It has been 30 years since the first planet beyond the solar system was discovered, and to date more than 5,000 have been found – but are they all alien worlds?
Scientists have been examining the thousands of exoplanet discoveries confirmed within the Milky Way Galaxy, and three of them have turned out to be stars.
A team from the Massachusetts Institute of Technology in Cambridge, looked through planets discovered using the NASA Kepler Space Telescope, double checking the measurements