Earth’s Moon

The Lunar Satellite

· Moon is Earth’s natural satellite

Diameter is ~3476 km

Gravity is 1/6^th of the Earth’s

- A person would only weigh 1/6^th of their Earth’s weight on the Moon

Moon has moonquakes- moons interior is similar to Earth’s

The Lunar Surface

· Moon is barren and lifeless

· Temps range from 130°C to -175°C

· no atmosphere= no weather

· Galileo

o First to look at the Moon with a telescope ~ 400 years ago

o Maria

§ Dark regions on the moon- long, flat plains

o Rilles

§ Long valleys cutting across the Maria

o Craters

§ Moon is covered with craters from meteorites (rocks from space hitting the surface)

§ Similar ones from ancient volcanic eruptions!

o Highlands

§ Mountainous terrain on the Moon

Moon’s Movements

· Moon has an elliptical orbit around the Earth

· Closed point to Earth: perigee Farthest point to Earth: apogee

· Moons revolution is the same as its rotations!

o ~27.3 days

o Since revolution and rotation are equal, we always see the same side of the moon

Origin of the Moon

· Daughter Theory

o Piece of Earth split off to form the Moon

§ Doesn’t explain why Moon is not composed of only Earth’s crust

§ no evidence to suggest Earth ever spun fast enough to eject a large mass

· Sister Theory

o Earth and Moon formed from gas/dust during formation

§ Can’t account for the differences in materials on Moon and Earth

· Capture Theory

o Earth captured Moon as Moon flew by!

§ No evidence

· Most Accepted Theory: Impact Theory

o Impact knocked large amount of Earth into space, Earth’s gravity captured the material and the Moon formed

Exploration of the Moon

· 1959: Luna 3 (Russia) first space craft to photograph the Moon

· 1967-1972: Apollo Program, America’s Moon program

o Landed on the Moon 6x from 1969-1972

Earth-Moon System

Phases of the Moon

· Moon is visible due to reflecting light off surface (use book to fill in)

New Moon- No moon visible

Waxing- moon is increasing in size

Gibbous- more than ½ the moon is lit

Full Moon- entire moon is lit

Waning- moon begins to shrink in size

Eclipses

· When one planet passes between the Sun and another body, it casts a shadow called an eclipse

· Umbra: light is completely blocked out

Penumbra: partial shadow where some light is blocked and other light fills it in

· Lunar Eclipse

o Moon moves into Earth’s shadow

o Earth’s shadow blocks sunlight from Moon

· Solar Eclipse

o Moon passes between sun and Earth

o Moon’s shadow falls on Earth, only covers small area

Tides

· Moons gravitational pull causes water of Earths oceans to rise

o Sea level rises and falls= tides

o Tides change ~ every 6 hours