MOON

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

CHARACTERISTICS

Table 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 own light ?

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

The moon reflects into space only 7% of the light that falls on it. The earth’s surface is a much better reflector. The albedo of the earth is measured to be 33, which means the earth reflects 33 % of the sunlight that falls on it.

Albedo of the Earth

During midday on the moon, when the sun is directly overhead, the temperature is 100°c. During midnight, this temperature drops to about -116°c

STRUCTURE OF THE MOON

The moon has dark regions which ancien observers believed as oceans. This gave rise to the Latin name “mare” or sea.

STRUCTURES SEEN ON THE SURFACE OF THE MOON

CRATERS

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

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

DOES THE MOON HAVE AN ATMOSPHERE?

PHASES OF THE MOON

TIDES SPRING TIDES when the range of the tide is largest NEAP TIDES when the range is smallest

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

THEORIES ON THE ORIGIN OF THE MOON

FISSION THEORY

BINARY ACCRETION THEORY

THE CAPTURE THEORY