This blue ‘ball of string’ actually records 2114 movements made by ESA’s XMM-Newton space telescope as it shifted its gaze from one X-ray object to another between August 2001 and December 2014. Orbiting in space since 1999, XMM-Newton is studying high-energy phenomena in the Universe, such as black holes, neutron stars, pulsars and stellar winds. See http://www.esa.int/spaceinimages/Images/2017/06/XMM-Newton_slew_tracks
