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It looks a bit like someone has accidentally got their thumb caught in front of lens as they take a picture of the Sun.

But this remarkable image shows the moon as it passes between a spacecraft and the sun - causing a partial eclipse.

In a first for NASA's SDO (Solar Dynamics Observatory), the camera was watching the Sun in a wavelength of extreme ultraviolet light just as the dark Moon began to pass in front.




The moon passing between the SDO and the sun on October 7th, 2010 in an image taken by Nasa's Solar Dynamics Observatory

Tendrils of super-heated plasma - known as solar flares - can be seen reaching far out into space.

Plasma loops like these can heat up to a blistering 20 million degrees Celsius.

The bright plasma loop streaking out on the far left of the image is around 860,000 miles across.
These images are not just nice to look at, however. Scientists who monitor the SDO say the partial eclipse will prove useful to them in improving how the equipment on board works.
The very sharp edge of the lunar limb allows us to measure the in-orbit characteristics of the telescope e.g., light diffraction on optics and filter support grids.

'Once these are characterized , we can use that information to correct our data for instrumental effects and sharpen up the images to even more detail.'

SDO provides better-than-HD quality views of the Sun at a variety of wavelengths and has been responsible for some of the spectacular solar flare images which have emerged in recent months as the Sun begins a period of heightened activity.


The SDO blasted off from Cape Canaveral, Florida in February 2010 and is on a five year mission which is expected to cost £550million.

The spacecraft, orbiting 22,000 miles above Earth, is 7.2ft by 14.8ft. The solar panels are 21ft across and produce 1450W of power.

Instruments on board have additional shielding because this is in the outer reaches of the Earth's radiation belt where levels can be quite high.
The spacecraft carries three instruments that take ultra-high resolution images of the Sun every minute. It is also able to study solar pressure waves generated on its surface.