Howdy Star Gazers and welcome to this episode
of Star Trails. I'm Drew and I'll be your guide
to the night sky for the week starting May the
4th through the 10th. This week the moon brightens,
some familiar planets are still hanging around,
and we have a unique opportunity to potentially
view an asteroid. Later in the show we'll take
a look at one of the most exciting fields in
astronomy the study of exoplanets and Some of
the weird worlds that have been discovered in
recent years So grab a comfortable spot under
the night sky and let's get started We kick things
off with the first quarter moon which arrives
tonight That means each night this week the moon
will be waxing, getting brighter and rising a
bit later each evening. It's a great time for
lunar observing. The shadows cast across the
surface give craters and mountain ranges some
awesome 3D definition through binoculars or a
telescope. By the end of the week, the moon will
be edging towards this month's full moon, known
as the Flower Moon, which also happens to be
another micro moon. That simply means that it's
farther from Earth in its slightly elliptical
orbit, and about 14 % smaller than a super moon.
Now onto the planets. Let's start with the evening
show. Right after sunset, look to the west and
you'll spot Jupiter, still holding on in the
twilight. It's bright and steady, easy to spot
with the naked eye. It'll set before midnight,
so catch it early. A little higher up, you'll
find Mars, the red planet. It's fainter than
Jupiter, but that warm, ruddy glow gives it away.
This week the moon passes near Mars in the evening
sky, resulting in a lovely pairing to check out
tonight, just after sunset. Let's shift our gaze
to the early morning. Venus, the morning star,
is rising in the east about 30 to 40 minutes
before sunrise. It's brilliant, by far the brightest
planet in the sky, and if you have a clear eastern
horizon, it's hard to miss. Just above Venus
sits Saturn, fainter and more subdued in golden
light, but still visible with binoculars and
definitely worth a look through a telescope if
you're up before dawn. Mercury is also hanging
out low in the eastern sky, but this one's a
bit trickier. It's hugging the horizon and may
get lost in the morning light. If you want to
try for it, aim for about 20 minutes before sunrise
and make sure you have a completely unobstructed
view of the east. This week we have a special
opportunity to see an asteroid. From now until
the end of the week is an excellent viewing window
to spot Vesta, the brightest asteroid visible
from Earth. Vesta is one of the largest bodies
in the asteroid belt, hanging out between Mars
and Jupiter. It spans about 326 miles across,
that's roughly the size of Arizona, and it's
the second largest asteroid after Ceres. What
makes Vesta especially cool is that it's big
and reflective enough that you might actually
see it with binoculars. Under really dark skies,
you might even catch it with the naked eye. Right
now, Vesta is near opposition. That just means
it's directly opposite the Sun in our sky, and
also the closest it will get to Earth this year.
It rises around sunset, stays up all night, and
sets at sunrise. Those are prime viewing conditions.
To find it, look toward the constellation Libra,
which is climbing in the southeastern sky after
dark. It's nestled just to the east of Virgo,
so if you can find the bright star Spica, You're
on the right track. You'll need a good star chart
or a stargazing app to pinpoint Vesta's exact
location, since it looks just like a faint star.
Here's one handy trick. If you make note of Vesta's
position one night and come back a day or two
later, you'll notice that it's moved. That slow
shift is how you know you're looking at an asteroid.
Right now Vesta is shining at about magnitude
5 .6, which puts it right on the edge of naked
eye visibility, but binoculars will give you
a much better chance. A basic pair of 7x50s or
higher will do just fine. So if you're outside
this week enjoying the night sky, take a few
minutes to track down Vesta. And if you'd like
to know more about the asteroid belt, Go back
and listen to episode 46, where we also take
a moment to highlight Ceres, the largest object
in the belt. We've gazed at the moon and planets
of our solar system. We've chased meteor showers.
We've traced the constellations, but tonight
we're heading out even farther. to planets orbiting
stars that aren't our sun. These are the exoplanets,
and once you start exploring them, it's hard
not to feel a sense of wonder that borders on
science fiction, except that it's all very real.
For most of human history, we had no solid evidence
that exoplanets existed at all. We guessed. Philosophers,
like Epicurus in ancient Greece, thought other
worlds must exist. After all, why would the universe
be built just for us? But until the late 20th
century, the existence of other planetary systems
was a complete unknown. Throughout my childhood,
I always wondered if there were other planets
out there. The science to find them simply didn't
exist. That started to change in 1992, with a
discovery that was both groundbreaking and kind
of weird. Astronomers Alexander Walceson and
Dale Frail found two planets orbiting a pulsar.
That's a dead, collapsed star spinning like a
cosmic lighthouse and blasting out radiation.
