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Peeling back layers of a warm Neptune

About 30 light-years away, a Neptune-sized planet is having some of its layers peeled back. Astronomers using NASA’s Hubble Space Telescope have discovered an immense cloud of hydrogen evaporating from a Neptune-sized planet. They call this planet GJ 436b.

The planet’s atmosphere is evaporating, the scientists say, because of extreme irradiation from its parent star — a process that might have been even more intense in the past.

David Ehrenreich of the Observatory of the University of Geneva in Switzerland is the study’s leader. He said:

The parent star, which is a faint red dwarf, was once more active. This means that the planet’s atmosphere evaporated faster during its first billion years of existence. Overall, we estimate that the planet may have lost up to 10 percent of its atmosphere.

GJ 436b is considered to be a warm Neptune. It’s similar is size to the planet Neptune in our solar system, but it’s warmer because it’s much closer to its sun. Orbiting at a distance of less than 3 million miles, the planet whips around the central red dwarf in just 2.6 Earth days. For comparison, the Earth is 93 million miles (150 million km) from the sun and orbits it about every 365 days. Neptune is 2.8 billion miles (4.5 billion km) from the sun and takes 165 years to complete a single orbit.

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Bottom line: NASA video discussed the discovery of an immense hydrogen cloud streaming off a Neptune-sized exoplanet 20 light years away.

Read more from NASA

November 3, 2015
Science Wire

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