Article Posted on : - Apr 26, 2010

An unusual, methane-free world is partially eclipsed by its star in this artist's concept. A NASA/JPL photo

PASADENA (BNS): NASA's Spitzer Space Telescope has hit upon a distant planet about the size of Neptune which lacks methane – an element found in many planets of our Solar System.

The new discovery has been made in the constellation Leo. The planet – GJ 436b – is located 33 light-years-away in the constellation and orbits its small parent star, an “M-dwarf”, in 2.64-day.

Large amount of Methane and small amount of carbon monoxide are usually found in planets having a common atmospheric mix of hydrogen, carbon and oxygen, and a temperature up to 1,000 Kelvin (1,340 degrees Fahrenheit). The carbon occurs in the form of methane at these temperatures.

At 800 Kelvin (or 980 degrees Fahrenheit), GJ 436b is supposed to have abundant methane and little carbon monoxide.

However, the Spitzer observations have shown the opposite. While carbon monoxide is present in the planet, there is no trace of methane.

“It's a big puzzle. Models tell us that the carbon in this planet should be in the form of methane. Theorists are going to be quite busy trying to figure this one out,” said Kevin Stevenson, a planetary sciences graduate student at the University of Central Florida in Orlando.

The finding appears in the latest edition of the journal Nature.