Free Astronomy Magazine July-August 2018

30 A n international team of as- tronomers, led by Jessica Spake, a PhD student at the University of Exeter in the UK, used Hubble’s Wide Field Camera 3 to discover helium in the atmos- phere of the exoplanet WASP-107b. This is the first detection of its kind. Spake explained the importance of the discovery: “Helium is the second- most common element in the universe after hydrogen. It is also one of the main constituents of the planets Jupiter and Saturn in our solar system. However, up until now helium had not been detected on exoplanets — despite searches for it.” The team made the detection by analyzing the infrared spectrum of the atmosphere of WASP- 107b. Previous detections of extended exoplanet atmospheres have been made by studying the spec- trum at ultraviolet and optical wavelengths; this detec- tion therefore demonstrates that exoplanet atmospheres can also be studied at longer wavelengths. The measurement of an exoplanet’s atmosphere is performed when the planet passes in front of its host star. A tiny portion of the star’s light passes through the exoplanet’s atmosphere, leav- ing detectable fingerprints in the spectrum of the star. The larger the by NASA/ESA Helium in an exoatmosphere detected for the first time JULY-AUGUST 2018 SPACE CHRONICLES