Central area of the Milky Way galaxy, released by astronomers at the European Southern Observatory's Paranal Observatory in Chile. The photo shows 84 million stars in an image measuring 108,500×81,500, which contains nearly 9 billion pixels, and is actually a composite of thousands of individual photographs shot with the observatory's VISTA survey telescope.
The “Black Widow” pulsar is moving through the galaxy at a speed of almost a million kilometers per hour. A bow shock wave due to this motion is visible to optical telescopes, shown in this image as the greenish crescent shape. The pressure behind the bow shock creates a second shock wave that sweeps the cloud of high-energy particles back from the pulsar to form the cocoon.