21 centimetre detection.

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A different way of weighing the same universe

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with the same kind of dish. Two techniques,

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two hemispheres. One question and the

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honest summary of today is that 109 flashes

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have walked into a fight with the giant

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surveys have been having for a decade and

266
00:10:56.300 --> 00:10:58.660
landed a punch storey too.

267
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Avery: And it's a discovery made without a telescope

268
00:11:01.540 --> 00:11:04.340
pointing anywhere. Yesterday, NASA announced

269
00:11:04.340 --> 00:11:07.140
a new class of cosmic object found

270
00:11:07.140 --> 00:11:09.780
in data that Chandra had already collected.

271
00:11:09.940 --> 00:11:12.620
And the reason nobody had noticed is that

272
00:11:12.620 --> 00:11:14.860
they're bright in exactly the place people

273
00:11:14.860 --> 00:11:16.100
don't usually look.

274
00:11:16.580 --> 00:11:17.700
Anna: Which place is that?

275
00:11:18.100 --> 00:11:20.500
Avery: The very bottom of the X ray band

276
00:11:21.020 --> 00:11:23.660
below about 3/10 of a kilo electron

277
00:11:23.660 --> 00:11:26.460
volt, which is the soft edge of what an X

278
00:11:26.460 --> 00:11:29.420
ray telescope can even register. The

279
00:11:29.420 --> 00:11:32.340
team's own criterion is stark. These

280
00:11:32.340 --> 00:11:34.860
things put out more than eight times as many

281
00:11:34.860 --> 00:11:37.700
photons in the lowest slice of the band as

282
00:11:37.700 --> 00:11:40.060
they do in the slice immediately above it.

283
00:11:40.460 --> 00:11:43.220
Look at them in a standard X ray image and

284
00:11:43.220 --> 00:11:45.900
they're there. Look at the same field at

285
00:11:45.900 --> 00:11:48.140
higher energies and they vanished.

286
00:11:48.640 --> 00:11:50.760
Anna: So they're being selected out routinely.

287
00:11:50.760 --> 00:11:53.280
Avery: By the way surveys are built. Mustafa

288
00:11:53.280 --> 00:11:56.040
Muhibullah at the University of Alabama with

289
00:11:56.040 --> 00:11:59.000
Jimmy Irwin there and Roseanne Distefano at

290
00:11:59.000 --> 00:12:01.400
the Centre for Astrophysics went looking

291
00:12:01.400 --> 00:12:04.160
specifically in that soft slice across six

292
00:12:04.240 --> 00:12:06.960
galaxies. Andromeda and the Pinwheel

293
00:12:07.120 --> 00:12:10.000
M M101, plus four ellipticals,

294
00:12:10.320 --> 00:12:13.280
84 of them hypersoft X ray

295
00:12:13.280 --> 00:12:15.770
sources. They're calling them Muhibulla's

296
00:12:15.770 --> 00:12:18.130
line. We've never encountered a group of

297
00:12:18.130 --> 00:12:19.610
objects that act like this.

298
00:12:20.410 --> 00:12:21.210
Anna: What are they?

299
00:12:21.690 --> 00:12:24.410
Avery: Best guess. And the paper keeps it a guess.

300
00:12:24.730 --> 00:12:27.650
A, uh, compact object pulling material off a

301
00:12:27.650 --> 00:12:30.490
companion star. A white dwarf, in

302
00:12:30.490 --> 00:12:33.450
some cases, possibly a black hole. That's

303
00:12:33.450 --> 00:12:36.410
a familiar picture. We know hundreds of X ray

304
00:12:36.410 --> 00:12:39.010
binaries. What isn't familiar is the

305
00:12:39.010 --> 00:12:41.890
combination. More than 10 to the 38

306
00:12:41.890 --> 00:12:44.730
ergs per second in that narrow soft band

307
00:12:44.730 --> 00:12:47.720
alone. And considerably more again in the

308
00:12:47.720 --> 00:12:50.080
extreme ultraviolet. Fierce

309
00:12:50.080 --> 00:12:53.040
ultraviolet paired with unusually feeble X

310
00:12:53.040 --> 00:12:55.840
rays. Nobody's seen those two together in

311
00:12:55.840 --> 00:12:56.640
one population.

312
00:12:57.440 --> 00:12:59.120
Anna: And there are two payoffs.

