moon

interior of the moon

Like Earth, the Moon has a distinct crust, mantle, and core. What is known about the Moons interior was determined from the analysis of rock samples gathered by astronauts and from unmanned spacecraft sent to the Moon (Figure The Moons small core, 600 to 800 kilometers in diameter, is mostly iron with some sulfur and nickel. The mantle is composed of the minerals olivine and orthopyroxene. Analysis of Moon rocks indicates that there may also be high levels of iron and titanium in the lunar mantle. A close-up of the Moon, showing maria (the dark areas) and terrae (the light areas); maria covers around 16% of the Moons surface, mostly on the side of the Moon we see. LCROSS crashed into the Moon in May 2009. This QUEST video describes the mission. After watching, look up the mission to see what they found! Click image to the left or use the URL below. URL: Click image to the left or use the URL below. URL:

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the lunar surface

The Moon has no atmosphere. Since an atmosphere moderates temperature, the Moons average surface temperature during the day is approximately 225 F, but drops to -243 F at night. The coldest temperatures, around -397 F, occur in craters in the permanently shaded south polar basin. These are among the coldest temperatures recorded in the entire solar system. Earths landscape is extremely varied, with mountains, valleys, plains and hills. This landscape is always changing as plate tectonics builds new features and weathering and erosion destroys them. The landscape of the Moon is very different. With no plate tectonics, features are not built. With no atmosphere, features are not destroyed. Still, the Moon has a unique surface. Lunar surface features include the bowl-shaped craters that are caused by meteorite impacts (Figure 1.2). If Earth did not have plate tectonics or erosion, its surface would also be covered with meteorite craters. Even from Earth, the Moon has visible dark areas and light areas. The dark areas are called maria, which means seas because thats what the ancients thought they were. In fact, the maria are not water but solid, flat areas of basaltic lava. From about 3.0 to 3.5 billion years ago the Moon was continually bombarded by meteorites. Some of these meteorites were so large that they broke through the Moons newly formed surface. Then, magma flowed out and filled the craters. Scientists estimate this meteorite-caused volcanic activity on the Moon ceased about 1.2 billion years ago, but most occurred long before that. The lighter parts of the Moon are called terrae or highlands (Figure 1.3). The terrae are higher than the maria and A crater on the surface of the Moon. include several high mountain ranges. The terrae are the light silicate minerals that precipitated out of the ancient magma ocean and formed the early lunar crust. There are no lakes, rivers, or even small puddles anywhere to be found on the Moons surface, but water in the form of ice has been found in the extremely cold craters and bound up in the lunar soil. Despite the possible presence of water, the lack of an atmosphere and the extreme temperatures make it no surprise to scientists that the Moon has absolutely no evidence of life. Life from Earth has visited the Moon and there are footprints of astronauts on the lunar surface. With no wind, rain, or living thing to disturb them, these footprints will remain as long as the Moon exists. Only an impact with a meteorite could destroy them.

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lunar characteristics

The Moon is Earths only natural satellite, a body that moves around a larger body in space. The Moon orbits Earth for the same reason Earth orbits the Sun gravity. The Moon is 3,476 km in diameter, about one-fourth the size of Earth. The satellite is also not as dense as the Earth; gravity on the Moon is only one-sixth as strong as it is on Earth. An astronaut can jump six times as high on the Moon as on Earth! The Moon makes one complete orbit around the Earth every 27.3 days. The Moon also rotates on its axis once every 27.3 days. Do you know what this means? The same side of the Moon always faces Earth, so that side of the Moon is what we always see in the night sky (Figure 1.1). The Moon makes no light of its own, but instead only reflects light from the Sun. (a) The near side of the Moon faces Earth continually. It has a thinner crust with many more maria (flat areas of basaltic rock). (b) The far side of the Moon has only been seen by spacecraft. It has a thicker crust and far fewer maria (flat areas of basaltic rock).

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instructional diagrams

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questions

the moons light is due to

a) nuclear fusion in its core.

b) reflected light from earth.

-->  c) reflected light from the sun

d) none of the above

the moon orbits earth every 27.3 days and rotates on its axis once every 27.3 days. this means

-->  a) the same side of the moon is always facing earth.

b) a lunar day is the same length of time as an earth day.

c) a lunar month is the same length of time as an earth month.

d) none of these.

the moon is earths only natural satellite.

-->  a) true

b) false

many of the lunar craters are due to volcanic eruptions.

a) true

-->  b) false

the moon has extreme temperatures because it has no

a) gravity

-->  b) atmosphere

c) night and day cycle

d) weathering and erosion

the footprints of astronauts on the moon could

a) be erased by weathering and erosion.

b) be erased by plate tectonics.

-->  c) be erased by a meteorite impact.

d) any of the above.

the lunar maria are _ that formed when _.

a) felsic silicate rocks; silicate minerals precipitated out of the ancient magma ocean.

b) felsic silicate rocks; violent volcanic eruptions created the rock.

c) basalt; convection in the mantle caused volcanic eruptions.

-->  d) basalt; meteorites caused volcanic eruptions.

the moons interior the same as earths interior; the same rock and metal make up the mantle and core in the same proportions.

a) true

-->  b) false

which of the following is true about the moons interior?

a) the core is large relative to earths core.

b) the composition of the moons mantle and core are very different from earths.

-->  c) the moons mantle and core are made of mafic rock and metal, respectively.

d) all of the above.

which of the following is true about the moons crust?

-->  a) it is a lot thicker on the far side than on the near side.

b) it is composed of the minerals olivine and orthopyroxene.

c) it is all the same age.

d) all of these.

diagram questions

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