Using data from Ralph, a visible and infrared imager/spectrometer aboard NASA’s New Horizons spacecraft, scientists have detected frozen methane on the surface of the dwarf planet Pluto.

“We already knew there was methane on Pluto, but these are our first detections. Soon we will know if there are differences in the presence of methane ice from one part of Pluto to another,” said Dr Will Grundy of the Lowell Observatory in Flagstaff, Arizona, a planetary scientists for the New Horizons mission.

Solid methane was originally detected on Pluto in 1976 by a group of Earth-based astronomers led by Dr Dale Cruikshank of NASA’s Ames Research Center, who is now a member of the New Horizons team.

According to researchers, this methane may be primordial, inherited from the Solar Nebula from which our Solar System formed 4.5 billion years ago.

New Horizons is now less than 11 million miles (18 million km) from Pluto. It is healthy and all systems are operating normally.

Just hours after its flyby of the Pluto system on July 14, 2015 the spacecraft will observe sunlight passing through the atmosphere of Pluto, to help researchers determine the atmosphere’s composition.

“It will be as if Pluto were illuminated from behind by a trillion-watt light bulb,” said Dr Randy Gladstone of Southwest Research Institute, San Antonio, a planetary scientist for the New Horizons mission.

On June 16, New Horizons’ ultraviolet imaging spectrograph called Alice successfully performed a test observation of the Sun from 3.1 billion miles away (5 billion km), which will be used to interpret the July 14 observations.