313
00:12:59.600 --> 00:13:02.560
Avery: Both good accreting, uh, white dwarfs are

314
00:13:02.560 --> 00:13:04.440
the leading candidate for the thing we've

315
00:13:04.440 --> 00:13:07.240
never caught in the act. The progenitor of a

316
00:13:07.240 --> 00:13:10.000
type 1A supernova. A white

317
00:13:10.000 --> 00:13:12.680
dwarf steadily eating a companion until it

318
00:13:12.680 --> 00:13:15.280
crosses a mass threshold and detonates.

319
00:13:16.000 --> 00:13:18.600
Anna: Which is the supernova we use as a standard

320
00:13:18.600 --> 00:13:19.200
candle.

321
00:13:19.600 --> 00:13:22.520
Avery: Exactly the one the explosion, the whole

322
00:13:22.520 --> 00:13:24.920
discovery of cosmic acceleration was built

323
00:13:24.920 --> 00:13:27.120
on. And the one we were talking about a

324
00:13:27.120 --> 00:13:29.680
fortnight ago with the dark energy rebuttal,

325
00:13:30.000 --> 00:13:32.680
we've been calibrating cosmology on a blast

326
00:13:32.680 --> 00:13:34.960
whose ancestors we couldn't identify.

327
00:13:35.440 --> 00:13:38.000
If these 84 are, uh, that population

328
00:13:38.320 --> 00:13:41.040
or part of it, that's a gap closed

329
00:13:41.710 --> 00:13:44.670
and the second ionisation. All

330
00:13:44.670 --> 00:13:47.670
that extreme ultraviolet strips electrons off

331
00:13:47.670 --> 00:13:50.190
surrounding gas and which gas is

332
00:13:50.190 --> 00:13:52.870
ionised feeds straight into how galaxies

333
00:13:52.870 --> 00:13:55.830
cool and form stars. There's been a

334
00:13:55.830 --> 00:13:58.270
persistent shortfall between the ionising

335
00:13:58.270 --> 00:14:00.830
radiation we can account for and what we

336
00:14:00.830 --> 00:14:03.550
actually observe. And here's a population

337
00:14:03.630 --> 00:14:05.950
that's been quietly contributing all along

338
00:14:06.350 --> 00:14:09.030
while staying nearly invisible to the surveys

339
00:14:09.030 --> 00:14:11.950
meant to find it. Caveat the

340
00:14:11.950 --> 00:14:14.830
obvious 184 objects across

341
00:14:14.830 --> 00:14:17.510
six galaxies is a class defined by a

342
00:14:17.510 --> 00:14:20.510
shared X ray signature, not by anyone

343
00:14:20.510 --> 00:14:23.430
knowing what each one is. Some may be several

344
00:14:23.430 --> 00:14:25.550
different things wearing the same colours.

345
00:14:26.029 --> 00:14:28.950
The work now is ultraviolet follow up and

346
00:14:28.950 --> 00:14:31.710
looking for variability. A nova

347
00:14:31.710 --> 00:14:34.110
leaves a very different fingerprint over time

348
00:14:34.270 --> 00:14:36.350
than a steadily accreting binary.

349
00:14:36.990 --> 00:14:39.870
But the headline stands a whole category

350
00:14:39.870 --> 00:14:42.830
of luminous object in nearby galaxies.

351
00:14:43.070 --> 00:14:45.790
In data we already had storey

352
00:14:45.790 --> 00:14:46.190
three

353
00:14:46.590 --> 00:14:49.230
Anna: and it's a plan rather than a result. But

354
00:14:49.230 --> 00:14:51.470
it's a serious one and it has a deadline.

355
00:14:51.710 --> 00:14:54.270
Hallie's comet comes back to perihelion in

356
00:14:54.270 --> 00:14:57.030
2061. A group of researchers

357
00:14:57.030 --> 00:14:59.350
has just published a worked trajectory for

358
00:14:59.350 --> 00:15:02.030
getting a spacecraft alongside it and staying

359
00:15:02.030 --> 00:15:02.350
there.

360
00:15:02.990 --> 00:15:05.230
Avery: Alongside, not passed.

