Download Section 13.15: Other Objects in the Solar System Planetary Moons

Section 13.15: Other Objects in the Solar System
Planetary Moons
Moons (also known as satellites) are large natural objects that revolve
around planets.
Several planets have more than one moon.
The most famous satellite of any planet is Earth’s Moon.
Information about the Moon:
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The moon orbits the Earth
The moon is the only natural satellite of the Earth
The moon completes one rotation after 27 and a third days.
The distance between the Earth and the Moon is 384,385 km.
The weight of the moon is 1/81 that of the Earth
The diameter is ¼ of the Earth's. (3479 km)
The moon has no atmosphere
Surface is filled with hills and valleys as well as craters (caused by
impact of objects from space)
• There have been 6 visits to the moon (between 1969 and 1972)
Asteroid:
Small rocky objects found in an asteroid belt around the Sun
between the orbits of Mars and Jupiter. (There is a large gap
between the orbits of Mars and Jupiter)
Scientists believe that the asteroids might have formed into a
planet if Jupiter’s gravitational pull hadn’t been so strong.
Could we someday mine the minerals on asteroids?!? Their
gravity would allow spacecraft carrying minerals to blast off
more easily.
Meteoroid: A lump of rock or metal that is trapped by Earth’s gravity and
pulled down through the Earth’s atmosphere.
Meteor:
A bright streak of light across the sky, caused by a burning
meteoroid. Meteoroids burn when they rub against molecules in
the air causing friction.
“Falling Stars” are actually Meteors. The 3 most active
Meteor Showers are: Perseid (August 12), Geminid (December
14) and Quadrantid (January 3 or 4)
Meteorite: A meteor that hits the Earth’s surface (creating a crater) before
it completely burns up in the Earth’s atmosphere.
Comet:
A chunk of ice and dust that travels in a larger orbit around the
Sun.
As the comet approaches the sun, the solar radiation causes the
frozen substances to become gases. The solar wind pushes these
gases outward, forming a tail that can be millions of kilometers
long.
Many comets have regular periods of revolution. (ex. Halley’s
Comet has a period of 76 years)