Phases of the moon

You can use your hands and fingers to measure angles in the sky. Fingers ~1/2 degree at arm’s length Fist ~ ?Hand ~ ?

Moon Fact Gives off no light, just reflects light from the sun Moon revolves around the Earth Goes through a regular cycle of phases taking a little more than 29 days Crosses sky at 12° per day

New Moon

Waxing Crescent

1 st Quarter

Waxing Gibbous

Full Moon

Wanning Gibbous

3 rd Quarter

Wanning Crescent

Although the Moon is always lit from the Sun, we see different amounts of the lit portion from Earth depending on where the Moon is located in its month-long orbit.

How long does it take to go from new moon to new moon? 27.3 days 29.5 days How long does it take the Moon to orbit Earth? Synodic monthSidereal month

Affects of the moon Production of tides – Due to gravitational forces between sun and mood Neap Tide – Least deformation of oceans Spring Tide – Greatest deformation of oceans

Eclipses

When the sun and moon line up precisely, we see an eclipse Happens when one celestial body falls on another What you see depends of your position – You are either in the shadow or looking at the shadow

Eclipses occur only when the Moon crosses the ecliptic during the new or full phase

Why Do We Not See Eclipses Twice a Month? Moon Orbits at a 5º angle to the ecliptic

Lunar Eclipse Occurs when the Moon passes through the earth’s shadow Can only occur at a full moon Total eclipse: Moon completely covered Penumbral: shadow of Earth blocks only some of the sunlight Partial: only some of the moon is covered by shadow

Types of Lunar Eclipses total eclipse partial eclipse

Solar Eclipse Occurs when the Moon’s shadow moves across the Earth’s surface – Moon moves in front of the sun – Would occur during the New Moon Annular: most of the sun is covered; umbra does not reach earth Penumbra (partial): only part of the sun is covered Total (Umbra): only the corona of the sun can be seen

Solar Eclipse Annular Eclipse Penumbra Eclipse Total Eclipse