Far Side | Today's Space News - Astronomy Daily: The Latest Space News

Anna: The side of the Moon we never see has been

quietly keeping a secret about our own

planet. And this week, two very different

groups of scientists arrived at the same

place from opposite directions.

Avery: One group read it out of the dirt. The other

argued about who gets to own it.

Anna: Meanwhile, a rocket sits on a pad in South

Texas waiting for a second chance.

Avery: And a star that vanished behind its own

wreckage 25 years ago has finally

stepped back into the light.

Anna: Welcome to Astronomy Daily. I'm Ana.

Avery: And I'm, um. Avery. It's Thursday 23rd

July 2026, and this is episode

148.

Anna: Coming up, Starship gets another go with

a caveat. What the far side of the Moon knows

about Earth's magnetic field, whether that

far side should be off limits to industry. A

one of a kind stellar explosion finally

identified. And the possibility that our

entire galaxy once turned over.

Avery: Uh, plus a skywatch closer with some

genuinely useful advice about the Delta

Aquarids, which is to not wait for the peak.

Anna: Let's get into it.

Avery: We start at Starbase, because today is meant

to be the day.

Anna: SpaceX is targeting Flight 13 of

Starship with a 90 minute launch window that

opens at 6:45 in the evening Eastern

Time. That's 5:45 Central and

3:45 in the afternoon on the Pacific coast.

For those of us on this side of the world,

that lands at a quarter to nine on Friday

morning Australian Eastern Time and a quarter

to 11 Friday morning in New Zealand.

Avery: So North America gets it over dinner and we

get it over breakfast for once, nobody has to

set an alarm for three in the morning for

once.

Anna: Although, and this is the part I want to be

upfront about, that schedule is not locked.

Meaning? Meaning the public schedule says

today, but the road and beach closure

notifications around Starbase suggest

additional testing is happening happening on

Pad 2. Those closure notices are one of the

more reliable tells in this business because

they have to be filed in advance and they

tend to reflect what's actually planned

rather than what's been announced. So there

is a realistic chance this

Avery: slides again, which would make it the third

date for Flight 13.

Anna: It would. Let's recap how we got here because

the arc matters. Flight 13 was first set

for Thursday 16th July. The countdown went

all the way to zero and then stopped. The

flight software triggered an automatic abort

right at T0 because four of the 33

Raptor engines on the Super Heavy booster

failed to reach acceptable starting

parameters.

Avery: And um, the threshold is 3, so

Anna: it missed by exactly one engine. That's the

system working as designed and it protected

both the vehicle and the pad. Elon Musk said

afterwards that two Raptors would be pulled

and replaced before the next attempt.

Avery: That's a remarkably narrow margin between a

scrub and a launch.

Anna: It is, and it's deliberate. The vehicle was

cleared to fly in the first place because the

SAA closed out its mishap investigation into

Flight 12 on 13 July. And the

booster had already completed a full duration

static fire of all 33 engines back on the

10th.

Avery: So the hardware had been through its paces.

It just didn't like the moment.

Anna: That's about the size of it. Here's what

makes this flight worth paying attention to.

Beyond the launch itself, Blight 13 is

carrying 20 V3 Starlink satellites,

the next generation of the Constellation, and

the first time Starship has ever deployed

them.

Avery: That's the whole point of the vehicle

eventually. Not the spectacle, the payload.

Anna: Right up to now, these have been test flights

carrying simulators and mass models. This is

the first time the thing does the job it was

built for. Even on a suborbital trajectory

and the flight profile. Oster and ship

separate as usual. Super Heavy steers

itself to a controlled splashdown in the Gulf

about seven minutes after liftoff. No

catch attempt with the chopstick arms on this

one. The ship continues on,

deploys the satellites and then comes down

for its own splashdown in the Indian Ocean

off the coast of Western Australia at around

Avery: minutes, which is worth flagging for our, uh,

listeners in Perth and along that coast. You

are not going to see it from the beach. It's

a long way offshore, but it is your patch of

ocean.

Anna: It is. And for anyone in North America

hoping to catch the launch itself, it's a

star based departure. So the viewing sites

around Boca Chica and South Padre island are

the ones that matter.

Avery: So assuming it goes.

Anna: Assuming it goes. If you're listening to this

on Thursday, check before you commit your

evening. If you're listening later, you

already know how it turned out and we'll pick

up the result in the next episode. Either

way, this ark has taught us not to get ahead

of ourselves.

