BrandonD » Tue Feb 04, 2014 2:08 pm wrote:The sun is exactly 400 times the size of the moon. The distance of the sun from the earth is exactly 400 times the distance of the moon from the earth.
None of this is so.
The sun's estimated
mass is approximately 27 million times that of the earth's moon. It is more than 1,100 times the mass of Jupiter. (Jupiter's mass is 2.5 greater than that of all the other planets in this system combined.)
The sun's
diameter according to our measurement is 402 times that of the moon. That's a measuring of the visible solar surface, the chromosphere, although of course the star is a process, from a fusion core generating photons out to a solar wind or atmosphere extending for a theorized 2 light years on the plane of its equator. The light in the sky is also the sun, it touches us. Present theory holds it can take 10,000 earth-years or many times that for light generated in the sun's core to reach the chromosphere and be released into space.
The distance of the earth from the sun in its current orbit varies between 92 and 94 million miles, thus by more than 2 million miles a year, since the orbits of the planets are elliptical. The variance alone is about 9 times greater than the earth's current average distance to the moon, which also varies. Thus one can never speak of an "exact" ratio of the earth's distance from the moon as opposed to from the sun.
Because of this, both celestial bodies are exactly the same size visually, from the perspective of the earth - and the moon precisely overlaps the sun during an eclipse.
The two bodies are frequently seen by the naked eye as having approximately the same size in earth's sky. This nevertheless varies greatly depending on one's latitude, the locations of the bodies in their orbits, and local atmospheric conditions. Even in perfectly aligned solar eclipses the moon might be smaller in the sky and fail to fully overlap the sun. These are called annular eclipses.
A special case of a solar eclipse is known as an annular eclipse. This occurs when the Moon is farther from the Earth than normal, and hence its apparent size is not quite sufficient to cover the Sun completely. Therefore, even though the Sun- Moon alignment is perfect, the Moon will appear slightly smaller in diameter than the Sun and a thin ring of sunlight will remain visible around the dark silhouette of the Moon. The name annular eclipse comes from the Latin annulus, meaning ring.
"The next total solar eclipse visible from the United States will occur on August 21, 2017."
The United States, of course, like all nations and many other forms of social structure, is an imaginary concept made real through shared belief in its existence.
We meet at the borders of our being, we dream something of each others reality. - Harvey of R.I.
To Justice my maker from on high did incline:
I am by virtue of its might divine,
The highest Wisdom and the first Love.
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