Jim Colyer
Phases -
Living in the heart of Nashville 15 years, I have not been able to see many stars. I have been aware of the moon. I have watched it from my balcony as it crossed the night sky from east to west. This is an illusion, of course, caused by the fact that the earth is spinning from west to east.
The moon orbits the earth from west to east as it goes through its monthly cycle. As it orbits the earth, its appearance changes. We call these changes "phases."
There are 8 phases of the moon, and they change quickly. The new moon becomes a full moon almost before we know it.
Phases have to do with the angles the sun, earth and moon form in the sky. When the three objects line up with the moon in the middle, there is a "new moon." We do not see the moon at this time because it is near the sun and its nighttime side is facing us. When the three objects line up with the earth in the middle, there is a "full moon."
"First quarter" and "last quarter" are when the three are at right angles. At first quarter the right side of the moon is lit. At last quarter the left side is lit.
The phases can be confusing until we visualize them. A waxing crescent comes after a new moon. A waning crescent comes before a new moon. Sometimes there are eclipses. If a new moon covers the sun, we have a solar eclipse. If the earth covers a full moon, we have a lunar eclipse.
Half of the moon is always lit except during a lunar eclipse. We see different portions of the lit side as the moon circles us.
"Gibbous" is a strange word. It means "bulging" or "swelling." The only time we see the word is in relation to a waxing gibbous moon or a waning gibbous moon.
The moon is like the earth in that it reflects sunlight. Standing on the moon, we see the earth go through phases. The earth remains stationary in the lunar sky. It is never seen from the far side of the moon.
The sky is always dark on the moon, even in the daytime, because the moon has no atmosphere. Nor is there any sound because sound waves travel through air.
Origin -
Man has long wondered where the moon came from. The accepted theory now is that the moon formed from debris after a Mars-size object impacted the earth.
The earth and moon have things in common. They have the same minerals. That the moon is made of material similar to that in the earth's mantle suggests that it formed from stuff thrown out by an impact. The interloper sunk into the supple earth and merged with it.
There are also differences. The earth is a water planet. The only water on the moon may be ice at the poles. The earth has an iron core. The moon has no iron and no magnetic field.
Earth-moon relationship -
The earth and moon affect each other. The earth has a greater gravitational affect on the moon because of its mass. The earth has slowed the moon's spin so that the same side of the moon faces the earth at all times. The moon rotates just once in its orbit around the earth. The earth has had a tidal affect on the moon's near side, pulling and thinning its crust so that lava flowed to create the maria.
It it not easy to understand the tides unless you live near the ocean. We see pictures in books of water bulging toward the moon. A second bulge appears on the opposite side of the earth because the earth is pulled away from the water. These bulges follow the moon's progress. I have wondered about the earth's atmosphere. It is so thin that it seems like the moon's gravity would strip it away. I guess not.
The moon is slowly moving away. A billion years from now, there will be no total solar eclipses.
Four craters:
Copernicus - This is an impact crater in the Oceanus Procellarum (Latin for "Ocean of Storms"
. It has a circular rim and a ray system although its rays are not as distinct as those of Tycho. Apollo 12 landed north of Copernicus.
Aristarchus - Named after the ancient Greek astronomer, Aristarchus of Samos, it is the brightest crater on the moon. It has a central peak and an outer wall covered with ejected material spreading out in rays. It is in the Ocean of Storms.
Plato - This crater stands out with its circular rim and dark floor. Transient lunar phenomena are sometimes seen near Plato, flashes of light and unusual colors.
Tycho - Named for Danish astronomer Tycho Brahe, this is a stunning crater in the southern lunar highlands. It is a young crater, a mere 108 million years old. Its ray system is brilliant.
Six Apollo landing sites:
Apollo 11 Sea of Tranquility - Apollo 11 landed here on July 20, 1969. Neil Armstrong told Houston, "The Eagle has landed." Early astronomers thought that the lava plains were water and called them "seas." Riccioli's nomenclature from 1651 is still used.
Apollo 12 Oceanus Procellarum - This is the only "ocean" on the moon because of its size. It is big, 1600 miles across. It was caused by volcanic eruptions. Alan Bean was on board this mission.
Apollo 14 Fra-Mauro Formation - This crater was supposed to be the landing site for Apollo 13. Apollo 14 got it instead. The Apollo 13 mission returned to earth after an oxygen tank blew up.
Apollo 15 Hadley Rille - A rille is a long, narrow valley. Hadley is 75 miles long and was created by molten lava.
Apollo 16 Descartes Highlands - They landed in the lunar highlands near Descartes Crater, an area covered with sharp rimmed craters. This site was chosen over the crater Alphonsus.
Apollo 17 Taurus-Littrow (valley) - The valley is located on the edge of the Sea of Serenity. Being in the Taurus mountains and south of Littrow crater, the Apollo 17 crew named it, and the International Astronomical Union IAU approved.
