Unit 6 Space Science C "Meets"

Question 1

Define a galaxy.

Answer 1

A galaxy is a huge group of individual stars, star systems, star clusters, dust, and gas held together by gravity.

Question 2

Summarize the big bang theory.

Answer 2

The big bang theory is the theory that the universe, including all energy, matter, space and time, began about 13.7 billion years ago in a rapid expansion.

Question 3

List the planets of our solar system in order from closest to the sun to farthest from the sun and identify them as terrestrial or as gas giants (Jovian).

Answer 3

1. Mercury – terrestrial
2. Venus – terrestrial
3. Earth – terrestrial
4. Mars – terrestrial
5. Jupiter – gas giant (Jovian)
6. Saturn – gas giant (Jovian)
7. Uranus – gas giant (Jovian)
8. Neptune – gas giant (Jovian)

Question 4

List and describe the three main differences between the terrestrial planets and the gas giant (Jovian) planets.

Answer 4

1. Size – Terrestrial are smaller, Jovian are larger.
2. Location – Terrestrial are closer, Jovian are farther from the sun
3. Composition – Terrestrial surfaces are rocky and denser, Jovian surfaces are gaseous and less dense.

Question 5

Describe the differences in the orbit, size and light output between moons, planets and stars.

Answer 5

• Orbit – Moons orbit planets, planets orbit stars, and stars orbit the center of the galaxy.
• Size – Moons are smaller than the planets they orbit, and planets are smaller than the stars they orbit.
• Light output – Stars produce energy and emit light. Planets and moons reflect the light.

Question 6

Explain how a star forms.

Answer 6

A star forms when a contracting nebula (a cloud of gas and dust) becomes dense and hot enough that nuclear fusion begins.

Question 7

Describe the process that produces energy in the sun and all main-sequence stars.

Answer 7

The sun produces energy through nuclear fusion where two hydrogen nuclei combine to form one helium nucleus.