(click on image to enlarge)
From NASA/ ESA, August 12, 2019: Although it looks more like an entity seen through a
microscope than a telescope, this rounded object, named NGC 2022, is
certainly no alga or tiny, blobby jellyfish. Instead, it is a vast orb
of gas in space, cast off by an ageing star. The star is visible in the
orb's centre, shining through the gases it formerly held onto for most
of its stellar life.
When stars like the Sun grow advanced in age, they expand and glow red. These so-called red giants
then begin to lose their outer layers of material into space. More than
half of such a star's mass can be shed in this manner, forming a shell
of surrounding gas. At the same time, the star's core shrinks and grows
hotter, emitting ultraviolet light that causes the expelled gases to
glow.
This type of object is called, somewhat confusingly, a planetary nebula, though it has nothing to do with planets. The name derives from the rounded, planet-like appearance of these objects in early telescopes.
NGC 2022 is located in the constellation of Orion (The Hunter).
Credit: ESA/Hubble & NASA, R. Wade
