The Solar System
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Chapter 7 : The Solar System
Topics covered in this snack-sized chapter:
Star: The Sun.
8 Planets + a few minor planets.
126 Moons around these planets.
Asteroids, Meteoroids and Comets.
A lot of nearly empty space.
The solar system is very flat.
Planetary orbits are nearly circular.
Almost all moons and planets (and Sun) rotate and revolve (orbit) in the same direction.
Planets are isolated in space.
Leftover STUFF exists in the solar system (Comets and Asteroids).
An Easy Mnemonic:
Two Kinds of Planets:
Distance from the Sun
Close to the Sun
Far from the Sun
Slow Rotation (1 - 243 days)
Fast Rotation (0.41 - 0.72 days)
Number of Moons
Heavy or Light Elements
Main Elements H, He
Comets are bright, fuzzy objects that appear relatively suddenly.
Most usually have a rather long, diffuse tail.
The Nature of Comets:
Comets are gravitationally bound to the Sun.
The orbits can be highly elliptical.
The orbital planes of the comets can be highly inclined with respect to the Earth’s orbital plane.
Sunlight and the solar wind blow the comet’s dust particles away from the Sun.
As a result, the tail always point away from the Sun.
~ 1 - 10 km ball of ice, dust.
Cloud of gas and dust around nucleus (~106 km across).
Always points away from the Sun.
A small body of matter from outer space that enters the earth's atmosphere, appearing as a streak of light.
Things that fall from the sky are called the Meteors.
There are many small chunks of matter orbiting around the Sun.
A piece that is in space is a meteoroid.
A piece that burns up in the Earth’s atmosphere is a meteor (a bright streak of light).
A piece that lands on the Earth is a meteorite.
During periods of high meteor activity, most of the events appear to come from one spot on the sky.
This point is roughly where the comet’s tail was.
Dust particles enter the atmosphere and burn up, causing a streak of light.
is the region of the Solar System located roughly between the orbits of the planets Mars and Jupiter.
Jupiter’s strong gravity disrupted these planet’s orbits and eject them out of the Solar System.
Asteroids have irregular shapes, and typically have craters and other features.
The Nebular Hypothesis is the most widely accepted model explaining the formation and evolution of the Solar System.
There is evidence that it was first proposed in 1734 by Emanuel Swedenborg.
Our Solar system was formed 4 billion years ago when a small part of a giant molecular cloud experienced a gravitational collapse.
Most of the collapsing mass collected in the center forming the Sun while the rest flattened into a protoplanetary disk, out of which the planets, moons, asteroids, and other small Solar System bodies formed.
Nebula: Cloud of interstellar dust and gas.
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