The constellation of the Big Dipper peers through the window of the entrance to a large glacier cave in Engadin, Switzerland. This is just one of the thousands of spectacular pictures entered into the 2017 Insight Astronomy Photographer of the Year competition.

Astronomy Photographer of the Year 2017 shortlist
Mr Big Dipper by Nicholas Roemmelt (Denmark). A stargazer observes the constellation of the Big Dipper perfectly aligned with the window of the entrance to a large glacier cave in Engadin, Switzerland. This is a panorama of two pictures, and each is a stack of another two pictures: one for the stars and another one for the foreground, but with no composing or time blending. Nicholas Roemmelt

The competition, which is run by the Royal Observatory Greenwich in association with Insight Investment and BBC Sky at Night Magazine, is now in its ninth year, received more than 3,800 entries from enthusiastic amateurs and professional photographers, from 91 countries across the globe.

The winners of the competition's nine categories and two special prizes will be announced on Thursday 14 September and the winning images will be displayed in a free exhibition at the Observatory's Astronomy Centre from Saturday 16 September. Until then, IBTimes UK presents a selection of the judges' shortlist.