Howdy Star Gazers and welcome to Star Trails.
My name is Drew and I'll be your guide to the
night sky for the week of October the 19th through
the 25th. The calendar says late October and
the heavens agree. Crisp air, long nights, and
a new moon make this one of the best observing
weeks of the year. And since Halloween creeps
ever closer, we're continuing our eerie tour
of the cosmos with a visit to a place both beautiful
and haunting, the Cosmic Graveyard, where dead
stars still whisper across time. Whether you're
tuning in from the backyard, the balcony, or
just your imagination, I'm glad you're here.
So, find a cozy spot, let your eyes adjust, and
let's see what the sky holds for us this week.
The moon disappears this week, reaching its new
phase on Tuesday, October 21st. That means a
stretch of wonderfully dark skies from Sunday
through Friday, perfect for galaxies, nebula,
and meteor watching. And speaking of meteors,
the Orionids peak Monday night into Tuesday morning.
These swift streaks are the dust of Halley's
Comet, burning up as Earth plows through the
debris field. With no moonlight to wash them
out, you could catch 10 to 20 per hour under
good conditions. Face southeast after midnight,
lie back, and enjoy one of autumn's finest shows.
Now for the planets. Saturn glows in the southeast
after dusk, nestled in Aquarius. It's still bright
and steady, and its moon Titan is visible in
modest telescopes. Jupiter rises around midnight
in Gemini, climbing higher each morning. Watch
for its shifting cloud belts and dancing moons.
Mars and Mercury linger low in the western twilight,
challenging but not impossible with binoculars
and a flat horizon. As the constellations wheel
overhead, Pegasus and the Great Square mark the
heart of the autumn sky. Follow the chain of
stars east to Andromeda, and you'll find the
glowing oval of M31, our neighboring galaxy,
easily seen in binoculars. Below that, seek out
M33, the Triangulum Galaxy, a faint but graceful
swirl of starlight. Farther west, Perseus rises
with a glittering double cluster, while Cassiopeia's
W shape rides high, tracing the Milky Way's rich
star fields. Down south near Saturn, swing your
scope toward M2 in Aquarius, a fine globular
cluster. And if you have a nebula filter, check
out the Helix Nebula, a ghostly ring of gas that
lives up to its nickname, the Eye of God. Stay
up past midnight and you'll see Taurus climb
the eastern sky, bringing the Hyades and the
Pleiades, the first messengers of winter. Before
we get into the second half of the show, I wanted
to respond to an excellent listener question,
and it's one that's been on my mind also. The
listener writes, I'm seeing the same artist's
depiction of a black hole everywhere lately,
notably as the logo for the AI service Grok,
which appears all over Twitter or X, but also
in movies like Interstellar. Is this really what
a black hole looks like? Thanks for that question,
and if you follow any space news, you probably
know exactly what the listener is referring to.
That striking, impossible -looking figure that
sort of resembles a ringed planet, maybe if designed
by MC Escher. It's sort of a glowing lopsided
ring with a dark center, and it's been plastered
across science videos, documentaries, space agency
posters, and yes, the logo for the ex -owned
AI service, Grok. It looks almost too perfect,
like some digital artist cooked it up after a
late -night sci -fi binge. In case you've never
seen one of these depictions, I'll include a
link to such an image in the show notes. Well,
here's the twist. That image is rooted in the
actual physics of how black holes warp light.
What looks like a sleek bit of graphic design
is possibly a very accurate visualization. Let's
unpack it. At the center of that image is a dark
patch. It isn't the black hole itself, because
you can't actually see a black hole. Think of
it as the shadow of a black hole. When light
from hot gas passes near the event horizon, the
black hole's gravity bends those paths. Photons
that get too close are trapped forever, creating
a dark silhouette slightly larger than the event
horizon. That's what we're looking at when we
see that central void. Surrounding it is the
bright thin ring. That's made of photons that
have orbited the black hole before escaping toward
us. Think of light caught in a cosmic racetrack
looping around at breakneck speed, then slingshotting
off to hit our telescopes. This is called the
photon ring, and its existence is a direct consequence
of Einstein's general relativity. But the part
that really gives the image its distinctive shape
is the crescent, the brighter arc on one side
of the ring. That asymmetry is due to a relativistic
effect called Doppler boosting. Contrary to what
we might think, black holes don't just suck in
matter from every direction. In almost all cosmic
environments, the gas around them has some spin.
