Anna: Picture an asteroid. You're probably
imagining a potato, one lump of
rock tumbling through the dark. Now
imagine three lumps joined at the neck
like a cosmic string of pearls and
a tiny moon keeping pace alongside.
Avery: That's a real object out in the main belt.
And until this week, nobody knew it looked
like that. We'll take you there first, and
then
Anna: we'll chase a wind. One that lights up
our own sky and the same kind of
wind that's slowly stripping a planet
bare.
Avery: G' day and welcome to Astronomy Daily. It's
Friday 31st July, 2026.
I'm Avery.
Anna: And I'm Anna. Four stories today,
a skywatch that spans both
hemispheres and a thread running right
through the back half of the show. Avery,
where do we start?
Avery: Where else? With the three faced asteroid.
Anna: So, asteroid 44
NISA. The number tells you it was one of
the early finds. Discovered back in
1857. One of the
brightest asteroids in the whole main
belt. That broad river of rubble between
Mars and Jupiter. It's about
75 kilometers across at its widest.
So a serious chunk of rock, one of the
largest of its particular type.
Its type matters here. NISA is
what astronomers call an E type. Its
surface is rich in a pale mineral called
instatite, which makes it unusually
bright and reflective. There aren't many
big E types, so NYSSA has always
been a bit of a favorite. But its shape
has been a nagging mystery for years.
Earlier observations hinted it might be
what's called a contact binary. Two
lobes stuck together, a bit like a
peanut or a snowman. We've seen
plenty of those. Comet 67P
that Rosetta visited, the little asteroid
Dimorphos that the NASA Dart mission crashed
into last year. Donald Johansen that
the Lucy spacecraft flew past last year.
Two lobes is almost normal.
BISA isn't normal. A team
led by Kate Minker at, uh, Lowell Observatory
has just announced in a study with the
wonderful title Unmasking 44
Nysa, that Nyssa appears to have
three lobes. Three joined by
two narrow necks, like, uh, a figure carved
with two deep waists around it.
If it holds up, it's the first tri
lobed asteroid ever seen.
Avery: Three lobes? How do you even see that? These
things are tiny dots, even in big telescopes.
Anna: That's the clever part. They used two of
the sharpest eyes on Earth. The Large
Binocular Telescope in Arizona. Its
main mirror is about eight meters, roughly
three times the size of Hubble's, running an
instrument called sharkvis, plus
the Very Large Telescope down in Chile.
And they used adaptive optics, a mirror
that flexes hundreds of times a second,
nearly 600 tiny actuators
pushing on it to cancel out the blurring of
our atmosphere in real time. The
result is sharper than Hubble. They imaged
NISA on two nights, 15
February and 21 March this year.
And both times the same strange
three part silhouette turned up.
Which brings us to the second surprise.
NISA has a moon, a little one,
about a kilometer across, orbiting at
least 170 kilometers out.
It's been given the placeholder name
S202644
1, and it
was hiding in plain sight, drowned out by
the glare of the much brighter asteroid next
to it. To dig it out, the team borrowed a
trick from a completely different corner of
high contrast imaging, the same family
of techniques we used to pull a faint
planet out of the glare of its star.
As one of the sharkvis scientists,
Gianluca Lee Cauce, put it, they used
that technique to catch a faint companion
whose light was being swamped by the primary.
And because they caught it moving across two
separate observing runs, they know it's
genuinely in orbit, not a background star.
Avery: Photobombing the shot and a, uh, moon is
useful, right?
Anna: Not just a bonus, it's enormously
useful. This is the thing I love about it.
Watch how fast the moon goes round and how
far out it sits and you can weigh the
asteroid. You get nice's mass.
Combine the mass with the size and you get
its density. And density is the whole
ball game here, because there are two
competing stories for what NYSA actually
is. Story one, it's a
genuine three part body, maybe a
contact trinary. Three chunks that
drifted together and gently stuck.
It's one solid, deeply dented lump
that only looks three lobed from our angle.
Density can help tell those apart. A loose
rubble pile reads light and fluffy. A
solid coherent rock reads dense.
So that little moon is going to help settle
what kind of world this is and how it got
so weird.
Avery: Any theories on the how?