Avery: Now, to the moon and to something I find

genuinely lovely about this next result,

which is that it turns lunar soil into a

record of Earth.

Anna: Go on.

Avery: The sun blows a continuous stream of charged

particles out across a solar system. The

solar wind. The moon has no atmosphere and

no global magnetic field to speak of. So

those particles hit the surface directly and

bury themselves in the soil over billions of

years. The regolith becomes an archive of

everything that struck it.

Anna: And noble gases are the good bookkeepers.

Avery: Exactly. Helium, neon, argon,

krypton, xenon. They don't react with

anything. So whatever went in stays in.

And how deep it went tells you how fast it

was traveling when it arrived.

Anna: So what did they find?

Avery: A team at the Chinese Academy of Sciences,

Institute of Geology and Physics analyzed

samples from Chang' E6. The mission that

returned material from the far side from the

south pole aitken Basin. That's

1,935 grams of soil,

just under 2 kilograms.

Anna: And that's the first far side material anyone

has ever had in a laboratory.

Avery: Every previous return sample, Apollo, Luna,

Chang' e5 came from the near side. So this

is the first time anyone could directly

compare the two hemispheres. They worked

through seven portions using stepwise heating

and laser extraction, measuring the isotopes

of all five noble gases. And the far side

soil is measurably different. The solar

wind went in faster and went in deeper.

Anna: Deeper, meaning higher energy.

Avery: Higher energy, yes. The clearest signal was

in neon. The ratio of Neon 20 to

Neon 22 in the Cheng' E6 material

sits below anything recorded in any near

sight sample, which points to stronger

processing on the way in. And the heavier

gases krypton and xenon come out of the

sample at different temperatures than they do

from Chang' E5 material, which is another way

of reading implantation depth.

Anna: So why would the far side get hit harder?

Avery: Because we're in the way. M

Earth magnetosphere. As the moon

travels around its orbit, it spends part of

each month downstream of Earth, inside the

long magnetic tail our planet trails behind

it. And in that region, the solar wind

gets slowed down before it reaches the lunar

surface. But it's the near side that's facing

us. So the near side is the one that catches

at the celerated wind. The far side is

permanently turned away and takes the full

unmoderated stream.

Anna: Earth has been sheltering the side of the

moon that looks at us for 4 billion

years.

Avery: For 4 billion years. And the team put

a number on it. Roughly a quarter of the

total solar wind exposure at the Chang' e 5

landing site involved that slowed down flow.

At the Chang' e 6 site on the far side,

there's no sign of it at all.

Anna: That's a beautiful result. And I assume it

cuts the other way as well.

Avery: That's the part that excites me most. If the

near site soil records how much shielding

Earth was providing, then heavy noble gases

in lunar Regolith become a fossil record of

our own magnetosphere. Combine that with the

rock magnetism record on Earth, and you have

a completely new way of reconstructing how

our magnetic field has changed over deep

time.

Anna: Which is not a small thing, given the

magnetosphere is the reason we still have an

atmosphere.

Avery: Not a small thing at all. The Moon has been

keeping notes on us, and it turns out the far

side has the cleaner copy. Which, as

it happens, is exactly why a room full of

astronomers spent Tuesday evening arguing

about what we're allowed to do out there.

Anna: So this was at the Royal Astronomical

Society's National Astronomy Meeting, which

is running this week at the University of

Birmingham. On Tuesday evening, they staged a

formal debate on a single proposition, that

the far side of the Moon should be preserved

solely for scientific endeavors.

Avery: And the answer is presumably not obvious or

there'd be no debate.

Anna: It's genuinely not. Arguing in favor were

Joe Silk of Johns Hopkins and Jonathan

McDowell, who most of our listeners will know

from Jonathan's space report and who is now

an honorary professor at Durham Space

Research Center. After decades at the Harvard

Smithsonian center for Astrophysica, um, and

against M. Nikita Chu, also at Durham, who

works on space technology governance, and

manuel Salvoldi, an Aram space engineer with

25 years across industry and academia.

Barton Ward convened it. The case for

protection rests on one physical fact. The

far side is the only radio quiet real

estate anywhere near Earth.

Avery: The Moon is tidally locked, so the same

hemisphere always faces us, which means the

far side is permanently shielded from every

transmitter, every radar, every broadcast on

this planet. And that matters because.

