The Moon... physical characteristics (teach)

Our Favorite

Little Satellite

The Moon

by Moira Whitehouse PhD

It glows because light from the Sun reflects from the Moon,

Since the Moon, like Earth is a rocky body and it is not on fire, it does not shine.

just as it would from the Earth if we could get far enough away to observe it.

Wikipedia commons

The diameter of the Moon is about ¼ the diameter of the Earth, butbecause it is made from lighter stuff, it is only 1/6 of Earth’s mass.

Although it looks small up there in the sky, the moon is a pretty large hunk ofrock.

Because the Moon’s mass is less , its gravity is also less than Earth’s—about one-sixth as much.Since weight depends on gravity, everything on the Moon would weigh about one-sixth as much as it does on Earth.

If this man weighed 240 lbs on Earth, he would weigh only 40 lbs on the Moon.

This boy weighs 60 pounds on Earth.

On the Moon he would only weigh 10 pounds.

Also, everything you lifted would be much lighter on the Moon that it would be on Earth. However, its mass (the amount of matter in it) would not change.

Astronaut Alan Shepard struck two golf balls with a golf club on the Moon, driving them, as he jokingly put it, "miles and miles and miles."

Because it has less gravity, astronauts made some fantastic jumps on the Moon.

Remember the gravitational pull of the Moon though less than that of the Earth causes water in the oceans to rise and fall resulting in tides.

The following should interest future astronauts: Thinking about being on the Moon…

Water on the Moon?

The landforms on the Moon?Atmosphere on the Moon?

South pole of Moon

Scientists recently found up to a billion gallons of water ice in the floor of a permanently-shadowed crater near the moon's south pole. That's enough, said researchers, to fill 1,500 Olympic-size swimming pools, all from one crater. If there is ice there, it probably exists in other places on the moon as well.

Water???

However, no liquid water or water vapor has been found on the moon.So what are some things that would or would not exist on the moon?

How about:Oceans?

Lakes?

Rivers?

Puddles?

Rain?

Clouds?

Plants?

Animals?

Bacteria?

The Moon has virtually no atmosphere.

Therefore, there is no weather on the Moon, no storms, no rain, no wind, no snow, but the temperature can fluxuate wildly.

The temperature on the Moon ranges from daytime highs of about 130°C = 265°F to nighttime lows of about -110°C = -170°F

Atmosphere???

The fact that the Moon has little or no air or water affects other things on the Moon.For example, there is no wind or water caused weathering, erosion or deposition on the Moon. Things do not erode.This footprint would look the same today as it did 30 years ago.

On the Moon, there is no air, so sound cannot travel above the surface.

The lack of atmosphere also affects sound as we know it. For sound to travel, there must be a medium for the waves to travel through.

When the Apollo astronauts were out on the Moon's surface, they could only talk to each other, and to mission control, by using the radios in their air filled helmets.

On Earth that would usually be air or water.

When the astronaut in the photo hit the moon’s surface with this shovel, no sound was made.

Even during the day time the sky looks black because the atmosphere is not there to scatter sunlight.

Another result of no atmosphere on the Moon:

What is the surface of the Moon like?

The surface of the moon has many landforms on it such as craters, lava plains, mountains, hills and valleys.

On a clear night looking at the moon, one can see that there are two types of topography on its surface—the dark colored regions called the maria and the light-colored highlands that surround the maria.

http://sos.noaa.gov/

Mare

Highlands

Photo of the near side of the Moon

Early astronomers named them maria (Mare, singular), whichmeans seas in Latin because they thought they were holes filled withwater.

The basin or crater created by the collision filled with lava from the Moon’s interior creating these smooth, flat plains we call maria.

http://starchild.gsfc.nasa.gov/

What really happened was that between 3 and 4 billion years ago, meteors hit the surface of the moon making huge depressions.

The flat, dark colored, smooth areas from Earth look like “seas”.

Maria

The highlands are hilly and heavily crateredand cover about 80% of the total lunar surface.

The far side of the Moon is made up almost entirely of highlands with many many craters and very few of the dark smooth basins called maria.

Highlands

Both the near and the far side of the Moon have craters. However, the far side has many more craters than the near side.

The vast majority of the moon's craters were formed by the impact of meteoroids, asteroids, and comets that over billions of years bombarded its surface.

Craters range in size from a diameter of less than one mile to over 100 miles across.

A crater consists of a thin elevated ring forming its perimeter.

The surface within the ring is below the surrounding edge and in the center there is often a peak.

The oldest basins are more irregularly shaped; the younger ones a more circular shape.

Möltke – a small bowl-shaped crater

Sabine and Ritter larger, more flattened craters

Sea of Tranquility

Most are either

How did the mountains form on the Moon?

1. rims or remains of rims of huge craters

or

2. peaks in the middle of huge craters

http://www.enchantedlearning.com

Here we see a diagram of the crater rim and the central peak of a huge impact crater on the Moon.

Rim of a huge crater

Peak in the middle of a huge crater

The prominent Sculptured Hills were photographed by astronauts Schmitt and Cerman on Apollo 17. Although these hills are quite impressive, the highest mountains on the moon are 15,000 to 20,000 feet high.

Earth has been more heavily impacted by meteoroids, asteroids and comets than the Moon.However, presently the Earth has only a few craters compared to the Moon .

There are two main reasons for the low number of craters on Earth.One is that most meteoroids burn up before they reach the surface of the Earth.The other is that the wind and water erode any craters that have formed so most are erased.

Whereas the Earth’s surface is constantly changing, the Moon’s surface has changed little over billions of years.

Astronaut Harrison Schmitt collecting rocks from the Moon during the Apollo XVII mission.

Does the Moon’s surface have rocks?

Big ones and small ones. The astronauts brought back some of the smaller ones.

Here are pictures of two moon rocks they brought back. The composition of these rocks is similar to Earth rocks. This makes scientists think that the Moon was once part of Earth. The only thing

about these rocks that changed when they were brought to Earth was their weight-- they weigh more on Earth than they did on the Moon.

What about soil? Does the Moon have soil?

Like Earth, the Moon has a layer of soil but it is very different than the soil found on Earth.

The lunar landscape is covered by a layer of ground-up, fine powdery cinder-like pieces of rock. This "lunar soil” contains no water or organic material. It has been built up over billions of years by the continuous bombardment of the Moon by large and small meteors, asteroids or comets not by weathering and erosion.

Astronaut Edwin E. "Buzz" Aldrin, Jr., lunar module pilot of the first lunar landing mission, is beside the U.S. flag during an Apollo 11 moon walk. The footprints of the astronauts are clearly visible in the soil of the moon.

After the earlier period when the maria were being formed (3.5-4.5 billion years ago), the surface of the Moon has not changed very much.There are some moonquakes which cause occasional landslides.The daily heating and cooling of rocks breaks up the rock but at a very slow rate.Since that time meteors have hit the Moon but very few compared the heavy bombardment in its early history.

A brief review

Name these features.

Name these features.

Craters

Maria

So how is the Moon like Earth?

And how is it different from Earth?