Which structure includes all matter and space that exists?

• A planetary system

• A star

• A galaxy

• The universe

What is a light-year?

• The distance light travels in one year

• A way to compare the speed of light to the speed of sound

• The amount of light energy emitted by stars during one year

• A way to measure the age of our universe

Earth is one of .... planets that orbit the sun, which is a star.

• five

• eight

• seven

• ten

A ..... is a large celestial body that is composed of gas and emits light.

• planet

• galaxy

• star

• moon

A ..... is a large collection of stars, gas, and dust

• moon

• star

• planet

• galaxy

The ....... is space and all the matter and energy in it.

• universe

• moons only

• starts only

• planets only

A ...... is a spherical body that orbits the sun.

• star

• planet

• galaxy

• solar system

All these planets are terrestrial planets except .....

• Mercury

• Venus

• Mars

• Jupiter

The four planets that orbit farthest from the sun are called gas giant planets. They are

• Jupiter, Saturn, Uranus, and Venus

• Jupiter, Saturn, Uranus, and Neptune.

• Jupiter, Saturn, Earth, and Mars

• Mars, Saturn, Uranus, and Neptune.

A ....... is the distance that light travels through space in one year.

• Meter

• Year

• light year

• kilometer