"What
is the Orion
nebula"
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. |