Anna: Because there are signals we want to detect

that are drowned out everywhere else. The

cosmic dark ages, the stretch of time after

the Big Bang before the first star switched

on. The radio emission from that era is faint

and it's low frequency. And Earth is far too

noisy a place to hear it. A far side radio

telescope is arguably the only way we ever

will.

Avery: That's a fairly specific and, um,

irreplaceable thing to be arguing about.

Anna: It is, and Cilk's framing was essentially

generational, that we should protect these

conditions for science. That won't be done

for decades, because the questions at stake

are whether we're alone and how the universe

began.

Avery: And, um, the physical case doesn't stop at

radio.

Anna: No. They also argued the far side would be an

exceptional site for gravitational wave

detection. No atmosphere, no weather, very

little seismic activity compared with Earth,

and no artificial light, which is becoming a

real problem for optical astronomy down here.

Avery: So what's the counterargument, because leave

it alone is easy to say.

Anna: The counterargument is about sustainability,

and I thought it was stronger than people

might expect. Few's position was that this

isn't a challenge to the value of the

science, it's a question of how you keep

going back at all. Lunar exploration that

depends entirely on government funding is

fragile. Commercial investment is what makes

it resilient. And her argument was that you

can have both under proper governance, that

an inclusive CIS lunar economy on the far

side doesn't have to turn into a free for

all.

Avery: Which is a fair point. A protected region

nobody can afford to reach is protected in a

fairly useless way.

Anna: That's the tension. Exactly. And McDowell's

put the stakes in the broadest possible

terms. His line was is the whole solar system

up for grabs or do we set aside reserves?

Avery: That's the real question, isn't it? Not the

Moon specifically.

Anna: Not the Moon specifically. His argument was

that whatever we decide in the next few years

becomes the precedent for everything after

Mars, the asteroids, all of it.

Avery: Did they take a vote?

Anna: They did. Before and after. By QR code.

Support for the motion went from 68%

to 76%, though the room moved

towards protection, which, given the

audience, isn't a shock. But an eight point

swing after hearing both sides is a real

result rather than a formality. And it fed

into a full session the next day on lunar

governance and regulation.

Avery: And in the meantime, Chang' E6 has just

demonstrated that the far side is

scientifically valuable in ways nobody had

directly measured measured until this month,

which rather

Anna: sharpens the argument staying at the National

Avery: Astronomy Meeting because there is a

genuinely extraordinary object I want to talk

about, and it lives in our skies.

Southern skies Puppis, which for our

Australian and New Zealand listeners is well

placed for a good chunk of the year, and for

northern listeners sits low on the south. The

object is V445 Puppis,

and it is the only confirmed helium nova in

the Milky Way.

Anna: Define helium nova.

Avery: So a nova, an ordinary nova,

is a white dwarf in a binary system stealing

gas off its companion. That gas piles

up on the surface, pressure and temperature

climb, and eventually you get a runaway

thermonuclear explosion. It doesn't

destroy the star, it just blows the

accumulated layer off. And in virtually

every case, that stolen material is

hydrogen rich, because hydrogen is what stars

are mostly made of.

Anna: And this one isn't.

Avery: This one has essentially no hydrogen at all,

which is a very strange thing for a stellar

explosion to be missing, given hydrogen is

the most abundant element in the universe. So

the obvious question is what is it stealing

from?

Anna: And nobody could see.

Avery: Nobody could see. V445

puppys erupted in late 2000, and it

threw out an enormous bipolar outflow. Two

lobes of material streaming in opposite

directions, more than a trillion miles

across. But the eruption also created a thick

disk of dust that completely swallowed the

system. For more than 20 years, astronomers

could watch the debris expanding, but they

could not see what was inside it. The dust

has now thinned enough. John Mills, a

researcher and PhD student at the University

of Warwick, put together observations

spanning two decades to finally see through

using what a stack of instruments.

Infrared from the Very Large Telescope in

Chile, Optical imaging from Hubble,

Long term spectroscopy from the Southern

African Large Telescope and photometry from

tess. And the answer is a white dwarf

feeding off a helium star.

Anna: And a helium star is a star

Avery: that has been stripped of its outer hydrogen

envelope, most likely by the companion it's

now feeding. They are genuinely rare.

The estimate is a few thousand stripped

helium stars among the hundreds of billions

of stars in the entire galaxy.

