International Space Agencies – Missions and Discoveries

K2-18b

Note4Students

From UPSC perspective, the following things are important :

Prelims level : K2-18b

Mains level : Read the attached story


  • K2-18b is now the only planet orbiting a star outside the Solar System known to have both water and temperatures that could be potentially habitable.

K2-18b

  • About 110 light years from Earth, an exoplanet eight times the mass of Earth orbits a star. Called K2-18b, it was discovered in 2015 by NASA’s Kepler spacecraft.
  • The researchers used 2016-17 data from the Hubble Space Telescope and developed algorithms to analyse the starlight filtered through K2-18b’s atmosphere.
  • The results revealed the molecular signature of water vapour, also indicating the presence of hydrogen and helium in the planet’s atmosphere.
  • It resides in a habitable zone — the region around a star in which liquid water could potentially pool on the surface of a rocky planet.
  • Scientists have found signatures of water vapour in the atmosphere of K2-18b. The discovery of water vapour is not the final word on the possibility of life.
  • That makes it the only planet orbiting a star outside the Solar System that is known to have both water and temperatures that could support life.

Not ‘Earth 2.0’

  • K2-18b is not ‘Earth 2.0’ as it is significantly heavier and has a different atmospheric composition.
  • For one thing, K2-18b’s size and surface gravity are much larger than Earth’s. Its radiation environment may be hostile.
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