1. Phases of the Moon

2. Phases of the Moon
The first astronomical event to be understood was the regular cycle of the phases of the moon.
On a monthly basis, we observe the phases of the moon as a change in the amount of the moon that appears lit.

3. Phases of the Moon Look at the new moon shown in the figure.
About two days after the new moon, a thin sliver (crescent phase) appears low in the western sky just after sunset.

4. Phases of the Moon
During the following week, the lighted portion of the moon visible from Earth increases (waxing) to a half circle (first-quarter phase) and can be seen from about noon to midnight.

5. Phases of the Moon
In another week, the complete disk (full-moon phase) can be seen rising in the east as the sun is sinking in the west.
During the next two weeks, the percentage of the moon that can be seen steadily declines (waning), until the moon disappears altogether (new-moon phase)

6. In the box draw and label each moon phase

7. Phases of the Moon
Lunar phases are a result of the motion of the moon and the sunlight that is reflected from its surface.
To an observer on Earth, the percentage of the bright side that is visible depends on the location of the moon with respect to the sun and Earth.

8. Phases of the Moon
When the moon lies between the sun and Earth, none of its bright side faces Earth.
This is a new moon.

9. Phases of the Moon After the new moon comes the waxing
crescent. (a crescent
shape can be seen
lit on the right side).

10. Phases of the Moon
After the waxing crescent comes a first quarter moon in which the right half of the moon appears lit.

11. Phases of the Moon Following the first quarter is the waxing gibbous
The moon is in
gibbous phase when
more than half of
it is lit.

12. Phases of the Moon
Following waxing gibbous is the full moon phase in which the entire side of the moon facing Earth appears lit.
From full moon the cycle moves to waning gibbous – The bulge appears on the left.

13. Click photo for video
From waning gibbous, the moon moves into 3rd quarter – the left half of the moon appears lit.
From 3rd quarter the moon moves into waning crescent, and finally back to new moon.

14. Eclipses
A lunar eclipse occurs when the Earth passes between the Moon and the Sun, and the Earth's shadow obscures the moon or a portion of it.
Only occur during full moon phases when Earth is between the sun and moon

15. Eclipses
A solar eclipse occurs when the Moon passes between the Earth and the Sun, blocking all or a portion of the Sun.

16. Umbra and Penumbra
Because the Sun appears as a disk ~1/2° across, Sun shadows are fuzzy rather than sharp.
This means shadows cast by the Earth & Moon are two-part shadows:
The Umbra - Inner core of total darkness The disc of the Sun is completely blocked.
The Penumbra - Outer, partial shadow Sun's disc is only partly blocked, with a bit peeking over the edge.

18. Click for Eclipse Video