A Distant Alien Planet With a Comet-Like Tail Spotted
A Neptune-size planet appears to be masquerading as a comet, with a gargantuan stream of gas flowing behind it like a comet’s tail.
The bizarre find is the first of its kind ever discovered by astronomers. The strange, comet-like planet, known as GJ 436b, is orbiting a red dwarf star and is about 22 times as massive as Earth. Astronomers detected the giant gas cloud around the planet using NASA’s Hubble Space Telescope and Chandra X-ray Observatory.
GJ 436b, located about 33 light-years from Earth in the constellation Leo, is a kind of world known as a warm Neptune. Such planets, at about 10 to 20 times the mass of Earth, are about the mass of “cold Neptunes” such as Uranus — and, naturally, Neptune — but they are as close, or closer, to their stars than Mercury is to our sun. With an orbit of only about 3 million miles (4.8 million kilometers), “GJ 436b is 33 times closer to its star than Earth is to the sun, and 13 times closer than Mercury.
The cloud of gas around GJ 436b, made up mostly of hydrogen, has a circular head that surrounds GJ 436b, and a tail trailing behind the planet. The diameter of the head is about 1.8 million miles (3 million km), or five times the width of the host star, which is about half that of the sun, Ehrenreich said. The length of the tail is uncertain, because the research team’s observations do not cover it entirely, but their computer models suggest it could be about 9.3 million miles (15 million km) long.
GJ 436b is the first planet for which a comet-like tail is confidently detected.
The scientists estimated that GJ 436b is currently blowing off up to 1,000 tons of gas per second. This means that GJ 436b is currently losing about 0.1 percent of its atmosphere every billion years, which is far too slow a rate to deplete its atmosphere in the lifetime of its parent red dwarf star.
The scientists detailed their findings online Wednesday (June 24) in the journal Nature.