1. 19.3 Phases, Eclipses, and Tides

2. The moon
We only see one side of the moon. The dark side of the moon never faces Earth and has only been seen by astronauts and in pictures. This is because of how the moon moves in space.
The moon rotates on its axis every 27.3 days and revolves around the Earth in the same time 27.3 days. Since its rotation and revolution are equal, the same side always faces Earth.

3. Phases of the moon
The changing positions of the Earth, moon and sun cause the phases of the moons, eclipses, and tides to occur.
Every revolution around the Earth the moon goes through a set of phases. Because sunlight lights up the moon where the moon sun and Earth are in relation to one another determines whether we see a full, quarter or crescent moon.

4. Phases of the Moon
The phase of the moon you see depends on how much of the sunlit side of the moon faces EARTH.

5. 1. New Moon Dark side faces Earth, lighted side faces Sun
Looks like the moon has disappeared
This is the first phase in 8 to take place

6. 2. Waxing Crescent
Thin slice of the moon is lit up by the Sun and is shown on Earth
Occurs about 24 hours after a new moon

7. 3. First Quarter Occurs about a week after a new moon
You can see half of the lighted side from Earth
Half of the lighted side is also called, one quarter

8. 4. Waxing Gibbous
More than one-quarter of the moon is visible from the earth

9. 5. Full Moon The whole surface of the moon facing Earth is lit up
Exact opposite of a new moon

10. 6. Waning Gibbous Occurs right after a full moon
The amount of the moons lighted side becomes smaller

11. 7. Third Quarter You can only see half of the lighted side from Earth
Just like first quarter, but backwards

12. 8. Waning Crescent Occurs just before a new moon
The amount of the moon seen on Earth becomes smaller
Only a small slice of the moon is shown
Cycle begins again at new moon.
The entire phases take 27.3 days.

13. Solar Eclipses

14. Solar Eclipse
Solar Eclipse- occurs when the moon moves directly between the sun and earth and casts a shadow on part of earth.

15. Parts of a Solar Eclipse
Umbra- darkest part of the moon’s shadow.
Only a person standing in the umbra can see a total solar eclipse.
Penumbra- lighter shadow on the earth’s surface surrounding the umbra.
A person standing in the penumbra can see a partial solar eclipse.

16. Parts (cont.)
The only part of the sun that is visible during a solar eclipse is part of its atmosphere, which appears as a pearly white glow around the edge of the eclipsing moon.

17. Caution!!
Regardless where you are, you should never look into a solar eclipse. The light will permanently damage your eyes. Scientists wear special glasses!

18. Lunar Eclipse Can only occur at Full Moon
Moon passes through some portion of Earth’s shadow
Penumbra-Earth blocks part of the sun’s rays from the Moon
Umbra-Earth blocks all direct sunlight from the Moon

20. Penumbral Lunar Eclipse
The Moon passes through Earth’s penumbral shadow
Subtle and quite difficult to observe
35% of eclipses are penumbral

21. Partial Lunar Eclipse
A portion of the Moon passes through Earth’s umbral shadow
Easy to see
30% of eclipses are partial

22. Penumbral Lunar Eclipse
The Moon passes through Earth’s penumbral shadow
Subtle and quite difficult to observe
35% of eclipses are penumbral

23. Total Lunar Eclipse
The entire Moon passes through Earth‘s umbral shadow
Quite striking, vibrant colors
35% of eclipses are total

24. Total Lunar Eclipse
The entire Moon passes through Earth‘s umbral shadow
Quite striking, vibrant colors
35% of eclipses are total

25. Tides Caused by the moon Occur every 6 hours
2 high tides and 2 low tides every day
Spring tides: tides are higher than normal
Neap tides: are less effective than normal