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Anna: G' day and welcome to Astronomy

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AstroDailyPod. I'm Anna.

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Avery: And I'm Avery. It's the weekend wrap for

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Saturday 8th August, and this is one of those

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rare weekends where the sky itself is the

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headline. We are four days out from a total

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solar eclipse and the peak of the Perseids

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landing on the very same night.

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Anna: We'll get you set for all of that in the sky

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watch at the end. Both hemispheres, proper

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local times and one eye safety rule.

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None of us are allowed to skip.

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But we start where the whole week has quietly

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been pointing at the sun.

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Avery: Then, um, three storeys at the find the week.

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A rocket stage that finally hit The Moon, a

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48 year old spacecraft that just bought

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itself another year of life, and the rescue

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mission that spent, uh, the week rescuing

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itself. Let's go.

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Anna: Here's the question that sounds simple and

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isn't. What does the surface of the sun

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actually look like up close? Not the

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postcard, the fine detail right down at

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the scale where the physics happens. This

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week for the first time, we got to see it.

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And the answer is it's covered in whirlpools.

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Avery: Whirlpools on the sun.

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Anna: Tiny ones, some only about 20

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kilometres across, which on the sun is almost

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microscopic. In a paper published Wednesday

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in Nature, a team led by David

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Kureads at the U.S. national Solar

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Observatory in Hawaii, the biggest solar

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telescope ever built, a four metre mirror

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on Haleakala, zoomed in on the

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edges of the sun's granules. And where

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earlier telescopes saw a smooth, slightly

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blurry boundary, Inoue saw

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structure curling, breaking, wave

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like swirls forming and dissipating

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everywhere along the magnetic boundaries.

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Avery: And, um, these have a name. They're not a

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total surprise, physically.

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Anna: Right, exactly right. And that's what makes

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it satisfying rather than baffling. They're

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called Kelvin Helmholtz instabilities.

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If you've ever watched wind peel the top of

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an ocean wave, or seen those rows of curling

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cloud that look like a breaking sea in the

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sky, that's the same effect. It happens

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whenever two fluids slide past each other at

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different speeds. Lord Kelvin and Hermann

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Helmholtz described the math back around

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1870.

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Avery: So the physics is 150 years old. The

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picture of it on the sun's surface is four

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days old.

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Anna: That's the whole storey in one line. We've

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seen these swirls in Earth's clouds, in the

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atmospheres of Jupiter and Saturn, even

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hinted at high up in the sun's outer

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corona. But never before down on the

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visible surface, the Photosphere where the

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solar wind and all that magnetic energy

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actually originate. The resolution

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simply wasn't there. Inui changed that.

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Avery: Walk me through why the surface is the

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important place to catch them.

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Anna: Because that's where the sun's magnetic field

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tangles with its boiling convection. Picture

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the granules, those bright cells of hot

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plasma, rising, cooling, sinking

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like a pot of porridge on the boil at the

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edges. Flows crash into each other, and the

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magnetic field lines get squeezed together.

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Bundle field lines tighter, and the field

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gets stronger. The stronger field resists

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the plasma flow. And that sudden change in

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speed is exactly the shear you need to set a

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Kelvin Helmh vortex spinning.

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Avery: And they didn't just eyeball it and declare

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victory.

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Anna: No, this is the part I like. They ran the

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same magnetic region through a state of the

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art physics simulation, A model called

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Maram, built purely from the laws of

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physics. No fudging. And the simulated sun

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grew the same swirls in the same places with

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the same shapes. Observation and theory

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shaking hands. The Max Planck team called the

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agreement remarkable. And that's the word

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that earns this a, uh, nature paper. Not we

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saw something odd, but we saw it. We

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understand why. And the model agrees.

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Avery: So why should someone with feet firmly on the

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ground care about micro whirlpools

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93 million miles away?

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Anna: Two reasons, and they're both big. The

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first is one of the great unsolved puzzles in

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solar physics. The corona problem. The

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sun's surface is around 6,000 degrees.

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Its outer atmosphere, the corona, is

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millions of degrees, hundreds of times

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hotter. Further away from the heat source.

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That should be impossible. Like standing

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back from a campfire and getting warmer.

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Something is carrying energy upward and

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dumping it into the corona. And these

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ubiquitous little vortices are a very good

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candidate for part of that pipeline.

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Avery: And the second reason is the one that reaches

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down and touches U.S. base weather.

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Anna: Those same swirls could feed the buildup of

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magnetic energy that the sun eventually

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releases as flares and coronal mass

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ejections. The blasts of charged

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particles that, when they're aimed our way,

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can knock satellites about, degrade GPS

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and stress power grids. The next step

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is to turn pattern recognition algorithms

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loose on long runs of ENOYE data

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to measure how much these instabilities

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actually shift. Nail that number, and

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you sharpen the models that forecast solar

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storms.

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Avery: Which is a lovely place to be starting an

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eclipse week. Honestly, everyone's about to

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point their attention at the sun anyway.

