Howdy Star Gazers and welcome to this episode
of Star Trails. My name is Drew, and I'll be
your guide to the night sky for the week of March
the 8th through the 14th. This week we continue
our month -long exploration of our solar system.
by leaving the warm terrarium of the inner planets
for the deep freezer of the outer planets. In
these far reaches, our sun is no longer a dominating
presence, but a bright star among many, and the
worlds we find here are as strange as they are
lonely. Later in the show, I'll report on my
efforts to observe a recent SpaceX rocket launch.
We'll press forth into the next two chapters
of Night Watch, And we'll look at what you can
expect to see in the night sky this week. Whether
you're tuning in from the backyard or the balcony,
I'm glad you're here. So grab a comfortable spot
under the night sky and let's get started. Tonight
we pick up where we left off in the last episode.
The rusty deserts of Mars are fading in the rear
-view mirror of our spaceship, and the sun begins
to shrink ever so slightly into something less
oppressive and more distant. Ahead of us lies
the asteroid belt, not the chaotic pinball machine
of science fiction, but a wide, mostly empty
region stretching between Mars and Jupiter. If
you could stand on Ceres, the largest object
there, and it's now classified as a dwarf planet,
you'd see a lonely landscape of ice and rock
under a dimmer sun. The belt contains millions
of objects, yes, but they're separated by vast
distances. Once we clear that frontier, the solar
system changes character. The outer planets are
not simply bigger versions of the inner ones.
They're a different category of existence. Jupiter
announces itself long before you arrive. It's
more massive than all the other planets combined.
A gravitational monarch presiding over the outer
solar system. It resides around 5 AU from the
sun, or about 465 million miles. Its diameter
could fit more than 11 Earths across. Its volume
could swallow more than 1 ,300 Earths whole.
And yet it's made mostly of hydrogen and helium.
The same stuff as our Sun. Just not quite massive
enough to ignite nuclear fusion. Sometimes people
call it a failed star, but that's poetic shorthand.
In reality, it would need about 80 times more
mass to shine. Jupiter's atmosphere is a masterpiece
of fluid dynamics. Cream and cinnamon -hued bands
wrap around the globe, driven by jet streams
moving hundreds of miles per hour. The Great
Red Spot, a storm larger than Earth, has been
raging for at least 350 years. It seems to be
shrinking, but it's still a planetary -scale
hurricane that refuses to die. Jupiter also radiates
more heat than it receives from the Sun. Deep
inside, gravitational compression slowly releases
energy, as if the planet is still settling into
itself. And then there are the moons. Four of
them were spotted in 1610 by Galileo Galilei,
Io, Europa, Ganymede, and Callisto. Tiny moving
points of light that quietly proved not everything
orbits Earth. Not surprisingly, we refer to these
as the Galilean moons, and even a small scope
will reveal them here on Earth. Io is the most
volcanically active world in the solar system.
Europa likely hides a global ocean beneath its
icy shell, twice as much water as all of Earth's
oceans combined. Ganymede is the largest moon
in the solar system and has its own magnetic
field. We've explored Jupiter extensively. Pioneer
10 and 11 first passed by in the 1970s. Voyager
1 and Voyager 2 gave us the iconic images that
have defined our view of Jupiter for four decades.
Galileo orbited the planet for eight years in
the 1990s and early 2000s, and today Juno continues
to dive over the poles, mapping gravity, magnetic
fields, and peering deep beneath the clouds.
Now let's drift outward another 400 million miles
to the ringed planet. Saturn feels like Jupiter's
more refined sibling. It's less massive, but
visually unforgettable. Its rings stretch hundreds
of thousands of miles wide, yet in places they're
only tens of meters thick. Thinner than a football
field is long. They're made of countless particles
of ice and rock, each one following Kepler's
laws with quiet obedience. Saturn's density is
so low that, in theory, it would float in water,
if you had an ocean large enough to hold a planet.
