Rabbi Allen S. Maller
In the 20 years before NASA launched the Kepler Space Telescope in 2009, about 325 exoplanets were discovered. Kepler was a full-time planet hunter that revolutionized astronomers’ understanding of exoplanets. It was particularly interested in finding Earth-sized planets orbiting sun-like stars at a distance where water on the surface could be stable in liquid form — the so-called habitable zone.
In the 9 years to date, data from Kepler have turned up 2,343 confirmed and 2,244 candidate exoplanets; and revealed that there could be more planets than stars in the Milky Way. Many of them are in multiple-planet systems like our solar system, and a large share of the exoplanets appear to be super-Earths — a class that’s bigger than our planet but smaller than Neptune.
Now TESS, the Transiting Exoplanet Survey Satellite which launches this week, will scan almost all of the sky for nearby stars in order to find planets that are smaller than Neptune, with a radius less than about four times that of Earth. A few of the worlds TESS finds may be small, rocky bodies, like Earth. And a few of those might, just possibly, be habitable places for life as we know it.
When TESS does get up, it will stare at stars for weeks at a time, hoping to catch the dips in brightness that occur when orbiting worlds traverse their faces. The expectation is that it could identify some 2,000-3,000 planets in its first two years of operation.
The satellite, which carries four camera-detectors, will essentially compile a catalogue that other telescopes – both on the ground and in space – can then focus in on for more detailed analysis.
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