For a long time we’ve been exploring the possibility that there are planets orbiting other stars in the Universe. But it was only in the 1990s that the first candidates were detected, in an indirect way.
It’s not easy to detect an exoplanet, since it emits no light of its own but instead reflects the luminosity of the star that it’s orbiting. In addition, the planets are much smaller than the stars. Thus, the first exoplanets discovered were gas giants. But with advances in telescopes and detection methods, smaller planets have since been flushed out.
Today, over 3,600 planets have been confirmed. It’s quite a throng, ranging from very large gas giants to little rocky planets. There’s such diversity that astronomers have had to rethink the theoretical models of planetary-system formation.
Exoplanets similar to the Earth
Astronomers are paying special attention to rocky planets similar in size to the Earth that are orbiting a star comparable to the Sun. Of particular interest are planets found in the “habitable zone”: an area around a star where liquid water could flow to the surface of planets.
The discovery in 2016 of an exoplanet around Proxima Centauri, the closest star to the solar system, started a number of people dreaming. Some even began to think about ways to set off and explore this New World.
But the ultimate objective of this research is to find life on an exoplanet. Such a discovery would undoubtedly challenge our vision of the world and lead us to reflect on our place in the Universe.
Until then, the search for exoplanets proceeds at a steady pace.
And who knows, maybe one day we’ll discover the planet that E.T. calls home!
In the spotlight
EXO, the new show at Planétarium Rio Tinto Alcan: http://calendrier.espacepourlavie.ca/space-next-exo-746919