1. SUN, EARTH, MOON

2. Highlight vocabulary words
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3. POSITION Sun is 150 million km from Earth
Moon is (on average) 384,000 km from Earth

4. SIZE The sun’s diameter is 100 times greater than Earth’s diameter
The moon’s diameter is 27% of Earth’s diameter

5. THE SUN Nearest star to Earth (1 of 100 billion just in the Milky Way)
Ball of hot gas powered by nuclear fusion (nuclei of atoms colliding and fusing together)
15,000,000°C at its core and 5,500°C at its surface
Small amount of that energy reaches Earth’s surface as light and thermal energy
The other planets in our solar system (including Earth) revolve around the sun

6. Earth’s Orbit
Orbit: the path an object follows as it moves around another object
Revolution: the motion of one object around another object
Earth’s orbit around the sun is nearly circular
One complete revolution around the sun takes ______ days (leap year)

7. WHY DOES THE EARTH ORBIT THE SUN?
The sun’s gravity pulls on Earth, causing the Earth to orbit it
The pull of gravity between two objects depends on the mass of the objects and the distance between them
The more mass an object has and the closer two objects are to each other, the greater the gravitational pull.
IF THE FORCE OF GRAVITY BETWEEN THE SUN AND EARTH WERE TO STOP, THEN EARTH WOULD FLY OFF INTO SPACE IN A STRIAGHT LINE!

8. Earth’s Rotation Rotation: a spinning motion
As Earth revolves around the sun, it rotates (or spins) on its axis (an imaginary line through its center)
Earth rotates on its axis in a counterclockwise direction from west to east
One complete rotation of Earth takes about 24 hours
This rotation helps produce the cycle of night and day
Antipoles: cHIU

9. Sun’s Apparent Motion
It appears the sun is moving from east to west across the sky from Earth
It is Earth’s rotation that causes the Sun’s apparent motion
The moon and stars also appear to move from east to west across the sky

10. Moon
The moon does not emit its own light! You only see the moon because light from the sun reflects off the moon and into your eyes.
Time for one rotation: 27.3 days
Time for one revolution around Earth: 27.3 days

11. The Moon’s Formation Giant Impact Hypothesis:
Shortly after Earth formed 4.6 billion years ago, an object about the size of Mars collided with Earth.
The impact ejected vaporized rock that formed a ring around Earth
Eventually, the material in the ring cooled and clumped together and formed the moon

12. The Moon’s Surface
Craters: formed when objects crashed into the moon more than 3.5 billion years ago
Maria: formed when lava flowed up through the crust and solidified
Highlands: light-colored areas where lava could not reach

13. What if the Earth stopped spinning?