S8-U2L2 - Gravity and the Solar System Part 2

S8-U2L2 - Gravity and the Solar System Part 2

Lesson vocabulary

Gravity

A force of attraction between objects that is due to their masses.

Orbit

The path that a body follows as it travels around another body in space.

Multiple Select

Does the moon orbit around the earth?

• yes

• no

Aphelion

In the orbit of a planet or the other body in the solar system, the point that is farthest from the sun.

Perihelion

the point of the orbit of the planet at which the planet is closest to the sun.

centripetal force

The inward force required to keep a particle or an object moving in a circular path.

solar nebula

a rotating cloud of gas and dust from which the sun and planets formed.

Planetesimal

A small body from which a planet originated in the early stage of development of the solar system.

The origins of the solar system

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How was the solar system born?

• The solar system began as a solar nebula.

• Gravity caused the nebula's center to collapse and this helped form the solar system.

What is your greatest question about the vastness of space?

• If you think space is infinite or has no end, discuss why you think this is so.

• If you think there are limits to its vastness, explain your thoughts.

• If you have other questions or ideas about the vastness of space, discuss them.

The solar system begins

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What was the solar nebula?

• The solar nebula was a rotating cloud of gas and dust from which the sun and planets formed.

Here comes the sun

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CORE CONCEPTS

What caused the center of the solar nebula to collapse?

• Gravity caused the collapse of the solar nebula.

What role does gravity play in the formation of a new star?

• Gravity causes nebular material to collapse and contract toward the center to eventually form a star.

When does a proto-star become a star? 

• A proto-star becomes a star when its center becomes so dense and hot that fusion begins.

• Energy is released, the proto-star ignites, and a star is born.

The protoplanetary disk

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VOCABULARY

What is a planetesimal?

• A planetesimal is a small body from which a planet originated in the early stages of the development of the solar system.

Forming the inner and outer solar systems

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EXTEND AND REFLECT

What role did heat play in the formation of the solar system?

• The heat from the sun caused inner planets to become rocky, whereas the outer planets were able to remain gaseous.

Check understanding

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EXTEND AND REFLECT

What effect would a stellar wind have on the formation of a new solar system?

• A stellar wind would stop formation of completely new planets, because material other than that collected into protoplanets is blown away. 

Extend understanding

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EXTEND AND REFLECT

After a solar system's planets are created, what other changes to them could occur?

• Their shapes, sizes, and orbits can still be affected by collisions and the changing effects of gravity as a consequence.

Reflect

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CORE CONCEPTS

Has our sun begun the fusion process?

• Yes. It has become a star, and fusion is the source of its heat and light.

EXTEND AND REFLECT

Could life exist on a planetesimal in a protoplanetary disk?

• It is very unlikely, as planetesimals are small, lack atmosphere, and are either too hot or cold, depending on location, to support life as we know it.

Summary

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EXTEND AND REFLECT

How likely is that that there is another planet like Earth somewhere in the universe?

• Perhaps, like many scientists, you think it is likely that another planet like Earth exists because our solar system is so vast.

CORE CONCEPTS

How do gravity and gas pressures balance each other in the early stages of solar system formation? 

• Hot gases tend to expand the rotating disk and the force of gravity tends to pull material toward the center. 

What is the role of gravity in the formation of the solar system?

• Because the attraction of gravity is constant, it pulls all things toward the center. The increasing density generates heat.

EVALUATE

How does studying the galaxy help us understand our own planet?

• Because the same processes are at work elsewhere, studying them helps us explain how our own solar system and planet came to be.

Lesson summary

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EXTEND AND REFLECT

How likely is that that there is another planet like Earth somewhere in the universe?

• Perhaps, like many scientists, you think it is likely that another planet like Earth exists because our solar system is so vast.