ROSAT X-ray image of sky, with the X-rays from Earth’s magnetosphere present (left) and removed (right)

An X-ray image of the sky taken by the US-German ROSAT mission, with the X-rays from Earth’s magnetosphere present (left) and removed (right).

[Image description: An oval image of the sky, with mixed blue, green, yellow and orange colours. The green, yellow and orange are mostly concentrated to the upper left and lower right, with green stripes connecting the two. It looks as though blue indicates a low level of something, whilst green, yellow then orange indicate progressively higher levels of something.]