NASA’s exoplanet-hunting spacecraft has discovered its first Earth-sized world in nearby solar system
- TESS spotted its first Earth-sized planet in a system roughly 53 light-years away
- It follows an orbit of about 36 days, giving it the longest period of TESS planet
- Researchers say it may have a substantial atmosphere, though cooler than ours
A spacecraft that launched last year on a mission to find new exoplanets has stumbled upon a planet roughly the same size as our own.
NASA’s Transiting Exoplanets Survey Satellite (TESS) spotted its first Earth-sized planet in a system roughly 53 light-years away.
Scientists estimate the distant world as a radius of about 2.7 times Earth’s, and may be home to a substantial atmosphere.
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The planet, dubbed HD 21749b, is what’s known as a sub-Neptune exoplanet, meaning it has less mass than Neptune and Uranus. It follows an orbit of about 36 days, giving it the longest period of a planet TESS has found yet, and has a mass of about 23 times that of Earth
After the TESS signals suggested the presence of a planet orbiting a star with roughly 80 percent of the sun’s mass, researchers were able to confirm the detection using the Planet Finder Spectrograph on the Magellan II telescope at Carnegie’s Las Campanas Observatory in Chile.
The planet, dubbed HD 21749b, is what’s known as a sub-Neptune exoplanet, meaning it has less mass than Neptune and Uranus.
It follows an orbit of about 36 days, giving it the longest period of a planet TESS has found yet, and has a mass of about 23 times that of Earth.
As scientists have expected mostly to find planets with orbital periods fewer than 10 days, the team says this discovery is unusual.
‘PFS is one of the only instruments in the Southern Hemisphere that can do these types of measurements,’ said Johanna Teske, from the Carnegie Institution for Science.
‘So, it will be a very important part of further characterizing the planets found by the TESS mission.’
The researchers are now hoping to refine their measurements to better understand what its atmosphere might be like.
Unlike Earth, the newfound planet is not a rocky planet and its atmosphere would be cooler.
According to the team, the planet also has a ‘sibling,’ which orbits its host star on a period of about eight days.
‘Measuring the exact mass and composition of such a small planet will be challenging, but more important for comparing HD 21749c to Earth,’ said Wang.
‘Carnegie’s PFS team is continuing to collect data on this object with this goal in mind.’
Scientists say this is likely the first of many Earth-sized planets that TESS will find during its surveys.
The groundbreaking craft can measure the properties of smaller exoplanets, which was never possible before.
‘For stars that are very close by and very bright, we expected to find up to a couple dozen Earth-sized planets,’ said lead author Diana Dragomir of MIT’s Kavli Institute for Astrophysics and Space Research.
‘And here we are – this would be our first one, and it’s a milestone for TESS. It sets the path for finding smaller planets around even smaller stars, and those planets may potentially be habitable.’