Two teams of astronomers captured images of four different planets orbiting stars. Three of them are orbiting the same star, while the fourth is circling a different one. The pictures show the planets as specks of white, nearly indecipherable except to the experts. All of them are trillions of miles away and none of them are remotely habitable or remotely like Earth. Even so, if they orbit a star, it’s likely that other habitable planets exist in that solar system.

The first team took photos with ground-based telescopes, while the second used the Hubble Space Telescope to gather images of the exoplanets. The research and the pictures will be published in Thursday’s online edition of the journal Science.

The fact that planets which circle stars exist is not a breakthrough, but the way in which they have been discovered is. In the past 13 years, scientists have discovered more than 300 planets outside our solar system, but this has been done indirectly, by measuring changes in gravity, speed or light around stars. NASA’s space sciences chief Ed Weiler told the media that this discovery fulfills the last of the major goals that the space agency had for the Hubble telescope before it launched in 1990. Of course, as every scientific breakthrough, there are voices saying that more study is needed to confirm these photos are proven planets and not just brown dwarf stars. Others have made earlier claims, but those pictures have yet to be confirmed as planets.

The exoplanet discovered by Hubble circles the star Fomalhaut, in the constellation Piscis Austrinus. Scientists compared a 2006 photo to a 2004 one to show that the planet orbited a star, being part of a massive red dust ring which is usually associated with planets. As for the first team, it spotted the first planet in 2007 but needed extra time to confirm the trio of planets circling a star in the Pegasus constellation. The star is called HR 8799, and the planets orbiting it are seven to 10 times larger than Jupiter.