The dramatic rearing horsehead nebula and mysterious glowing Bow of Orion are just two of the unforgettable images that have been entered into the Astronomy Photographer of the Year 2009 competition.

More than 500 entries from around the world - from dedicated amateurs as well as true beginners - have been sent in, including some taken with mobile phones.

Categories include 'Earth and Space', 'Our Solar System', 'Deep Space' and 'Young Space Photographer.'

Some opted to capture 'nearby' cosmic phenomena such as the Northern Lights (where Earth’s atmosphere interacts with a stream of particles from the Sun), and ghostly images of the Moon. Others delved deeper into space to picture the Orion constellation and even Centaurus A, a galaxy around 14million light-years away.

The winners will be announced on Wednesday and the images will then be showcased in a free four-month exhibition at the Royal Observatory in Greenwich. Rob Edwards, the observatory's head of science education, and one of the competition's judges, said: 'Most of these photographs have been taken by amateurs and the images are comparable with those taken by the best telescopes in the world a few decades ago.'