When you gaze up at the night sky, you're not just looking at celestial objects far away in space. You're looking at objects far away in time, too.

The light from a distant star can take thousands of years to reach Earth. That means astrophotography — images of the night sky — is the closest thing we may have to a time machine. The best astrophotography is breathtakingly beautiful to boot.

Below are several images shortlisted for the Insight Astronomy Photographer of the Year 2017 awards , meaning they represent the most stunning astrophotography work in the world. They include images of the Northern Lights, a crescent Moon, and the Milky Way.

The final winners of the contest will be announced Sept. 14 at London's Royal Observatory Greenwich.