Podcaster: Richard Drumm
Title: Space Scoop: Pitch-Black Planet Gobbles Up Light
Organization:365 Days Of Astronomy
Link : astrosphere.org ; http://unawe.org/kids/unawe1724/
Description: Space scoop, news for children.
Bio: Richard Drumm is President of the Charlottesville Astronomical Society and President of 3D – Drumm Digital Design, a video production company with clients such as Kodak, Xerox and GlaxoSmithKline Pharmaceuticals. He was an observer with the UVa Parallax Program at McCormick Observatory in 1981 & 1982. He has found that his greatest passion in life is public outreach astronomy and he pursues it at every opportunity.
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Transcript:
This is the 365 Days of Astronomy Podcast. Today we bring you a new episode in our Space Scoop series. This show is produced in collaboration with Universe Awareness, a program that strives to inspire every child with our wonderful cosmos.
Pitch-Black Planet Gobbles Up Light
Exciting news for all werewolves, vampires and other creatures of the night! No, Halloween hasn’t come a month early this year, but a pitch black planet has been discovered!
The new world is an exoplanet, which means it orbits a star far beyond our Solar System. To date, we’ve found more than 3,500 exoplanets, and some of them are strange indeed.
There are worlds being ripped apart by their parent stars, while others are battered by winds moving at thousands of miles an hour.
In fact, it seems like the rarest planets in the Universe are those like our home, Earth.
The planet’s Sun-like star, 870 light years away in the direction of the wintertime constellation Auriga, the Charioteer, the star is called WASP-12A and the planet is called WASP-12b.
WASP-12b was discovered in 2008 by the transit method, where we detect the planet crossing in front of it’s parent star and dimming the light ever so slightly.
By the way, WASP stands for Wide Area Search for Planets, a search program specifically for transiting exoplanets. It’s operated by a consortium of the observatory operators Isaac Newton Group, the IAC of the Canary Islands and 6 UK universities.
The 2 telescopes that the WASP group operates are in the Canary Islands and South Africa and they are arrays of 8 200mm Canon lenses and professional CCD imagers.
The system covers 490 square degrees of sky and acquires images about once a minute. The scopes can monitor millions of stars simultaneously!
Computers do all the grunt work and sift through all the data looking for the dimming of starlight.
Astronomers have determined that 12b has an atmosphere and that there’s water in that atmosphere. The planet is so close to its star that it has been distorted into an egg-like shape and the star is pulling the hydrogen and helium atmosphere away from the planet.
The planet may only last another 10 million years or so before it’s gone. Anthropomorphically speaking, it’s not a happy place.
The Hubble Space Telescope’s STIS instrument, the Space Telescope Imaging Spectrometer, was used in this new study.
So, why are we excited about this spooky black planet? Because it’s amazing that we were able to work out its color at all!
Exoplanets are so small and so crazy far away that it’s incredibly difficult to see them. It’s pretty much impossible to make out any details.
Luckily, astronomers have a few tricks up their sleeves.
Exoplanets don’t make their own light, they simply reflect the light of their star. By measuring how much light the planet reflects, we can work out a number of details, including its color.
Surfaces like snow and ice reflect a lot of light, while darker surfaces, like grass or asphalt, are less reflective.
WASP-12b is blacker than fresh asphalt and soaks up most of the starlight that hits it. In fact, only 6.4% of the incoming light is reflected.
The dark color is due to the planet’s temperature, which reaches well over 2,000 degrees Celsius. The extreme heat affects the planet’s atmosphere and stops clouds from forming, which would reflect more light.
So this is what we call a hot Jupiter type planet, with a year that’s only 26 hours long. Yeah, a very unhappy place, a tortured, dying planet.
But don’t cry for WASP-12b. Nothing lives there. Way too hot.
Hey, Here’s A Cool Fact:
To put all this albedo talk into perspective, the most reflective world in our Solar System is one of Saturn’s many icy moons, Enceladus.
Our own Moon only reflects 12% of the light that hits it, while Enceladus reflects 81%! Earth has an average albedo of 30-35% for comparison.
Dr. Sharon E. Nicholson of Florida State University wrote a book titled “Dryland Climatology” that gives us a more down-to-Earth perspective on all this reflectivity business.
Sand dunes in the Sahara Desert can have an albedo of 50% or more, though most of the region has an albedo of 30-40%. Salt flats can be even brighter than that 50%.
Tropical rainforests on Earth have an albedo of 7-12% and mid-latitude forests have 15-20% albedos. Forest canopies can exhibit so-called “canopy trapping” where the tree leaves reflect light back to other leaves and not back into space.
So you can see from the albedo numbers that the tropical forest is better at this trapping than mid-latitude forests.
Grasslands have 15-25% albedos. Dry soil is from 15 to 25% too, like the grasslands. Wet soil is darker, typically 10%. Clouds can reflect 70-80% of the light, as you might have guessed. They’re white after all.
Water has an albedo of about 5%, but it does tend to reflect light off in a specular fashion, like a mirror. So if the Sun is low on the horizon the percentage of light that gets reflected can be as high as 90%.
Just a little something to think about the next time you see the Sun set at the beach!
Thank you for listening to the 365 Days of Astronomy Podcast!
End of podcast:
365 Days of Astronomy
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The 365 Days of Astronomy Podcast is produced by Astrosphere New Media. Audio post-production by Richard Drumm. Bandwidth donated by libsyn.com and wizzard media. You may reproduce and distribute this audio for non-commercial purposes. Please consider supporting the podcast with a few dollars (or Euros!). Visit us on the web at 365DaysOfAstronomy.org or email us at info@365DaysOfAstronomy.org. This year we will celebrate more discoveries and stories from the universe. Join us and share your story. Until tomorrow! Goodbye!