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Anna: It really is. For decades, this was a

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prediction on a chalkboard. This week, it

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became a picture. The Sun's surface

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isn't a smooth glowing ball, it's a

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sea and it's full of breaking waves

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from the sun to

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Avery: the moon and to a storey. This show first

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flagged back in the autumn. Early Wednesday

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morning, a spent SpaceX Falcon 9 upper

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stage slammed into the far western edge of

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the moon near Einstein Crater at around half

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past two in the morning US Eastern time.

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Anna: This is the one astronomer Bill Grey had been

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tracking since April.

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Avery: The very one. Catalogue number

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2025 010D.

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Roughly four tonnes of hollow metal, about 12

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metres long. It launched in January last

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year, carrying two commercial lunar landers,

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Firefly's Blue Ghost and I. Space's

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resilience. Under NASA's Commercial Lunar

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Programme, its job done, it was left

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drifting. And for 19 months, sunlight

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and gravity nudged it around cislunar space

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until the numbers lined up on a collision

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course.

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Anna: And it hit at genuinely startling speed,

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Avery: about 5,400 miles an hour,

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seven times the speed of sound, releasing

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energy like roughly three tonnes of TNT.

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The catch for skywatchers, it came down on

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sunlit ground, so any flash was washed out by

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daylight. Nobody on Earth got the fireworks.

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Anna: So how do we actually confirm it happened

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and see the scar from orbit?

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Avery: And this is where it gets good. NASA's Lunar

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Reconnaissance Orbiter and South Korea's

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Dhanuri spacecraft are retasking to

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photograph the site. Because we know almost

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exactly where and when it struck. We get

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a rare before and after. A fresh crater

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expected somewhere between 18 and 30

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metres wide, appearing on a patch of moon we

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already had mapped. I'll be honest, those

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high resolution images aren't in hand yet.

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They depend on lighting and orbital geometry

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over the coming weeks. But the impact itself

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is confirmed.

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Anna: And there's a bigger point sitting underneath

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the spectacle.

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Avery: There is.

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This is only the second known unintentional

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lunar impact by a rocket stage. The first was

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a Chinese Booster back in 2022. But the

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traffic up there is climbing fast and there's

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still no binding rulebook for disposing of

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hardware on these high energy paths.

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SpaceX says this stage was passivated by the

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book and is now working with NASA on

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prevention. Fittingly, the international

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meeting that produced the latest

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recommendations for the moon was held right

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here in Sydney. The recommendations are real.

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The requirements aren't there yet.

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Anna: A new crater and a, uh, nudge to write some

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rules before the next one.

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Now to the most distant good news, Storey,

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you'll hear all year. Voyager 2, launched

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in 1977, now more than

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21 billion kilometres away out

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in Interstellar space has just been given

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at least another full year of science by

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engineers who can't touch it, can't send it

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apart and have to wait about 19 and a

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half hours just for a command to arrive.

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Avery: And they've given the manoeuvre a wonderful

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name.

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Anna: They're calling it the Big Bang. Here's the

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problem it Voyager runs on

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plutonium radioisotope generators

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that turn heat from decay into electricity

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and that supply drops by about 4

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watts every single year. It's a

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spacecraft slowly running out of power. And

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for years the fix has been to switch

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instruments off one by one without action.

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Voyager 2 would have had to shut down another

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of its three remaining instruments before the

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end of this year.

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Avery: So why Big Bang? What's dramatic about a

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power swap?

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Anna: Because it all had to happen at once. They

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switched off a set of power hungry devices

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and swapped in lower power alternatives.

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But the catch is that the very same power

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also produces heat. And out there, near

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absolute zero, if the wrong component gets

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too cold, it freezes and dies

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permanently. You can't do it gently, one

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step at a time. The thermal sums only

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balance if you throw the switches

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simultaneously. As one of the engineers put

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it, they couldn't afford to be wrong. And

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it worked exactly to plan.

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Avery: And Voyager 1 is next in the queue.

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Anna: It is. The team is stepping through the same

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process on Voyager 1 in the coming weeks. And

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the early tests have gone smoothly. Two

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probes, 48 years old, still

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humanity's only instruments physically out in

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interstellar space, kept alive by people

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rewriting how the hardware is used from

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13 billion miles back. That's not

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a rescue. That ends the storey. The power

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keeps falling. But it's another year of

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listening to the space between the stars.

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Avery: And now our, uh, running saga of the week.

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The rescue mission that spent the week being

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rescued. You'll remember the setup. NASA

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Swift Observatory, 22 years old, a

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first responder for gamma ray burst is

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sinking. Its orbit is decaying and it can't

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lift itself. And without help, it's likely to

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re enter this spring, our time. Once it drops

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below about 300 kilometres.

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Anna: Enter link. Built at extraordinary

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speed to go up and give Swift a boost.

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Avery: A commercial servicing spacecraft from

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Catalyst Space built clean sheet in about

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nine months. Launched last month. First of

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its kind. A private robot grabbing a

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government satellite that was never designed

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to be serviced, except that during

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commissioning, Link itself tumbled into a

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multi axis spin up to 9 degrees a

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second. With two of its three reaction wheels

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out of action and some loss in its cold gas

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thrusters. The rescuer needed a rescue.

