The Moon

Earth’s Moon National Optical Astronomy Observatories composite image

The Moon! What is the Earth’s natural satellite? What does it look like? What is its surface like? Why does it have phases? What are the phases?

What is the Moon? A natural satellite One of more than 171 known moons in our Solar System! There are probably more around the larger planets that have yet to be discovered. The only moon of the planet Earth The Moon is our moon (see the difference?)

Lunar Origin Capture – Once a separate body that was gravitationally captured by Earth. But, requires an interaction of three bodies and is thus very improbable. Fission – Moon split off from a very rapidly rotating young Earth. But, such a rapid rotation probably would have broken Earth into many small bodies Co-formation – Earth and Moon formed together with their final properties. But, they should resemble each other more closely in the chemical and structural properties Impact on Earth of a Mars-sized Planet – Resulted in a fraction of the Earth’s crust and mantle thrown into a region around the Earth. Material then coalesced to form Moon. Best explains lunar properties.

Origins of the moon

Birth of the Moon “Born” 4-5 billion years ago Formed from impact of Mars-sized “planetesimal” on Earth Debris from both objects melted together to form the Moon

Cut to the Core 3 major divisions of the Lunar interior Crust - average thickness of about 70 kilometers Mantle Core - radius is between 300 and 425 kilometers The Moon’s make up is much like the surface layers of the Earth

The Moon’s Surface (you should know this) 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

Theory on Crater Formation Water drop example

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

Likely interior of the Moon The meteor broke through

Moon Earth-facing Side“Far” Side (From Clementine I )

Maria Craters Can you see the rays? Does this photo show us a limb or terminator line?

Region of Tycho and Clavius Craters Photo by H.A. McAlister 29 March 1969

Moon (Copernicus Crater Close-Up) (From Lunar Orbiter ) 93 miles

Moon (Perpetually Shadowed South Pole) (From Clementine I ) 300 km

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”

Movements of the Moon (you should know all of this) 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

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. What might this suggest?

One common misconception is that the Moon is only visible at night. However, the time of day in which the Moon is in our sky varies depending on its phase. This picture clearly displays the Moon, visible during the day.

FULL QUARTER CRESCENT GIBBOUS FOUR MAIN SHAPES

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.

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

Show BrainPop Phases of the Moon

Show BrainPop Eclipses Show BrainPop Eclipses

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

Lunar Eclipse calendar Link

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 Eclipse MapSolar Eclipse Map Hyperlink

Exploring the Moon 1950s to 1960s - probes Neil Armstrong First man on the Moon – July 20, 1969 Six Apollo missions ( ) –382 kg (842 lbs) rocks 12 Americans have walked on the moon

Moon (The Apollo Program) Six Landings Neil Armstrong’s Footprint Apollo Buzz Aldrin Apollo

Name this phase! Full Moon What time does this phase rise and set?

Name these features. Craters Maria

Does this image show us the near side or far side of the moon? Far Side How can you tell?

Is this line the limb or terminator? Limb Terminator

Name this phase! First Quarter

Name this phase! Waxing Crescent

Does this image show the near side or the far side of the moon? Near Side

Name this phase! Waning Gibbous

Name this phase! Third Quarter

From what direction does the moon rise? The East

Name this phase! Waxing Gibbous

Name this phase! Waning Crescent

What might be happening in this image? Lunar Eclipse

Is this line the limb or the terminator? Limb

Name this phase! Look closely! Waxing Gibbous

True or False: The Far Side and the Dark Side of the moon are the same thing. False!

Name this phase! Full Moon

Name this phase! New Moon

Does the moon rise or set in the west? It sets in the west.

Name this phase! Waning Gibbous

Name this phase! Waning Crescent

Name this phase! Waning Gibbous