European astronomers have discovered a real life waterworld – a planet made of hot ice, orbiting another star. The distant planet, which is four times as wide as Earth, is almost entirely made up of water. But that water is in a very different state to any known on Earth.
Extremely high pressures mean the water must be solid. However this “frozen” water must also be hot because the planet lies just 2.5 million miles from its parent star.
Scientists say the suituation is like that of carbon which can exist in solid form as both coal and diamonds.
The discovery team, led by Michael Gillon, from Liege, Belgium, discovered the new planet from François-Xavier Bagnoud observatory at St-Luc in Switzerland. They watched it pass in front of a red dwarf star 30 light-years away from Earth called GJ 436. This transit allowed them to measure its size as similar to Neptune and to tell what it is made of.
The new planet’s surface temperature is expected to be at least 300C (600F) so that it has an atmosphere of steam. But inside, the water is crushed under intense pressure to a state unknown on Earth outside the laboratory. Dr Gillon said: “This discovery is an important step towards the detection and study of Earth-like planets.”
News of the discovery comes a month after reports that water had been detected in the atmosphere of another alien planet. That was followed by news of the first extrasolar planet that could be a rocky world like the Earth.
Incidentally, the St-Luc observatory website shows this picture of Dr Gillon performing a rather unorthodox analysis of the transit using a bottle opener and with some famous Belgian beer at his side.
The above photo of François-Xavier Bagnoud observatory is courtesy the University of Liege.