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Anna: And this week is where that turned a corner.

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Avery: It genuinely did. Using thruster

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burns, the team has wrestled that spin all

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the way down from 9 degrees a second, uh, to

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1.47 degrees. And they're holding

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it steady there. The D spin effectively is

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one the mission has now shifted from a

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stabilisation problem to a software one.

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Because so much of the original attitude

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control system is offline, they're preparing

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a major flight software upgrade to restore

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full control using what still works.

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Anna: And only once that lands can the chase

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actually begin.

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Avery: Right, software update first, then the

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phasing manoeuvres to line Link's orbit up

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with Swift. Then a rendezvous and, uh, a

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grapple with its three robotic arms targeted

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around the end of August. If it all comes

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off, Lynx slowly walks Swift back up toward

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its old orbit over a couple of months, then

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peels away and burns up itself. It's down

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to the wire. But a week ago, this looked

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close to lost. And today it looks like a

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spacecraft catching its breath. Breath before

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the hardest part.

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Anna: We will absolutely keep you posted as that

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end of August window comes up.

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And so to the sky. And What a, uh, four days

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we're heading into. On Wednesday 12th

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August, two of the year's marquee events land

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together. A, uh, total solar eclipse and

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the peak of the Perseid meteor shower.

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Avery: Let's be straight with everyone about who

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sees what, because this one is lopsided.

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Anna: It is. So let's do it. Honestly, the

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total eclipse, the full daytime darkness,

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corona blazing spectacle, belongs to the

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far north. The path of totality crosses the

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Arctic, eastern Greenland, western Iceland

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and clips northern Spain and the very

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northeast of Portugal near sunset. If you're

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anywhere near there, you're in for one of the

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sky's greatest sights, under two and a half

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minutes of it.

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Avery: And, um, for our North American listeners,

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our largest audience, the honest picture is a

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partial and only in one corner.

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Anna: That's right. No part of North America sees

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totality this time. But in the afternoon on

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the 12th, Eastern Canada and the northeastern

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United States get a genuine partial in parts

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of Atlantic Canada, roughly half the sun

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covered at maximum. A smaller bite across New

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England and the Northeast further west, it

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fades to little or nothing. If you're in

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that eastern window, cheque local times for

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your exact town. It's an afternoon event. And

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dig out your eclipse glasses.

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Avery: Which brings us to the rule we

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Anna: never, ever skip the non

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negotiable. To look at any partial phase

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of the sun safely, you need proper solar

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filters. That meet the ISO

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123122 standard

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certified eclipse glasses or a safe solar

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viewer M ordinary sunglasses do not work

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no matter how dark. Only someone standing

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inside the path of totality may remove them

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and only during the brief total phase.

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Everyone seeing a partial, that's all of

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North America and most of Europe keeps them

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on the entire time. Damage to your eyes

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is painless and permanent. Please don't risk

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it.

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Avery: And if you're nowhere near the track, which

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includes all of us down here in the south,

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NASA streams the whole thing live from about

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a quarter past one eastern.

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Anna: Now the Perseids that same night and here the

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news is good for the northern half of the

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world. The peak lies the night of the 12th

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into the 13th and this year the peak is

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essentially moonless. The eclipse falls on a

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new moon so the sky is dark and the faint

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meteors get their moment from the mid

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northern latitudes after midnight that's

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potentially dozens an hour under clear skies.

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North America, Europe, this is your gift of

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the week.

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Avery: But the Perseids are a northern shower. The

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radiant barely lifts above the horizon.

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Anna: For those of us down here it barely clears

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it. So from Sydney or Auckland you'll catch

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only a stray few low in the north before

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dawn. So here's what the southern hemisphere

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actually gets and it's worth setting an alarm

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for before sunrise. This week the morning

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sky is stacked a long line of planets

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Saturn, Mars, Uranus and

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Neptunewith Jupiter low and Mercury

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climbing strung across the pre dawn.

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Venus is your brilliant evening star after

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sunset and for the patient Comet

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10P Tempel 2 is rising late in the

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evening around half past nine. If you've got

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binoculars and a dark

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Avery: horizon so nobody misses out. North gets

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the eclipse and the meteors. South gets the

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planet parade and a comet and the livestream

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is there for all of us.

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Anna: Both hemispheres eyes up all week, just

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protect them around that sun.

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Avery: That's the weekend wrap for Saturday 8th

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August. The Sun's hidden whirlpools, a

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fresh crater on the moon, Voyager 2's

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extra year and a rescue mission back on its

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feet.

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Anna: We're back with your daily fix on Monday and

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all week we'll be counting down to that

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eclipse and Perseid Wednesday. Find the full

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back catalogue, the news feed and the

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00:16:24.310 --> 00:16:27.150
newsletter@uh astronomydailyio

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and say hello@astronomydailypod

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until Monday from Anna and me.

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Avery: Look after those eyes and clear skies.