The Moon

Facts:• Called Luna by the Romans• Selene and Artemis by the Greeks• 2nd brightest object in sky after the Sun. • Orbits around Earth once per month.• The angle between the Earth, Moon and

Sun changes; • We see this as the Moon's phases.

Phases• New Moon to New Moon is 29.5 days

(709 hours), • Different than the sidereal orbital

period of 27.3 days (measured against the stars).

A Terrestrial Planet?• Due to its size and composition;• sometimes classified as a terrestrial

"planet" along with • Mercury, • Venus, • Earth, & • Mars.

Spacecraft• First visited by the Soviet spacecraft Luna 2 in

1959. • Only extraterrestrial body visited by humans. • First landing was on July 20, 1969.• Last was in December 1972. • The first of two bodies in which samples have

been returned to Earth.• Other being from comet Wild 2,

Collected 2004 - Returned 2006.

The Luna Probe

Luna Missions• Luna 1 1/2/59 Lunar flyby Passed over the Moon at 5000-6000 kilometers on 1/4/59 • Luna 2 9/12/59 Lunar landing Impacted Moon 9/13/59 at 22:02:04 UT

Palus Putredinis, 29.10°N lat., 0.0° long.• Luna 3 10/4/59 Lunar flyby Photographed the farside of the Moon on 10/7/59 • Luna 9 1/31/66 Lunar landing Landed on Moon 2/3/66 at 18:44:52 UT

Oceanus Procellarum, 7.08°N lat., 295.63°E long. • Luna 10 3/31/66 Lunar orbiter Entered lunar orbit on 4/3/66• Luna 11 8/24/66 Lunar orbiter Entered lunar orbit on 8/28/66• Luna 12 10/22/66 Lunar orbiter Entered lunar orbit on 10/25/66 and returned images • Luna 13 12/21/66 Lunar landing Landed on Moon 12/24/66 at 18:01:00 UT

Oceanus Procellarum, 18.87°N lat., 297.95°E long. • Luna 14 4/7/68 Lunar orbiter Entered lunar orbit on 4/10/68 Luna 14 • Luna 15 7/13/69 Lunar lander Crashed on Moon 7/21/69 at 15:51 UT

Mare Crisium,17°N lat., 60°W long.Believed to have been an attempted sample-return mission, similar to Luna

16, 20, and 24

Luna Missions• Luna 16 9/12/70 Lunar sample return Landed on Moon 9/20/70 at 05:18:00 UT

Mare Fecunditatis, 0.68°S lat., 56.30°E long• Luna 17 11/10/70 Lunar lander Landed on Moon 11/17/70 at 03:47:00 UT

Mare Imbrium, 38.28°N lat., 325.00°E long.Lunar Rover - Lunokhod 1

• Luna 19 9/28/71 Lunar orbiter Entered lunar orbit on 10/3/71 and returned images • Luna 20 2/14/72 Lunar landing Landed on Moon 2/21/72 at 19:19:00 UT

Mare Fecunditatis, 3.57°N lat., 56.50°E long.Lunar sample return to Earth 2/25/72

• Luna 21 1/8/73 Lunar landing Landed on Moon 1/15/73 at 23:35:00 UTMare Serenitatis, 25.51°N lat., 30.38°E long.Lunar Rover - Lunokhod 2

• Luna 22 6/2/74 Lunar orbiter Entered lunar orbit around 6/3/74 and returned images• Luna 24 8/14/76 Lunar sample return Landed on Moon 8/18/76 at 02:00:00 UT

Mare Crisium, 12.25°N lat., 62.20°E long.

Lunar transfer orbits. (NASA) Spacecraft modules: CM, command module; CSM, command-service module; LM, lunar module; SM, service module; S-IVB, Saturn IVB.

Apollo 1 Saturn IB • Grissom, White, Chaffee • No LM • February 21, 1967 (Planned) • Unlaunched - On January 27, 1967

Gus Grissom, Edward White, and Roger Chaffee were killed when a fire erupted in their Apollo spacecraft during a test on the launch pad.

