1. Earth-Moon-Sun System
Astronomy

2. Everything is Moving
The Earth, Sun, and Moon are all moving through space
Every object we see in the night sky is also moving through space
Question: How do the Earth, sun, and moon interact?

3. From Earth, we watch the moon rise and shine at night, while the sun rises and shines in the day
Planets and stars also rise and set
The whole night sky seems to move through time

5. Perspective We see the stars, sun, and moon orbit around us
This view is called Geocentrism, meaning “Earth at the Center”
The Earth-Moon orbit the sun along with the rest of the planets
This view is called Heliocentrism, meaning “Sun at the Center”

6. Which is Accurate?

8. The Earth is not at the center
Heliocentrism more simply explains what we observe from the Earth
The Earth orbits the sun and the moon orbits the earth

10. Lunar Phases The moon orbits the Earth
It completes its orbit in about 27 days
We see the moon change in brightness as it reflects sunlight
Depending on the position of the earth-sun-moon, we see a different moon phase

12. Lunar Phases Cont. When the moon is fully lit, it’s called a full moon
When the moon is completely dark, it’s called a new moon
When the moon is slowly getting brighter, it waxes
When the moon is slowly getting darker, it wanes