Anna: Nothing locked in. And that honesty is
the fun of it. It could be a record of
gentle slow motion collisions in the belt,
bodies bumping and merging over billions of
years. It could be the aftermath of a
bigger smash that left a battered
survivor. Or observations of that
moon will narrow it down. For now, we've got
a brand new kind of object, a triple
lobed asteroid with its own satellite
sitting in a part of the sky we thought we
understood. And that's the quiet lesson of
NISA. It was found in
1857. It's one of the best
studied bright asteroids we have. And in
2026, it still had two secrets
left. A shape nobody expected and a
moon nobody had seen. The solar system
is not done surprising
Avery: us from a world we can nearly
touch to one we may never reach,
but might one day actually see.
NASA has just backed a genuinely audacious
idea. A plan to photograph the surface of a
planet around another star. Not detect
it, not measure it, see it.
Continents, oceans, weather.
Anna: Hang on, we can't do that. I feel
like we have pictures of exoplanets.
Avery: We have dots. Every exoplanet we've
ever found is, in a sense, invisible. We
infer it from a star's tiny wobble or a faint
dip dip in brightness as the planet crosses
in front. In the very best cases, we've
captured a single pixel of light. Nobody
has ever resolved a surface. The problem is
brutal. A star can be around 10 billion times
brighter than the little Earth sized planet
beside it. And the two sit almost on top of
each other in the sky. The new concept comes
from physicist Paul Stankis at Brookhaven,
and it's one of 18 early stage ideas NASA
just funded through its innovative Advanced
Concepts Program. Nyack. These are
seed grants, small money, nine months,
permission to chase something wild. His is
called Mapping Alien Continents. It works in
two moves. First, a new kind of light
canceling instrument, another that blots out
the star's glare while keeping the planet's
light at a contrast of 10 billion to one or
better. Then the really bold bit. You fly
two of these on separate spacecraft about a
hundred kilometers apart and combine their
beams till they act as one enormous
telescope, big enough in principle to resolve
features on the planet's face.
Anna: A telescope a hundred kilometers wide
made of two spacecraft flying in formation.
Avery: That's a dream. And I want to be honest about
where this sits. It's a concept study, not a
mission on a launch pad. It may never fly in
this form, but this is exactly how the big
leaps begin. Someone asks what if we could
actually look? And NASA hands him a little
funding to find out whether the physics
holds. If it ever came together, it would
turn exoplanets from statistics into
places.
Now, Anna, speaking of things, we can
Anna: see from right here, we've got weather coming
in space. Weather forecasters at
noaa, uh, are tracking a couple of clouds of
solar material heading our way. Coronal
mass ejections, big blobs of charged
gas flung off the sun. These two
are faint and they're only likely to give
Earth a glancing blow over the next day or
so.
Avery: Glancing, but not nothing.
Anna: Not Nothing. Layer those CMEs
on top of a fast stream already flowing from
a coronal hole, a gap in the Sun's
outer atmosphere, and the models suggest we
could tip into a G1 storm. That's
the mildest rung on the scale. No drama for
the power grid, but enough to nudge the
aurora to slightly lower latitudes than
usual. The so over the coming nights. It's
worth a look if you're up high, and I'll give
you the where and when in the skywatch.
Here's the thread, though. That same solar
wind, the constant outflow from the sun
is gentle at Earth because we've got a strong
magnetic field and a thick atmosphere
shrugging it off. Auroras are the pretty
side of that shrug. But not every world
is so lucky. Some planets have been
standing in that wind for billions of years
with no shield at all.
Avery: Which is the perfect cue for my next 1mi
escapade, a pair of NASA's craft
nicknamed Blue and Gold after the University
of California, Berkeley colors, built by
Rocket Lab and launched last November on a
blue origin. New Glenn. They're Mars bound.
And right now they're loitering out near a
spot called L2, about a million miles
beyond Earth, waiting for the road to Mars to
open. While they wait, one of them turned its
cameras back toward home and snapped a family
portrait. Earth and the Moon together as
two slim crescents. In ordinary
visible light, they look exactly as you'd
hope, two bright sunlit sickles against the
black. But these cameras also see in thermal
infrared heat, and that view is stranger
and honestly, a bit beautiful. The night
side of Earth glows softly with its own
warmth, while the Moon's dark half sits
far, far colder. A portrait in
light and a portrait in heat of the same two
worlds.
