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Why the moon looks black and white

Ever wondered why the Moon looks black and white. Well Scottish researchers might have the answer now.

india Updated: Feb 07, 2007 12:32 IST

Scientists find out why the Moon looks black and white Home

Ever wondered why the Moon looks black and white. Well Scottish researchers might have the answer now.

Scientists here have recreated a Moon rock in a laboratory, mimicking the low-oxygen conditions found on the lunar surface, and simulated the conditions of an asteroid explosion to learn why our closest heavenly neighbour has a distinctive black and white colouration.

According to them, the tremendous heat released as the Moon cooled turned its surface white.

The Moon was formed 4.5 billion years ago when the Earth collided with a massive comet. A large chunk of the debris was trapped in the earth's gravitational pull.

According to the research team, the collision released a huge amount of energy, in the form of heat, which turned much of the Moon's surface into a lunar ocean of magma, or lava. The lava then cooled and solidified, giving it a white appearance, even as its centre remained black.

As part of their study, geologists at the Edinburgh University created artificial pieces of Moon rock based on the chemical compositions of samples brought back from the Apollo space missions.

The researchers then used a special furnace to heat the artificial rock to 1,500 degrees Celsius, turning it to magma, and then watched it cool.

They found that the white crystals were the first to form into magma, floating on top of the black liquid, suggesting that during its original formation, the Moon was covered by a perfect white sheen.

The centre of the sample remained black, much like the Moon.

According to the scientists, some 2.5 billion years ago, an asteroid shower must have hit the Moon, rupturing its white exterior and causing volcanic explosions of black lava.

The lava - dark in colour because of its high concentration of iron - was slowly pulled by the Moon's weak gravity into valleys, exposing dark craters and white "lunar highlands".

This is why the Moon is white and black, said Dr Stephan Klemme, the lead researcher.

"When you look at rocks from the Moon and from the Earth, they are very similar. The black rock on Arthur's Seat in Edinburgh, for example, is not much different from black Moon rock. However, there are crucial differences that have baffled scientists," the Scotsman quoted him as saying.

"Our experiments have shown that the minerals creating the white rock - seen in the lunar highlands - would have crystallised first, whereas the dark and heavy iron-rich minerals would have sunk in the magma oceans, creating darker rock that would have been buried deep inside the Moon," he said.

"The reason that the darker rocks are now visible on the surface of the Moon is proof of a later period of intensive meteorite showers. The iron-rich minerals that were deep inside the Moon proved to be especially high in hafnium and low in tungsten, and would have erupted to the surface as molten rock, filling the valleys on the Moon and leaving a darker shade we observe today," he added.

First Published: Feb 06, 2007 19:42 IST