361
00:15:05.390 --> 00:15:07.670
Anna: That's the whole point. Remember what

362
00:15:07.670 --> 00:15:10.630
happened last time? In 1986 we sent

363
00:15:10.630 --> 00:15:12.790
the largest international fleet ever

364
00:15:12.790 --> 00:15:15.710
assembled to one object. The Haley

365
00:15:15.710 --> 00:15:18.709
Armada, ESA's Giotto, the

366
00:15:18.709 --> 00:15:21.190
Soviet Vega 1 and 2, Japan's

367
00:15:21.190 --> 00:15:23.590
Suisei and Sakigake and a

368
00:15:23.590 --> 00:15:26.550
repurposed NASA spacecraft. Giotto

369
00:15:26.550 --> 00:15:29.030
got within about 600 kilometres and returned

370
00:15:29.030 --> 00:15:31.450
the first images of a cometary nucleus and

371
00:15:31.600 --> 00:15:32.080
ever taken.

372
00:15:32.720 --> 00:15:34.240
Avery: And how long did that take?

373
00:15:34.800 --> 00:15:37.600
Anna: Minutes. Giotto went past at, uh, roughly

374
00:15:37.600 --> 00:15:40.120
68 kilometres per second, about

375
00:15:40.120 --> 00:15:42.640
245,000 kilometres an hour

376
00:15:42.960 --> 00:15:45.320
and was hit by a dust grain and knocked off

377
00:15:45.320 --> 00:15:48.120
its spin axis on the way through. Everything

378
00:15:48.120 --> 00:15:50.920
we learned about Haley up close we learned in

379
00:15:50.920 --> 00:15:52.720
the time it takes to make a cup of tea.

380
00:15:53.200 --> 00:15:54.320
Avery: Why so fast?

381
00:15:54.800 --> 00:15:57.730
Anna: Because Hailey goes the wrong way. Its orbit

382
00:15:57.730 --> 00:16:00.210
is retrograde against the direction the

383
00:16:00.210 --> 00:16:02.810
planets travel and steeply inclined.

384
00:16:02.970 --> 00:16:05.770
So a spacecraft on a normal solar orbit meets

385
00:16:05.770 --> 00:16:08.530
it nearly head on to match velocity.

386
00:16:08.530 --> 00:16:10.650
Instead you'd have to reverse a large

387
00:16:10.650 --> 00:16:12.730
fraction of your own motion around the sun.

388
00:16:13.049 --> 00:16:15.330
And the propellant bill for that has always

389
00:16:15.330 --> 00:16:16.810
been considered fantasy.

390
00:16:17.370 --> 00:16:19.450
Avery: And this paper says otherwise.

391
00:16:19.930 --> 00:16:21.850
Anna: With hardware that has already flown.

392
00:16:22.580 --> 00:16:25.460
Roberto Flores and Elena Fantino at Khalifa

393
00:16:25.460 --> 00:16:28.380
University in Abu Dhabi with Mauro Pontani

394
00:16:28.380 --> 00:16:31.260
at Sapienza in Rome and Ivano Bertini

395
00:16:31.260 --> 00:16:33.780
and Cesare Barbieri at Padua. And

396
00:16:33.780 --> 00:16:36.460
Barbieri is worth a pause because he worked

397
00:16:36.460 --> 00:16:39.100
on the camera that took those 1986 Giotto

398
00:16:39.100 --> 00:16:41.980
images. 50 years on planning the

399
00:16:41.980 --> 00:16:42.740
return trip.

400
00:16:43.220 --> 00:16:44.260
Avery: So what's the trick.

401
00:16:44.740 --> 00:16:47.060
Anna: Two unpowered gravity assists,

402
00:16:47.300 --> 00:16:50.080
Jupiter, then Saturn, stitched together

403
00:16:50.080 --> 00:16:52.920
with long, low thrust arcs in deep space.

404
00:16:53.480 --> 00:16:55.800
The assists do the expensive bending and

405
00:16:55.800 --> 00:16:58.520
slowing for free. And a Hall effect ion

406
00:16:58.520 --> 00:17:00.960
thruster running off a standard radioisotope

407
00:17:00.960 --> 00:17:03.240
generator. Does the patient work in between

408
00:17:03.960 --> 00:17:06.240
their two worked examples? Launch in August

409
00:17:06.240 --> 00:17:09.200
2036 or September 2037 on

410
00:17:09.200 --> 00:17:11.880
an existing launcher at roughly 2,000

411
00:17:11.880 --> 00:17:14.200
kilogrammes, including propellant. About

412
00:17:14.200 --> 00:17:16.040
750 of that instruments

413
00:17:16.860 --> 00:17:19.740
arriving when? 2060, about

414
00:17:19.740 --> 00:17:22.420
a year before perihelion. Deliberately early,

415
00:17:22.420 --> 00:17:24.820
so it's in place and settled before the comet

416
00:17:24.820 --> 00:17:27.260
warms up and switches on. Then it flies

417
00:17:27.260 --> 00:17:30.180
alongside and watches months instead

418
00:17:30.180 --> 00:17:32.660
of minutes, and the whole transition from a

419
00:17:32.660 --> 00:17:35.620
cold, quiet nucleus to a fully active

420
00:17:35.620 --> 00:17:38.380
comet recorded from a few kilometres away.

