NASA announced its discovery of water on the super-Earth-like planet last week, revealing K2-18b to the world on September 11. The distant exoplanet is considerably larger than Earth but its atmosphere shows signs of being rich in water vapour. More importantly, NASA’s scientists said the planet is found in a habitable distance from its host star, meaning K2-18b’s surface temperatures are just right for liquid water to exist. Water is a critical building block of life and its presence on an exoplanet is exciting news for planetary scientists.
The exoplanet discovery was made possible by NASA’s and the European Space Agency’s (ESA’s) Hubble Space Telescope and the Kepler Space Telescope.
The planet sits an approximate 110 light-years or 646,648,790,000,000 miles from Earth in the constellation Leo.
But Hubble’s scientists still face many unanswered questions about the conditions on the planet’s surface.
According to NASA’s Dr Jennifer Wiseman, K2-18b’s presence in the so-called Goldilocks Zone is not proof of alien life just yet.
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The scientist said: “We don’t know whether or not there could be life on this exoplanet, this is the next step in kind of studying what exoplanets are like.
“We’re trying to understand if any of them could be very similar to Earth and could be habitable for life.
“One piece of that equation is to find planets like this one, where the temperature might be moderate enough to allow water to be in liquid form – not so cold that it’s frozen as ice, not so hot that it boils away.
“This planet seems to be at that right Goldilocks distance from its parent star to potentially have liquid water and now we’ve seen water vapour in its atmosphere.”
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If further observations of K2-18b confirm water on the exoplanet, it will be the only known world to have a mix of water welcoming temperatures.
But these are not the only indicators of alien life NASA’s scientists look for when studying exoplanets.
Another crucial characteristic is the activity of the planet’s host star.
Active stars threaten to lash the planets in their solar systems with intense radiation and solar storms that can render worlds uninhabitable.
In this case, Dr Wiseman said K2-18b is closer to its white dwarf star than Earth is to the Sun.
The white dwarf appears active with frequent flaring, which means K2-18b could be experiencing heavy solar radiation.
NASA fears the levels of solar activity make K2-18b “hostile” towards life.
Dr Wiseman said: “It might make it difficult for advanced life to thrive.
“We just don’t know but we’ve made the next step now of finding a super-Earth with water vapour in the atmosphere and that’s an exciting step to make.”
