The Moon

Theories on moon’s creation

• The Fission Theory: – Part of earth– Thrown out due to extreme rotation– Basin in Pacific Ocean – Earth’s gravity pulled it in– Composition resembles earth’s composition

• 2. Capture Theory – – Moon made in solar system– Came into contact with earth’s gravitational field– Pulled into orbit around earth

• 3. Condensation Theory –– both condensed from gases at the beginning of

the solar system

• 4. Giant Impact Theory – ( most believed)– Small planet impacted earth after it was first made– Material was thrown into space– Material congealed to make a small planetoid – Earth’s gravity captured the small planetoid to

orbit earth

Moon rocksRocks made of basalt from

volcanic eruptions and minerals, such as plagioclase feldspar and olivine,

No organic materials

It's gray with very fine grained particles like sand or even dust and extremely dry because there is no water on the moon

Lunar Breccia

• These fragments are the white pieces visible in the rock and are composed of feldspar.

• feldspar, pyroxene, and olivine.

basalt

Moon’s orbit

• Ellipse• Rotation rate: once

every 27.3 days– This keeps one side of

the moon facing the earth at all times

• Revolution rate:– 27.3 days

Moon’s orbit

• Apogee – point in moon’s orbit furthest from earth

• Perigee – point in moon’s orbit closest to earth

Moon phases• Waning moon – moon is

getting smaller

• Waxing moon – moon is getting larger

• Length – 29.5 days– Extra days from revolution

due to position of S E and M to return to starting position

• Tides – Rise and fall of the sea level due to the gravitational pull of the moon and sun on the earth’s waters and solid crust.

• - moon has a greater effect due to its distance to the earth.

Kinds of tides

• Spring tides – when the sun and moon are both on the same side of the earth.

• - high tides

• Neap tides – when the moon and sun are at rt. angles to each other

Gravitational pull is against each other

Low tides

Since the moon moves around the Earth, it is not always in the same place at the same time each day. So, each day, the times for high and low tides change by 50 minutes.

Causes of tides:

• 1. position of moon and sun to earth• 2. gravitational pull of moon and sun on

earth’s waters• 3. rotation of earth in and out of the waters

Moon’s light• Moon light is light reflected

from the sun off the moon’s surface.

• Libration: wiggling of moon in its orbit

• b/c of this we see 59% of the moon.

• http://www.youtube.com/watch?v=3f_21N3wcX8

• Regolith – lunar soil• On the Moon, regolith

occurs as a mixture of powdery dust and broken rock. Lunar regolith is formed by the impact of meteorites on the body’s surface.

• Lunar gravity = 1/6 of earth

• Weight: pull of gravity on an object.

• Mass: amt. Of matter in an obj.

• Since the Moon is smaller, and has much less mass, it pulls with less gravity.

Lunar eclipse• Moon passes into the

shadow of the earth• Umbra – darkest part of the

shadow– complete eclipse

• Penumbra – lighter part of the shadow

• -partial eclipse• Two lunar eclipses each

year• Duration – 1 hour

• Solar eclipse when the earth moves into the moon’s shadow.

• Small area on earth in umbra.

• Total eclipse in umbra• Lasts 8 minutes

• Annular eclipse – when • moon’s shadow does

not touch the earth’s surface.

Solar eclipse

Moon features

• Mares – Lt. seas • smooth dark areas on

moon - lava flows - youngest rocks

• Craters – depressions made from impact of meteors

• Copernicus• Plato• Crater Walls – surround

crater

• Chained craters – craters joined together

• Rays – light colored material extending outward from crater

• - splash material from impact

• Rilles - Rilles are trenches a few kilometers wide and hundreds of meters deep. Straight rilles are faults in the lunar crust whereas sinuous rilles are collapsed lava tubes.

• Wrinkled ridges – found in maria result from cooling

• Domes – small swelling on surface

• - domed volcanoes

• - laccoliths pushing upward

• Mountain ranges- mountains on the moon

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