Other Objects in the Solar System

• So far, we have studied:– Planets– Stars

• Which make up galaxies, constellations and asterisms

• The solar system also contains:– Moons– Asteroids– Meteors– Comets

What Else is Out There?

Satellites

• Objects that revolve around planets are called satellites

• Satellites can be– Natural (not man-made)

• Example: moons

– Artificial (man-made)• Example: GPS and TV satellites

Moons

• A moon is a natural satellite

• The moons of other planets weren’t discovered until after the telescope was invented

• Earth’s moon has been visited six times between 1969 and 1972

Planet # of known moons

Mercury 0

Venus 0

Earth 1

Mars 2

Jupiter 39

Saturn 30

Uranus 20

Neptune 8

Pluto 1

Earth Jupiter (Europa & Io)

Mars (Phobos & Deimos)

Pluto (Charon)

Eclipses

1. Solar Eclipse- The Moon passes between the Earth and the Sun- This blocks our view of the Sun- Only occurs during New Moon

2. Lunar Eclipse- The Earth passes between the Moon and the Sun- The Moon is plunged into darkness as Earth’s shadow

moves across it- Only occurs during Full Moon

Asteroids• Asteroids are small, rocky objects that never

formed into planets

• The ring of asteroids between the orbits of Mars and Jupiter is the asteroid belt

• The orbits of some asteroids cross the path of Earth and pose a potential collision hazard

• The largest asteroid, Ceres, is 1000 km in diameter

Eros

Ceres

Asteroid Belt

Meteors, Meteoroids and Meteorites

• A meteoroid is a lump of rock or metal that is pulled through Earth’s atmosphere

• Friction between the meteoroid and the atmosphere causes the meteoroid to heat up

• Small meteoroids will vaporize

• Large meteoroids can burn up and generate enough light to become visible

Meteors, Meteoroids and Meteorites

• This fireball appears as a bright streak in the sky and is called a meteor– Sometimes called a shooting star

• Fragments of the meteor that are large enough or tough enough don’t burn up and strike Earth’s surface.

• A meteorite is a meteor remnant that survives to strike the Earth’s surface

Meteor Meteor Shower

The Barringer Meteorite Crater

4,000 ft

570 ft

Comets

• A comet is a chunk of frozen ice and dust that travels in a very long orbit around the Sun

• Occasionally, a comet gets bumped from its orbit and passes close to the Sun

• The frozen gases that make up the comet melt and evaporate as it approaches the Sun

• This forms a bright glowing tail that can be thousands of kilometers long and visible for several months

Halley’s Comet

Comet Hyakutake