Enormous clouds of dust and gas are found throughout the galaxy. One of the closest is the Orion Nebula, which is 1500 light-years from Earth and measures several light-years across.

It is visible to the human eye as a fuzzy patch in the constellation of Orion.
The galaxy contains tens of thousands of dark nebulae, so-called because the dust and gas obscure the light of stars behind them.

Over time clumps of higher density gas form and grow within some of these, their gravitational attraction drawing matter from the surrounding cloud. As a clump grows, the weight of layer upon layer of gas builds up, increasing the pressure and temperature at the clump's core.

The pressure continues to rise until hydrogen nuclei are packed so tightly together that they fuse, igniting a thermo-nuclear reaction that signals the birth of a star.


We see this happening in the Orion Nebula - it is the birthplace of stars.