Moon Properties and Characteristics

Earth Science

Reaching for the Moon1. Plans for a crewed lunar expedition began in

the late 1950s.

The Moon

a) In 1957 the Soviet Union launched the first satellite, Sputnik I.

b) In 1961, Soviet cosmonaut Yuri A. Gagarin became the first human in space.

c) On May 5, 1961, Alan B. Shepard Jr. became the first American in space as part of Project Mercury followed by the two-person crews of Project Gemini.

d) On July 20, 1969, the Apollo program landed Neil Armstrong and Buzz Aldrin on the Moon, during Apollo 11.

The Lunar Surface

The Moon

1) The albedo of the Moon, the amount of sunlight that its surface reflects, is only about 0.07 (7 percent) contrasted with Earth’s average of 0.31 (31 percent).

2) No atmosphere.3) Surface temperatures can range from 400 K (127°C) in

sunlight.4) 100 K (–173°C) where it is dark.

The Lunar Surface

The Moon

5) The surface of the Moon consists of several features:

A) The Highlands are lunar regions that are light in color, mountainous, and heavily covered with craters.

B) The Maria (singular, mare) are lunar regions that are dark, smooth plains, which on average are 3 km lower in elevation than the highlands.

The Lunar Surface

The Moon

– The surface of the Moon consists of several features:

C) Impact craters were formed when objects from space crashed into the lunar surface.

d) Ejecta is material blasted out during impacts that fell back to the surface.

e) Rilles are meandering, valleylike structures that are found in the Maria.

• 6) There is no erosion on the Moon—except for surface creep and wear caused by recent impacts—because it has no atmosphere or flowing water.

– Craters on the Moon are preserved until one impact covers another.

1) Composition

The Moon

– The Moon is made up of minerals similar to those of Earth—mostly silicates.

– The highlands are predominately lunar breccias, which are rocks formed by the fusing together of smaller pieces of rock during impacts.

– The maria are predominately basalts that contain no water.

History of the Moon• Radiometric dating of lunar rocks from the

highlands indicates an age between 3.8 and 4.6 billion years.

The Moon

• 2) Regolith is a layer of loose, ground-up rock on the surface of the Moon that formed as a result of the heavy bombardment during its first 800 million years.

• 3) The maria which are between 3.1 and 3.8 billion years old formed when lava welled up from the Moon’s interior and filled in the large impact basins.

History of the MoonTectonics on the Moon?

The Moon

1 & 2. Although the Moon experiences moderate moonquakes approximately once a year, scientists theorize that the Moon is not tectonically active.

3.. That the Moon has no active volcanoes and no significant magnetic field supports this conclusion.

• The Moon, like Earth, has a layered structure, which consists of the crust, the upper mantle, the lower mantle, and the core.

History of the Moon2. Formation Theories

The Moon

– The capture theory proposes that as the solar system was forming, a large object ventured too near to the forming Earth, became trapped in its gravitational pull, and formed into what is now the Moon.

– The simultaneous formation theory states that the Moon and Earth formed at the same time and in the same general area, and thus the materials from which they formed were essentially the same.

History of the Moon6. Formation Theories

The Moon

– The impact theory is the most commonly accepted theory of how the Moon formed.

– This theory proposes that the Moon formed as the result of a gigantic collision between Earth and a Mars-sized object about 4.5 billion years ago, when the solar system was forming.