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badal
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on Wed Jan 16, 2019 11:46 am
The truth, however, is that we actually get to see more of it over the course of its elliptical orbit: 59 percent (almost three-fifths).
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badal
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on Wed Jan 16, 2019 11:47 am
The truth, however, is that we actually get to see more of it over the course of its elliptical orbit: 59 percent (almost three-fifths).
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badal
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on Wed Jan 16, 2019 11:47 am
The moon's rate of rotation is uniform but its rate of revolution is not, so we're able to see just around the edge of each limb from time to time
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badal
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on Wed Jan 16, 2019 11:47 am
Put another way, the two motions do not keep perfectly in step, even though they come out together at the end of the month. We call this effect libration of longitude.
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badal
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on Wed Jan 16, 2019 11:47 am
So the moon "rocks" in the east and west direction, allowing us to see farther around in longitude at each edge than we otherwise could
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badal
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on Wed Jan 16, 2019 11:47 am
The remaining 41 percent can never be seen from our vantage point; and if anyone were on that region of the moon, they would never see the Earth.
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badal
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on Wed Jan 16, 2019 11:48 am
The full moon shines with a magnitude of -12.7, but the sun is 14 magnitudes brighter, at -26.7.  The ratio of brightness of the sun versus the moon amounts to a difference of 398,110 to 1.
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badal
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on Wed Jan 16, 2019 11:48 am
So that's how many full moons you would need to equal the brightness of the sun.  But this all a moot point, because there is no way that you could fit that many full moons in the sky.
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badal
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on Wed Jan 16, 2019 11:48 am
The sky is 360 degrees around (including the half we can't see, below the horizon), so there are over 41,200 square degrees in the sky.
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badal
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on Wed Jan 16, 2019 11:49 am
The moon measures only a half degree across, which gives it an area of only 0.2 square degrees. So you could fill up the entire sky, including the half that lies below our feet,  with 206,264 full moons — and still come up short by 191,836 in the effort to match the brightness of the sun.
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badal
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on Wed Jan 16, 2019 11:49 am
If the moon's surface were like a perfectly smooth billiard ball, its surface brightness would be the same all over. In such a case, it would indeed appear half as bright.[Phases of the Moon Explained]
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badal
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on Wed Jan 16, 2019 11:49 am
But the moon has a very rough topography. Especially near and along the day/night line (known as the terminator), the lunar landscape appears riddled with innumerable shadows cast by mountains, boulders and even tiny grains of lunar dust.  Also, the moon's face is splotched with dark regions.
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badal
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on Wed Jan 16, 2019 11:49 am
The end result is that at first quarter, the moon appears only one eleventh as bright as when it's full.
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badal
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on Wed Jan 16, 2019 11:50 am
If it completely blocks the sun, a narrow ring of light surrounds the dark disk of the Earth; our atmosphere backlighted by the sun.
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badal
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on Wed Jan 16, 2019 11:50 am
The ring appears to have a ruddy hue, since it's the combined light of all the sunrises and sunsets occurring at that particular moment.  That's why during a total lunar eclipse, the moon takes on a ruddy or coppery glow.
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badal
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on Wed Jan 16, 2019 11:50 am
When a total eclipse of the sun is taking place here on Earth, an observer on the moon can watch over the course of two or three hours as a small, distinct patch of darkness works its way slowly across the surface of the Earth.
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badal
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on Wed Jan 16, 2019 11:50 am
It's the moon's dark shadow, called the umbra, that falls on the Earth, but unlike in a lunar eclipse, where the moon can be completely engulfed by the Earth's shadow, the moon's shadow is less than a couple of hundred miles wide when it touches the Earth, appearing only as a dark blotch.
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badal
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on Wed Jan 16, 2019 11:51 am
The lunar craters were formed by asteroids and comets that collided with the moon. Roughly 300,000 craters wider than 1 km (0.6 miles) are thought to be on the moon's near side alone.

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badal
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on Wed Jan 16, 2019 11:51 am
These are named for scholars, scientists, artists and explorers. For example, Copernicus Crater is named for Nicolaus Copernicus, a Polish astronomer who realized in the 1500s that the planets move about the sun
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badal
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on Wed Jan 16, 2019 11:51 am
Archimedes Crater is named for the Greek mathematician Archimedes, who made many mathematical discoveries in the third century B.C.
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badal
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on Wed Jan 16, 2019 11:51 am
the custom of applying personal names to the lunar formations began in 1645 with Michael van Langren, an engineer in Brussels who named the moon's principal features after kings and great people on the Earth
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badal
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on Wed Jan 16, 2019 11:52 am
On his lunar map he named the largest lunar plain (now known as Oceanus Procellarum) after his patron, Phillip IV of Spain.
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badal
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on Wed Jan 16, 2019 11:52 am
Today the IAU continues to decide the names for craters on our moon, along with names for all astronomical objects. The IAU organizes the naming of each particular celestial feature around a particular theme.

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badal
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on Wed Jan 16, 2019 11:52 am
If you survey the Internet for temperature data on the moon, you're going to run into quite a bit of confusion. There's little consistency even within a given website in which temperature scale is quoted: Celsius, Fahrenheit, even Kelvin.

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badal
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on Wed Jan 16, 2019 11:52 am
It is possible to tell time on the moon.  In fact, back in 1970, Helbros Watches asked Kenneth L. Franklin, who for many years was the chief astronomer at New York's Hayden Planetarium, to design a watch for moon walkers that measures time in what he called "lunations," the period it takes the moon to rotate and revolve around the Earth; each lunation is exactly 29.530589 Earth days.
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