The first exoplanets were discovered almost thirty years ago. In the years following this initial discovery, scientists continued to find hundreds and then thousands of exoplanets. As of June 1, 2022 there were 5,059 confirmed exoplanets with thousands of other "candidate" exoplanets detected. We now believe our galaxy contains at least 100 billion planets.
Planets form from dust and gas around young stars. Over millions of years, the dust coagulates to form a rocky planet. If the planet becomes large enough, its gravity will also sweep up some of the gas to create large gaseous planets like Jupiter or Neptune.
Earth is the only planet we know of that contains life, but we don’t know exactly what makes earth so special. There are a few things, in addition to being a rocky planet, that scientists agree are essential for life as we know it on earth. These include water and organic molecules, but whether these ingredients are sufficient for life is still an open question.
Watch to learn more about the search for life on exoplanets from Harvard astronomy professor Karin Öberg.