Eclipse image lights dark side of moon

Detailed images from two orbiting observers were perfectly matched to reconstruct the entire eclipse.

Nasa combines data from two observatories in space to produce a clear view of what normally can't be seen

The US space agency NASA has come up with a startling image of an eclipse.

Except it is not quite what it seems - it is a composite creation, taken and assembled at NASA's Goddard Space Flight Centre in Maryland using data collected on two separate missions.

Scientists from the Solar Dynamics Observatory (SDO) and the Lunar Reconnaissance Orbiter (LRO) matched information to get this combined result.

The solar observatory is in orbit around the sun. Twice a year its view is obscured by the moon crossing the solar disc. The LRO is in orbit around the moon and gathering impressive pictures of its surface.

By combining detailed pictures of an SDO lunar transit from October 7, 2010, and pictures of the surface by the LRO, NASA was able to perfectly match and reconstruct the entire eclipse.

Massive amounts of data and precise calculations had to be used to match the images of the moon's shadow and its surface, NASA said.

In effect, the image lights up the face of the moon which would usually be pitch black.

Specialists Ernie Wright and Scott Wiessinger used animation software to obtain the remarkable features which emerge in the image, all seeming correct as to angles and distances.

Said Wiessinger: "It's a great example of everything working: SDO image header data, which contains the spacecraft's position; our information about lunar libration, elevation maps of the lunar surface."

The numbers

• 2.44 - Average number of lunar eclipses each year
• 173 - Number of days each year in which an eclipse could occur
• 384,000km - Distance of the moon from Earth
• 3,476km - Diameter of the moon
• 27.3 days - Time it takes the moon to orbit Earth
• 655 hours - Time it takes the moon to rotate once around its own axis
• 327.5 hours - Length of a lunar day

Source: NASA