Solar System and Stellar Concepts

According to Newton’s First Law of Motion, what will happen to a body in motion if no external force acts on it?

• It will stay in motion at the same speed.

• It will stop moving immediately.

• It will change direction randomly.

• It will speed up continuously.

What force attracts a body with less mass toward a body with more mass?

• Gravity

• Magnetism

• Friction

• Electricity

What percentage of the mass of the solar system does the sun make up?

• 99%

• 50%

• 75%

• 10%

Why do the planets stay in motion orbiting the sun?

• Because of Newton’s First Law of Motion and the gravitational pull of the sun.

• Because the planets have engines.

• Because the sun pushes them away.

• Because of the moon’s gravity.

If the sun makes up 99% of the mass of the solar system, what percentage do all the planets combined make up?

• 1%

• 10%

• 50%

• 25%

How does the gravitational pull of Earth affect the moon?

• It holds the moon in orbit around Earth.

• It pushes the moon away from Earth.

• It makes the moon spin faster.

• It causes the moon to stop moving.

The moon orbits the Earth and rotates on its axis at the same speed. How long does this take?

• 27.3 days

• 1 day

• 365 days

• 7 days

Imagine if the sun only made up 50% of the mass of the solar system instead of 99%. How might this affect the orbits of the planets?

• The gravitational pull of the sun would be weaker, so planets might not stay in orbit as easily.

• The planets would orbit faster.

• The planets would become larger.

• The sun would become colder.

Why is it important that the moon orbits the Earth and rotates on its axis at the same speed?

• It causes the same side of the moon to always face the Earth.

• It makes the moon brighter.

• It changes the color of the moon.

• It makes the moon move closer to the sun.

What is a New Moon?

• When the moon appears to be completely dark.

• When the moon is at its brightest.

• When the moon is half visible.

• When the moon is red.