Saturn deserves more than it has rings. That's
like introducing Jimi Hendrix by saying he dabbled
in guitar. So let's widen the lens. First, Saturn
is not just a smaller Jupiter. It's structurally
different in subtle but important ways. While
both are gas giants, comprised mostly of hydrogen
and helium, Saturn's core is proportionally larger
relative to its total mass. That may tell us
something about how and where it formed in the
early solar system. Planet formation models suggest
Saturn may have grown more slowly than Jupiter,
accreting gas after Jupiter had already become
the dominant gravitational bully. Now let's talk
about those rings in more depth because they're
not permanent. The rings are likely young on
cosmic timescales. Current models suggest they
may be only a hundred to four hundred million
years old, possibly the remains of a shattered
moon torn apart by tidal forces after wandering
too close. When dinosaurs walked Earth, Saturn
may have looked different in the sky. The rings
are organized into major divisions, A, B, and
C rings, with the prominent Cassini division
separating A and B. That gap isn't empty. It's
sculpted by gravitational resonances with Saturn's
moons. In other words, the moons are choreographing
the rings. Tiny shepherd moons like Prometheus
and Pandora actively confine ring material, preventing
it from dispersing. Even so, the rings are slowly
dissolving. At current rates, they may vanish
in a hundred million years or so. Saturn's North
Pole hosts a bizarre persistent hexagonal storm
system. It's not a trick of the eye, it's a stable
wave pattern in the atmosphere, larger than Earth.
Saturn currently holds the record for the most
known moons, well over a hundred confirmed objects,
though many are tiny captured rocks. Titan and
Enceladus get the spotlight, but Iapetus is a
wonder too. One hemisphere bright as snow, the
other dark as coal. The yin -yang moon. The real
golden age of Saturn exploration came with Cassini
-Huygens. For 13 years, Cassini orbited Saturn,
transforming it from a distant ringed icon into
a richly detailed world. It watched seasons change.
It flew through the rings. It revealed Enceladus
spraying plumes of water vapor from its south
pole. evidence of a subsurface ocean. It delivered
the Huygens probe to Titan, where it parachuted
down through a thick orange atmosphere and landed
on a surface shaped by methane rain. Titan has
lakes and rivers, weather, dunes, a hydrological
cycle built not on water but on hydrocarbons.
When Cassini ended its mission in 2017, it deliberately
plunged into Saturn's atmosphere to avoid contaminating
potentially habitable moons. A spacecraft choosing
its own fiery end to protect alien oceans is
poetic engineering. And now we reach the ice
giants, Uranus and Neptune. It's wild to think
that through most of my childhood, we didn't
have any detailed images of either of these worlds.
All the books I grew up reading just featured
artist's renditions, and both planets today still
remain some of the least imaged. Of the two,
Uranus is the real oddball. It rotates on its
side, tilted 98 degrees. It essentially rolls
around the sun. Its seasons last about 20 years
apiece. For decades at a time, one pole faces
the sun in continuous daylight, while the other
endures unbroken darkness. Its pale blue color
comes from methane in its atmosphere, which absorbs
red light and reflects blue. Beneath the atmosphere
lies a mantle of super pressurized water, ammonia,
and methane ice. Some models suggest that under
those immense pressures, carbon could crystallize
into diamonds that rain downward through the
interior. That remains a working hypothesis,
but it's consistent with high pressure physics
experiments. Like Saturn, Uranus has a ring system,
although they are very different in almost every
way. They were discovered in 1977 during a stellar
occultation experiment. Astronomers were watching
Uranus pass in front of a distant star. Instead
of the star dimming once as the planet moved
across it, it flickered multiple times before
and after the main event. That meant something
thin and structured was blocking the starlight.
That something turned out to be rings. Uranus'
rings are narrow, dark, and composed mostly of
relatively large particles mixed with radiation
-processed material that makes them charcoal
-colored. They don't shine so much as they lurk.
There are currently 13 known rings, named mostly
with Greek letters, alpha, beta, gamma, and so
on, along with a few more recently discovered
faint outer rings. Like Saturn's, Uranus's rings
are shaped and maintained by shepherd moons.
