Earth Formation

A celestial cloud of dust and gas is called . . .

• nebula
• supernova
• accretion disc
• bombardment

How old is our solar system?

• 4.6 billion years
• 13.8 billion years
• 6,000 years
• 15,000 years

A massive explosion of a star is called . . .

• supernova
• nebula
• pulsar
• black hole

What celestial body eventually evolved into our modern solar system?

• a nebula
• a supernova
• a quasar
• a galaxy

Smaller particles collecting together into larger and larger objects is called . . .

• accretion
• contraction
• explosion
• rotation

When the inner planets (and moons) were bombarded by asteroids, what did the asteroids leave behind?

• craters
• calderas
• mountains
• valleys

Why is Mercury covered with craters, but Earth is not?

• Earth's atmosphere protects and weathers
• Earth's moon blocks asteroids
• asteroids just missed Earth
• most asteroids land in Earth's oceans

When you spin any mass, what shape will it likely take?

• Sphere
• Disc
• Cylinder
• Cloud

The sun and all the planets and other bodies that revolve around it make up the

• universe
• galaxy
• solar system
• neighborhood

The 4 rocky planets closest to the sun are known as the 

• inner planets
• outer planets
• gas giants
• tiny four