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NASA’s exoplanet-hunting spacecraft discovers Earth-sized world

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.’

WHAT IS THE TESS SPACECRAFT?

NASA’s new ‘planet hunter,’ set to be Kepler’s successor, is equipped with four cameras that will allow it to view 85 per cent of the entire sky, as it searches exoplanets orbiting stars less than 300 light-years away.

By studying objects much brighter than the Kepler targets, it’s hoped TESS could uncover new clues on the possibility of life elsewhere in the universe.

Its four wide-field cameras will view the sky in 26 segments, each of which it will observe one by one.

In its first year of operation, it will map the 13 sectors that make up the southern sky.

Then, the following year, it will scour the northern sectors.

‘We learned from Kepler that there are more planets than stars in our sky, and now TESS will open our eyes to the variety of planets around some of the closest stars,’ said Paul Hertz, Astrophysics Division director at NASA’s Headquarters. 

‘TESS will cast a wider net than ever before for enigmatic worlds whose properties can be probed by NASA’s upcoming James Webb Space Telescope and other missions.’

 

Tess is 5 feet (1.5 meters) wide and is shorter than most adults.

The observatory is 4 feet across (1.2 meters), not counting the solar wings, which are folded for launch, and weighs just 800 pounds (362 kilograms). 

NASA says it’s somewhere between the size of a refrigerator and a stacked washer and dryer. 

Tess will aim for a unique elongated orbit that passes within 45,000 miles of Earth on one end and as far away as the orbit of the moon on the other end.

It will take Tess two weeks to circle Earth.   

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