NASA’s TESS probe discovers new planet 3 times the size of Earth

NASA's planet-hunting probe, Transiting Exoplanet Survey Satellite (TESS) has discovered a new world outside our solar system, orbiting a dwarf star 53 light years away. This is the third new planet confirmed by the TESS since its launch in April last year. The planet, named HD 21749b, orbits a bright, nearby dwarf star about 53 light years away, in the constellation Reticulum, and appears to have the longest orbital period of the three planets so far identified by TESS. The probe scans a new segment of the sky every month. Over two years, TESS will cover the entire 360 degrees of sky visible from Earth’s orbit.

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"It's the coolest small planet that we know of around a star this bright," said Diana Dragomir, a postdoc in Massachusetts Institute of Technology (MIT) in the US, who led the discovery.

"We know a lot about atmospheres of hot planets, but because it's very hard to find small planets that orbit farther from their stars, and are therefore cooler, we haven't been able to learn much about these smaller, cooler planets. But here we were lucky, and caught this one, and can now study it in more detail," Dragomir said.

“The surface of the new planet is likely around 300 degrees Fahrenheit and is relatively cool, given its proximity to its star, which is almost as bright as the sun,” said the team from the Massachusetts Institute of Technology in Boston.

The researchers have also detected evidence of a second planet, though not yet confirmed, in the same planetary system, with a shorter, 7.8-day orbit. If it is confirmed as a planet, it could be the first Earth-sized planet discovered by TESS.

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Earlier, TESS had shared the first image that was captured on its initial round of data collection. The data from the telescope’s initial science orbit included a detailed picture of the southern sky taken with all four of the spacecraft's wide-field cameras. The images were captured using all four of the spacecraft's wide-field cameras during a 30-minute period on August 7 last year.

The target stars of TESS are 30 to 300 light-years away and about 30 to 100 times brighter than Kepler's targets, which are 300 to 3,000 light-years away.