Because the planet is tilted on its side, the
rings are tilted with it. So from Earth, over
decades we see the ring system dramatically change
orientation. Sometimes they're wide open and
visible, and other times we see them nearly edge
on and they almost disappear. During Uranus's
equinox, which happens only twice every 84 Earth
years, the sun shines directly on the ring plane.
producing unusual lighting effects and stirring
up dynamic changes in the system. Voyager 2 gave
us our only close -up look in 1986, and at the
time the rings looked simple and sparse. But
modern observations from the Hubble Space Telescope
and large ground -based telescopes have revealed
faint dusty components and more complex structure
than Voyager initially detected. There's never
been a return mission to Uranus. We know considerably
more about it than we did before the Voyager
flyby, but much of it has remained a pale turquoise
mystery. At nearly 2 billion miles away, the
sun is just a bright point of light at Uranus.
And Uranus moves slowly. It takes 84 Earth years
to complete one orbit. That means since its discovery
in 1781 by William Herschel, Uranus has only
completed a little more than two full orbits
around the sun. Neptune lies even farther out,
nearly 3 billion miles from the sun. It was the
first planet discovered by mathematics before
observation. Astronomers noticed irregularities
in Uranus's orbit and predicted another world
must be tugging at it. They calculated where
it should be. Then they looked, and in 1846 they
found it. It takes Neptune 165 Earth years to
complete one orbit. It completed its first full
orbit since discovery in 2011. Neptune's beautiful
blue color comes from methane in its atmosphere,
but it's a deeper, more vivid blue than Uranus.
That difference likely comes from subtle atmospheric
chemistry and haze layers we still don't fully
understand. Neptune is also wildly dynamic for
such a distant cold world. Its winds are the
fastest in the solar system, reaching more than
1200 miles per hour. That's supersonic, in a
place where temperatures hover around minus 350
degrees Fahrenheit. Neptune radiates more heat
than it receives from the Sun, much like Jupiter.
Its interior is still warm from formation. Triton
is Neptune's largest moon and likely a captured
Kuiper belt object. It orbits backwards, which
is a huge clue that it didn't form alongside
Neptune. As for exploration, Neptune has been
visited exactly once. Voyager 2 flew past in
August 1989. It revealed the Great Dark Spot,
a storm similar to Jupiter's Red Spot, along
with a ring system. After that brief encounter,
Voyager kept going. Since then, it's only been
studied by Hubble and some ground -based observatories,
leaving a lot of unanswered questions. The outer
planets hold most of the mass and angular momentum
of our solar system. They sculpt cometary paths.
They influence the asteroid belt. They may have
helped make Earth stable enough for life. And
yet, in terms of direct exploration, only Jupiter
and Saturn have received sustained attention.
Uranus and Neptune remain frontier worlds. There
are serious proposals right now for a dedicated
Uranus orbiter, but nothing has been launched
yet. In some ways, the outer solar system still
feels like it's stuck in the 1970s. And that's
astonishing. When you step outside this evening
and see Jupiter and Saturn blazing in the twilight,
you're looking at a system of worlds we've actually
visited. And beyond it lie two giants we've barely
touched. We've mapped Mars with rovers and drones.
We've landed on comets, but the ice giants remain
largely unexplored. That should humble us a little,
and maybe excite us. As we step back from this
tour of the outer planets, it's natural to ask
a bigger question. Why are the worlds closest
to the sun small and rocky, while the outer planets
are enormous spheres of gas and ice? The answer
goes all the way back to the birth of the solar
system, about 4 .6 billion years ago. At that
time, the young sun was surrounded by a vast
rotating disk of gas and dust. Close to the sun,
temperatures were extremely high. In that hot
inner region, only heavy materials like iron,
nickel, and rocky minerals could condense into
solid grains. Lighter substances, things like
water, methane, and ammonia, remained vaporized.
That meant the inner planets formed from relatively
limited ingredients, building small, dense, rocky
worlds like Mercury, Venus, Earth, and Mars.
