Twenty-fifth anniversary of the discovery of the first exoplanet

Twenty-five years ago today, on 9 January 1992, astronomers published the first unambiguous discovery of an exoplanet — a planet beyond our Solar System. Since then the search for, and study of, exoplanets has become an exciting and productive branch of astronomy, one in which researchers in Queen Mary's School of Physics and Astronomy are actively engaged.

Unusually, this first exoplanet was not found in orbit around a 'conventional' star; instead it orbits an object known as a pulsar, a very exotic object left over after a star much bigger than the Sun has undergone a massive explosion — a supernova — at the end of its life.

Probably the most compelling question behind the study of exoplanets is: can we find evidence for life on any of them? The pulsar in question is host to no fewer than three planets, but they are certainly not candidates for harbouring any form of life, given the extreme conditions near to the pulsar. But the total number of exoplanets now known exceeds three thousand, and many of these are in orbit around stars similar to the Sun. Quite a few of them are thought likely to be capable of supporting life, including the planet known as Proxima b which was recently discovered in orbit around the nearest star to the Sun by a team of astronomers led by Dr Guillem Anglada Escudé of the School of Physics and Astronomy.

Researchers in the School of Physics and Astronomy are studying many aspects of exoplanets, via theoretical models and programmes of observation. Alongside Dr Anglada Escudé’s hunt for the planets themselves, Dr Izaskun Jimenez-Serra is studying the interstellar medium — the mixture of gas and dust from which stars and planets form — to look for molecules that could be the building blocks of life; Prof. Richard Nelson and Dr Sijme-Jan Paardekooper use theoretical models and computer simulations to study how planets form and evolve; Prof. Carl Murray and Dr Craig Agnor study how systems of planets are affected by the gravitational forces acting on them; and Dr James Cho investigates the behaviour of planetary atmospheres.

Together they are advancing our understanding of other worlds, where we may one day find vital clues that there could indeed be life elsewhere in the Universe.

The image shows a disc of material surrounding the star HL Tauri. In this disc, known as a protoplanetary disc, astronomers are confident a system of planets is forming. This remarkable image was obtained with the Atacama Large Millimeter/submillimeter Array (ALMA), just one of the telescopes that astronomers in the School of Physics and Astronomy use to study the formation of planets around other stars.

Image credit: ALMA (ESO/NAOJ/NRAO)