Astronomers find Water Vapor in atmosphere of Neptune-sized Exoplanet
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The discovery will help those astronomers who are trying to find whether or not smaller planets have environment similar to our planet earth.
As it is not an easy task to examine the molecular contents of exoplanet's atmosphere, astronomers wait for it to pass in front of its star. They then examine light of the star that filters through the translucent gassy shell around the exoplanet's outline. If astronomers find water in planet's slim atmospheric lining, it absorbs filtered light's wavelength, and leaves chemical fingerprint for astronomers. The phenomenon is called as transmission spectroscopy.
It is very difficult for scientists to apply the process on small planets, so they only probe contents of air and water on planets of big size, such as Jupiter. Big planets have extended and wider atmosphere as compared to small planets, which offers researchers to search the possibilities of air and water.
Grinnell College's astronomer Eliza M.R. Kempton said, "Searching for water-vapor absorption in the atmosphere of an exoplanet passing in front of its host star is akin to looking for a tiny insect passing in front of a bright coastal lighthouse lamp".
Sometimes, clouds hide the atmosphere of an exoplanet and make things difficult for astronomers studying the planet. Until the 1970s, researchers could investigate a few things about Earth's nearby planet Venus, because it was blanketed by sulfuric acid's clouds, Kempton said.
Scientists have tried to discover about small planets' atmosphere by using NASA's Hubble Space Telescope. They already have studied four Neptune-sized planets.
University of Maryland's researchers examined HAT-P-11b that rotates around its star every five days. According to transmission spectrum, the planet has water vapor and hydrogen.
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