The Carbon County Environmental Education Center has postponed its eclipse party tonight because of the dangerous cold temperatures.

The partial stage of the lunar eclipse begins at 10:34 p.m. tonight with the total eclipse beginning at 11:41 p.m. Totality lasts for about an hour, and then the moon will exit the partial eclipse phase at 1:51 a.m. Monday. Webcasts are available at Slooh.com, timeanddate.com and several other sites, as well as at Space.com.

Dr. Carl Frankel, scheduled presenter for the local program said lunar eclipses typically last close to an hour.

 A full moon happens when the moon is directly "behind" the earth (relative to the sun), so that those of us looking up in the night sky see the whole surface of the moon illuminated with sunlight. But since this happens when the moon is "behind" the earth, why isn't it in the earth's shadow? That's where the shadow is - behind the earth.

In other words, why isn't there an eclipse during every full moon? It's because the orbit of the moon around the earth is tilted (5 degrees) with respect to the earth's orbit around the sun, as shown in the diagram. So during most full moons, the moon is passing above or below the earth's shadow. Only occasionally do the moon's and earth's orbits line up in such a way that the moon passes through the shadow and we get an eclipse. This is not a really rare event.

There is a lunar eclipse visible somewhere on earth about once a year.