The moon's final tetrad until 2032 - Alamogordo Daily News

The moon orbits around the Earth, and goes through its cycle of phases, in a period of time slightly less than a month; indeed, the very word month comes from the orbital cycle of the moon. If the moon's orbit around Earth were in the same plane as the Earth's orbit around the sun, then every month at new moon, the moon would pass directly between the Earth and the sun and some place on Earth would experience a solar eclipse. However, since the moon's orbit is tilted some five degrees with respect to the Earth's orbit, solar eclipses can occur only when new moon takes place near the same time that the moon is crossing the plane of the Earth's orbit; such eclipse seasons take place at approximately six-month intervals. During such an eclipse season there may also be a lunar eclipse, i.e., the moon will pass through at least part of the Earth's shadow, during either the preceding or following full moon.

We are going through an eclipse season right now. The solar eclipse took place two weeks ago, on Sept. 13; this was a partial eclipse that was visible from far southern Africa, the southern Indian Ocean, and parts of Antarctica. Now, we are approaching full moon, which takes place on Sunday evening, Sept. 27, and accordingly we have a lunar eclipse; this is a total eclipse, wherein the moon crosses completely into the Earth's shadow.

Read Full Story