Water Discovered On Planet K2-18b


Twenty years ago, two teams of astronomers independently found a unique exoplanet a planet outside our solar system which they named K2-18b. They speculate they might have found Earth’s cosmic twin.

Now two different teams now independently announced their discovery of water on the planet. It is known that the planet is in a habitable zone, a spot which is warm enough to also sustain water. Angelos Tsiaras, an astronomer at University College London, states, “This is the only planet right now that we know outside the solar system that has the correct temperature to support water.” Tsiaras and his teammates used advanced computer models to find signs of water vapor on the exoplanet using data from the Hubble Space Telescope. This planet is the only known planet at this point which might be habitable to support life.

The Hubble telescope does not reveal how much water is in the upper atmosphere. It may be either a whiff or an ocean’s worth of moisture. It could possibly contain gases such as methane, carbon dioxide and ammonia. K2-18b is approximately twice the size of Earth. The exoplanet nestles in a 33-day orbit around a dim, cool, red, dwarf star. They were able to find this information because studies show that the star gives off less than 3% of the light of our sun, since the exoplanet is close to it, it receives 5% more starlight than our own planet. The light touches the top atmosphere of the exoplanet, it releases light into the telescope so they can transmit the information from the gases in droplets deeper down. They also found evidence of clouds and rain. Bjorn Benneke of the University of Montreal stated, “Finding water vapor is great, but what is so special about k2-18 b is that our models suggest parts of its atmosphere have sufficient temperature and pressure for that vapor to form droplets of liquid water. And these, like in Earth’s atmosphere, will form clouds and fall as rain. Just as on Earth, there should be an interplay between condensation and evaporation, an active water cycle between the clouds and the gaseous part of the atmosphere.”

Could it be possible to live there? This exoplanet comes with many similarities to our planet Earth. It may be that there is no surface on this planet, or to imagine a human walking in it, but there may be some extreme microbe that might be able to live in those water clouds.

[Source: scientificamerican.com]

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