Our Moon A Closer look at…

The moon is a “natural satellite”. A satellite is anything that orbits the earth. Artificial satellites have four main uses: –Communications –Monitoring the weather –Observing the Earth –Exploring the solar system

The moon is a cold, dry orb whose surface is studded with craters and strewn with rocks and dust. The moon has no atmosphere. Recent lunar missions indicate that there might be some frozen ice at the poles.

The Moon’s movement  The moon revolves around the Earth in about one month (27 days 8 hours). It rotates around its own axis in the same amount of time. The same side of the moon always faces the Earth; it is in a synchronous rotation with the Earth.

How far away is the Moon?  The moon is about 238,900 miles (384,000 km) from Earth on average.  At its closest point the moon is 221,460 miles (356,410 km) from the Earth.  At its farthest approach the moon is 252,700 miles (406,700 km) from the Earth.

Size of the Moon  The moon's diameter is 2,140 miles (3,476 km), the Earth is 7,900 miles (12,742 km) in diameter. That's how far you would have to tunnel to dig to the other side of the Earth!  The circumference of the moon is 6,790 miles (10,864 km). The circumference of the earth at the equator is 24, miles (40,075 km).

How much does the Moon weigh? The moon's mass is about 1/81 of the Earth's mass. The moon's gravitational force is only 17% of the Earth's gravity. For example, a 100 pound person would weigh only 17 pounds on the Moon.

The Atmosphere on the Moon  TEMPERATURE The temperature on the Moon ranges from daytime highs of about 130°C = 265°F to nighttime lows close to -310 °F. ATMOSPHERE The moon has no atmosphere. On the moon, the sky is always appears dark, even on the bright side (because there is no atmosphere). Also, since sound waves travel through air, the moon is silent; there can be no sound transmission on the moon.

The surface of the moon is scarred by millions of (mostly circular) impact craters, caused by asteroids, comets, and meteorites. There is no atmosphere on the moon to help protect it from bombardment from potential impactors (most objects from space burn up in our atmosphere). Also, there is no erosion (wind or precipitation) and little geologic activity to wear away these craters, so they remain unchanged until another new impact changes it.

Man on the Moon There have been many missions to the moon, including orbiters missions and moon landings. On July 20, 1969 Neil Armstrong was the first person to set foot on the moon. His first words upon stepping down the Lunar Module's ladder onto the lunar surface were, "That's one small step for man, one giant leap for mankind." Aldrin described the lunar scenery as "magnificent desolation."

How did the Moon form? Most scientists believe that the moon was formed from the ejected material after the Earth collided with a Mars-sized object. This ejected material gathered into the moon that went into orbit around the Earth. This catastrophic collision occurred about 60 million years after Earth itself formed (about 4.3 billion years ago). This is determined by the dating of moon rocks.

Vocabulary Axis: An axis is an imaginary straight line around which an object, like a planet, turns. Circumference: the distance around the equator Diameter: the width from one side to the other through the center Orbit: path that an object takes as it moves around another body Revolve: w hen an object moves in orbit around another object Rotate: to turns or spin around a central point or axis. One day is defined as the time it takes the planet to rotate around its axis. Satellite: objects that orbit a planet or a moon.