MOONMOON

What is Moon?What is Moon?

A natural satelliteA natural satellite

The most prominent feature in the The most prominent feature in the skysky

One of more than 96 moons in our One of more than 96 moons in our Solar SystemSolar System

The only moon of the planet EarthThe only moon of the planet Earth

CHARACTERISTICSCHARACTERISTICS

Table 17.1 FACTS ABOUT THE MOONTable 17.1 FACTS ABOUT THE MOON

Mean distance from the earth’s center 238, 900 miles(384, 000 km)

Maximum distance from the earth’s center (apogee) 252, 000 mi (406, 000 km)

Minimum distance from the Earth’s center (perigee) 226, 000 mi (363, 000 km)

Diameter (about ¼ of the Earth’s) 2, 160 miles (3, 476 km)

Sidereal month (time to orbit Earth) 27.322 days

Synodic month (days between new moons) 29.531 days

Rotation on axis One every sidereal month

Gravity About 1/6 of earth’s

Temperature range at surface 243°F to 215°F

The moon moves about the Earth at an average distance of 238, 857 miles and an average speed of about 3.700 km/hr

Does the moon has its Does the moon has its own light ?own light ?

The percentage of light reflected by the moon is known as its ALBEDO.

The moon reflects into space only 7% The moon reflects into space only 7% of the light that falls on it. of the light that falls on it.

The earth’s surface is a much better The earth’s surface is a much better reflector. The albedo of the earth is reflector. The albedo of the earth is measured to be 33, which means the measured to be 33, which means the earth reflects 33 % of the sunlight earth reflects 33 % of the sunlight that falls on it.that falls on it.

Albedo of the Earth

During midday on the moon, During midday on the moon, when the sun is directly when the sun is directly overhead, the temperature is overhead, the temperature is 100°c.100°c.

During midnight, this temperature During midnight, this temperature drops to about -116°cdrops to about -116°c

STRUCTURE OF THE STRUCTURE OF THE MOONMOON

The moon has dark regions which The moon has dark regions which ancien observers believed as ancien observers believed as oceans.oceans.

This gave rise to the Latin name This gave rise to the Latin name “mare” or sea.“mare” or sea.

STRUCTURES SEEN ON THE STRUCTURES SEEN ON THE SURFACE OF THE MOONSURFACE OF THE MOON

CRATERSCRATERS

BAILLYBAILLY

The largest distinct crater, about The largest distinct crater, about 295 km (about 183mi) wide and 295 km (about 183mi) wide and 13, 000 ft deep13, 000 ft deep

MARE IMBRIUMMARE IMBRIUM

The largest mare or sea which is about 1200 km wide.

DOES THE MOON HAVE DOES THE MOON HAVE AN ATMOSPHERE?AN ATMOSPHERE?

PHASES OF THE MOONPHASES OF THE MOON

TIDES

SPRING TIDES when the range of the tide is

largest

NEAP TIDESwhen the range is smallest

The tides are due mainly to the moon’s gravitational pull on the Earth’s oceans.

THEORIES ON THE THEORIES ON THE ORIGIN OF THE MOONORIGIN OF THE MOON

FISSION THEORYFISSION THEORY

BINARY ACCRETION BINARY ACCRETION THEORYTHEORY

THE CAPTURE THEORYTHE CAPTURE THEORY