2 Planetary MoonsLarge natural objects that revolve around planets are called satellites or moons.Moons range in size, shape, terrain, and geological activity just like planets.Several planets have more than one moon. Probably the most famous satellite of any planet is Earth’s Moon.The moon has no atmosphere, and its surface is filled with hills and valleys, as well as craters caused by the impact of large and small objects from space.
3 Planetary Moon Count (1998) # of known moonsMercuryVenusEarth1Mars2Jupiter16Saturn18Uranus17Neptune8Pluto
4 AsteroidsThere is an asteroid belt between the orbits of Mars and Jupiter.Thousands of small rocky objects, high in minerals, called asteroids revolve around the Sun together.Some asteroids actually have an orbit they follow and come close to the Earth.Very small – 1000km width max.
5 Meteoroids, Meteors, and Meteorites A meteoroid is any lump of rock or metal that is being pulled to the Earth by Earth’s gravity.As it falls, it rubs against the molecules of the air. This rubbing, causes the rock to become hot and vaporize, and the air to glow. This is called a meteor, a bright streak of light across the sky. (shooting star)A meteorite is a rock which does not completely burn up and hits the Earth and creates a crater.
6 Where do meteoroids come from? The largest are probably asteroids in orbits that cross Earth’s orbit. The millions of tiny meteoroids that produce spectacular displays called meteor showers probably come from the debris left behind by comets.
7 CometsA comet is a chunk of frozen matter that travels in a very long orbit around the Sun.Haley’s comet circles once every 76 years. (1986)The glowing tail of a comet is the melting of the comets core which produces gases. The gases always point away from the Sun and the gaseous tail only happens near the Sun. The bright, glowing tail may be over millions of kilometers long.
8 In ConclusionIn our Solar system, the planets and the Sun are considered the major bodies while comets, meteoroids, asteroids, and moons are considered minor bodies.
9 Questions p. 433: 1,2,3,5 a) What is an asteroid? An asteroid is a fairly small, irregular, rocky object that travels in an orbit around the Sun.b) Where is the asteroid belt?The asteroid belt is located between Mars and Jupiter.a) Explain the difference between a meteoroid and a meteorite.A meteoroid is a lump of rock or metal that is pulled by Earth’s gravity through the atmosphere. A meteorite is a meteoroid that was large enough to land on Earth’s surface before it vapourized.b) Why are meteorites less common than meteors?Most meteors vaporize before they get to Earth.
10 3.Using a labelled diagram, describe what causes the glowing tails of the comets. Comets’ tails are caused when the comets get close to the Sun. The outer layers of ice turn into gases that are pushed away from the Sun by solar wind. These gases glow brightly.5.When will Haley’s comet next be close enough to the Sun to be seen?2062 ( )