Space Science

In a diagram depicting the solar system as heliocentric, what is located at the center?

• Earth

• the sun

• the moon

• Mars

The orbit of a planet around the sun is a(an)

• ellipse.

• straight line.

• circle.

• parabola.

Which of the following helps explain why the planets remain in motion around the sun?

• density

• gravity

• inertia

• Both gravity and inertia

Which of the following objects does NOT orbit directly around the sun?

• planets

• comets

• moons

• all of the above

The moon most likely formed

• from a collision of Earth with a Mars-sized object.

• in another region of space and drifted toward Earth.

• from material in the solar system that came together.

• in the same way as Earth was formed.

Ocean tides are the result of

• the rotation of Earth.

• the sun’s gravitational pull on Earth.

• changes in Earth’s orbital position around the sun.

• differences in both the sun’s and moon’s gravitational pull on Earth.

Study Figure 25-1. Suppose you are an astronaut on the side of the moon facing Earth during a total lunar eclipse. Which would you see as you look toward Earth?

• Earth illuminated by reflected moonlight.

• The normal view; there is always reflected light from the moon’s surface.

• You could not see the sun because Earth blocks its light.

• The light from the sun behind Earth would be blinding.

What will happen to the relative amounts of hydrogen and helium in the sun over the next few billion years?

• Hydrogen will increase and helium will decrease.

• Hydrogen will decrease and helium will increase.

• Both hydrogen and helium will decrease.

• Both hydrogen and helium will remain the same.

The distance between stars is typically measured in

• light-years

• liometers

• astronomical units

• miles

Astronomers classify stars according to their

• distance from Earth.

• color, size, and absolute brightness.

• age and parallax.

• all of the above