421
00:17:39.020 --> 00:17:41.940
Avery: 24 years of flight, which is the real

422
00:17:41.940 --> 00:17:42.300
cost.

423
00:17:42.880 --> 00:17:45.640
Anna: That's a career and then some. But it's a

424
00:17:45.640 --> 00:17:48.000
rendezvous with Hallie's comet using proven

425
00:17:48.000 --> 00:17:50.640
parts, and the launch window is 10 years

426
00:17:50.640 --> 00:17:53.520
away. Somebody has to decide fairly soon.

427
00:17:54.000 --> 00:17:56.480
Avery: And there's a southern footnote, a lovely

428
00:17:56.480 --> 00:17:56.800
one.

429
00:17:57.040 --> 00:17:59.800
Anna: Hallie belongs to us down here in a way it

430
00:17:59.800 --> 00:18:02.000
doesn't to the north. The

431
00:18:02.000 --> 00:18:04.960
1986 apparition was poor from

432
00:18:04.960 --> 00:18:07.800
northern latitudes and much better from the

433
00:18:07.800 --> 00:18:10.590
southern hemisphere. Hallie's dust

434
00:18:10.590 --> 00:18:13.150
gives us the Eta Aquariids. Every May,

435
00:18:13.550 --> 00:18:16.390
a decidedly southern shower. And

436
00:18:16.390 --> 00:18:19.190
Edmond Hallie made his name by sailing to St

437
00:18:19.190 --> 00:18:22.110
Helena at 20 to catalogue the southern

438
00:18:22.110 --> 00:18:24.670
stars no European had properly charted.

439
00:18:25.150 --> 00:18:27.710
He was a southern sky observer before he was

440
00:18:27.710 --> 00:18:28.590
a comet man.

441
00:18:29.310 --> 00:18:30.110
Avery: Last storey.

442
00:18:30.430 --> 00:18:32.830
And it's a change of subject entirely.

443
00:18:33.230 --> 00:18:35.880
On Tuesday, you, US Space Command

444
00:18:35.880 --> 00:18:37.960
announced it had just completed something

445
00:18:37.960 --> 00:18:40.920
called Apollo Manoeuvres 2026,

446
00:18:41.480 --> 00:18:44.280
the first live fly exercise of its kind

447
00:18:44.520 --> 00:18:47.480
using real satellites actually moved

448
00:18:47.560 --> 00:18:50.120
across three different orbital regimes.

449
00:18:50.760 --> 00:18:53.080
Anna: Live fly meaning not a simulation?

450
00:18:53.880 --> 00:18:56.280
Avery: Not a simulation. Which is the

451
00:18:56.280 --> 00:18:59.160
newsworthy part? Space exercises

452
00:18:59.160 --> 00:19:02.040
are almost always tabletop or synthetic.

453
00:19:02.670 --> 00:19:05.550
This one took existing operational satellites

454
00:19:05.550 --> 00:19:08.430
and manoeuvred them in low Earth orbit,

455
00:19:08.430 --> 00:19:10.670
in medium orbit and out at

456
00:19:10.670 --> 00:19:13.670
geosynchronous, 22,000 miles

457
00:19:13.670 --> 00:19:16.470
up. Allied partners from Operation

458
00:19:16.470 --> 00:19:19.230
Olympic Defender took part, which includes

459
00:19:19.230 --> 00:19:21.870
Australia and commercial operators were

460
00:19:21.870 --> 00:19:24.310
folded in through what Space Command calls

461
00:19:24.310 --> 00:19:26.270
its Commercial Integration Cell.

462
00:19:26.750 --> 00:19:28.110
Anna: Why is that a departure?

463
00:19:28.910 --> 00:19:31.470
Avery: Because of how satellites are normally flown.

