The number of planets detected around other stars - or exoplanets - is set to hit the 4,000 mark.Read more
Science editor, BBC News website
Nasa's latest space telescope should find thousands of planets beyond our Solar System.
Nasa's Transiting Exoplanet Survey Satellite (Tess) searches for new planets.
The Tess mission will survey nearly the entire sky and is expected to find thousands of new worlds.