This drawing represents the expansion of gases leaving a supernova in the form of a shock wave.
Click on image for full size
When the wave from the supernova reaches our nebula, it squeezes the cloud of gas and dust. Squeezing makes the cloud start to collapse, as gravity pulls the gas and dust together.
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Shop Windows to the Universe Science Store!
Learn about Earth and space science, and have fun while doing it! The games
section of our online store
includes a climate change card game
and the Traveling Nitrogen game