464
00:19:32.030 --> 00:19:34.270
A, uh, satellite carries a fuel budget

465
00:19:34.270 --> 00:19:37.030
calculated for one staying

466
00:19:37.030 --> 00:19:39.510
where it was put, Station

467
00:19:39.510 --> 00:19:42.470
keeping, a bit of debris avoidance and a

468
00:19:42.470 --> 00:19:45.470
final nudge to a disposal orbit. At end of

469
00:19:45.470 --> 00:19:48.270
life. Every gramme of propellant is

470
00:19:48.270 --> 00:19:50.990
hoarded because when it runs out, the

471
00:19:50.990 --> 00:19:53.910
satellite's working life is over, regardless

472
00:19:53.910 --> 00:19:56.350
of whether anything on board still functions.

473
00:19:57.120 --> 00:19:58.880
Anna: And this is the opposite philosophy.

474
00:19:59.440 --> 00:20:01.640
Avery: This is treating manoeuvre as something you

475
00:20:01.640 --> 00:20:04.040
do on purpose for position and

476
00:20:04.040 --> 00:20:06.840
accepting the cost. General Stephen

477
00:20:06.840 --> 00:20:08.960
Whiting's framing was that to perform,

478
00:20:09.600 --> 00:20:12.040
survive and gain advantage in the space

479
00:20:12.040 --> 00:20:14.960
domain, they need manoeuvrability and

480
00:20:15.040 --> 00:20:17.120
survivability in their capabilities.

481
00:20:18.000 --> 00:20:20.720
The exercise even borrows its name from

482
00:20:20.720 --> 00:20:23.400
history, the Louisiana manoeuvres of

483
00:20:23.400 --> 00:20:26.280
1941, when the US army

484
00:20:26.280 --> 00:20:28.800
moved several hundred thousand troops around

485
00:20:28.800 --> 00:20:31.280
the American south to work out how

486
00:20:31.280 --> 00:20:33.960
mechanised warfare actually functioned

487
00:20:33.960 --> 00:20:35.160
before it had to.

488
00:20:35.560 --> 00:20:37.600
Anna: And the implication for everyone else in

489
00:20:37.600 --> 00:20:40.520
Avery: orbit, that's the part I'd flag. And

490
00:20:40.520 --> 00:20:42.960
it cuts both ways. If

491
00:20:42.960 --> 00:20:45.600
satellites start manoeuvring routinely rather

492
00:20:45.600 --> 00:20:48.360
than exceptionally, then the catalogues and

493
00:20:48.360 --> 00:20:50.600
conjunction warnings that the whole industry

494
00:20:50.680 --> 00:20:53.400
relies on get harder to keep accurate.

495
00:20:53.880 --> 00:20:56.280
Those systems assume objects follow

496
00:20:56.280 --> 00:20:59.040
predictable paths and are updated on a

497
00:20:59.040 --> 00:21:01.960
schedule. Everyone tracking the sky,

498
00:21:02.120 --> 00:21:04.840
civil and military, has to work with

499
00:21:04.840 --> 00:21:07.720
more uncertainty. There's also a design

500
00:21:07.880 --> 00:21:10.640
consequence coming. Refuelling and

501
00:21:10.640 --> 00:21:13.640
servicing in orbit stop being a nice idea

502
00:21:13.720 --> 00:21:16.280
and start being the thing that determines how

503
00:21:16.280 --> 00:21:17.360
long a satellite

504
00:21:17.360 --> 00:21:20.200
Anna: is useful for, which is a commercial storey

505
00:21:20.200 --> 00:21:21.560
as much as a defence one.

506
00:21:21.720 --> 00:21:24.520
Avery: Very much so, and that's why it's on this

507
00:21:24.520 --> 00:21:27.280
show. Whatever you think about militaries

508
00:21:27.280 --> 00:21:30.120
manoeuvring in orbit, and there are entirely

509
00:21:30.120 --> 00:21:32.720
reasonable views in both directions, the

510
00:21:32.720 --> 00:21:35.600
practical consequence is more moving objects

511
00:21:35.600 --> 00:21:38.120
in a region that is already more crowded than

512
00:21:38.120 --> 00:21:40.400
it has ever been. That affects

513
00:21:40.400 --> 00:21:43.400
observers, operators and astronomers alike,

514
00:21:43.960 --> 00:21:46.630
Anna: and to the sky. This is a good week. And the

515
00:21:46.630 --> 00:21:49.630
reason is simple. New Moon falls Tomorrow,

516
00:21:49.630 --> 00:21:52.550
Friday the 11th, at 27 minutes past

517
00:21:52.550 --> 00:21:55.470
2 in the afternoon. Sydney time. That's

518
00:21:55.470 --> 00:21:57.550
just after 4 in the morning, Universal Time,

519
00:21:57.870 --> 00:21:59.990
which means tonight and tomorrow night are

520
00:21:59.990 --> 00:22:02.550
the darkest of the month. Whatever you have

521
00:22:02.550 --> 00:22:04.670
been meaning to look at, look at it now.

