Latest / Star Trails: From Backyard Astronomy to Cosmic Wonder / Tracking Vesta and Exploring Alien Worlds

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Tracking Vesta and Exploring Alien Worlds · Star Trails: From Backyard Astronomy to Cosmic Wonder

• 0:07
  Howdy Star Gazers and welcome to this episode
• 0:10
  of Star Trails. I'm Drew and I'll be your guide
• 0:13
  to the night sky for the week starting May the
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  4th through the 10th. This week the moon brightens,
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  some familiar planets are still hanging around,
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  and we have a unique opportunity to potentially
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  view an asteroid. Later in the show we'll take
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  a look at one of the most exciting fields in
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  astronomy the study of exoplanets and Some of
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  the weird worlds that have been discovered in
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  recent years So grab a comfortable spot under
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  the night sky and let's get started We kick things
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  off with the first quarter moon which arrives
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  tonight That means each night this week the moon
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  will be waxing, getting brighter and rising a
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  bit later each evening. It's a great time for
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  lunar observing. The shadows cast across the
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  surface give craters and mountain ranges some
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  awesome 3D definition through binoculars or a
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  telescope. By the end of the week, the moon will
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  be edging towards this month's full moon, known
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  as the Flower Moon, which also happens to be
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  another micro moon. That simply means that it's
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  farther from Earth in its slightly elliptical
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  orbit, and about 14 % smaller than a super moon.
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  Now onto the planets. Let's start with the evening
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  show. Right after sunset, look to the west and
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  you'll spot Jupiter, still holding on in the
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  twilight. It's bright and steady, easy to spot
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  with the naked eye. It'll set before midnight,
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  so catch it early. A little higher up, you'll
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  find Mars, the red planet. It's fainter than
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  Jupiter, but that warm, ruddy glow gives it away.
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  This week the moon passes near Mars in the evening
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  sky, resulting in a lovely pairing to check out
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  tonight, just after sunset. Let's shift our gaze
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  to the early morning. Venus, the morning star,
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  is rising in the east about 30 to 40 minutes
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  before sunrise. It's brilliant, by far the brightest
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  planet in the sky, and if you have a clear eastern
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  horizon, it's hard to miss. Just above Venus
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  sits Saturn, fainter and more subdued in golden
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  light, but still visible with binoculars and
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  definitely worth a look through a telescope if
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  you're up before dawn. Mercury is also hanging
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  out low in the eastern sky, but this one's a
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  bit trickier. It's hugging the horizon and may
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  get lost in the morning light. If you want to
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  try for it, aim for about 20 minutes before sunrise
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  and make sure you have a completely unobstructed
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  view of the east. This week we have a special
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  opportunity to see an asteroid. From now until
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  the end of the week is an excellent viewing window
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  to spot Vesta, the brightest asteroid visible
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  from Earth. Vesta is one of the largest bodies
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  in the asteroid belt, hanging out between Mars
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  and Jupiter. It spans about 326 miles across,
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  that's roughly the size of Arizona, and it's
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  the second largest asteroid after Ceres. What
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  makes Vesta especially cool is that it's big
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  and reflective enough that you might actually
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  see it with binoculars. Under really dark skies,
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  you might even catch it with the naked eye. Right
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  now, Vesta is near opposition. That just means
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  it's directly opposite the Sun in our sky, and
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  also the closest it will get to Earth this year.
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  It rises around sunset, stays up all night, and
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  sets at sunrise. Those are prime viewing conditions.
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  To find it, look toward the constellation Libra,
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  which is climbing in the southeastern sky after
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  dark. It's nestled just to the east of Virgo,
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  so if you can find the bright star Spica, You're
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  on the right track. You'll need a good star chart
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  or a stargazing app to pinpoint Vesta's exact
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  location, since it looks just like a faint star.
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  Here's one handy trick. If you make note of Vesta's
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  position one night and come back a day or two
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  later, you'll notice that it's moved. That slow
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  shift is how you know you're looking at an asteroid.
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  Right now Vesta is shining at about magnitude
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  5 .6, which puts it right on the edge of naked
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  eye visibility, but binoculars will give you
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  a much better chance. A basic pair of 7x50s or
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  higher will do just fine. So if you're outside
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  this week enjoying the night sky, take a few
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  minutes to track down Vesta. And if you'd like
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  to know more about the asteroid belt, Go back
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  and listen to episode 46, where we also take
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  a moment to highlight Ceres, the largest object
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  in the belt. We've gazed at the moon and planets
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  of our solar system. We've chased meteor showers.
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  We've traced the constellations, but tonight
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  we're heading out even farther. to planets orbiting
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  stars that aren't our sun. These are the exoplanets,
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  and once you start exploring them, it's hard
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  not to feel a sense of wonder that borders on
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  science fiction, except that it's all very real.
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  For most of human history, we had no solid evidence
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  that exoplanets existed at all. We guessed. Philosophers,
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  like Epicurus in ancient Greece, thought other
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  worlds must exist. After all, why would the universe
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  be built just for us? But until the late 20th
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  century, the existence of other planetary systems
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  was a complete unknown. Throughout my childhood,
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  I always wondered if there were other planets
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  out there. The science to find them simply didn't
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  exist. That started to change in 1992, with a
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  discovery that was both groundbreaking and kind
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  of weird. Astronomers Alexander Walceson and
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  Dale Frail found two planets orbiting a pulsar.
