The hunt for exoplanets, planets outside the solar system, has reached a milestone. NASA astronomical scientists have reported the discovery of the 5,000th exoplanet, with the number of potentially existing exoplanets in the cosmos available to detect them estimated to be in the hundreds of billions.
The 5,000th milestone was reached last week after a new "batch" of 65 planets discovered during the Kepler Space Telescope's extended K2 mission was confirmed through additional observations. This brings the total number of exoplanets discovered to 5,005, and among them is a system with five small planets orbiting the red dwarf star K2-384. Note that the K2-384 system is very similar to the TRAPPIST-1 system and it has become the subject of increased interest from scientists to search for traces of life.
Most of the other confirmed planets are in the super-Earth and mini-Neptune class, and they also include several Jupiter-sized planets.
The resulting catalogue of 5000+ exoplanets can be roughly divided into three main categories. The first category includes gas giants like Jupiter and Saturn, the second includes ice giants like Neptune and Uranus, and the third includes planets like Super-Earth, a class not represented in our solar system. Smaller planets like Earth and Mars are so few that it is impossible to put them in a separate category.
We remind our readers that the very first exoplanet in history was discovered in 1992. The pace of new exoplanet discoveries has picked up with the launch of the Kepler Space Telescope in 2009, which has accounted for two-thirds of all known exoplanets discovered. The exoplanet-hunting process was continued with the launch of the new TESS telescope in 2018, which is currently continuing its mission.
"Of the five thousand exoplanets known to date, 4,900 are located within a few thousand light years of us," says Jessie Christiansen, NASA's Exoplanet Archive project manager, "If we extrapolate all this to our entire galaxy, we get a number of 100 to 200 billion exoplanets that we have yet to discover and explore."
And to conclude, the exoplanet-hunting process is about to pick up the pace as it gets a new instrument in the form of the Nancy Grace Roman Space Telescope. And the James Webb Space Telescope, recently launched into space, will allow the most interesting and promising exoplanet specimens to be accurately measured and studied in more detail.