522
00:22:05.310 --> 00:22:08.230
Southern hemisphere first from Sydney and

523
00:22:08.230 --> 00:22:10.910
similar latitudes. The core of the Milky Way

524
00:22:10.910 --> 00:22:13.850
is still high after dark. Sagittarius and

525
00:22:13.850 --> 00:22:16.130
Scorpius up towards the zenith in the early

526
00:22:16.130 --> 00:22:18.650
evening. And on a moonless night away from

527
00:22:18.650 --> 00:22:21.570
town, it is genuinely startling. This

528
00:22:21.570 --> 00:22:23.730
is the last really good fortnight of it for

529
00:22:23.730 --> 00:22:26.490
the year. Binoculars, no plan,

530
00:22:26.730 --> 00:22:28.370
half an hour, that's the whole

531
00:22:28.370 --> 00:22:29.130
recommendation.

532
00:22:29.770 --> 00:22:30.730
Avery: And, um. Venus.

533
00:22:31.290 --> 00:22:34.290
Anna: Venus is the evening object, low in the

534
00:22:34.290 --> 00:22:37.050
west southwest, and it wants dealing with

535
00:22:37.050 --> 00:22:39.820
promptly 45 minutes after sunset.

536
00:22:39.820 --> 00:22:42.420
It's less than 5 degrees up, about three

537
00:22:42.420 --> 00:22:45.020
finger widths at arm's length. So you need a

538
00:22:45.020 --> 00:22:48.020
genuinely flat horizon. The compensation

539
00:22:48.020 --> 00:22:50.700
is that it's brilliant. And Spica sits a bit

540
00:22:50.700 --> 00:22:53.180
over 7 degrees away, both in one

541
00:22:53.180 --> 00:22:55.940
binocular field. Is a nice catch and it's

542
00:22:55.940 --> 00:22:58.220
still brightening. Greatest Brilliancy on the

543
00:22:58.220 --> 00:23:00.980
18th at magnitude -4.8.

544
00:23:01.380 --> 00:23:03.460
This is an apparition where the geometry

545
00:23:03.460 --> 00:23:05.920
favours the south. From mid northern

546
00:23:05.920 --> 00:23:08.080
latitudes, Venus is scraping the horizon in

547
00:23:08.080 --> 00:23:10.640
twilight From Sydney it's a clean

548
00:23:10.640 --> 00:23:13.240
naked eye object. Saturn.

549
00:23:13.640 --> 00:23:16.200
Saturn is the good news for everybody. It

550
00:23:16.200 --> 00:23:18.760
rises in the east about an hour after sunset

551
00:23:18.840 --> 00:23:21.520
and three hours after sunset it's more than

552
00:23:21.520 --> 00:23:23.800
20 degrees up in the east southeast.

553
00:23:24.280 --> 00:23:27.000
Opposition is on the 4th of October, close

554
00:23:27.000 --> 00:23:29.240
enough now to matter. And the rings are only

555
00:23:29.240 --> 00:23:32.000
about 7 degrees from edge on, which makes

556
00:23:32.000 --> 00:23:34.680
this an unusual year to look at it. Any

557
00:23:34.680 --> 00:23:37.120
telescope and quite a few decent binoculars

558
00:23:37.120 --> 00:23:39.760
on a tripod will show it North

559
00:23:39.760 --> 00:23:40.440
America.

560
00:23:40.440 --> 00:23:41.120
Avery: Your turn.

