Astronomers recently observed water vapor and clear skies on the Neptune-size exoplanet called as HAT-P-11b for the first time using data from the NASA/ESA Hubble Space Telescope, the Spitzer Space Telescope, and the Kepler Space Telescope.
The planet would be about the size of Neptune, making it the smallest exoplanet ever on which water vapor has been detected.
Clouds in the atmospheres of planets could block the view of what lies beneath them. The molecular makeup of these lower regions could reveal important information about the composition and history of a planet.
Nikku Madhusudhan, from the University of Cambridge, UK, said that they set out to look at the atmosphere of HAT-P-11b without knowing if its weather would be cloudy or not and by using transmission spectroscopy, they used Hubble to detect water vapour in the planet.
This told them that the planet didn't have thick clouds blocking the view and was a very hopeful sign that they could find and analyze more cloudless, smaller, planets in the future.
The results from all three telescopes demonstrated that HAT-P-11b was blanketed in water vapour, hydrogen gas, and other yet-to-be-identified molecules. So in fact it was not only the smallest planet to have water vapour found in its atmosphere but was also the smallest planet for which molecules of any kind have been directly detected using spectroscopy.
The study is published in the online version of the journal Nature.