Water discovered for first time on planet that may be habitable

A handout artist's impression from ESA  Hubble shows the K2-18b super-Earth the only super Earth exoplanet known to host both water and temperatures that could support life

A handout artist's impression from ESA Hubble shows the K2-18b super-Earth the only super Earth exoplanet known to host both water and temperatures that could support life

Scientists have discovered water vapor in the planet's atmosphere for the first time. The exoplanet has eight times the mass of Earth and is twice its size.

That's because this 33-day orbit is right smack-bang in the middle of the star's habitable zone - not too hot that liquid water would evaporate from the surface, and not so cold that it would totally freeze.

The finding is the first detection of water on an exoplanet in the habitable zone, where the water molecules could be liquid, making it an exciting step toward finding a planet that could support life as we know it.

The far-off planet (it's about 110 light-years away) was discovered in 2015 by NASA's Kepler space telescope.

"This study contributes to our understanding of habitable worlds beyond our Solar System and marks a new era in exoplanet research, crucial to ultimately place the Earth, our only home, into the greater picture of the Cosmos", said Tsiaras.

The planet is called K2-18 b, and orbits its parent star - K2-18 - at roughly 0.14 astronomical units (one AU is the distance from our sun to Earth). None have been confirmed yet, however. Its star, a red dwarf, is considerably smaller and cooler than our sun, a yellow dwarf, and its atmosphere is also different than ours.

The authors believe that other molecules, including nitrogen and methane, may be present but they remain undetectable with current observations. It might have clouds, but if so, scientists' observations suggest they aren't very thick.

Co-author Dr Ingo Waldmann said: "With so many new super-Earths expected to be found over the next couple of decades, it is likely that this is the first discovery of many potentially habitable planets". The effect is seen as a smoking gun for water vapour in the planet's atmosphere. Their evidence also suggests the presence of hydrogen. It is also necessary that the planet has an atmosphere to protect the planet from any harmful radiation coming from its host star.

"This is one of the biggest questions in science and we have always wondered if we are alone in the Universe".

NASA’s planet-hunting satellite TESS helps discover a'super-Earth and two gaseous sub Neptune-sized planets orbiting a nearby star 73 light years away

The researchers studied Hubble data to analyze K2-18 b's transit, or its movement across its host star's face, using a technique known as transit spectroscopy.

A faraway planet in the constellation of Leo has been named the most habitable known world beyond the solar system after astronomers detected water vapour in its atmosphere.

This image taken aboard the International Space Station, shows the limb of the Earth at the bottom transitioning into the orange-colored stratosphere, the lowest and most dense portion of the Earth's atmosphere.

This isn't the first time water's been detected in the atmosphere of an exoplanet, but previous candidates have had extremely hostile environments-like a Saturn-like behemoth with scorching surface temperatures, reports National Geographic's Michael Greshko.

She contrasted this planet's atmosphere with that of Mars. Additionally, the planet's stellar irradiation levels are similar to Earth's (except for the high flare activity typical of red dwarfs).

"K2-18b is not "Earth 2.0", he said. Benneke opined that the research scientists are conducting is aiming toward "being able to study real, true Earth-like planets ..." Over 4000 exoplanets have been detected but we don't know much about their composition and nature. "To actually understand how habitability evolves in a hydrogen-rich atmosphere is going to be a very intense subject of study over the next 10 years". For now, there's no way to know what conditions on its surface are like. While not ideal for detecting a wide range of molecular elements in distant exoplanets, Hubble is, however, capable of detecting water vapour.

Next-generation telescopes such as the James Webb Space Telescope, due to launch in 2021, and the European ARIEL mission in 2028 will explore these questions in much more detail. That's because the new tools will be able to observe light across a broader range of wavelengths.

However, more tests are needed to prove this. It is one of hundreds of planets with a mass between that of Neptune and the Earth.

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