Stunning new map of Mercury

By Paul Harper

A stunning new map of the surface of Mercury has revealed the planet to be a "fascinating, dynamic and complex world".

The false colour image was created by mosaicking thousands of images taken by NASA's Messenger spacecraft's Wide Angle Camera over the course of a year.

The image is the first 360-degree high resolution image of the planet.

While the planet is in reality brown, the map consists of images taken through eight different colour filters on Messenger's cameras. This allows the different components of the planet's surface to be identified, according to mission scientist Dr David Blewett, from Johns Hopkins University Applied Physics Laboratory.

"The areas that you see that are orange - those are volcanic plains. There are some areas that are deep blue that are richer in an opaque mineral which is somewhat mysterious - we don't really know what that is yet," he told BBC News.

"And then you see beautiful light-blue streaks across Mercury's surface.

Those are crater rays formed in impacts when fresh, ground-up rock is strewn across the surface of the planet."

Dr Blewett revealed the map at the annual meeting of the American Association for the Advancement of Science.

The map covers more than 99 per cent of the planet's surface, with an average resolution of about 1km per pixel.

Messenger - which stands for MErcury Surface, Space ENvironment, GEochemistry, and Ranging - is the first ever spacecraft to orbit Mercury.

The planet was previously thought to be similar to our Moon. However, the new image shows Mercury to be a "fascinating, dynamic and complex world", Dr Blewett said.

"We know now for sure that it is an oddball planet. It is the smallest of the eight planets but it has the highest density. The entire structure is different from other planets," he said.

"The geological history is different than the Moon or Mars, the surface composition is enigmatic. It consists of rock types that we really do not have much experience with."

The new images also confirm the planet's poles are capped with ice, despite the planet's close proximity to the sun. This is because the planet's axis of rotation around the sun barely tilts from vertical, meaning the poles do not receive sunlight.

- nzherald.co.nz

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