Anna: Gorgeous. But that's not why they built it,
is it?
Avery: It's not. And here's where our, uh, thread
lands. Escapade exists to study exactly what
we were just talking about. Its whole job,
once it reaches Mars in 2027, is to measure
how the solar wind strips away the Martian
atmosphere. Mars doesn't have a global
magnetic shield like ours, so the same wind
that just gives us auroras has, over billions
of years, helped peel Mars from a warmer,
wetter world. The thin, cold desert we see
today. Two spacecraft taking readings from
two vantage points at once, watching a planet
lose its air in real time. That Earth and
Moon portrait was really a calibration check,
a chance to point the cameras at uh, familiar
targets before the main event, but it doubles
as a quiet reminder. A shielded world
and an unshielded one are separated by
not very much at
Anna: all the wind that paints our sky
and the wind that scours Mars. The same
sun. Lovely thread Avery
right out under the sky.
First the moon. We've just come off the full
buck moon on the 29th, so we're in a
bright waning gibbous stretch. M beautiful
to look at, but that glare will wash out
anything faint for the next several nights.
Worth knowing before you plan meteors.
The southern Delta Aquariids and the Alpha
Capricornids have just passed their peak on
the 30th in into the 31st. From here
in the southern hemisphere, the Delta
Aquarids still favor us. But with the moon
this bright, keep expectations modest
and watch for the occasional slow bright
Capricornid fireball which both
hemispheres can catch. The better news is
what's coming. The Perseids build to
their peak on the night of the 12th into the
13th of August, and this year the Moon is
nearly new, so it's a genuinely dark
generous window. For North America,
that's prime. Find a dark spot, look
up after midnight and the northern sky can
deliver a meteor a minute at its best.
From the southern hemisphere, the Perseids
sit low in the north so you'll see fewer.
But a clear northern horizon is worth a try.
Mark the 12th. Also on the 12th of
August, a uh, total solar eclipse. The
path of totality runs across Greenland,
Iceland and a slice of Spain, with
partial phases for parts of northern North
America and Europe. If you're anywhere near
it, never look at the partial sun without
certified eclipse glasses that meet the
ISO
123122
standard. Ordinary sunglasses will not
protect your eyes. Totality only is
safe to view with the naked eye and only for
those precious seconds it lasts. Planets
quickly, both hemispheres. The pre dawn
sky is the place to be with the brighter
planets gathering low in the east before
sunrise. From Sydney, look to the eastern
horizon in the hour before dawn. From
North America, the same window an hour or
so before your local sunrise. One
quick diary item and this one's for our
telescope owners. On the 5th of August, a uh,
dead SpaceX Falcon 9 upper stage
space junk we tracked since it launched
Firefly's Blue Ghost lander back in January
of last year is expected to smack
into the moon near Einstein Crater at
about half past six Universal Time.
For North America, that's the small hours of
the 5th and you're the best placed to try for
it. Aim for the faint dust plume near the
Moon's eastern edge. Not a naked eye
flash. You'll want a decent telescope from
Sydney. The Moon isn't up at impact, so down
here we'll be leaning on the afterimages from
orbiters like NASA's Lunar Reconnaissance
Orbiter. And to close our thread, the
aurora. If those solar storms land
as forecast, watch the high latitudes over
the coming nights across the northern tier of
the United States and up into Canada in the
north and down towards Tasmania,
southern New Zealand and southern Victoria in
the south. Same sun, same wind,
both ends of the Earth. And if you catch a
glow, you'll know exactly what you're looking
at.
Avery: Everything we talked about today, the links,
the images of NISA and that Earth and moon
portrait is at
astronomydaily.IO, along with the
daily newsfeed and the newsletter signup.
Anna: And if you spotted an aurora or bagged a
Perseid, tell us. There's a listener contact
form on the site. And we love hearing what
you've seen.
Avery: That's Astronomy daily for Friday 31st
July. I'm Avery.
Anna: And I'm Anna. Until next time. Click. Clear
Skies.