Astronomers Have Been Finding 1 New Exoplanet A Day On Average Since Kepler Launched in 2009
The Kepler space telescope has been instrumental in discovering planets orbiting stars outside of our solar system. The sheer volume of data that has come out of the mission has allowed scientists to discover thousands of exoplanets that would have been difficult, if not impossible, to see from Earth.
Of those candidate bodies, around 2,350 of them have been verified as planets, all of them found by Kepler. Taking into account the time it took to calibrate the telescope and start sending back usable data, it’s averaging around one exoplanet found every day.
Most of the discoveries from Kepler come in large batches, as data is gathered and compared to what we know to be exoplanet signals, scientists often find several, sometimes hundreds, of planets at one time. In mid-2013, a reaction wheel failure that occurred after a similar failure a year earlier caused the spacecraft to stop its primary mission. 2014 brought about the K2 mission which was devised as a way to keep the space telescope operable and sending back at least some scientific data.
Finding exoplanets the size of Jupiter is interesting because it proves that a star has the possibility of holding additional planets within its orbital plane. What scientists (and the public) really want to see are planets similar in size to Earth, orbiting its host star within a fairly narrow range (the exact width of the range depends on the size and type of start it orbits) that would allow liquid water to be present on the surface.
As of early 2017, scientists have found around 13 exoplanets that are potentially habitable. These planets have to be similar to Earth in both mass and distance from the star it orbits. Searching for an atmosphere and possible a hydrosphere is the next step in determining whether or not these Earth-like planets could be suitable for human-like life. One of the more exciting discoveries is known as Proxima Centauri b, the exoplanet closest to Earth at about 4.4 light years away, which also happens to be a candidate for possessing the characteristics required for life as we know it to exist.