The Moon
Our closest neighbor in space is the moon. What is the moon? The moon is the brightest object in the night time, but surprisingly does not give off any of its own light. When the moon "shines" it is actually just reflecting light from the sun. Some nights, the moon appears as a round globe and others it appears to be a thin slice. In reality, the moon does not change in shape or size and its appearance changes as different parts of it are lighted by the sun.
What is the Moon?
The moon travels around the earth once every 27 1/3 days. The average distance between our satellite is about 238,857 miles across. By rocket, it would take six days to travel to and from the moon.
Since the moon is fairly close to the earth, it seems larger than the stars and even as large as the sun. It is 2,160 miles across and is 400 times smaller than the sun. The moon has no life on it in any form. It has not changed much over the years. The moon has no air, wind, or water. The sky is always black and the stars can always be seen. At night the temperature becomes colder than any place on earth and in the day time, the temperature of the rocks is higher than boiling water.
Since the moon is fairly close to the earth, it seems larger than the stars and even as large as the sun. It is 2,160 miles across and is 400 times smaller than the sun. The moon has no life on it in any form. It has not changed much over the years. The moon has no air, wind, or water. The sky is always black and the stars can always be seen. At night the temperature becomes colder than any place on earth and in the day time, the temperature of the rocks is higher than boiling water.
Internal Structure
The moon very likely has a very small core just 1 to 2 percent of the moon's mass and roughly 420 miles (680 km) wide. It likely consists mostly of iron, but may also contain large amounts of sulfur and other elements.
Its rocky mantle is about 825 miles (1,330 km) thick and made up of dense rocks rich in iron and magnesium. Magmas in the mantle made their way to the surface in the past and erupted volcanically for more than a billion years — from at least four billion years ago to fewer than three billion years past.
The crust on top averages some 42 miles (70 km) deep. The outermost part of the crust is broken and jumbled due to all the large impacts it has received, a shattered zone that gives way to intact material below a depth of about 6 miles (9.6 km).
Its rocky mantle is about 825 miles (1,330 km) thick and made up of dense rocks rich in iron and magnesium. Magmas in the mantle made their way to the surface in the past and erupted volcanically for more than a billion years — from at least four billion years ago to fewer than three billion years past.
The crust on top averages some 42 miles (70 km) deep. The outermost part of the crust is broken and jumbled due to all the large impacts it has received, a shattered zone that gives way to intact material below a depth of about 6 miles (9.6 km).
Surface Composition
The moon is rocky. It's pockmarked with craters formed by asteroid impacts millions of years ago. Because there is no weather, the craters have not eroded.
The average composition of the lunar surface by weight is roughly 43 percent oxygen, 20 percent silicon, 19 percent magnesium, 10 percent iron, 3 percent calcium, 3 percent aluminum, 0.42 percent chromium, 0.18 percent titanium and 0.12 percent manganese.
The moon has a very thin atmosphere, so a layer of dust can sit undisturbed for centuries. Daytime temperatures on the sunny side of the moon reach 273 degrees F; on the dark side it gets as cold as -243.
The average composition of the lunar surface by weight is roughly 43 percent oxygen, 20 percent silicon, 19 percent magnesium, 10 percent iron, 3 percent calcium, 3 percent aluminum, 0.42 percent chromium, 0.18 percent titanium and 0.12 percent manganese.
The moon has a very thin atmosphere, so a layer of dust can sit undisturbed for centuries. Daytime temperatures on the sunny side of the moon reach 273 degrees F; on the dark side it gets as cold as -243.
Phases of the Moon
Happens when the moon is at a 90 degree angle with respect to the earth and sun. So we are seeing exactly half of the moon illuminated and half in shadow.
After the new moon, the sunlit portion is increasing, but less than half.
Occurs when the moon is positioned between the earth and sun. The three objects are in approximate alignment (why "approximate" is explained below). The entire illuminated portion of the moon is on the back side of the moon, the half that we cannot see.
Which wanes until the light is completely gone -- a new moon.
Happens when the moon is at a 90 degree angle with respect to the earth and sun. So we are seeing exactly half of the moon illuminated and half in shadow.
After the full moon (maximum illumination), the light continually decreases.
The earth, moon, and sun are in approximate alignment, just as the new moon, but the moon is on the opposite side of the earth, so the entire sunlit part of the moon is facing us. The shadowed portion is entirely hidden from view.
After the first quarter, the sunlit portion is still increasing, but now it is more than half.
Types of Eclipse
An eclipse is the total or partial obscuring of one celestial body by another. It may occur when one celestial body passes in front of another therefore cutting off some or all of its light. It may also occur when a celestial body passes through all or part off the shadow of another celestial body.
Lunar Eclipse
An eclipse of the Moon, or lunar eclipse, is when the Earth is between the Sun and Moon and only occurs if the Moon passes through all or some portion of Earth's umbra shadow therefore blocking sunlight directly striking the Moon’s surface. This can occur only when the Sun, Earth, and Moon are aligned exactly, or almost exactly.
A lunar eclipse occurs at night and only when there is a Full Moon. A lunar eclipse can last for many hours, and can be seen from the entire night side of the Earth.
Solar Eclipse
An eclipse of the Sun, or a solar eclipse, is when the Moon is between the Sun and Earth and only occurs when the Moon is at just the right distance and angle in the sky to cover the Sun, this can only occur when the Sun, Moon and Earth are exactly aligned producing a Total Solar Eclipse. The Moon also has to be at or near one of its nodes; a node is simply the point at which the Moon crosses the eliptic from south to north or vice versa as it orbits the Earth.
Tidal Effects
The moon's gravitational force pulls on water in the oceans so that there are "bulges" in the ocean on both sides of the planet. The moon pulls water toward it, and this causes the bulge toward the moon. The bulge on the side of the Earth opposite the moon is caused by the moon "pulling the Earth away" from the water on that side.
If you are on the coast and the moon is directly overhead, you should experience a high tide. If the moon is directly overhead on the opposite side of the planet, you should also experience a high tide.
During the day, the Earth rotates 180 degrees in 12 hours. The moon, meanwhile, rotates 6 degrees around the earth in 12 hours. The twin bulges and the moon's rotation mean that any given coastal city experiences a high tide every 12 hours and 25 minutes or so.
If you are on the coast and the moon is directly overhead, you should experience a high tide. If the moon is directly overhead on the opposite side of the planet, you should also experience a high tide.
During the day, the Earth rotates 180 degrees in 12 hours. The moon, meanwhile, rotates 6 degrees around the earth in 12 hours. The twin bulges and the moon's rotation mean that any given coastal city experiences a high tide every 12 hours and 25 minutes or so.