Farther from the sun, however, temperatures dropped
dramatically. Beyond a certain distance, what
astronomers call the frost line, water and other
compounds could freeze into solid ice. Suddenly,
there was far more material available to build
planets. With ice joining rock and metal, planetary
embryos in the outer solar system could grow
much larger. Once these growing worlds became
massive enough, their gravity began pulling in
the surrounding hydrogen and helium gas from
the disk, ballooning into the giant planets we
see today. So the solar system naturally divided
itself into two very different neighborhoods
The inner region gave rise to small terrestrial
planets made mostly of rock and metal While the
cooler outer region produced the giant planets
Jupiter and Saturn with their vast envelopes
of hydrogen and helium and Uranus and Neptune
with interiors rich and frozen compounds like
water methane and ammonia All the planets, in
a way, represent the structure of the original
disk that formed our solar system. It's a fossil
record of temperature, chemistry, and gravity
written across billions of miles of space. After
a quick break, we'll be back to discuss what
you can actually see in this week's sky and how
to spot these distant planets for yourself. Stay
with us. Welcome back. Before we get into this
week's sky, I have a quick observation report.
Last week, a series of SpaceX launches were carried
out from Cape Canaveral to deliver Starlink satellites
into orbit. Some of these launches were in the
evening or early morning, which means folks along
the eastern seaboard hundreds of miles away can
see them soaring into orbit if conditions are
right. These launches weren't even on my radar
until my brother -in -law, Chris, shared a post
with me on Sunday afternoon. With nothing better
to do, we decided to find a nice high elevation
with an eastern view of the sky and see if we
could spot a Falcon 9 rocket. We arrived at the
site around 940 for the nearly 10pm launch. We
both had the SpaceX live feed on our phones so
we could hear the countdown and launch. About
30 seconds after launch, looking south, Chris
thought he spotted a red dot making its way upward
into the east. then we didn't see anything. Some
moments passed and then to the east and some
30 degrees off the horizon, we spotted a bright
reddish object, which morphed subtly for a few
seconds, then winked out as fast as it appeared.
It didn't look like the plumes we normally associate
with SpaceX launches. We think the significant
cloud cover may have affected our view, but based
on Chris's initial observation and the direction
it was heading, We're pretty certain we saw the
rocket, 20 stories of fire and fury climbing
into space at 17 ,000 miles per hour. Several
days later, another Falcon took flight in the
pre -dawn hours, and local observers captured
some really stunning images of the rocket's plume
as it blasted across the sky, backlit high in
the atmosphere by the sun before it peeked over
the horizon. Sadly, I wasn't awake for that launch.
From now on, I'm going to make it a point to
routinely check out what's launching from the
Cape, using a website like Space Flight Now to
see what's on deck. I'll include a link to that
in the show notes. If there's an evening or nighttime
launch window and you live in the viewable zone,
it could make for a nice observation or even
a photo op. Keep in mind the Kennedy Space Center
isn't the only NASA launch pad. West coasters
can try viewing rockets from Vandenberg Space
Force Base in California. Farther up the East
Coast, Wallops Flight Facility on the coast of
Virginia is used for supply missions to the ISS.
Alaska has a spaceport, and SpaceX's private
launch site is in South Texas. There's surprisingly
a lot of rocket action, so keep an eye on spaceflight
now and maybe you can catch a launch from the
Cape or from one of these alternate locations.
Now, let's see what's in the sky above our own
backyard this week. First, a quick note about
daylight saving time. Clocks sprung forward one
hour this morning. That pushes darkness later
into the evening. Your best deep sky observing
window will now start later after sunset, even
as overall night length slowly increases toward
the spring equinox on March 20. This week the
moon is still in its waning gibbous to waning
crescent phase. By March 14, it's a thin crescent
with about 20 % illumination. Perfect for viewing
surface detail near the terminator with binoculars
or a telescope. After sunset in the western sky,
brilliant Venus dominates low over the horizon.
It's the brightest star you'll see after dusk.
And early in the week you might spot Saturn just
above or beside it. A visual pairing that will
linger near the western horizon for several evenings
as the planets slowly separate. A pair of binoculars
will show them together easily, and around tonight
or tomorrow that conjunction is tightest. In
the southern evening sky, high above the horizon,
Jupiter shines like a beacon. It's visible well
after dark at this time of year and doesn't set
until the late night hours. Its steady bright
light makes it excellent for telescopic views.
The Galilean moons and cloud belts are easy pickings.
Mercury will be very low after sunset early in
this window and quickly lost to twilight glow.
