Astronomy

Saturn is a...

• Moon

• Planet

• Star

• Solar system

Astronomy is the ​ (a)   of the ​ (b)   and everything in it.

• study
• universe
• star
• planet
• thinking
• space

The planets orbiting a star are called a _____ ______.

Choose the best label for this picture.

c

Horsehead nebula

The sun

The Solar System

Spiral galaxy

A ​ (a)   is a collection of ​ (b)   of stars.

• galaxy
• billions
• solar system
• star
• a few
• hundreds

What can be described as an exploding ball of gas?

• Planet

• Galaxy

• Star

• Universe

Choose the best label for this picture.

d

The Purple Eye

Black hole

Pillars of Creation

Crab Nebula

How many km across is a light-year?

• 10 km

• 10 trillion km

• 186,000 km

• 12,700 km

Why do we not know how big the universe is?