Thanks to the conservation of angular momentum,
that gas can't just fall straight in. It forms
a flat, spinning accretion disk. Over time, turbulence
and magnetic forces shuffle angular momentum
outward, letting material slowly spiral inward
and heat up. This disk is what lights up so brightly
that we can actually see the black hole's surroundings,
even though the hole itself remains invisible.
The gas in the accretion disk is whipping around
the black hole at a significant fraction of the
speed of light. On the side rotating towards
us, the light is intensified. On the opposite
side, it's dimmed. The result is that glowing
curve you see. In 2019, the Event Horizon Telescope
gave us the first real image of a black hole's
shadow in the galaxy M87, and it looked a lot
like these simulation images. A glowing asymmetric
ring around a dark center. So far, it's our best
glimpse at gravity in its purest, most extreme
form. In a moment, we'll leave the living sky
behind and step into a darker realm, a place
where suns have burned out, galaxies devour one
another, and time itself decays to silence. We're
headed into the cosmic graveyard. That's coming
up after the break. Stay with us. Welcome back.
Tonight we walk among the tombstones of the universe.
Our destination is not a place, but a condition.
The cold and quiet aftermath of creation itself.
This is the Cosmic Graveyard. When you look up,
the stars seem eternal. But many of those pinpoints
are already dead, their light still traveling
towards us, tricking our eyes with the glow of
long -expired suns. The universe is a cemetery
of extinguished stars and broken galaxies, a
realm where everything bright must one day fade.
First, let's take a look at white dwarves, the
embers of suns. Stars like our sun end their
lives gently. They swell into red giants, shed
their outer layers, and leave behind a dense
core about the size of Earth. That remaining
ember is a white dwarf, a glowing cinder cooling
slowly for billions of years. Someday, each will
fade to invisibility. becoming a black dwarf,
though the universe isn't old enough for any
to exist yet. They are the quiet ashes of creation.
Then there are neutron stars, the undead pulsars.
Massive stars die violently. Their cores collapse
in a flash, crushing protons and electrons into
neutrons. The resulting neutron star packs the
sun's mass into a sphere just a dozen miles wide.
A teaspoon of that matter outweighs a mountain.
Some spin rapidly, beaming radio pulses into
space. We call them pulsars, rotating corpses
that tick like cosmic clocks. When first discovered
they were nicknamed LGM 1 for little green men
But these aren't signals from aliens. They're
the heartbeats of dead stars that refuse to stop
Then there are black holes Graves with no bottom
for the heaviest stars gravity wins completely
their cores collapse beyond recovery forming
black holes, regions where not even light can
escape. They devour nearby stars, twist time
and shape entire galaxies. They're tombs without
headstones, yet they also sculpt the cosmos.
But even black holes will not endure forever.
Physicist Stephen Hawking showed that black holes
leak energy. tiny sparks of radiation. And that
means given enough time, even these ultimate
graves will evaporate into nothing. Even galaxies
can die, and they cannibalize each other. Galaxies
themselves expire through consumption. Big ones
devour small ones, scattering stellar remains
across the cosmos. Our own Milky Way is guilty.
Right now, it's consuming the Sagittarius dwarf
galaxy. It's stars smeared across the sky like
ashes scattered by a cosmic wind. And in about
four billion years, Andromeda will collide with
us. Two spirals locked together, merging into
a single bloated relic. Even in death, gravity
hungers. The far future brings the great dimming.
Eventually, star birth ceases, the last red dwarfs
fade, the galaxies darken, and black holes evaporate.
The cosmos cools toward absolute zero, the heat
death of everything. It's a state of perfect
equilibrium where no energy remains to power
change, light, or life. Just the last photons
drifting through infinite darkness. If the stars
spoke to you this week or if a question's been
on your mind, I'd love to hear it. Visit StarTrails
.Show where you can contact me and explore past
episodes. Be sure to follow Star Trails on Blue
Sky and YouTube. Links are in the show notes.
Until we meet again beneath the stars, clear
skies everyone.