This artist’s view shows the hot Jupiter exoplanet 51 Pegasi b, sometimes referred to as Bellerophon, which orbits a star about 50 light-years from Earth in the northern constellation of Pegasus (The Winged Horse). This was the first exoplanet around a normal 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.

The discovery is a testament to the method that the astronomers used, whose usefulness in studying the properties of exoplanets was established only in 2010.
The exoplanet called 51 Pegasi b was discovered in 1995 to international acclaim. Though the first exoplanet had been discovered three years prior orbiting a pulsar, 51 Peg b was the first found to be orbiting a main sequence star. Main sequence is astronomy speak for a star’s being positioned on the Hertzsprung-Russell diagram, which categorises stars according to their brightness and colour. If a star is said to be on the main sequence, then it’s simply a conventional star. Indeed, 51 Peg b orbits 51 Pegasi, a star much like our Sun.
At the time, Michael Mayor and Didier Queloz detected the planet by studying how it was making its host star wobble – using changes in the measurement of the star’s radiation as a proxy. Their measurements indicated …