561
00:23:41.680 --> 00:23:44.040
Anna: Saturn is your evening object too for the

562
00:23:44.040 --> 00:23:46.360
same reasons and it's a far better bet for

563
00:23:46.360 --> 00:23:48.960
you than Venus. Venus is technically there in

564
00:23:48.960 --> 00:23:51.720
the west after sunset, but it's a hard low

565
00:23:51.720 --> 00:23:54.720
catch from mid northern latitudes. Worth a

566
00:23:54.720 --> 00:23:57.200
try. With a clear horizon, not worth planning

567
00:23:57.200 --> 00:24:00.010
an evening around. The morning sky though is

568
00:24:00.010 --> 00:24:02.050
where northern observers do well this week.

569
00:24:02.370 --> 00:24:04.690
Before sunrise there are two planets in the

570
00:24:05.330 --> 00:24:08.250
Mars higher moving through Gemini and

571
00:24:08.250 --> 00:24:10.930
Jupiter below it in Cancer. Mars

572
00:24:10.930 --> 00:24:13.330
passes right by Castor on Saturday the 12th

573
00:24:13.330 --> 00:24:16.290
and by Pollux on the 17th. So you can watch

574
00:24:16.290 --> 00:24:18.610
a planet walk past the twins over a week

575
00:24:19.090 --> 00:24:21.450
from southern latitudes. Both are lower and

576
00:24:21.450 --> 00:24:23.730
later. This one belongs to the north

577
00:24:24.520 --> 00:24:24.540
and

578
00:24:24.540 --> 00:24:25.960
Avery: um, there's live weather.

579
00:24:26.040 --> 00:24:28.520
Anna: There is and it's why I'd keep an eye out

580
00:24:28.520 --> 00:24:31.280
tonight. A run of coronal mass ejections

581
00:24:31.280 --> 00:24:33.960
left active region 4524

582
00:24:34.360 --> 00:24:37.320
on the 5th and 6th and has been arriving in

583
00:24:37.320 --> 00:24:39.959
convoy since Tuesday. Two have already

584
00:24:39.959 --> 00:24:42.120
produced minor geomagnetic storming

585
00:24:43.320 --> 00:24:45.880
with G2 possible as the last arrive

586
00:24:46.200 --> 00:24:48.360
and forecasters expect it to settle from

587
00:24:48.360 --> 00:24:51.040
today. Aurora chances have reached the

588
00:24:51.040 --> 00:24:53.890
northern United States, the UK and northern

589
00:24:53.890 --> 00:24:56.650
France. And down here for the

590
00:24:56.650 --> 00:24:59.450
aurora Australis. A uh G1 to G2

591
00:24:59.450 --> 00:25:02.370
storm puts Tasmania in with a real chance.

592
00:25:02.530 --> 00:25:04.850
Coastal southern Victoria if it strengthens.

593
00:25:05.170 --> 00:25:07.170
And the south island of New Zealand well

594
00:25:07.170 --> 00:25:10.130
placed. Look south, get away from town lights

595
00:25:10.130 --> 00:25:12.730
and give your camera a long exposure even if

596
00:25:12.730 --> 00:25:15.450
your eyes see nothing, A phone on night mode

597
00:25:15.450 --> 00:25:18.020
will often pick up colour the eye can't. And

598
00:25:18.020 --> 00:25:20.140
with New Moon there's no moonlight in the

599
00:25:20.140 --> 00:25:20.380
way.

600
00:25:20.780 --> 00:25:22.860
Avery: Safety passage, yes.

601
00:25:23.020 --> 00:25:25.220
Anna: And this one is in every episode for a

602
00:25:25.220 --> 00:25:27.700
reason. With Venus this bright, some people

603
00:25:27.700 --> 00:25:29.940
go looking for it in daylight, which is a

604
00:25:29.940 --> 00:25:32.940
real and rewarding thing to do. And also the

605
00:25:32.940 --> 00:25:35.620
one time of year we get nervous. Venus in

606
00:25:35.620 --> 00:25:37.660
daylight sits close to the sun in the sky.

607
00:25:38.220 --> 00:25:40.340
Never sweep for it with binoculars or a

608
00:25:40.340 --> 00:25:42.340
telescope without a proper solar filter

609
00:25:42.340 --> 00:25:44.990
fitted at the front. A fraction of a second

610
00:25:44.990 --> 00:25:47.270
of direct sunlight through magnifying optics

611
00:25:47.510 --> 00:25:50.150
causes permanent, painless retinal damage.

612
00:25:50.550 --> 00:25:52.510
If you're looking anywhere near the sun with

613
00:25:52.510 --> 00:25:55.030
your eyes alone, use eclipse glasses

614
00:25:55.030 --> 00:25:56.310
certified to ISO

615
00:25:56.310 --> 00:25:58.710
123122.

