Scientists find water on planet outside solar system

Scientists from University College London (UCL) announced Wednesday that they had detected water vapor in the atmosphere of an exoplanet eight times the mass of Earth and 110 light years away.

The so-called super-Earth, known as K2-18b, is twice the size of Earth and is located in the Leo constellation in the Milky Way. The scientists reported in the Nature Astronomy journal that K2-18b is in a "Goldilocks," or habitable zone with the right proximity to its sun to make water in liquid form, and thus life, possible.

Looking to answer the big question

Angelos Tsiaras, who was the lead author of the UCL study published in the latest issue of the journal, said: "K2-18b is not 'Earth 2.0' as it is significantly heavier and has a different atmospheric composition. However, it brings us closer to answering the fundamental question: Is the Earth unique?"

Tsiaras and his colleagues made the discovery while using open-source algorithms to analyze data captured by the ESA/NASA Hubble Space Telescope.

Their analysis of starlight filtered through K2-18b's atmosphere pointed to the unmistakable molecular signature of water vapor.

Scientists analyzing the Hubble data say they found hydrogen and helium in K2-18's atmosphere as well.

Heavy gravity and intense radiation

Though the discoveries would suggest the potential for sustaining life, given the planet's extreme gravity and intense UV radiation, it would still be impossible for humans to inhabit it.

Still, scientists are excited. Giovanna Tinetti, who co-authored the UCL report, says, "We cannot assume that it has oceans on the surface, but it is a real possibility."

'The first of many'

Another co-author, Ingo Waldmann, says: "It is likely that this is the first of many discoveries of potentially habitable planets. This is not only because super-Earths like K2-18b are the most common planets in our galaxy, but also because red dwarfs — smaller stars than our sun — are the most common stars."   

K2-18b was discovered by NASA's Kepler Space Telescope in 2015. It is one of hundreds of planets with a mass between that of Neptune and the Earth.

Scientists are confident that many more such planets will be discovered in the near future by NASA's James Webb Space Telescope and the European Space Agency's ARIEL Space Mission, which is set to launch in 2028.

js/rt (AFP, dpa)

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