Download The Solar System

Build Your Foundation II
21 Sep 2000
ASTR103, GMU, Dr. Correll
1
The Solar System
• How many stars are there in the solar system?
• Was the solar system created as a direct result
of the birth of the universe?
• How long has the Earth existed?
• Is Pluto the farthest planet from the sun?
• What typical shapes do moons have?
21 Sep 2000
ASTR103, Sec 3, GMU, Dr. Correll
2
The Solar System
• The solar system
formed from an
interstellar cloud of
gas and dust--the solar
nebula
– Mostly hydrogen and
helium (created in the
big bang)
– Also contain heavier
elements--silicates,
iron, etc (created in
larger stars)
21 Sep 2000
ASTR103, Sec 3, GMU, Dr. Correll
3
The Solar System
• Solar nebula
contracts
– flattens and spins
– Sun begins to
shine
– gas expelled from
inner disk by
solar radiation
– ice and dust
accrete to form
planetesimals
(~10 km in size)
and then planets
21 Sep 2000
ASTR103, Sec 3, GMU, Dr. Correll
4
The Solar System
• Computer simulations show formation of inner solar
system takes as little as 150 million years--only
about 1/30 the age of the solar system
21 Sep 2000
ASTR103, Sec 3, GMU, Dr. Correll
5
The Solar System
• Stellar
nebula seen
in other star
formation
regions
21 Sep 2000
ASTR103, Sec 3, GMU, Dr. Correll
6
The Solar System
21 Sep 2000
ASTR103, Sec 3, GMU, Dr. Correll
7
The Solar System
21 Sep 2000
ASTR103, Sec 3, GMU, Dr. Correll
8
The Solar System
21 Sep 2000
ASTR103, Sec 3, GMU, Dr. Correll
9
The Solar System
21 Sep 2000
ASTR103, Sec 3, GMU, Dr. Correll
10
The Solar System
• Thought experiment:
– If I’m looking at a star with one large planet in orbit
around the star, what kind of motions do I see?
• Remember Newton’s 3rd law of motion--for every action
there is an equal and opposite reaction
– If planet is very tiny?
– If planet is very large?
21 Sep 2000
ASTR103, Sec 3, GMU, Dr. Correll
11
The Solar System
• Thought experiment:
– OK, so I see both the star and the planet circling each
other (or more accurately, there common center of
gravity)
– If I’m looking at the light from the Star, using a
spectroscope, what do I notice about the absorption and
emission lines?
21 Sep 2000
ASTR103, Sec 3, GMU, Dr. Correll
12
The Solar System
• Thought experiment:
– Right, I’ll see the absorption/emission lines Doppler
shifted. From this I can measure relative velocities.
– From the velocities and periods of orbits, I can calculate
the masses of the star AND the planet!
21 Sep 2000
ASTR103, Sec 3, GMU, Dr. Correll
13
The Solar System
21 Sep 2000
ASTR103, Sec 3, GMU, Dr. Correll
14
The Solar System
• How many stars are there in the solar system?
– One, our Sun.
• Was the solar system created as a direct result
of the birth of the universe?
– No, the universe was created 13-18 Billions years
ago; the solar system is about 4.6 Billion years old
• How long has the Earth existed?
– About 4.6 Billion years old
• Is Pluto the farthest planet from the sun?
– Sometimes Neptune is
• What typical shapes do moons have?
– Irregular spheroids, e.g.--potatos
21 Sep 2000
ASTR103, Sec 3, GMU, Dr. Correll
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