NASA spots Earth-sized, rocky Planet

NASA’s Transiting Exoplanet Survey Satellite (TESS) mission has discovered a second Earth-sized, rocky planet within the habitable zone of its star – the range of distances where liquid water could occur on a planet’s surface. The planet, named TOI 700 e, is one of only a few systems with multiple, small, habitable-zone planets that we know of. The discovery was made by a team led by Emily Gilbert, a postdoctoral fellow at NASA’s Jet Propulsion Laboratory in Southern California.

Previously Discovered Planets in the TOI 700 System

Astronomers have previously discovered three planets in the TOI 700 system, named TOI 700 b, c, and d. Planet d also orbits within the habitable zone, but the scientists needed an additional year of TESS observations to discover TOI 700 e. “That makes the TOI 700 system an exciting prospect for additional follow up. Planet e is about 10 per cent smaller than planet d, so the system also shows how additional TESS observations help us find smaller and smaller worlds,” said Gilbert.

About the TOI 700 Star System

TOI 700 is a small, cool M dwarf star located around 100 light-years away in the southern constellation Dorado. In 2020, Gilbert and others announced the discovery of the Earth-size, habitable-zone planet d, which is on a 37-day orbit, along with two other worlds. The innermost planet, TOI 700 b, is about 90 per cent Earth’s size and orbits the star every 10 days. TOI 700 c is over 2.5 times bigger than Earth and completes an orbit every 16 days.

Habitable Zone and Tidal Locking

The newly discovered planet, TOI 700 e, takes 28 days to orbit its star, placing it between planets c and d in the so-called optimistic habitable zone. Scientists define the optimistic habitable zone as the range of distances from a star where liquid surface water could be present at some point in a planet’s history. This area extends to either side of the conservative habitable zone, the range where researchers hypothesize liquid water could exist over most of the planet’s lifetime. TOI 700 d orbits in this region. TOI 700 e, which may also be tidally locked, is one of the planets that have the possibility of having liquid water on its surface.

Significance of the Discovery

“Finding other systems with Earth-size worlds in this region helps planetary scientists learn more about the history of our own solar system,” said Gilbert. The discovery was presented by Gilbert at the 241st meeting of the American Astronomical Society in Seattle, and a paper about the newly discovered planet was accepted by The Astrophysical Journal Letters. The discovery of TOI 700 e expands the known sample of potentially habitable rocky planets, and opens the door to future studies to understand the habitability of these worlds and search for signs of life on them.

Category: Science & Technology Current Affairs