New 0% Illuminated First Quarter 50% Illuminated on RHS Waxing Gibbous 75% Illuminated on RHS Full 100% Illuminated Third (Last) Quarter 50% Illuminated on LHS Waning Crescent 25% Illuminated on LHS
Rising/Meridian/Setting Times
Lunar Periods Sidereal Period – 27.3 days Synodic Period – 29.5 days - The time between successive alignments of the earth, moon, and the sun
- The period of the cycle of lunar phases
- The moon is entirely inside the earth’s umbra
Partial Lunar Eclipse - The moon is partially inside the earth’s umbra
Penumbral Lunar Eclipse - The moon is inside the Earth’s penumbra
- These happen regularly and no one notices. The brightness of the moon only decreases by 10% to 20%
Solar Eclipses - The moon completely obscures the sun for an observer at this location on the Earth
Partial Solar Eclipse - The moon partially obscures the sun for an observer at this location on the Earth
Annular Solar Eclipse - The moon is near apogee and its angular diameter is insufficient to completely cover the sun. An observer for whom the moon and sun are aligned will see a ring of the sun around the moon
Tides - caused by differential gravitational forces exerted by the moon (the moon pulls more on one side of the earth than the other) Even though the sun’s gravitational force is much larger than the moon’s, its differential force is smaller (since the size of the earth is small compared to the earth-sun distance) This moon’s differential force causes “water bulges” on the earth on both sides of the line to the moon. Tides are caused by the Earth’s rotation carrying observers through a water bulge. Thus, typically high tide occurs twice a day. - Neap Tides – weak tides which occur when the moon’s and sun’s pull are perpendicular
- Spring Tides – strong tides when the moon and sun are aligned.
Dostları ilə paylaş: |