The Trifid Nebula (or M20 in the Messier Catalog
, or NGC
is an emission
and reflection nebula
in the constellation Sagittarius
It got its name from it's three-lobed appearance, which also
caused William Herschel to assign four different numbers
to it, and he was also the one who gave it the name "Trifid".
It consists of a red emission nebula, surrounded by a larger
blue reflection nebula, which is particularly visible in the
Its visual magnitude is somewhat uncertain; estimates lie between
6.8 and 9.0. Its distance from Earth is not know either,
findings vary from 2,200 light years to 7,600 light years. Most
seem to use 5,200.
The nebula is particularly interesting to students of the stellar
life cycle, as it harbours an area of active star formation.
However, many of the new stars trying to form will end up
starving for gas as the surrounding material
is blown away by the strong light and radiation from a hot new star.