NASA's 'TESS' Discovers Its First Earth-Size Habitable-Zone World
NASA ’s Transiting Exoplanet Survey Satellite (TESS) has found its first Earth-size planet in its star’s habitable zone – the range of distances where conditions might allow for the presence of liquid water on the surface. The discovery, called TOI 700 d, was confirmed by scientists using NASA’s Spitzer Space Telescope. The scientists have modeled the planet’s potential environments to help inform future observations. TOI 700 d is one of only a few Earth-size planets discovered in a star's habitable zone so far. Others include several planets in the TRAPPIST-1 system, and other worlds discovered by NASA’s Kepler Space Telescope. TOI 700 is a small, cool M dwarf star that is located a little over 100 light-years away in the southern constellation Dorado. The innermost planet, TOI 700 b, is almost exactly Earth-size.
Transcript
00:00:01 [Music] nasa's test mission has found its first earth-sized world in its star's habitable zone this means the planet called toi 700d has the potential for liquid water on its surface test stares at patches of sky for long stretches recording light from thousands of stars
00:00:20 some of these stars have planets that cross or transit in front of them tess sees these events as tiny regular dimmings of the host's stars one star where tess saw transits is toi 700 it's a red dwarf about 40 percent the mass and size of our sun and roughly half its temperature one set of transits announced the presence of a planet close to the star
00:00:44 called toi 700b another set revealed a second planet named toi 700c a little farther out the deeper shorter transit means the planet is larger than the first and the plane of its orbit is slightly tipped a final set of transits showed toi 700d orbiting even farther out tess observed the system for nearly 11 months and saw each planet transit
00:01:09 multiple times scientists determine that the inner and outer planets are almost earth size and may be rocky the middle world is more than twice as large and most likely made of gas all three may be tidally locked rotating just once each orbit so the same side always faces the star but most importantly toi 700d is within
00:01:32 the star's habitable zone scientists wanted independent confirmation of toi 700d so they monitored its star with nasa's spitzer space telescope spitzer saw a clear transit from the outer planet affirming its existence and improving scientist certainty of the planet's size toi 700d is one of only a few
00:01:54 earth-sized planets found in potential habitable zones others include discoveries by kepler and several planets in the trappist-1 system because toi 700 is bright and nearby the planets are good candidates for precise mass measurements by ground-based telescopes future missions may also tell us if the worlds have atmospheres but scientists
00:02:17 need to know what kinds of signals to look for researchers at nasa's goddard space flight center created models of the planet to explore its potential conditions one version is a water covered world with an atmosphere similar to early mars but denser another looks like a completely dry version of today's earth
00:02:37 both models have vastly different surface temperatures light passing through their atmospheres creates distinct signals because different molecules are present by simulating these data now scientists can make predictions for real future observations and narrow the range of toi 700d's possible conditions we still have much to learn about the
00:02:59 toi 700 system but thanks to tess spitzer and the work of many scientists were beginning to form a picture of its exciting new worlds