Podcaster: Richard Drumm
Title: Space Scoop: Small Telescopes Spot Blue Skies on an Alien World
Organization: 365 Days Of Astronomy
Link : astrosphere.org ; http://www.spacescoop.org/en/scoops/1548/small-telescopes-spot-blue-skies-on-an-alien-world/
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 365 Days of Astronomy. 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.
Today’s story is:
Small Telescopes Spot Blue Skies on an Alien World
Everyone loves a clear blue sky. But do you know why the sky is blue? Why isn’t it green or yellow or pink? The answer to this question can be found by looking at the blanket of particles surrounding Earth. We call this Earth’s atmosphere.
Earth’s atmosphere is composed of gasses and dust. The principal gasses are nitrogen, 78%; oxygen, 21%; and a little argon, 0.9%; and even less carbon dioxide at 0.03%. This dust, though, is different from the dust under my bed. THAT dust is made of cotton fibers that broke off from my sheets & blankets and tiny bits of skin cells that I’ve shed. Some of these skin cells are eaten by relatives of spiders, the dust mites, and their poo becomes part of that dust as well.
Yuck!
The dust in our atmosphere, though, is made up of exhaust from cars, trucks, busses and coal-fired power plants. It comes from pickup trucks driving on dirt roads, forest fires and even wind storms that stir up dust from deserts. The dust particles from exhausts & fires are very tiny bits of carbon compounds. The other dust particles are bits of dirt and pieces plant material, like dried leaves broken into a powder.
As light from the Sun travels through the atmosphere, most colors of the light are able to reach the surface without a problem. However, blue light from the Sun has a shorter wavelength and as a result is just the right size to knock into the tiny dust particles in the air and bounce off them in all directions, making the sky look blue. We call this Rayleigh scattering.
This is the exact same reason that sunsets and sunrises are red. The red part of Sunlight goes through the dust in our atmosphere with no scattering at all. It goes straight through, no problem.
Meanwhile, as the Sun is setting where you are, a few hundred kilometers out to your West that same sunlight is passing through a bunch of late afternoon skies, and the blue part of the spectrum is scattered away, making their skies blue and leaving the Sun looking red and orange over to the East where you are.
Kinda cool, eh?
Where was I? Oh yeah!
Well, in 2014 astronomers at LCOGT, the Las Cumbres Observatory Global Telescope network spotted Rayleigh scattering in the atmosphere of a distant alien world! They looked at a star that is 100 light years away called GJ 3470 and its planet, called GJ 3470b. This is a planet that crosses in front of the host star in what we astronomers call a transit.
The star is a red dwarf, a very common type, and the planet is described as a “warm Neptune”, meaning that it’s about Neptune’s size, 4 times Earth’s size, and somewhat close to the parent star.
The astronomers think the best explanation for the bluish light they detected is that the planet has a hydrogen and helium atmosphere with high altitude clouds and hazes. An artist’s interpretation of this is shown in our album artwork for this episode. You can see the blue fringe on the left side of the planet in the image.
There’s a transit of our planet Mercury coming up on May 9th, so do make the acquaintance of an astronomy club in your area and enjoy the show! It’ll start around 6:14 AM here on the East coast of America and will last till about 1:39 in the afternoon. Europe and the Americas will be in a good position to view it.
The astronomers were using the LCOGT network of 1, 11/2 and 2 meter telescopes, that’s 40, 60 & 80 inches diameter, which are much smaller than telescopes previously used to make these sorts of measurements.
The astronomers want to perform infrared spectroscopy observations next to see if they can detect water and carbon molecules in the planet’s atmosphere. They may even be able to determine the thickness of the atmosphere!
This is the first time blue skies have been spotted on such a small exoplanet. Plus, the discovery shows that even small to medium-sized telescopes can play a large role in studying the atmospheres of alien worlds!
Here’s the cool fact:
LCOGT’s telescopes are used by schoolchildren to explore the cosmos! What would you study if you could use 1-metre, robotic telescopes? Tell us at unawe@cardiff.ac.uk and you might win some telescope time of your own!
Thank you for listening to 365 Days of Astronomy!
End of podcast:
365 Days of Astronomy
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