The solar system

What is the solar system?

The Sun and all objects that orbit it.

What is a light-year?

The distance light travels in one year.

What is a dwarf planet?

An object that orbits the Sun and is round but has not cleared its orbit

Why is Pluto no longer considered a planet, and what is it now?

Pluto has not cleared its orbit, so it is now a dwarf planet.

What are asteroids?

Rocky objects that orbit the Sun, mostly between Mars and Jupiter.

What is the difference between a meteoroid, meteor, and meteorite?

• Meteoroid: rock in space

• Meteor: rock burning in Earth’s atmosphere

• Meteorite: rock that hits Earth’s surface

What is rotation? (Use Earth as an example)

Rotation is when Earth spins on its axis.

What is revolution? (Use Earth as an example)

Revolution is when Earth orbits the Sun.

How many days does it take for:

• Earth’s rotation: 1 day (24 hours)

• Earth’s revolution: 365 days

• Moon’s revolution around Earth: about 28 days

What causes the seasons?

Earth’s tilt and its revolution around the Sun.

What are the phases of the Moon?

The different shapes of the Moon we see due to its position relative to Earth and the Sun.

What is an eclipse?

When one object in space blocks light from another.

What are the two types of eclipses we can see from Earth?

• Solar eclipse

• Lunar eclipse

How does a solar eclipse occur?

When the Moon blocks the Sun from Earth.

How does a lunar eclipse occur?

When Earth’s shadow falls on the Moon.

What is a natural satellite? Give an example.

A natural object that orbits a planet; example: the Moon.

What is an artificial satellite? Give an example.

A man-made object that orbits Earth; example: GPS satellite.

What is space junk?

Old or broken human-made objects orbiting Earth.

Describe three ways artificial satellites benefit society.

• Communication (phones, TV, internet)

• Navigation (GPS)

• Weather forecasting