Eclipse Day

Many skywatchers have been planning for this day for years. The Moon will pass directly between Earth and Sun today, creating a total solar eclipse from Oregon to South Carolina. Day will turn to night, and stars and planets will pop into view. And tens of millions of Americans are expected to see the spectacle in person.
A solar eclipse is the result of a complex ballet involving Earth, the Moon, and the Sun.
The Moon pirouettes against the background of stars and planets every 27 and a half days. But because the Sun is also moving against that background, it takes a couple of days longer for the Moon to catch up to it.
While the Moon passes the Sun roughly once a month, most months it doesn’t cause an eclipse. Instead, it usually glides a little above or below the Sun, because its orbit is tilted relative to the Sun’s path across the sky. A solar eclipse occurs only when the new Moon crosses that path. And even then, most eclipses are only partial: the Moon covers only part of the Su