Front

What does it indicate when all planets orbit in the same direction as the Sun rotates?

Back

It indicates that they all formed at about the same time and relative space.

Front

What do astronomers use to model the origin of the solar system based on current observations?

Back

Models.

Front

Is our solar system the same as others in the galaxy?

Back

False.

Front

What best describes terrestrial planets?

Back

No or very few moons; solid surfaces; moderate atmospheres.

Front

How many extrasolar planets has the Kepler spacecraft discovered so far?

Back

Thousands.

Front

What is the main topic of the formation of planetary systems?

Back

The processes and conditions that lead to the formation of planets around stars.

Front

What are the four terrestrial planets in our solar system?

Back

Mercury, Venus, Earth, and Mars.

Front

What is retrograde motion?

Back

The apparent backward motion of a planet as observed from Earth.

Front

What is the significance of the solar nebula theory?

Back

It explains the formation of the solar system from a rotating disk of gas and dust.

Front

What are gas giants?

Back

Planets that are primarily composed of hydrogen and helium, such as Jupiter and Saturn.