- The planet, GJ 357 d, orbits a star around 31 light years away in a habitable zone
- In this region, it’s possible for water to exist on the planet’s surface if it is rocky
- NASA’s Tes technology (Transiting Exoplanet Survey Satellite) noticed the star
Nasa‘s planet spotting telescope has uncovered another three planets, which scientists say include the first nearby super-Earth spotted by TESS that could be habitable.
The planet, called GJ 357 d, orbits a star around 31 light years away in the so-called habitable zone, an area far enough from its star to not be too hot but close enough to not be too cold.
In this region, it is possible for liquid water to exist on the surface of a planet if it is rocky, although further research is needed to work out whether GJ 357 d’s atmosphere is dense and warm enough to host liquid water.
The news comes just days after three new planets were found in a star system just 73 light years away from Earth — including two planets that may be ‘missing links’ in planetary formation.
‘GJ 357 d is located within the outer edge of its star’s habitable zone, where it receives about the same amount of stellar energy from its star as Mars does from the Sun,’ said Diana Kossakowski, from the Max Planck Institute for Astronomy in Heidelberg.
‘If the planet has a dense atmosphere, which will take future studies to determine, it could trap enough heat to warm the planet and allow liquid water on its surface.’
Lisa Kaltenegger, a professor of astronomy at Cornell University who published a separate paper in the Astrophysical Journal Letters, suggests the planet could harbour life.
‘This is exciting, as this is humanity’s first nearby super-Earth that could harbour life – uncovered with help from Tess, our small, mighty mission with a huge reach,’ she said.
‘With a thick atmosphere, the planet GJ 357 d could maintain liquid water on its surface like Earth and we could pick out signs of life with upcoming telescopes soon to be online.’
GJ 357 d orbits its star every 55.7 days at a range of about 20 per cent of Earth’s distance from the sun, it is claimed.
The three planets orbit a star known as GJ 357, an M-type dwarf, which is around 40 per cent cooler than our own sun and about a third of its mass and size.
Tess (Transiting Exoplanet Survey Satellite) – Nasa technology used to discover exoplanets beyond our solar system – noticed the star dimming slightly every 3.9 days in February, a hint that planets were circulating around it.
The nearest of the three planets, GJ 357 b, is around 22% larger than Earth, orbiting its star 11 times closer than Mercury does to the sun.
‘We describe GJ 357 b as a ‘hot Earth’,’ said Enric Palle, an astrophysicist at the Institute of Astrophysics of the Canary Islands.
‘Although it cannot host life, it is noteworthy as the third-nearest transiting exoplanet known to date and one of the best rocky planets we have for measuring the composition of any atmosphere it may possess.’
The middle planet, GJ 357 c, has a mass at least 3.4 times Earth’s, and orbits around its star every 9.1 days.
Details of the planet’s discovery was published in the journal, Astronomy & Astrophysics.
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.