Nasa have released the most detailed images yet from the Hubble Space Telescope's eXtreme Deep Field, or XDF, imager.

The pictures map over 5,500 galaxies, some shown when the universe was just 500 million years old.

Over 2,000 pictures caputred using two million seconds of exposure looked back deep into a tiny patch of the night sky, adding intricae details to a previous survey taken in 2004.

The pictures were formed by images from Hubble's Advanced Camera for Surveys and its near-infrared Wide Field Camera 3, which were combined to form the XDF.

"The XDF is the deepest image of the sky ever obtained," astronomer Garth Illingworth, with the University of California at Santa Cruz, said in a statement. "It allows us to explore further back in time than ever before."