Myths about the Moon
The Moon is made of cheese!
There is a Man in the Moon.
The Moon and the Sun chase each other across the sky.
The Moon disappears during certain days of the month.
There are men or other creatures living on the Moon.
The Moon was put in the sky by a person or animal.
The Moon is a living creature or a god.
The Moon controls how we act and how we feel.
During a full moon, some people turn into werewolves.
The Moon is pulled across the sky by a person, animal, or force.

Myths
• Greek goddess Artemis, roman goddess Diana

Myths
• Chinese mythology: Chang’e
• Moon festival

• The current standard calendar is solar calendar
(Gregorian calendar) – counting days
• The moon phases have a period of 29.5 days, a good measure of time
• Lunar calendars – counting days and months
• E.g. Islamic calendar is a lunar calendar
• 29.5 * 12 = 354, 11 days less than 365
• Lunisolar calendar – Chinese calendar, Hebrew calendar
• Adding leap months, with a circle of 19 years

• The earth’s only natural satellite
• Orbit around the earth is an eclipse
• Average distance from the earth to the moon is 384,403 kilometers
(238,857 miles) – 30 times the diameter of the earth
• Diameter of 3,474 km, ¼ of the earth
• Gravity 1/6 of the earth

• The orbit period around the earth – 27.3 days
• The spin period is exactly the same!
• We always see the same side of the moon!
( precisely speaking 59% of the surface during the whole period of the moon revolution.
Reason: libration)
• The period of Lunar Phase – 29.5 days
• Because of the earth’s revolution in the space
• The orbit plane of the moon is tilted by ~5 degree with respect to the earth’s orbit around the sun, unlike other planets

• The orbit plane of the moon is tilted by ~5 degree with respect to the earth’s orbit around the sun, unlike other planets

Near Side Far Side

Highland
Maria
Crater
• Maria (sigular mare, ‘sea’ in Latin)
– Dark areas and were thought to be seas
– Cover 31% of the near side, but only
2% of the far side
– No water but vast pools of solidified lava that flowed into basins formed by comets/metors colliding
– Nomenclature
• Latin terms describing the weather and abstract concepts
– Smaller dark regions
• Lacus (Lake)
• Palus (marsh)
• Sinus" (bay)

Highland
Maria
• Highland
– Lighter color regions, or called Terrae
– Many are impact basins’ outer rims
– In contrast to earth, no major lunar mountains were formed as a result of tectonic events
– Mountains and mountain ranges
– Different brightness of the highlands and maria is because they are composed of different rock types
Crater

• Formed when asteroids/comets hit the lunar surface
• Half a million craters with diameters larger than 1km
• Crater counting – to estimate the age of the lunar surface
• The largest crater is South
Pole-Aitken basin , with 2,240 kms in diameter and 13 kms in depth
• Nomenclature:
– Large craters, deceased famous scientists, artists
– Small craters, common first names • Daedalus, 93 km in diameter
• Proposed as a site for a large radio telescope

Known maria, highlads and craters

• Born from the earth - broke off from the earth by centrifugal forces, and left the pacific ocean behind
• Captured by the earth’s gravity
• Co-formation with the earth
• Giant impact hypothesis
– An impact of a Mars-sized body collide w/ the proto-
Earth and ejected materials to orbit around the earth – the Moon

• Ancient people observed the moon by naked eyes, and wrote poems and essays, and told myths
• Galileo first observed the moon using an telescope
• The only celestial body the human being has orbited and landed
– First impact: Luna 2 of Soviet Union in 1959
– First far side picture: Luna 3 in 1959
– First soft landing: Luna 9 in 1966
– First men’s step on the moon: Apollo 11 in 1969

• Why does the moon change phases?
• Lunar phases are the result of our eyes seeing the illuminated half of the Moon from different viewing geometries
• Due to the Moon’s orbital positions

Complete this
Say, Sun rises at 6am and sets at 6pm
Moon Phase
New Moon
Waxing Crescent
First Quarter
Waxing Gibbous
Full Moon
Waning Gibbous
Third Quarter
Waning Crescent
Moon Rise Time
Sunrise/6am
9am
12pm
3pm
6pm
9pm
12am
3am

When new moon occurs, what is the phase of the earth if you stand on the moon?
Full earth!
The earth always has an opposite phase to the moon.

• Have you seen eclipses?
• What are eclipses in nature?
– One celestial object casts its shadow on the other one

• Sun – the shadow of the moon on the earth
Total solar eclipse in 1999

A – total eclipse
B – annular eclipse
C – partial eclipse

• Moon – the shadow of the earth on the moon

What’s the moon phase when a solar eclipse occurs?
New Moon
What’s the moon phase when a lunar eclipse occurs?
Full Moon

Why aren’t there solar eclipses and lunar eclipses on EVERY new moon and full moon?

Two conditions must be satisfied for an eclipse to occur
1. The nodes of the moon’s orbit must be nearly aligned with the Sun and the
Earth
2. The phase of the moon must be new or full

• Every year there are at least two lunar eclipses
• Lunar eclipses and solar eclipses always come in pairs
• Lunar eclipses can be seen everywhere on the earth, but the solar eclipses may only be seen on part of the earth

Solar eclipses