Artist's impression of exoplanet 51 Pegasi b

The domain of exoplanets was officially born with the detection of 51 Pegasi b in 1995 by scientists Michel Mayor and Didier Queloz, who won the Nobel prize in 2019 for this discovery. The planet weighing half the mass of Jupiter, orbits its star in a close orbit in just over four days, making it the very first ‘hot Jupiter’. The discovery rocked the astronomical world as its characteristics did not fit into the theory of planetary formation at the time. The planet is tidally locked to its star, so it always shows the same side to its star. In 2017, astronomers discovered the presence of water particles in its atmosphere.