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.
Shop Windows to the Universe Science Store!
Our online store
includes issues of NESTA's quarterly journal, The Earth Scientist
, full of classroom activities on different topics in Earth and space science, ranging from seismology
, rocks and minerals
, and Earth system science