London, May 28 (IANS): An international team of researchers has for the first time predicted the occurrence of aurorae visible to the naked eye on a planet other than Earth.

The upper atmosphere of Mars glows blue depending on the activity of the Sun.

The result was achieved through numerical simulation and a laboratory experiment, called the Planeterrella, used to simulate the aurora.

"The study indicates that the strongest colour in the Martian aurorae is deep blue. Green and red also occur, just like on Earth. An astronaut looking up while walking on the red Martian soil would be able, after intense solar eruptions, to see the phenomena with the naked eye," said Cyril Simon Wedlund, researcher at the department of radio science and engineering, Aalto University, Finland.

The aurorae on Mars were observed for the first time in 2005 with the help of the European Space Agency ESA's Mars Express satellite.

The new prediction is based on a laboratory experiment conducted with the Planeterrella simulator and a theoretical and numerical model developed by the Grenoble Institute of Planetology and Astrophysics (IPAG, France) and NASA.

Aurorae occur when electrically charged particles of solar origin are driven down along the local magnetic field lines, where they enter the planetary atmosphere and excite its atoms and molecules.

On Earth, aurorae are essentially green or red, from atomic oxygen, but even blue-purple, from ionized molecular nitrogen, can be seen.

Only 17 planeterrellae simulators are currently in use in different parts of the world.

The study was published in Planetary and Space Science.