Not exactly a peaceful place. But there they
were, two exoplanets, small and rocky, caught
in the gravitational grip of a dead sun. The
way they discovered the exoplanets was unique.
Pulsars are like cosmic clocks, and pulse in
very regular intervals. In this case, the pulsar
being studied is about 2300 light years away.
Every now and then, scientists noticed the pulses
were a little off. although the off -beats still
came at predictable intervals. After some theorizing,
Waltzesen and Frail determined there had to be
two planets up to four times the mass of Earth
orbiting the pulsar approximately every 67 and
98 days. Just three years later came the breakthrough
that truly kickstarted the exoplanet era, 51
Pegasi b. This was the first planet discovered
orbiting a sun -like star. It's a gas giant,
but it orbits extremely close to its star, completing
a full orbit in just over four days. Imagine
if your year lasted less than a school week.
This type of world came to be known as a hot
Jupiter. Massive like our own Jupiter, but much
closer to its star. The reason we found hot Jupiters
first is simply because they're big, they orbit
fast, and they interact with their stars in a
way that we can actually detect. You'd think
we'd just point our telescopes at stars and spot
their planets, but it's not that easy. Imagine
trying to see a tiny, unlit mosquito buzzing
around a floodlight from hundreds of miles away.
The star completely overwhelms the faint light
from the planet, especially since exoplanets
don't give off their own light, they just reflect
it. So, astronomers had to get clever. The first
method that really worked was the radial velocity
method, also called the wobble method. As a planet
orbits a star, its gravity tugs on the star just
a little bit, enough to make the star wobble
very slightly. We can measure that wobble by
looking at the star's spectral lines. Those are
the fingerprints of elements in the starlight.
If the lines shift back and forth like a Doppler
effect, we know the star is being tugged and
a planet is the likely culprit. Then came the
transit method, which completely changed the
game. If a planet happens to pass in front of
its star from our line of sight, the light from
the star dips just a tiny bit. If it does this
on a regular schedule, we probably have a planet.
This method is what made the Kepler Space Telescope
a superstar. Launched in 2009, Kepler stared
at more than 150 ,000 stars and ended up discovering
more than 2 ,600 confirmed exoplanets, with thousands
more candidates. It was like turning on a light
in a dark room. Suddenly, we weren't just hoping
there were other worlds, we knew. But even with
Kepler and now TESS, the Transiting Exoplanet
Survey Satellite, it's still a challenge. Planets
have to line up just right for the transit method
to work. If their orbit tilts even slightly,
we might miss them entirely, and some signals
are so faint they can get lost in the stellar
noise, like trying to hear a whisper during a
rock concert. However, the tools keep getting
better. Enter the James Webb Space Telescope.
Not only can Webb detect exoplanets, it can analyze
their atmospheres. That's done through something
called transmission spectroscopy. When a planet
passes in front of its star, a tiny bit of starlight
filters through the planet's atmosphere. By studying
that light, we can tell what the atmosphere is
made of. Water vapor, methane, carbon dioxide,
and more. It's like doing a chemical test on
something a hundred light years away. Let's talk
about some notable exoplanets, and some of these
are quite weird. HD 189733b is a cobalt blue
gas giant with winds up to 5400 miles per hour,
and it's thought to have glass rain that whips
sideways. Kepler -16b orbiting two suns is a
real -life Star Wars scenario, like the planet
Tatooine, where Luke Skywalker grew up. Wasp
-12b, which is so close to its star that it's
slowly being consumed, is actually falling apart.
GJ 1214b is a mini -Neptune, covered in thick
clouds of water vapor, and maybe even has a planet
-wide ocean. And you may have heard of this one,
Trappist 1, a red dwarf star with seven rocky
planets. At least three are in the habitable
zone, a place where liquid water might exist.
We're still trying to answer the big questions.
How common are Earth -like planets? Are we likely
to find one nearby? And the biggest of them all,
could any of them harbor life? We're getting
closer to finding the ingredients for life, and
future missions like the Nancy Grace Roman Space
Telescope and the European Space Agency's PLATO
mission will keep scanning the skies. Some upcoming
concepts even include star shades, screens that
block out a star's light so we can see the faint
planets next to it. So next time you're looking
at the sky, pick a star. Odds are it has planets.
Maybe rocky, maybe gaseous, maybe icy, maybe
just like Earth. We've gone from guessing they
existed to discovering more than 5 ,000 of them,
and We're just getting started. If you found
this episode helpful, let me know and feel free
to send in your questions and observations. The
easiest way to do that is by visiting our website,
StarTrails .Show. This is also a great way to
share the show with friends. Until next time,
keep looking up and exploring the night sky.
Clear skies everyone!