Apollo 7 Saturn IB• Schirra, Eisele, Cunningham • No LM • October 11, 1968 15:02 GMT • 10d 20h 09m 03s • First manned Apollo flight, first

manned flight of the Saturn IB.

Apollo 8 Saturn V • Borman, Lovell, Anders • No LM • December 21, 1968 12:51 GMT • 06d 03h 00m 42s • First manned flight around the Moon, • first manned flight of the Saturn V.

http://upload.wikimedia.org/wikipedia/commons/e/ec/Saturn_V_diagram_from_Apollo_6_Press_Kit.jpg

Apollo 9 Saturn V • McDivitt, Scott, Schweickart • LM - Gumdrop Spider • March 3, 1969 16:00 GMT • 10d 01h 00m 54s • First manned flight of the Lunar

Module.

Apollo 10 Saturn V • Stafford, Young, Cernan • CM - Charlie Brown • LM - Snoopy • May 18, 1969 16:49 GMT • 08d 00h 03m 23s • First manned flight of the Lunar

Module around the Moon.

Apollo 11 Saturn V • Armstrong, Collins, Aldrin • CM - Columbia • LM - Eagle • July 16, 1969 13:32 GMT • 08d 03h 18m 35s • First manned landing on the Moon,

July 20.

Apollo 12 Saturn V • Conrad, Gordon, Bean • CM - Yankee Clipper • LM - Intrepid • November 14, 1969 16:22 • GMT 10d 04h 36m 24s • First precise manned landing on the Moon.

• Recovered part of Surveyor 3 probe.

Apollo 13 Saturn V• Lovell, Swigert, Haise • CM - Odyssey • LM - Aquarius • April 11, 1970 19:13 GMT • 05d 22h 54m 41s • Oxygen tank exploded en route, forcing

cancellation of landing. • First (to date) manned non-orbital lunar

flight.

Apollo 14 Saturn V• Shepard, Roosa, Mitchell • CM - Kitty Hawk • LM - Antares January 31, 1971 21:03 GMT • 09d 00h 01m 58s • Alan Shepard, the sole astronaut of the

Mercury MR-3 mission - and thus the first American in space - walks (and plays golf) on the Moon.

Apollo 15 Saturn V• Scott, Worden, Irwin • CM - Endeavour • LM - Falcon • July 26, 1971 13:34 GMT • 12d 07h 11m 53s • First mission with the Lunar Rover

vehicle.

Apollo 16 Saturn V• Young, Mattingly, Duke • CM - Casper • LM - Orion • April 16, 1972 17:54 • GMT 11d 01h 51m 05s • First landing in the lunar highlands.

Apollo 17 Saturn V • Cernan, Evans, Schmitt • CM - America • LM - Challenger • December 7, 1972 05:33 GMT • 12d 13h 51m 59s • Final Apollo lunar mission, first night

launch, only mission with a professional geologist.

Spacecraft• 1994 - very extensively mapped by

the spacecraft Clementine • 1999 – again by Lunar Prospector. • 2007 – Lunar Reconnaissance

Observer• 2013 – LADEE (Lunar Atmosphere

and Dust Environment Explorer)

Why the Same side Towards Earth?

• Tides slowing of Earth's rotation by 2 milliseconds/century.

• This reduces the energy associated with the Moon’s orbit.

• It then raises the Moon into a higher orbit by about 3.8 centimeters per year.

Tidal Lock• Eventually, the Earth's rotation will be

slowed to match the Moon's period.• As is the case with Pluto and Charon.

Librations• The Moon appears to wobble a bit

(due to its slightly non-circular orbit).• A few degrees of the far side can be

seen.• The majority of the far side was

completely unknown until the Soviet spacecraft Luna 3 photographed it in 1959.

How much of the moon can be observed from Earth?

