EARTH’S MOONKey Concepts

What features are found on the moon’s surface?What are some characteristics of the moon?How did the moon form?

Key Terms

Telescope Craters Maria meteoroids

The Moon’s Surface Maria – dark, flat areas; hardened rock

formed from lava flows 3-4 billion years ago

Craters – large round pits caused by impacts of meteoroids (chunks of rock or dust from space)

Highlands – light colored features, mountains that cover much of the moon’s surface

9 Main Maria on Near side

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Characteristics of the Moon Distance from Earth – about 384,000 km

Size – 3,476 km in diameter (1/4 Earth’s diameter)

Density - 1/80 the mass of earth, Earth has dense core and less dense outer layers. Whole moon’s density is similar to

Earth’s outer layers.

Characteristics of the Moon Temperature and Atmosphere

– surface = 130C in direct sunlight, -180C at night Reason for such is extremes is

that the moon has no atmosphere

Moon’s surface gravity is so weak that gases escape into space

Water – No liquid water, but evidence of solid (ice) water at poles and in craters where areas are shielded from sunlight and remain frozen

Water on Moon October, 2009 L-CROSS (lunar crater

observation and sensing satellite) probe found significant amounts of water ice (solid water) when it was crashed into the moon’s south pole

Debris from the impact was viewed by lunar reconnaissance orbiter, LRO and other space and ground based telescopes

Chemicals in debris were analyzed by spectrometers which measures light waves absorbed by different chemicals

Origin of the MoonCollision-ring theory –

Present theory that best fits the data a planet sized object (Theia)

collided with the Earth. Materials from the object

and Earth’s outer layers was ejected into orbit around Earth

Formed a ring, gravity eventually caused it to combine and form the moon