616
00:25:59.030 --> 00:26:01.270
Cheque them for scratches or pinholes first

617
00:26:01.350 --> 00:26:03.870
and understand what they're for. They are

618
00:26:03.870 --> 00:26:06.510
made for the naked eye only and must never be

619
00:26:06.510 --> 00:26:08.910
used in combination with binoculars, a

620
00:26:08.910 --> 00:26:11.680
telescope or a camera viewfinder. The

621
00:26:11.680 --> 00:26:13.960
safe way to find Venus in daylight is to use

622
00:26:13.960 --> 00:26:16.800
a solid object, a building edge, a

623
00:26:16.800 --> 00:26:19.480
wall to block the sun completely before you

624
00:26:19.480 --> 00:26:20.000
start looking.

625
00:26:20.640 --> 00:26:23.160
Avery: And looking ahead the equinox on the

626
00:26:23.160 --> 00:26:25.440
Anna: 22nd, which is spring for us and autumn for

627
00:26:25.440 --> 00:26:27.880
the north. Then Saturn's opposition on the

628
00:26:27.880 --> 00:26:30.600
4th of October and on the 6th of October

629
00:26:30.600 --> 00:26:32.760
there's a pre dawn lunar occultation of

630
00:26:32.760 --> 00:26:35.000
Jupiter that is being billed as the year's

631
00:26:35.000 --> 00:26:37.670
best. We'll build up to that one properly.

632
00:26:38.230 --> 00:26:39.670
Avery: Something to look forward to.

633
00:26:40.150 --> 00:26:42.590
Anna: That's Astronomy daily for Thursday 10th

634
00:26:42.590 --> 00:26:45.310
September. A hundred and nine radio flashes

635
00:26:45.310 --> 00:26:47.510
weighing the ordinary matter of the universe

636
00:26:47.510 --> 00:26:49.950
and finding more of it than the X rays could

637
00:26:49.950 --> 00:26:52.590
see. 84 new objects that were in the

638
00:26:52.590 --> 00:26:55.270
archive the whole time. A uh, worked plan to

639
00:26:55.270 --> 00:26:58.270
fly alongside Hallie's Comet in 2060 and

640
00:26:58.270 --> 00:27:00.390
satellites being moved around on purpose.

641
00:27:01.120 --> 00:27:03.080
Avery: Everything we covered with links to the

642
00:27:03.080 --> 00:27:05.800
papers and the source releases is in the show

643
00:27:05.800 --> 00:27:08.560
notes and at astronomydaily IO

644
00:27:08.960 --> 00:27:10.920
where you'll also find the full back

645
00:27:10.920 --> 00:27:13.600
catalogue and the newsletter. If you'd rather

646
00:27:13.600 --> 00:27:14.320
have it in your

647
00:27:14.320 --> 00:27:17.159
Anna: inbox and the contact form on the site is

648
00:27:17.159 --> 00:27:19.760
real and we read it. Several of the storeys

649
00:27:19.760 --> 00:27:21.960
we've run in the past fortnight started as a

650
00:27:21.960 --> 00:27:24.160
listener question, so if there's something

651
00:27:24.160 --> 00:27:26.720
you want explained or followed up, tell us.

652
00:27:26.970 --> 00:27:28.970
Avery: You'll find this on X, Facebook,

653
00:27:29.370 --> 00:27:32.090
Instagram, TikTok, YouTube and

654
00:27:32.090 --> 00:27:34.410
Tumblr at astrodaily. Pod

655
00:27:34.490 --> 00:27:36.410
Astronomy AstroDailyPod is part of the

656
00:27:36.410 --> 00:27:38.570
bytes.com podcast network.

657
00:27:39.370 --> 00:27:40.170
Anna: I'm Anna.

658
00:27:40.250 --> 00:27:43.250
Avery: And I'm Avery. Clear skies and

659
00:27:43.250 --> 00:27:45.530
if you're anywhere south tonight, look up.

660
00:27:45.610 --> 00:27:47.050
It's as dark as it gets.

661
00:27:53.360 --> 00:27:53.600
Anna: The.

662
00:27:58.320 --> 00:27:58.960
Storeys.

663
00:28:06.800 --> 00:28:07.440
Avery: We told

664
00:28:10.650 --> 00:28:10.670
Anna: M.