Reality jibes with simulations in this composite image of a shock wave. On the left is a laser-produced shock wave; on right, a simulation of a collapsing shock wave from before galaxies started forming. Brighter colors show the shock region of higher density or temperature.
#PencilNebula | This shock wave plows through space at over 500,000 kilometers per hour. Moving toward to bottom of this beautifully detailed color composite, the thin, braided filaments are actually long ripples in a sheet of glowing gas seen almost edge on. About 5 light-years long and a mere 800 light-years away, the Pencil Nebula is only a small part of the #VelaSupernovaRemnant.