Anna: So one of the rarest kinds of stars in the

only known example of one of the rarest kinds

of explosions.

Avery: And it's already loading the gun again. The

system is actively transferring material once

more. The two stars orbit each other every

3.7 days, which is around twice as

long as anyone previously thought.

Anna: You said there was a mystery.

Avery: The bullets. The bullets embedded in the

outflowing debris are discrete clumps of gas,

possibly oxygen rich, though the composition

isn't nailed down. Moving at up to 20

million miles an hour, that's roughly

9,000 kilometers per second, around

3% of the speed of light.

Anna: And nothing like that has been seen

elsewhere.

Avery: Nothing like it in any other nova anywhere.

Mills suspects they formed after the outburst

rather than during it. But as he put it,

their origin is a mystery.

Anna: Which is the honest answer. And I appreciate

that he said it.

Avery: So do I. Now, the reason this matters. Beyond

its own strangeness, Astronomers suspect that

repeated helium rich eruptions on a white

dwarf might be one of the pathways that

eventually produces a type 1A supernova.

Anna: And type IAs are the standard candles.

Avery: They are. They explode with remarkably

consistent brightness, which is what makes

them useful as distance markers across the

universe. They're how we measured cosmic

expansion. The work that won the Nobel Prize

for the discovery that the expansion is

accelerating.

Anna: So the ruler we use to measure the universe

depends on understanding how these things

detonate.

Avery: It does. And whether helium novae actually

get there is still an open question. But

V445 Puppis is now the clearest

laboratory anyone has for testing it. And it

took 25 years of dust clearing to get the

door open.

Anna: Last story before we look up. And it's the

biggest one in terms of sheer scale. There's

a case being made that the entire Milky Way

once flipped over.

Avery: Flipped over how exactly? Because a galaxy

doesn't have a right way up.

Anna: It doesn't. And that's the right instinct.

What's being proposed is a change of

orientation. That the disk of our galaxy

reoriented itself by more than 90 degrees

relative to the halo of old stars around it.

Avery: And what put that idea on the table?

Anna: A puzzle that's been sitting there since

Gaia. Our galaxy has a flat disk where

most of the stars live. And around that a

much larger, much sparser stellar halo.

Mostly stars that formed in smaller galaxies

and got absorbed when those galaxies were

Avery: pulled in debris from past meals.

Anna: Essentially. And Gaia showed that the halo

barely rotates. It creeps around at something

like 10 to 20 kilometers per second. The

disk by comparison is moving at about

220.

Avery: That is a very large discrepancy.

Anna: It is. And nobody had a satisfying

explanation. So Kirill Botrikov at

Durham went looking for one in simulations.

The Auriga Suite, which models Milky Way like

galaxies in detail. He took 25 of them

and followed their evolution across roughly

11 billion years. And the

galaxies that ended up with the most slowly

rotating halos had two things in common.

They'd experienced a major head on merger

and their disks had reoriented by more than

90 degrees.

Avery: And we know we had a major head on merger.

Anna: We do. Gaia Sausage, Enceladus. The

collision roughly 10 billion years ago that

dumped an enormous quantity of stars into our

halo and is the reason the halo looks the way

it does.

Avery: So the proposal is that the same collision

exerted a gravitational torque on our disk

and slowly turned it over inside the

surrounding dark matter halo.

Anna: Slowly meaning over hundreds of

millions of years. Nothing about this was

sudden, but the end state is that the plane

the sun orbits in today may bear no

relationship to the plane stars were orbiting

in before the collision.

Avery: That does something odd to my sense of place.

Anna: It does mine too. And I want to be careful

here because Botcherkov himself is careful.

His position is that a disk flip is a likely

explanation given how slowly the halo turns,

but that it's too early to claim it with full

confidence. What he wants is independent

signatures, other scars that a reorientation

on that Scale should have left behind.

Avery: Is there anything pointing the same way

already?

Anna: There is, and it's suggestive rather than

conclusive. Separate work this year led by

Ling Xu used the motions of more than

600,000 giant stars from Gaia and the

LAMOST survey to reconstruct the shape of our

dark matter halo. And the outer halo appears

to be oriented almost vertically relative,

uh, to the

Avery: stellar disk, which is what you'd expect if

the inner part tilted and the outer part

didn't.

