Unit 2: Astronomy

Lesson 2: Objects in the Universe

Stars

Massive, hot balls of super heated gas called plasma.

Planets

Orbits the sun Round Dominates its orbit

Dwarf Planets

Orbits the sun Round Has not cleared it’s orbit

Moons (satellites)

Natural or artificial objects that revolve around larger objects like planets.

All planets except for Mercury and Venus have moons.

Mars’ moon, Phobos

Comets

A small object made of rock and ice that orbit the sun.

When a comet passes close enough to the sun, the solar radiation heats up the ice causing it to melt and form a gas in the form of a tail.

Asteroids

Small, rocky object that orbits the sun.

Have irregular shapes (not round). Most asteroids orbit the sun in the

wide region between Mars and Jupiter – this is called the Asteroid Belt.

Meteoroid

Small, rocky object that orbits the sun Smaller than an asteroid

Meteorite – when the meteoroid

enters the Earth’s atmosphere and strikes the ground.

Meteor – the bright streak formed when a meteoroid or a comet burns up in the atmosphere.

Today’s Activity

Solar System Sort