10,000 Galaxies, 1 Image: Hubble Ultra Deep Field in 4K

The Hubble Ultra Deep Field (HUDF) is a composite image; it uses data collected by the Hubble Space Telescope, launched in 1990 at a cost of c.$6bn. Between 24 September 2003 and 16 January 2004, it observed a small area of sky in the Fornax constellation, completing 400 orbits of Earth in the process. The Advanced Camera for Surveys, a wide-field camera, took 800 exposures - the total exposure time was ~ 1 million seconds or 11.3 days on aggregate. Is it a true-colour image? It is to an extent - the area of sky was observed in visible to near-infrared light, using r,g,b and near-infrared filters. The image has since been updated so as to include data from a greater number of wavelengths. The Hubble eXtreme Deep Field (XDF) was released in 2012 and is roughly 80% the size of the 2004 HUDF in terms of field of view. Then, in 2014, another Deep Field was released—confusingly named the HUDF! This adds crucial UV data, which is eXtremely useful (see what I did there?)