The purple lines and blotches in this image show all of the X-ray sources that were serendipitously detected – that is, not intentionally targeted – by the European Space Agency’s XMM-Newton X-ray space observatory from 2000 to 2017.
The observations were made by XMM-Newton’s European Photon Imaging Camera (EPIC), an instrument capable of detecting very faint sources and rapid changes.
And while the patterns may appear random, the ESA says some structure can be seen.
The oval represents the celestial sphere, an abstract perspective upon which our observations of the universe are projected. The data are plotted in galactic coordinates, such that the centre of the plot corresponds to the centre of our Milky Way galaxy – and this can be seen in the image.
Through the centre of the oval is a horizontal line, where patches of purple appear to draw together. This line is the plane of the Milky Way galaxy, with the large splotch of colour in the centre corresponding to our galaxy’s core, where XMM-Newton made a higher number of serendipitous detections.
XMM-Newton has been orbiting the Earth since 1999, hunting for X-rays coming from high-energy phenomena such as black holes, stellar winds, pulsars, and neutron stars.