• About 65% ?????• Librations help tilt Moon a bit• Different observing locations on Earth

(North - South)• Different time observed (East - West

motion of observing location)• Inclination of Moon’s orbit. Sometime we

observe from below, sometimes from above.

The Dark Side• There is no "dark side" of the Moon• All parts of the Moon get sunlight half

the time...• except for a few deep craters near the

poles.

Water? • Clementine suggested that there may

be water ice in some deep craters near the Moon's south pole which are permanently shaded.

• Reinforced by the Lunar Prospector. • There is apparently ice at the north

pole as well.

Moon Interior - Crust• Averages 68 km thick• Varies from essentially 0 km under

Mare Crisium to 107 km near the crater Korolev on the lunar far side.

Moon Interior - Mantle• Found below the Crust

Moon Interior – Core?• Maybe a small core, 340 km radius

and 2% of the Moon's mass.

Moon Interior • The Moon's interior is no longer

active. • Curiously, the Moon's center of mass

is offset from its geometric center by about 2 km in the direction toward the Earth.

• Also, the crust is thinner on the near side.

Lunar Terrain• Two types:• Heavily cratered and very old

highlands

Relatively bright areas when observed with eye or telescope

• Relatively smooth and younger maria

Relatively dark areas

Terrain• The maria (16% of the Moon's

surface) are huge impact craters, later flooded by molten lava.

• They are concentrated on the near side.

Regolith• Most of the lunar surface is covered

with regolith….• a mixture of fine dust and rocky

debris produced by meteor impacts.

Moon Color• This is the Moon's true colors! If our eyes were able to detect the subtle color differences, this is what we would

see.  The colors are due to different chemical makeup of the moon's crust. Specifically, lavas low in Titanium (TiO2) are red, while lavas with high TiO2 content are blue.  I stole this from: www.coronaborealis.org/.../full_moon_color.html

Crater Names• Most are famous figures in the history

of science such as • Tycho,

Copernicus, and • Ptolemaeus.

Crater Names• Features on the far side have more

modern, mostly Russian biased references such as…

• Gagarin and • Korolev.

The Big Ones:• The Moon also has the huge craters:• South Pole-Aitken - on the far side which

is 2250 km in diameter and 12 km deep • That makes it the largest impact basin in

the solar system. • Orientale - on the western limb.• A splendid example of a multi-ring crater.

Moon Samples• 382 kg of rock samples were returned to

the Earth by the Apollo and Luna programs. Provide most of our detailed knowledge of the Moon.

• Particularly valuable being in that they can be dated.

• Over 30 years after the last Moon landing, scientists still study these samples.

Age• Most rocks on the surface seem to be

between 4.6 and 3 billion years old. • Matches oldest Earth rocks ~ 3 billion

years old. • Provides evidence about the early

history of the Solar System not available on the Earth.

Origin• Prior to the study of the Apollo

samples, there was no consensus about the origin of the Moon.

• There were three principal theories:

Co-Accretion • Asserts that the Moon and the Earth

formed at the same time from the Solar Nebula;

Fission • Asserts that the Moon split off of the

Earth;

Capture • Moon formed elsewhere and was

subsequently captured by the Earth.

• However;• None of these work very well.• They each have their own problems.• New and detailed information from

the Moon rocks lead to the

Impact Theory: • Earth collided with a very large object

(as big as Mars or more)• The Moon formed from the ejected

material. • Details always being worked out, but

theory is now widely accepted.

Magnetic Field• No global field. • Some surface rocks exhibit remnant

magnetism • Indicates there may have been a field

early in the Moon's history.

Atmosphere• Very thin---almost a pure vacuum.• Only particles and atoms from the

Sun and gases expelled from the lunar rocks and soil.

• These particles don’t hit the Earth’s surface because of our atmosphere.

Solar Wind Studies• The Moon's surface is exposed

directly to the solar wind. • Over 4 billion years many ions from

the solar wind have become embedded in the Moon's regolith.

• Samples of returned by the Apollo missions proved valuable in solar wind studies.