WHAT IS A NEBULA?
A nebula is a huge region of gas and dust
in space. Some nebulae are places where
new stars are forming, while others are
made from material expelled by dying stars.
The gas can be illuminated by nearby stars,
causing some nebulae to glow brilliantly
across the night sky.
HOW DO STARS FORM?
Inside some dense molecular clouds,
gravity slowly pulls gas and dust together.
As material collapses, the center becomes
hotter and denser. Eventually, a protostar
forms and can develop into a new star.
These stellar nurseries can contain
thousands of young stars.
NEBULAE FROM DYING STARS
Not every nebula is a birthplace.
When some stars reach the end of their
lives, they eject material into space.
Massive stars can explode as supernovae,
creating expanding clouds of gas and dust.
Other stars create planetary nebulae as
they shed their outer layers.
WHY DO NEBULAE HAVE DIFFERENT COLORS?
Different gases emit light at different
wavelengths.
Hydrogen, oxygen and other elements can
produce characteristic colors when they
are energized by nearby stars.
The colors seen in astronomical images
can also be enhanced or assigned to
different wavelengths to reveal structures
that human eyes cannot see directly.
MAJOR TYPES OF NEBULAE
EMISSION
Hot, energized gas emits its own light.
These nebulae can glow brightly around
young, massive stars.
REFLECTION
Dust scatters light from nearby stars,
creating a glowing cloud that shines
mainly by reflected starlight.
DARK
Dense clouds of dust block light from
objects behind them, appearing as dark
silhouettes against brighter regions.
PLANETARY
Shells of gas expelled by dying
low- to intermediate-mass stars.
SUPERNOVA REMNANT
Expanding debris and shock-heated gas
left behind after a massive star
explodes.
MOLECULAR CLOUD
Cold, dense regions rich in molecular
gas and dust where new stars can form.
DID YOU KNOW?
The elements released by stars into
nebulae can eventually become part of
new stars, planets and other worlds.
In that sense, nebulae are part of the
cosmic cycle of matter.
NEBULAE AS STELLAR LABORATORIES
Nebulae connect different stages of stellar evolution. Cold molecular clouds can collapse to form new stars, while aging stars return gas and chemically enriched material to interstellar space through winds, planetary nebulae and supernova explosions.
Astronomers combine visible, infrared and radio observations to study dust, molecules, ionized gas and embedded young stars that may be hidden at visible wavelengths.
Stars · Supernovae · James Webb