Clear skies on exo-Neptune

This is a very hopeful sign that we can find and analyse more cloudless, smaller, planets in the future - Nikku Madhusudhan Astronomers have discovered clear skies and steamy water vapour on a gaseous planet outside our solar system. The planet, known as HAT-P-11b, is about the size of Neptune, making it the smallest-ever planet for which water vapour has been detected. 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.