1. Learning Intention: 8.ESS1.2 Gravity & Our Solar System
Science
Standard 15
Date
Learning Intention: 8.ESS1.2
Gravity & Our Solar System
Explain the role of gravity in the formation of our sun and planets. Also explain gravity’s effect on the motion of celestial objects in our solar system and Earth’s ocean tides.
Science and Engineering Practice(s)
Obtain and communicate information, Construct Explanations
Crosscutting Concepts
Cause & Effect, Systems & System Models, Stability and Change
I Can Statement
By the end of this unit I will be able to say...
...I can explain how gravity formed and effects celestial objects
in our solar system.

2. Formation of Our Solar System
Gravity is a "pulling" force that causes every particle of matter to be attracted to every other particle of matter.
Gravity formed our solar system from a nebula.
This is called the nebular theory (watch video).
Video Link (3:05): The Nebular Theory

3. Nebulas rotate due to the force of gravity.
Gravity formed our solar system from a nebula
Nebulas are huge clouds of cosmic dust (mostly hydrogen) consisting of elements left over from exploded stars.
Nebulas rotate due to the force of gravity.

4. Gravity formed our solar system from a nebula
A) Over time, gravity pulled the particles (atoms/elements) in the nebula together into clumps.

5. Gravity formed our solar system from a nebula
B) Larger clumps had stronger gravity and pulled even more clumps together.

6. This explains the round (spherical) shape of stars and planets.
Gravity formed our solar system from a nebula
C) The gravity from these large clumps pulled in all directions forming a roughly spherical shape.
This explains the round (spherical) shape of stars and planets.
The Sun
Jupiter
Earth

7. This motion is called rotation.
Gravity formed our solar system from a nebula
D) Gravity caused these large clumps to start spinning.
This motion is called rotation.
This is why the sun, planets, and moons rotate.

8. This is how our sun was formed
Gravity formed our solar system from a nebula
E) Once a huge mass of hydrogen atoms were pulled together, the gravity caused nuclear fusion to occur forming a new star.
This is how our sun was formed

9. This is how planet Earth was formed
Gravity formed our solar system from a nebula
F) Smaller masses of clumps of matter formed into planets and moons.
This is how planet Earth was formed

10. Gravity causes our sun and planets to rotate (spin)
Rotation-when an object spins on its axis
Gravity causes our planets and moons to revolve (orbit)
Revolution-when an object circles around another object
Gravity keeps Earth, and all the other planets, from “flying off” into space as they revolve (orbit) around the sun.
Question: What keeps our planet from falling into the sun?
Answer: The inertia (momentum) of the planet’s motion as it revolves (orbits) the sun.

11. Gravity keeps the moon from “flying off” as it orbits the Earth.
The Earth’s gravity is pulling on the Moon, and at the same time, the Moon’s gravity is pulling on the Earth.
Gravity keeps the moon from “flying off” as it orbits the Earth.
Question: What keeps the Moon from falling into the Earth?
Answer: The inertia (momentum) of the Moon’s lateral motion as it revolves around the Earth.
Rotation
Revolution

12. What Are Tides?
Tides: daily rise and fall of Earth’s oceans along the coastlines.
High tides are when the water reaches its highest point.
Low tides are when the water reaches its lowest point.
Cause: The Moon’s gravitational pull and Earth’s rotation.
Effect: the ocean water bulges upwards producing the tides.
High Tide
Low Tide

13. Link (4:28): Tides Are Tricky-Here's How they Work
More About Tides
Sublunar High Tide: The Moon’s gravity “pulls” on the oceans that are facing towards the Moon.
Antipodal High Tide: oceans also bulge on the opposite side of the Earth away from the Moon. (antipodal point).
Two Possible Causes of Antipodal Tides:
1) Inertia/momentum of the water from the Earth’s spin.
2) The Moon’s gravity pulls the entire planet towards it causing water to bulge upwards on the side opposite from the Moon.
Antipodal
High Tide
Sublunar
High Tide
Link (4:28): Tides Are Tricky-Here's How they Work