It re -emerges in the morning sky later in March.
Mars remains too close to the Sun for effective
evening observing right now. Uranus is technically
still placed in western Taurus and can be tracked
down in binoculars or a small scope if the moon
hasn't risen and your sky is dark. But Neptune
is too close to conjunction with the Sun to be
seen this week. Now let's talk deep sky objects.
March evenings are rich with open star clusters
and faint nebula that reward patients and optics,
especially once the moon sets. The Hyades cluster
near Aldebaran and Taurus is a sprawling binocular
-friendly grouping. Look for the broad V of stars
that makes up the head of the bull. The Rosette
nebula and its embedded cluster in Monoceros
is a favorite for long exposures and narrow band
imaging. A pair of binoculars under dark skies
will show the cluster and a camera will begin
to tease out nebulosity. The Beehive cluster
M44 in Cancer sits higher in the late evening
once the moon dips below the horizon. This object
is beautiful through small scopes and even in
urban skies. While there's no major meteor shower
peaking this week, a few minor streams may be
detectable after midnight under truly dark skies.
Finally, don't forget the spring constellations
rising in the east late evening. Leo, with its
graceful sickle, and regal regulus, and Cancer
just above, are home to loose stellar groupings.
These aren't the obvious constellations like
Orion or Ursa Major, but they'll reward viewers
who take time with their charts and optics. For
this week's book club segment, we're looking
at chapters 6 and 7 of Nightwatch, covering the
deep sky and the planets. And what I appreciate
most about these chapters is that Terrence Dickinson
continues what he's done throughout the book.
He manages expectations. In chapter 6, when he
describes deep sky objects like galaxies, nebula,
and globular clusters, he tells you plainly what
they actually look like in the eyepiece. They're
dim, subtle, often colorless, and that's just
how our eyes work. Under low light, our eyes
rely mostly on rod cells. Rods are incredibly
sensitive to faint light, which is why they allow
us to see these ghostly smudges in the first
place. But rods don't detect color well. The
cone cells that do perceive color require much
brighter light to activate. So when you look
at the Orion Nebula or the Andromeda Galaxy through
a telescope, you're not seeing the saturated
pinks and blues of astrophotography. You're seeing
what the human visual system can gather in a
fraction of a second. A camera can collect photons
for minutes. It can stack exposures for hours.
Your retina resets continuously. Dickinson explains
this, and I think that's crucial. I think new
astronomers expect the sky to look like processed
long exposure images. But visual astronomy is
quieter than that. It's about contrast, texture,
and shape. It's about learning to recognize faint
structure at the edge of perception. And then
Dickinson gives us something very practical.
Maps. The deep sky charts in chapter 6 are clean,
readable, and focused. They highlight specific
objects. They indicate magnitude. They note what
size instrument might be needed. They help you
plan a session instead of overwhelming you with
thousands of targets. There's something philosophical
there. He's not encouraging you to conquer the
sky. He's encouraging you to spend time with
it. Then in chapter 7, when he turns to the planets,
he does something similar. Again, he calibrates
expectations. Saturn will not look like a glossy
NASA poster. Mars won't resemble a spacecraft
mosaic. Jupiter's belts may be subtle. Features
will shift from night to night. And that's the
point. Planets reward repeated observation. You
begin to notice the tilt of Saturn's rings changing
over years, the shrinking and expanding of Mars's
polar caps, the steady dance of Jupiter's moons.
Patience is the key here. I think both of these
chapters serve as nice companions to this podcast,
especially the chapter on the planets, since
we've been discussing them all month long. We
mention Deep Sky objects on nearly every episode,
and while smartphone apps and computer databases
make it easy to locate and track these objects,
those great maps included in Nightwatch are really
helpful for planning and laying out what's what
and where it's located in relation to common
constellations. We'll be back in two weeks with
a discussion on the next two chapters. That's
going to do it for this week. If you found this
episode interesting, please share it with a friend
who might enjoy it. The easiest way to do that
is by sending folks to our website, StarTrails
.show. And if you'd like to support the show,
use the link on the site to buy me a coffee.
That really helps. 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!