Anna: That's the reading. The outer halo kept the

old orientation. The disk and inner halo

swung round. Two independent lines of

evidence converging on the same story from

completely different data. Not proof,

but it's the kind of thing that turns a

curiosity into a research program. And

I rather like that. The biggest structural

question about our own galaxy is one we can

only answer by looking at it from the inside.

Avery: Right, Time to look up.

And Anna, uh, we have actual advice today

rather than a countdown.

Anna: We do. And the advice is don't wait for the

peak.

Avery: Explain.

Anna: The southern Delta Aquarids are running now.

The shower is already active and it stays

active into late August. The American Meteor

Society puts maximum activity around the

30th of July.

Avery: And the problem with the 30th is the moon.

Anna: The moon is the problem. Full moon falls on

the 29th of July. So on peak night, you're

looking at a sky that is something like 98%

illuminated. That will wash out most of the

shower. Because Delta Aquariad meteors tend

towards long, graceful trails rather than

bright fireballs. They're exactly the kind

that moonlight erases.

Avery: So the peak is the worst night of the run.

Anna: Close to it. But here's the good news. This

shower has no sharp maximum. It

rambles. Rates build slowly and stay

roughly level for well over a week. Which

means the mornings between now and about the

27th are better than peak night because the

waxing gibbous moon still sets before the

radiant gets high.

Avery: So the window is after moonset, before

Anna: dawn, after moonset, before dawn. That's

your window. And it applies wherever you are.

Where do we look? The radiant sits near the

star Skat in Aquarius. The easiest way

in is to find Fomalhaut bright and

noticeably alone in a fairly empty patch of

sky. And work from there. The Great Square of

Pegasus helps as well.

Avery: And, um, that's a very different experience

depending on which hemisphere you're in.

Anna: Completely different from Australia and New

Zealand. The radiant climbs close to overhead

in the pre dawn hours. This is genuinely

our Shower. The southern part of the world

gets the best of it every year from Sydney or

Auckland, anywhere from about 2 in the

morning until first light.

Avery: And for our North American listeners, who are

the largest part of this audience,

Anna: you still get a good showing, but the

radiance stays lower in the southern sky, so

you'll see fewer of them and they'll come in

at shallower angles. And the upside of a low

radiant is Earth grazers, meteors that

skim along the atmosphere and leave much

longer trails than usual. The best hours are

the same from around 2 in the morning local

time, uh, until dawn. So 2 to 5am, um,

eastern and the equivalent across Central

Mountain and Pacific.

Avery: And get south facing and dark.

Anna: Get south facing, get away from lights and

give your eyes 20 minutes to adapt before you

judge whether it's working.

Avery: One more thing. And, um, this one is a watch

this space rather than a forecast.

Anna: The sun has woken up.

Avery: Sunspot 4493.

Anna: That one. It appeared essentially from

nothing over the space of a couple of days

and grew fast. And it now has what's called

a beta gamma delta magnetic

classification, which is the most complex

classification there is. Regions like that

are, uh, where the big flares come from.

Avery: And it's already produced some 3M M

Anna: class flares inside a single day. The

Strongest an M M3.4, each of

them causing brief minor radio blackouts

across different parts of the world.

Forecasters have been putting the odds of

further M M class activity at better than

even with a smaller chance of an X class

event.

Avery: So it's worth keeping an eye on the aurora

alerts it is.

Anna: Earlier this week, a fast solar wind stream

from a coronal hole pushed conditions to

minor storm level, with aurora possible as

far equatorward as Hobart in the south and

Seattle and Edinburgh in the north. That

particular stream is easing now. But with a

region that complex facing us, the situation

can change quickly.

Avery: And Southern hemisphere observers have the

advantage of long winter nights right now,

while northern observers are fighting short

summer ones. Swings and

roundabouts.

Anna: That's episode 148, Starship waiting

on a window that may or may not hold, a far

side that's been quietly recording our

magnetic field and an argument about whether

we should leave it alone.

Avery: Plus a star that spent 25 years behind a

curtain and the galaxy that may have rolled

over in its sleep.

Anna: Show notes, sources and everything else are

at astronomydaily, IO or

astrodaily Pod, wherever you like to find us.

Avery: If you're up before dawn this week chasing

Delta Aquariids, we'd love to see what you

catch.

Anna: We'll be back tomorrow.

Avery: Until then, clear skies.

In this episode