How can the sun and moon appear to be the same size during an eclipse?
Although the sun is much larger than the moon, it is much farther away–about 93 million miles away, as opposed to about 250,000 miles for the moon. By an odd coincidence, the ratios of distance and size are just right to make them appear the same size in the sky, so that during a solar eclipse, the moon completely blocks the sun. However, the moon is very slowly getting farther away from the earth–about 2 inches further each year. Astronomers predict that in about 600 million years, the moon will appear too small to completely block the sun.
