Presentation on theme: "Phases of the Moon New 0% Illuminated"— Presentation transcript:
1Phases of the Moon New 0% Illuminated Waxing Crescent 25% Illuminated on RHSFirst Quarter 50% Illuminated on RHSWaxing Gibbous 75% Illuminated on RHSFull % IlluminatedWaning Gibbous 75% Illuminated on LHSThird (Last) Quarter 50% Illuminated on LHSWaning Crescent 25% Illuminated on LHS
2Rising/Meridian/Setting Times PhaseRisingMeridianSettingNew6 amNoon6 pmWaxing Crescent9 am3 pm9 pmFirst QuarterMidnight3 amFullWaning GibbousThird QuarterWaning Crescent*Assuming the moon is always on the celestial equator and above the horizon 12 hours per day.
3Lunar Periods Sidereal Period – 27.3 days Synodic Period – 29.5 days The time between successive alignments of the earth, moon, and a starThe true orbital period of the moonSynodic Period – 29.5 daysThe time between successive alignments of the earth, moon, and the sunThe period of the cycle of lunar phases
4Lunar Eclipses Total Lunar Eclipse Partial Lunar Eclipse The moon is entirely inside the earth’s umbraPartial Lunar EclipseThe moon is partially inside the earth’s umbraPenumbral Lunar EclipseThe moon is inside the Earth’s penumbraThese happen regularly and no one notices. The brightness of the moon only decreases by 10% to 20%
5Solar Eclipses Total Solar Eclipse Partial Solar Eclipse The moon completely obscures the sun for an observer at this location on the EarthPartial Solar EclipseThe moon partially obscures the sun for an observer at this location on the EarthAnnular Solar EclipseThe 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
6Tides- 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 perpendicularSpring Tides – strong tides when the moon and sun are aligned.