K2 – 18b: The urge for searching life outside earth has led scientists to detect a water holding planet named K2 – 18b, which was discovered in 2015 by the Kepler spacecraft in 2015 (now retired). This planet is found lying within its star’s habitable zone. A habitable zone describes the range of orbits present around a star within which a planetary surface can support liquid water with sufficient atmospheric pressure like in our solar system where the sun is that star.
Quick facts about K2 – 18b
K2 – 18b is present in the constellation Leo and is around 110 light years away from earth.
K2 -18b is also nicknamed as the “Super-Earth” as it is eight times more massive than the earth and twice as wide. Its density is similar to that of the Mars indicating that it must be having a rocky composition. It orbits around a red dwarf star that is one-third of the mass of the sun and is colder than our sun.
K2 – 18b circles around this red dwarf star about seven times closer than Earth does around sun. It was in the years 2016 and 2017, when the Hubble Space Telescope captured the data showing the telltale signs of water on this planet but could not determine the actual amount of water. Its atmosphere is assumed to contain 0.01 % to 50 % of the water vapours. It is still not clear whether the water is present on its surface or in its atmosphere. The planet’s surface might have oceans or may be completely dry (containing water as water vapours in the atmosphere only).
The James Webb Telescope and the ARIEL satellite (next generation of space observatories) may help to reveal the amount of water and the presence of other molecules like ammonia and methane.
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