Structure of the Universe

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

• galaxy

• planet

• star

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

• solar system

• galaxy

• planets

is the collection of large and small bodies that orbit our central star, the sun.

• planet

• galaxy

• solar system

is a spherical body that orbits the sun.

• planet

• moon

• star

What do you call to the four planets that orbit nearest to the sun?

• terrorist planet

• territorial planets

• terrestrial planets

The terrestrial planets are all rocky, dense, and relatively small. The planets that belong to this category are:

• Earth, Mars, Uranus, Neptune

• Mercury, Venus, Earth, Mars

• Jupiter, Saturn, Uranus, Neptune

Jupiter, Saturn, Uranus, and Neptune are the four planets that orbit farthest from the sun. These large planets have thick, gaseous atmospheres; small, rocky cores; and ring systems of ice, rock, and dust. What do you call them?

• gas giant planets

• terrestrial planets

• planetary objects

Earth has only one moon, but Jupiter has more than ____.

• 20

• 60

• 40

In this process, stars fuse lighter elements, such as hydrogen, into heavier elements, such as helium. What do you call this process?

• nuclear wave

• nuclear version

• nuclear fusion

Which galaxy does our Solar System belong?

• Milky Way galaxy

• Cloud Nine galaxy

• Andromeda galaxy