20,000 years ago, a star exploded leaving its remnants to expand into space. The resulting nebula, called the Cygnus Loop, forms a bubble-like shape that is about 120 light-years in diameter. The distance to its center is approximately 2,600 light-years from Earth.

Astronomers used Hubble to examine a very small slice of the leading edge of this expanding supernova bubble, where the supernova blast wave plows into surrounding material in space.This close-up look at a nearly two-light-year-long section shows filaments of glowing hydrogen.

Image Credit: NASA / ESA / STScI