The Week - Junior

Super-Earth is the most likely home for alien life


Afaraway planet, known only as K2-18b, has been named as the most likely home for alien life after water vapour was found in its atmosphere. This discovery was made by scientists at University College London (UCL).

The planet is known as a superEarth because it is twice as big as our home planet, and has eight times its mass. It orbits a type of star known as a red dwarf, taking 33 days to complete a circuit (so a year on K2-18b is about as long as a month on Earth). The planet is much closer to its star than Earth is to the Sun, but the star’s heat and light are weaker, so temperatur­es on the planet are similar to Earth’s.

The team discovered the planet when it passed in front of the red dwarf star and blocked out some of its light. The team used NASA’s Hubble Space Telescope (HST) to study how the light from the star was changed as it passed through the air around K2-18b on its way to Earth. Different chemicals absorb different colours of starlight, allowing experts to work out what’s in a planet’s atmosphere. The starlight revealed the atmosphere of K2-18b contains water vapour.

Water is essential to all life on Earth, and would almost certainly be needed by living things on other worlds too. This is the first time that the liquid been found on a world with temperatur­es similar to those on Earth. Dr Angelos Tsiaras, from UCL, said the discovery makes K2-18b “the best candidate for habitabili­ty that we know right now”.

Don’t expect anyone to visit and check for life soon, though. K2-18b is 600 trillion miles away and, at a speed of 20,000mph, it would take you 3.7 million years to get there. Scientists will now use telescopes on Earth and in space to learn more.

 ??  ?? An imagined view of K2-18b.
An imagined view of K2-18b.
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