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Nebulae
“Nebula” comes from the
Latin word for cloud.
“Nebulae” is the plural. It is
loosely applied to anything
that looks fuzzy or extended
in a telescope.
To astronomers in the early 1900s, galaxies were
classified as nebulae, because they looked like fuzzy
“blobs”. Today we know galaxies are collections of
billions of stars. We will limit our nebulae to clouds of
gas floating in space.
The Order of things:
You live on Earth
The Earth is one of eight identified
planets that orbit around the Sun
in our Solar System
The Sun is just a star, an
average star. It just looks
so big and bright, because
it is so close, compared
with other stars.
The Sun is just one of hundreds of billions of stars in
our galaxy, the Milky Way
The known universe contains
at least 1,000,000,000 galaxies
There are four types of
Nebulae:
Emission
Reflection
Dark
Planetary
Emission Nebulae are made of ionized
hydrogen. When free protons recapture
electrons, the electrons emit specific
wavelengths (colors) of light, often ending up
with a distinctive pink color.
An emission nebula is caused when a cloud of
hydrogen gas is heated by a nearby O or B star
(25000 K).
Reflection Nebulae are caused
when clouds of dust scatter the
starlight from behind them. They
tend to be bluer in color, as short
wavelengths of light scatter
easier than longer wavelengths.
Dark Nebula are cold, dense
clouds of gas and dust that
block out the light from behind
them.
Planetary Nebulae are the
remains of a dying star
throwing off its outer layers
http://www.youtube.com/watch?v=8x41n9t
hAU8&feature=topics
Quiz!
Identify what the following pictures are:
Emission Nebula
Reflection Nebula
Dark Nebula
Planetary Nebula
Galaxy
Number 1 – 8 on a separate sheet
1
2
3
4
5
6
7
8
Check yourself
1.
2.
3.
4.
5.
6.
7.
8.
Emission nebula
Emission nebula
Galaxy
Planetary nebula
Reflection nebula
Dark nebula
Emission nebula
Dark nebula