Why do solar eclipses occur?
When the New Moon passes directly between the Sun and Earth, it casts a shadow on our planet, just as a baseball does if held above the ground in direct sunlight. That, in a nutshell, is what causes a solar eclipse. There’s a New Moon every month, so why don’t we have a solar eclipse every month, too? The answer is that the Moon’s orbit is slightly tilted compared to the Earth’s orbit around the Sun — by 5 degrees, to be exact. So when the Moon comes between the Earth and the Sun, it’s usually a little above or below the plane of Earth’s orbit, and its shadow misses the Earth. Only occasionally — about twice a year — can eclipses occur. Above: Click to view a Quicktime animation of the Moon’s shadow sweeping across Earth during a total solar eclipse. Credit: Digital Radiance. As any seasoned eclipse watcher can testify, a solar eclipse is not only an astronomical event — it’s a biological one, too. Adding to a sense of the surreal during a total eclipse, many creatures begin to act
