7 new Earth-sized planets discovered
Astronomers have spotted 7 Earth-sized planets revolving around a star called TRAPPIST-1. Thomas Zurbuchen, associate administrator of the Science Mission Directorate at NASA Headquarters said this was a "major step forward". This is the first time cosmologists have discovered so many Earth-sized planets orbiting the same sun (star). With this new discovery, the tally of authenticated exoplanets stands at 3,449.
Time of great discoveries: First exoplanets discovered
An exoplanet (also known as an extrasolar planet) is a "planet located outside the Solar System". The first validated discovery of exoplanets was declared in 1992, with 2 planets found circling a pulsar. Some of the exoplanets have been seen directly by telescopes, however, a vast majority have been discovered through complicated methods like the "transit method and the radial-velocity method".
Most important exoplanet discoveries
Gamma Cephei Ab: The first exoplanet detected. PSR 1267+12 B and C: First pulsar planets. One was a Super-Earth. 51 Pegasi b: First planet around Sun-like star. Kepler 186f: First Earth-size planet circling in the habitable zone of its star. Kepler 11-f: Circled a Sun-like star and had "2.3 times the mass of Earth". Mu Arae c: First hot Neptune discovered.
Alien Planet Count Passes 1,000 Worlds, a milestone
Merely 2 decades after first discovering planets circling a star apart from our own sun, scientists have reached a big milestone i.e the 1,000th alien planet. While the 5 principal exoplanet-discovery databases have differing tallies it's widely agreed that we have surpassed the 1,000 figure. However, this is a small fraction of that discovered from the "billions of stars in our galaxy".
Varying tallies for the exoplanets discovered
The 5 primary exoplanet-discovery databases are: "the Extrasolar Planets Encyclopedia (1,010); the Exoplanets Catalog, run by the Planetary Habitability Laboratory (1,010); the NASA Exoplanet Archive (919); the Exoplanet Orbit Database (755); and the Open Exoplanet Catalog (948)."
Hurray! Possibility of newer Earths opens up
Of the 7 exoplanets discovered, 3 are in the habitable zone. This is because there is a possibility of the existence of liquid water on the surface of rocky planets. Moreover, it's neither too hot nor cold. The space agency termed the discovery of the captivating solar system "record-breaking" The exoplanets are approximately 40 light years away which is reasonably close to each other.
