In orbit around a star 437 light years away, is a planet known as HAT-P-26b that is roughly the size of Neptune, but much closer to its host star. The “warm neptune” planet is not a world made entirely of water, but the atmosphere is relatively clear of clouds and has a strong signature of water. It is the best known measurement of water on a planet outside the solar system, so far. The planet has a primitive atmosphere, made up almost entirely of hydrogen and helium.

The discovery challenges conventionally accepted ideas of planetary formation. The planet is closer to the host star than the planets of similar sizes in our own solar system. This has lead scientists to believe that either the large planet formed closer to the host star, or late in the development of the planetary system, or both. The star is believed to be twice as old as our Sun. The chemical composition of the atmosphere of the planet was identified by analysing the chemical signatures on the light as the planet passed in front of the star in relation to Earth.

Hannah Wakeford, a postdoctoral researcher at Nasa’s Goddard Space Flight Center in Greenbelt, Maryland said, “Astronomers have just begun to investigate the atmospheres of these distant Neptune-mass planets, and almost right away, we found an example that goes against the trend in our solar system. This kind of unexpected result is why I really love exploring the atmospheres of alien planets.”

The planet was identified by using data drawn from both the Hubble Space Telescope, as well as the Spitzer Space Telescope. The finding shows that there is plenty of diversity in the exoplanets beyond our solar system and that our own solar system is in no way representative of all the planetary systems out there.

Publish date: May 12, 2017 4:18 pm| Modified date: May 12, 2017 4:18 pm

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