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  That's a dead, collapsed star spinning like a
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  cosmic lighthouse and blasting out radiation.
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  Not exactly a peaceful place. But there they
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  were, two exoplanets, small and rocky, caught
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  in the gravitational grip of a dead sun. The
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  way they discovered the exoplanets was unique.
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  Pulsars are like cosmic clocks, and pulse in
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  very regular intervals. In this case, the pulsar
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  being studied is about 2300 light years away.
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  Every now and then, scientists noticed the pulses
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  were a little off. although the off -beats still
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  came at predictable intervals. After some theorizing,
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  Waltzesen and Frail determined there had to be
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  two planets up to four times the mass of Earth
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  orbiting the pulsar approximately every 67 and
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  98 days. Just three years later came the breakthrough
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  that truly kickstarted the exoplanet era, 51
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  Pegasi b. This was the first planet discovered
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  orbiting a sun -like star. It's a gas giant,
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  but it orbits extremely close to its star, completing
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  a full orbit in just over four days. Imagine
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  if your year lasted less than a school week.
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  This type of world came to be known as a hot
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  Jupiter. Massive like our own Jupiter, but much
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  closer to its star. The reason we found hot Jupiters
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  first is simply because they're big, they orbit
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  fast, and they interact with their stars in a
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  way that we can actually detect. You'd think
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  we'd just point our telescopes at stars and spot
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  their planets, but it's not that easy. Imagine
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  trying to see a tiny, unlit mosquito buzzing
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  around a floodlight from hundreds of miles away.
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  The star completely overwhelms the faint light
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  from the planet, especially since exoplanets
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  don't give off their own light, they just reflect
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  it. So, astronomers had to get clever. The first
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  method that really worked was the radial velocity
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  method, also called the wobble method. As a planet
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  orbits a star, its gravity tugs on the star just
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  a little bit, enough to make the star wobble
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  very slightly. We can measure that wobble by
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  looking at the star's spectral lines. Those are
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  the fingerprints of elements in the starlight.
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  If the lines shift back and forth like a Doppler
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  effect, we know the star is being tugged and
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  a planet is the likely culprit. Then came the
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  transit method, which completely changed the
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  game. If a planet happens to pass in front of
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  its star from our line of sight, the light from
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  the star dips just a tiny bit. If it does this
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  on a regular schedule, we probably have a planet.
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  This method is what made the Kepler Space Telescope
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  a superstar. Launched in 2009, Kepler stared
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  at more than 150 ,000 stars and ended up discovering
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  more than 2 ,600 confirmed exoplanets, with thousands
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  more candidates. It was like turning on a light
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  in a dark room. Suddenly, we weren't just hoping
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  there were other worlds, we knew. But even with
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  Kepler and now TESS, the Transiting Exoplanet
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  Survey Satellite, it's still a challenge. Planets
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  have to line up just right for the transit method
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  to work. If their orbit tilts even slightly,
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  we might miss them entirely, and some signals
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  are so faint they can get lost in the stellar
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  noise, like trying to hear a whisper during a
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  rock concert. However, the tools keep getting
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  better. Enter the James Webb Space Telescope.
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  Not only can Webb detect exoplanets, it can analyze
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  their atmospheres. That's done through something
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  called transmission spectroscopy. When a planet
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  passes in front of its star, a tiny bit of starlight
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  filters through the planet's atmosphere. By studying
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  that light, we can tell what the atmosphere is
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  made of. Water vapor, methane, carbon dioxide,
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  and more. It's like doing a chemical test on
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  something a hundred light years away. Let's talk
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  about some notable exoplanets, and some of these
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  are quite weird. HD 189733b is a cobalt blue
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  gas giant with winds up to 5400 miles per hour,
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  and it's thought to have glass rain that whips
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  sideways. Kepler -16b orbiting two suns is a
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  real -life Star Wars scenario, like the planet
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  Tatooine, where Luke Skywalker grew up. Wasp
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  -12b, which is so close to its star that it's
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  slowly being consumed, is actually falling apart.
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  GJ 1214b is a mini -Neptune, covered in thick
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  clouds of water vapor, and maybe even has a planet
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  -wide ocean. And you may have heard of this one,
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  Trappist 1, a red dwarf star with seven rocky
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  planets. At least three are in the habitable
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  zone, a place where liquid water might exist.
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  We're still trying to answer the big questions.
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  How common are Earth -like planets? Are we likely
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  to find one nearby? And the biggest of them all,
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  could any of them harbor life? We're getting
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  closer to finding the ingredients for life, and
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  future missions like the Nancy Grace Roman Space
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  Telescope and the European Space Agency's PLATO
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  mission will keep scanning the skies. Some upcoming
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  concepts even include star shades, screens that
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  block out a star's light so we can see the faint
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  planets next to it. So next time you're looking
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  at the sky, pick a star. Odds are it has planets.
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  Maybe rocky, maybe gaseous, maybe icy, maybe
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  just like Earth. We've gone from guessing they
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  existed to discovering more than 5 ,000 of them,
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  and We're just getting started. If you found
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  this episode helpful, let me know and feel free
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  to send in your questions and observations. The
• 13:36
  easiest way to do that is by visiting our website,
• 13:40
  StarTrails .Show. This is also a great way to
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  share the show with friends. Until next time,
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  keep looking up and exploring the night sky.
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  Clear skies everyone!