A look at our nearest neighbor in Space! The Moon Free powerpoints at

What is the Moon? A natural satellite One of more than 96 moons in our Solar System The only moon of the planet Earth

Location, location, location! About 384,000 km (240,000 miles) from Earth 3,468 km (2,155 miles) in diameter (about ¼ the size of Earth) Apollo astronauts left retro-reflectors on the Moon to precisely measure the distance.

LUNAR DIMENSIONS EarthMoon Radius6,371,000m1,737,400m Mass5.972x10 24 kg7.347x10 22 kg Volume Density Surface gravity

LUNAR DIMENSIONS EarthMoon Radius6,371,000m1,737,400m Mass5.972x10 24 kg7.347x10 22 kg Volume1.083x10 21 m *10 19 m 3 Density5.51x10 3 kg/m 3 or 5.51g/cm x10 3 kg/m 3 or 3.34g/cm 3 Surface gravity9.81m/s m/s 2

Birth of the Moon “Born” 4-5 billion years ago Formed from impact of Mars-sized planetiod (baby planet) on Earth. This ripped away the Earth’s mantle and coalesced (melted together) to form the moon. Accretion theory

What else about the Moon… In lunar rocks, the ratio of oxygen isotopes are the same as on Earth. This is evidence that the Moon formed at the same time as Earth. In lunar rock, the rocks were extremely dry suggesting the Moon couldn’t have formed side by side with the Earth.

The Moon’s Surface No atmosphere No liquid water Extreme temperatures –Daytime = 130  C (265°F) –Nighttime = -190  C (-310  F) 1/6 Earth’s gravity

Lunar Features - Highlands Mountains up to 7500 m (25,000 ft) tall Rilles (trenchlike valleys)

Lunar Features - Craters Up to 2500 km (1,553 miles) across Most formed by meteorite impact on the Moon Some formed by volcanic action inside the Moon

Lunar Features - Maria Originally thought to be “seas” by early astronomers Darkest parts of lunar landscape Filled by lava after crash of huge meteorites on lunar surface 3-4 billion years ago Mostly basalt rock

Movements of the Moon Revolution – Moon orbits the Earth every 271/3 days The moon rises in the east and sets in the west The moon rises and sets 50 minutes later each day Rotation – Moon turns on its axis every 27 days Same side of Moon always faces Earth – Tidally locked!

TIDAL LOCKING Note that the Moon always shows the same face to the Earth. This occurs over millions and billions of years as a result of torque between two orbiting bodies. So a day on the Moon lasts just as long as it takes the Moon to revolve around the Earth. In effect, a lunar day = a lunar year! 33 moons in the solar system are confirmed to be tidally locked, and many smaller ones probably are.

TIDAL LOCKING

Far Side of the Moon First seen by Luna 3 Russian space probe in 1959 Surface features different from near side –More craters –Very few maria –Thicker crust

It’s Just a Phase Moonlight is reflected sunlight Half the moon’s surface is always reflecting light From Earth we see different amounts of the Moon’s lit surface The amount seen is called a “phase”

PHASES

Waxing and Waning New moon Waxing Crescent moon First Quarter moon Waxing Gibbous moon Full moon Waning Gibbous moon Third Quarter moon Waning Crescent moon New moon

Earth Moon Plane of earth’s orbit Plane of lunar orbit

Lunar Eclipses Moon moves into Earth’s shadow – this shadow darkens the Moon –Umbra –Penumbra About 2-3 per year Last up to 4 hours Remember -moonlight is reflected sunlight – this is why you can still see the Moon during a total lunar eclipse!

Solar Eclipses Moon moves between Earth and Sun Moon casts a shadow on part of the Earth Total eclipses rare – only once every 360 years from one location!

SOLAR ECLIPSES Question: If the Moon revolves around the Earth (spoiler: it does) then why isn’t there a solar eclipse each month? Answer: The plane of the Moon’s orbit is not flat relative to Earth’s orbit around the Sun. So some months there are partial eclipses, and most months no eclipse at all.

The Tides Tides caused by pull of Moon’s gravity on Earth High tide – –Side facing Moon and side away from Moon –Every 12 hours, 25 ½ minutes Low tide – –On sides of Earth

CONSERVATION OF ANGULAR MOMENTUM The Moon is getting further and further away. The Moon’s gravity pulls on the oceans and causes the tides. This motion of the ocean (hey, that rhymes!) creates drag (friction) on the spinning Earth, causing our rotation to slow very slightly. So our day gets slightly longer, year after year. If the Earth’s rotation slows down, then the Earth loses angular momentum to the Moon.

CONSERVATION OF ANGULAR MOMENTUM Angular momentum is one of those physics quantities that can’t be created or destroyed – it is conserved. So if the Moon gains angular momentum then it revolves around the Earth a little faster, and moves into a slightly wider orbit. The Moon is currently receding at 38mm/yr. Eventually it will move far enough away that total solar eclipses no longer happen.

CONSERVATION OF ANGULAR MOMENTUM Students having fun!

Genesis Rock This rock sample was collected during the Apollo 15 mission by David Scott and James Irwin. It is an anorthosite, a sparkly rock composed of little else but the mineral feldspar. The crystals showed that the rock had been metamorphosed by great heat, demonstrating the lunar surface was once completely molten at one time. Important because it helps us in understanding the origin of the Moon’s crust, the rock was nicknamed the “genesis rock.”

“Genesis Rock" returned by the Apollo 15 lunar mission

Photo resources tmhttp:// tm ery-moon.html#apollohttp://nssdc.gsfc.nasa.gov/photo_gallery/photogall ery-moon.html#apollo n.htmlhttp://cass.jsc.nasa.gov/pub/research/clemen/cleme n.html ate/ ate/ pxmoon.htmlhttp://seds.lpl.arizona.edu/nineplanets/nineplanets/ pxmoon.html

More photo resources movies_index.htmlhttp:// movies_index.html pses/article_99_1.asphttp://skyandtelescope.com/observing/objects/ecli pses/article_99_1.asp em/moon_nss_ htmlhttp:// em/moon_nss_ html

This powerpoint was kindly donated to is home to over a thousand powerpoints submitted by teachers. This is a completely free site and requires no registration. Please visit and I hope it will help in your teaching.