Mechanics of the Eclipse :

How does it work (what is a lunar eclipse)? One face of the Earth always faces the Sun, and thus there is a "shadow" from the Earth that points outward into space on the opposite side from the Sun. The shadow lies in the Earth-Sun orbital plane. The moon has an orbit that is plane that tilts just slightly with respect to the Earth-Sun plane. Occasionally, the Moon will cross the Earth-Sun plane (twice an orbit) - and even more rarely, it will make that pass when the Earth's shadow is there (causing the light from the Sun to be blocked by the Earth). [The Moon can also touch the Earth-Sun plane between the Earth and the Sun - causing a Solar Eclipse.] Notice that the adjective in front of the word eclipse tells what object is being "blocked" ... a lunar eclipse has the Earth blocking the light to the Moon and a solar eclipse has the Moon blocking the light from the Sun.

It is a fortunate situation that the Moon's angular size (how big it appears in the sky) is basically the same as the Sun (sometimes larger, sometimes smaller). Now, as for the tilt of the Moon orbit - that prevents the eclipses from happening roughly twice a month (every 27.3 days). Is that a good thing or bad thing? Well, without the tilt .. eclipses would be "humdrum" - they would occur so often we would take them for granted. When they are rare, we do foolish things like sit outside all night in January in Michigan to take a few snapshots (more on that later!).

Eclipse Photography!

This can be done very cheaply (simple 35 mm camera can take some very interesting shots!). Here are some from the Internet, and some that I took myself during this past January's Lunar eclipse (it was cold!!) You can see more from my outing here.

Montage Photo by Akira Fujii
Shows size of Earth's shadow.

Telescope Image during Totality

Scott Schneider's Eclipse Montage !

Eclipse Trail Photo by Fred Espenak
Leave camera open to record change in brightness.


Why are the images near totality reddish in color? You have to see the eclipse page to find out!

More information about the Moon Eclipses and Solar Eclipses