Other objects in the Solar System

S1-4-08b Differentiate between the major components of the universe.

KEY WORDSMoon Asteroid TrojanMeteoroid Meteorite MeteorComet

Moons

Moon: Large natural object (rock/metals) that revolves around a planet – also called a satellite.

• Probes (robot explorers) have investigated moons of Mars, Jupiter and Saturn

The Roman goddess of the moon was Luna

Planet (2006) Known moonsMercury 0

Venus 0Earth 1Mars 2

Jupiter 63Saturn 60Uranus 27

Neptune 13Pluto 3

• (Oct 2008) 172 known moons in our Solar System

Io - only moon known to have active volcanoes

Europa – contains more ice and water than Earth and may contain life.

Humans have visited the moon’s surface six times between 1969 and 1972.

• 1st- Soviet Luna 2 (1959)• 2nd brightest object in sky

• No atmosphere• ¼ diameter of Earth

The gravitational pull of the moon on our

ocean is what causes the tide to rise and

fall

Asteroids

Asteroid: Chunk of rock/metal that orbits the Sun but too small to be planets – minor planets.

• Asteroid that cross path with Earth called TrojansThe fear is that a Trojan passes close enough to get

pulled in by Earth’s gravity and collide

• Asteroid belt in large gap from Mars – Jupiter• Largest is only 1000 Km in diameter

• Asteroids are rich in minerals – future mining

Meteoroids

Meteoroid: lump of rock that is trapped by Earth’s gravity and pulled into the atmosphere.

The only difference between meteoroid and asteroid is that a meteoroid is random, an asteroid orbits the Sun

Falling meteoroids bump into air molecules heating up (friction) until the air glows – and the meteoroid burns up

and breaks apart.

• Meteoroid that completely burns up - meteor• producing a streak of light - shooting star

Meteorite: fragment of a meteoroid that doesn’t burn up and strikes the Earth (space rock).

• Large meteorites make craters• Westhawk Lake is a crater

Meteorite impact crater in Arizona

Comets

• Some have regular periods of revolution around the Sun

Comet: chuck of ice/dust that orbits the Sun. • Made of the head (coma) and the tail

• Tail: passing by Sun heats trailing gas and debris then blown out by solar wind - millions of km long

Halley’s comet: last seen in 1986 it has a period of 76 years

CAN YOU ANSWER THESE QUESTIONS?

S1-4-08b:What other objects make up our solar system?

KEY WORDSMoon Asteroid TrojanMeteoroid Meteorite MeteorComet