Free Astronomy Magazine July-August 2015

31 JULY-AUGUST 2015 SPACE CHRONICLES front of the planet, which primarily provides information about the exo- planet’s temperature. The new technique does not de- pend on finding a planetary transit, and so can potentially be used to study many more exoplanets. It al- lows the planetary reflected light spectrum to be directly detected in visible light, which means that dif- ferent characteristics of the planet that are inaccessible to other tech- niques can be inferred. The host star’s spectrum is used as a template to guide a search for a sim- ilar signature of light that is expect- ed to be reflected off the planet as it describes its orbit. This is an ex- ceedingly difficult task as planets are incredibly dim in comparison to their dazzling parent stars. The signal from the planet is also easily swamped by other tiny ef- fects and sources of noise (the chal- lenge is similar to trying to study the faint glimmer reflected off a tiny insect flying around a distant and brilliant light). In the face of such adversity, the success of the technique when applied to the HARPS data collected on 51 Pegasi b provides an extremely valuable proof of concept. T his artist’s view shows the hot Jupiter exoplanet 51 Pegasi b, sometimes referred to as Bellero- phon, which orbits a star about 50 light-years from Earth. This was the first exoplanet around a nor- mal star to be found in 1995. Twenty years later this object was also the first exoplanet to be be directly detected spectroscopically in visible light. [ESO/M. Kornmes- ser/ Nick Risinger (skysurvey.org)]