This is a very hopeful sign that we can find and analyse more cloudless, smaller, planets in the future.
- Nikku Madhusudhan
Using data from the NASA/ESA Hubble Space Telescope, the Spitzer Space Telescope, and the Kepler Space Telescope, an international team including astronomers from the University of Cambridge found that HAT-P-11b is blanketed in water vapour, hydrogen gas, and other yet-to-be-identified molecules. The results are published today (24 September) in the online version of the journal Nature.
“This discovery is milepost on the road to eventually searching for molecules in the atmospheres of smaller, rocky planets more like Earth,” said John Grunsfeld, assistant administrator of NASA’s Science Mission Directorate. “Such achievements are only possible when we combine the capabilities of these unique and powerful observatories.”
Clouds in the atmospheres of planets can block the view to underlying molecules that reveal information about the planets’ compositions and histories. Finding clear skies on a Neptune-size planet is a good sign that smaller planets might have similarly good visibility.
“When astronomers go observing at night with telescopes, they say ‘clear skies’ to mean good luck,” said Jonathan Fraine of the University of Maryland, the study’s lead author. “In this case, we found clear skies on a distant planet. That's lucky for us because it means clouds didn't block our view of water molecules.”
HAT-P-11b is a so-called exo-Neptune — a Neptune-sized planet that orbits another star. It is located 120 light-years away in the constellation of Cygnus (The Swan). Unlike Neptune, this planet orbits closer to its star, making one lap roughly every five days. It is a warm world thought to have a rocky core, a mantle of fluid and ice, and a thick gaseous atmosphere. Not much else was known about the composition of the planet, or other exo-Neptunes like it, until now.
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Image:Illustration of the view from HAT-P-11b
Credit: NASA/JPL-Caltech
Reproduced courtesy of the University of Cambridge
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