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Sizes & Distances in the Sun-Earth-Moon System

The sun is an average star at the edge of an average spiral galaxy, and the Earth is but one of its many satellites. The moon is the Earth's satellite and is tidally locked, which means that one face is always turned toward the Earth. The sun and the moon take up the same amount of space in Earth's sky -- 0.5 degree of arc. Because the moon can so perfectly cover the sun as it passes before it, this makes total solar eclipses possible.

The Sun
- The sun is a yellow dwarf star that was born around 4.6 billion years ago out of a cloud of hot hydrogen gas. Though it's not a very large star it is by far the largest object in the solar system. It is 99 percent of the mass of the solar system.
Physical Properties
- The temperature at the sun's core is approximately 26,999,540 degrees Fahrenheit, and the surface temperature is 11,000 degrees Fahrenheit. The sun rotates on its axis like other bodies in the solar system, but because it's made of gas its equator rotates every 27.275 days while the polar regions rotate every 34 days. The sun's diameter is 870,331.25 miles, its mass is 4.3939 x 10(30) lbs. The sun continually ejects a stream of hot plasma called the solar wind, whose speed ranges from 450,000 mph to 2 million mph. The solar wind carries 3,000 tons of subatomic particles away from the sun every hour.
The Earth
- The Earth is the third planet from the sun and so far the only body in the solar system that has life. Earth's core is about 4,200 miles in diameter, with a temperature of about 11,000 degrees Fahrenheit, or the same temperature as the surface of the sun. This temperature makes the core mostly molten. The movement of the core gives the Earth its magnetic field. Above the core is the Earth's mantle, which is about 1,800 miles thick, and then the crust, which ranges from 25 to barely five miles thick. The diameter of the Earth is 7,926 miles and it's 94,240,000 miles from the sun at its farthest, or aphelion, or 91,140,000 miles away at its closest, or perihelion. The Earth's mass is 2.7166 x 10(24) lbs., the rotational period is 23.93 hours or 23 hours and 56 minutes. The time it takes to complete a full rotation around the sun is 365.2 days.
The Moon
- Unlike Earth, the moon doesn't have much of an atmosphere.
  
  Earth's moon is the fifth largest moon in the solar system. The lunar day is equal to the lunar month at 29 days, 12 hours and 44 minutes. The moon has phases of being full, half, quarter, crescent and new. The diameter of the moon is 2159.89 miles and it's 252,698 miles from the Earth. Its mass is 3.34 x 10(22) lbs. The mean surface temperature is 0 degrees Fahrenheit, the maximum surface temperature is 279 degrees Fahrenheit and the minimum minus 273.2 Fahrenheit.

Astronomy