Living in the heart of Nashville 15 years, I have not been able to see many stars. I have been aware of the moon. I have watched it from my balcony as it crossed the night sky from east to west. This is an illusion, of course, caused by the fact that the earth is spinning from west to east.
The moon orbits the earth from west to east as it goes through its monthly cycle. As it orbits the earth, its appearance changes. We call these changes "phases."
There are 8 phases of the moon, and they change quickly. The new moon becomes a full moon almost before we know it.
Phases have to do with the angles the sun, earth and moon form in the sky. When the three objects line up with the moon in the middle, there is a "new moon." We do not see the moon at this time because it is near the sun and its nighttime side is facing us. When the three objects line up with the earth in the middle, there is a "full moon."
"First quarter" and "last quarter" are when the three are at right angles. At first quarter the right side of the moon is lit. At last quarter the left side is lit.
The phases can be confusing until we visualize them. A waxing crescent comes after a new moon. A waning crescent comes before a new moon. Sometimes there are eclipses. If a new moon covers the sun, we have a solar eclipse. If the earth covers a full moon, we have a lunar eclipse.
Half of the moon is always lit except during a lunar eclipse. We see different portions of the lit side as the moon circles us.
"Gibbous" is a strange word. It means "bulging" or "swelling." The only time we see the word is in relation to a waxing gibbous moon or a waning gibbous moon.
The moon is like the earth in that it reflects sunlight. Standing on the moon, we see the earth go through phases. The earth remains stationary in the lunar sky. It is never seen from the far side of the moon.
The sky is always dark on the moon, even in the daytime, because the moon has no atmosphere. Nor is there any sound because sound waves travel through air.
Origin -
Man has long wondered where the moon came from. The accepted theory now is that the moon formed from debris after a Mars-size object impacted the earth.
The earth and moon have things in common. They have the same minerals. That the moon is made of material similar to that in the earth's mantle suggests that it formed from stuff thrown out by an impact. The interloper sunk into the supple earth and merged with it.
There are also differences. The earth is a water planet. The only water on the moon may be ice at the poles. The earth has an iron core. The moon has no iron and no magnetic field.
Earth-moon relationship -
The earth and moon affect each other. The earth has a greater gravitational affect on the moon because of its mass. The earth has slowed the moon's spin so that the same side of the moon faces the earth at all times. The moon rotates just once in its orbit around the earth. The earth has had a tidal affect on the moon's near side, pulling and thinning its crust so that lava flowed to create the maria.
It it not easy to understand the tides unless you live near the ocean. We see pictures in books of water bulging toward the moon. A second bulge appears on the opposite side of the earth because the earth is pulled away from the water. These bulges follow the moon's progress. I have wondered about the earth's atmosphere. It is so thin that it seems like the moon's gravity would strip it away. I guess not.
The moon is slowly moving away. A billion years from now, there will be no total solar eclipses.
Four craters:
Copernicus - This is an impact crater in the Oceanus Procellarum (Latin for "Ocean of Storms"
. It has a circular rim and a ray system although its rays are not as distinct as those of Tycho. Apollo 12 landed north of Copernicus. Aristarchus - Named after the ancient Greek astronomer, Aristarchus of Samos, it is the brightest crater on the moon. It has a central peak and an outer wall covered with ejected material spreading out in rays. It is in the Ocean of Storms.
Plato - This crater stands out with its circular rim and dark floor. Transient lunar phenomena are sometimes seen near Plato, flashes of light and unusual colors.
Tycho - Named for Danish astronomer Tycho Brahe, this is a stunning crater in the southern lunar highlands. It is a young crater, a mere 108 million years old. Its ray system is brilliant.
Six Apollo landing sites:
Apollo 11 Sea of Tranquility - Apollo 11 landed here on July 20, 1969. Neil Armstrong told Houston, "The Eagle has landed." Early astronomers thought that the lava plains were water and called them "seas." Riccioli's nomenclature from 1651 is still used.
Apollo 12 Oceanus Procellarum - This is the only "ocean" on the moon because of its size. It is big, 1600 miles across. It was caused by volcanic eruptions. Alan Bean was on board this mission.
Apollo 14 Fra-Mauro Formation - This crater was supposed to be the landing site for Apollo 13. Apollo 14 got it instead. The Apollo 13 mission returned to earth after an oxygen tank blew up.
Apollo 15 Hadley Rille - A rille is a long, narrow valley. Hadley is 75 miles long and was created by molten lava.
Apollo 16 Descartes Highlands - They landed in the lunar highlands near Descartes Crater, an area covered with sharp rimmed craters. This site was chosen over the crater Alphonsus.
Apollo 17 Taurus-Littrow (valley) - The valley is located on the edge of the Sea of Serenity. Being in the Taurus mountains and south of Littrow crater, the Apollo 17 crew named it, and the International Astronomical Union IAU approved.