Transiting exoplanet HAT-P-7b (artist's impression)

This is an artist’s concept of the extrasolar planet HAT-P-7b. It is a “hot Jupiter” class planet orbiting a star that is much hotter than our Sun. For its millionth observation, the NASA/ESA Hubble Space Telescope’s was trained on this planet to look for the presence of water vapour and to study the planet’s atmospheric structure via spectroscopy. Planets with orbits inclined nearly edge-on to Earth can be observed passing in front of and behind their stars. This allows for the planetary atmospheres to be studied by Hubble’s spectrometers. Hubble’s unique capabilities allow astronomers to do follow-up observations of exoplanets to characterise the composition and structure of their atmospheres.