What Keeps the Planets and Moons in

Orbit?

E.ST.05.21Describe the motion of planets and moons in terms of

rotation on axis and orbits.

Advanced Note-Taking Practice 101!

• Every time you see something typed in YELLOW…you need to write it down.

• “But Miss…what if it is not in YELLOW and I still want to write it down?”

• Answer: As Nike once said, “Just Do It.” (translation that’s fine)

CO: I can examine how and why the planets remain in orbit. • Please skip a line after reading and writing your content

objective for the lesson.

• Why do you think the planets orbit the sun?

• In your groups, please take 1-2 minutes to discuss and brainstorm an answer. Have one person report out their answer.

What does the science book says?Let’s read and take some outline notes• From pg. D8 of your science text…

What Keeps the Planets in Orbit?

“The planets orbit the Sun, but what holds them in place? What keeps them from flying off into space?”

CO: I can examine how and why the planets remain in orbit.

Why do you think the planets orbit the sun?

What Keeps the Planets in Orbit?

Looking at why planets do not float into space…

Read on…

Gravity“Over 300 years ago, Sir Issac Newton described an invisible

force holding the sun and a planet together. He called the invisible force gravity. He described gravity as a property of all matter. It is a force of attractions, or pull, between any object and any objects around it.”

CO: I can examine how and why the planets remain in orbit.

Why do you think the planets orbit the sun?

What Keeps the Planets in Orbit?

Looking at why planets do not float into space…

I. Gravity a. Gravity: is a force of attraction, or pull, between 2 objects

1. Picture:

Read on…

“Gravity depends on two measurements- mass and distance. The more matter or mass, in an object, the greater the pull in an object’s direction. The closer two objects are, the stronger the pull of gravity between them.”

• What two factors impact gravity? Give me a thumbs up when you have your answer.

• Use the sentence stem…”The two factors that impact gravity are______________ and ______________. • https://www.youtube.com/watch?v=6f6maa9xPDM

b. Two Factors effect gravity1. Mass (how much something weighs) 2. Distance between the two objects

Read on…

“The Sun has far more mass than any of the planets, so its gravity is such stronger, too. The Sun’s gravity holds all of the object in the solar system together. Without gravity, everything orbiting the sun would go flying off into space.”

Could we survive if we went flying into space?

b. Two Factors effect gravity1. Mass (how much something weighs) 2. Distance between the two objects

c. Sun has more mass=more gravity 1. Without gravity planets fly into space

Read on…

Inertia (a new heading)“Gravity is not the only reason the planets stay in their orbits.

Gravity alone would pull the planets into the Sun, because the Sun is so massive. That doesn’t happen because the planets are moving. All objects including the planets have a property called inertia. Inertia is a tendency of a moving object to keep moving in a straight line.”

b. Two Factors effect gravity1. Mass (how much something weighs) 2. Distance between the two objects

c. Sun has more mass=more gravity 1. Without gravity planets fly into space

II. Inertia a. Inertia: is the tendency of a moving object to keep spinning.

1. Picture:

Read on…

“Without gravity, the planets’ inertia would keep them moving in straight lines. Gravity “steers” the planets in their oval paths around the Sun. Together, gravity and inertia keep the planets in their orbits.”

b. Two Factors effect gravity1. Mass (how much something weighs) 2. Distance between the two objects

c. Sun has more mass=more gravity 1. Without gravity planets fly into space

II. Inertia a. Inertia: is the tendency of a moving object to keep spinning.

1. Picture:

b. Gravity and inertia work together1. Gravity “steers” and inertia stomps on the gas

Homework or Classwork?

• In your science notebook or on a separate sheet of paper, answer the following question.

• How do gravity and inertia keep a planet in orbit? (pictures are optional but encouraged)