Little-known fact of the day: most craters on Mercury are named after famous writers and artists.

This one, for example, is known as ‘Dickens’, after Charles Dickens.

Since Charles Dickens wrote A Christmas Carol, it seems like an appropriate shot for an Advent calendar.

The picture comes from NASA’s amazing photostream on Flickr and was taken from the MESSENGER spacecraft, the first ever to orbit the planet Mercury.

And while we are on the subject of NASA and Christmas, here’s an awesome shot of a kind of celestial snow angel.

Taken on 14 December, it shows ‘a bipolar star-forming region, called Sharpless 2-106’. It is nearly 2,000 light years away from Earth and the ‘wings’ of the nebula are several light years across. More mind-blowing information here.