In a tempting first, scientists have discovered water on a planet outside our solar system that has temperatures suitable for life.
Two research groups have announced this week that they have found water vapor in the atmosphere of a planet 110 light years away from the constellation of Leo. This so-called Super Earth is at the right distance from its star to conceivably host life.
It is the only exoplanet so far known to have both water and the temperatures necessary for life, the University College London team reported Wednesday in the journal Nature Astronomy. But the lead author Angelos Tsiaras pointed out: "This is definitely not a second Earth".
His star and the atmosphere are so different from ours, "Earth-like conditions are not possible," Tsiaras told reporters. "The only question we are trying to ask here, and we are pushing forward, is the question of habitability".
A team led by Canada announced similar results Tuesday. In an article just published in the Astronomical Journal for publication, these scientists suggest that it might even rain there.
"This represents the biggest step yet taken towards our ultimate goal of finding life on other planets, of demonstrating that we are not alone," the study's leading astronomer, Bjorn Benneke of the University of Montreal, said in a statement. .
Discovered in 2015, the planet known as K2-18b is twice as big as Earth with eight times the mass. While it is thought to be rocky, no one knows if the water flows on the surface. Its star, a red dwarf, is considerably smaller and fresher than our sun, a yellow dwarf, and its atmosphere is also different from ours.
However, Tsiaras said that K2-18b could help determine, "Is the Earth unique?"
The results are doubly exciting, noted Tsiaras, since this is not only the first Super Earth with water detected in its atmosphere, but the planet also resides in the habitable zone of its star.
Research teams used data stored by the Hubble Space Telescope and other spacecraft to analyze the planet's atmosphere. Further observations are needed to determine whether the planet is truly a real water world, using next-generation observatories such as NASA's James Webb Space Telescope and the European Space Agency Ariel, both due to launch over the years. .
Future telescopes on Earth and in space should help to discover more Super Earths orbiting red dwarf stars – believed to be the most common planets and stars in our Milky Way galaxy. The Super Earths are defined as having a mass greater than the Earth but inferior to the gas giants like Uranus and Neptune; more than 1,260 have been confirmed to date.
While the water has already been identified in the atmospheres of the hot gas giants surrounding other stars, the latest discoveries represent the first detection of water vapor in the atmosphere of another type of exoplanet, Tsiaras said.
A NASA count currently lists over 4,000 confirmed extrasolar planets and 4,000 other potential candidates. Most were detected using the transit method, in which the telescopes observe a light and fleeting darkening of the light of a star while a planet passes into the visual field.
For now, scientists know that K2-18b takes 33 days to orbit its star, so a year is a month here. At this distance, temperatures range from minus-100 degrees to 116 degrees Fahrenheit (minus 73 degrees to 47 degrees Celsius.)
The star, which shines red in the daytime sky, is believed to bombard the planet with radiation strong enough to rapidly inflict cancer on all human visitors, even though "life there may have evolved differently" to survive, Ingo noted Waldmann of the London team. A twin planet, meanwhile, orbits closer to the star and is probably too hot to be in the habitable zone.
The cloud cover is not too thick on K2-18b, otherwise it would have obscured the water vapor in the atmosphere, according to the scientists.
The surface, meanwhile, may be wet or dry. London data suggests that water vapor makes up anywhere between 0.01% and 50% of the atmosphere – "a fairly wide range", Waldmann acknowledged. However, given the mass of the planet, it would be difficult to walk on the surface.
"Maybe it's not your vacation destination yet," joked Waldmann.
© Nine Digital Pty Ltd 2019