Lunar+Eclipse+Project

Weather permitting on March 3, at least some of a total lunar eclipse will be visible across North America east of a line connecting the Arizona and Idaho borders.

Sunset and moonrise occur almost simultaneously and on the far side of the sky from each other at about 6:19 p.m. local standard time. The Moon may be difficult to see at first, if the horizon is hazy. When it clears the horizon haze, you may see the Moon completely in Earth's shadow (so it will not look at all like a "normal" rising full moon) or you may only see a portion of the Moon because some of it will still be in the umbra, the main portion of Earth's shadow. As the Moon rises higher in the east it will also be moving out of the shadow, until it leaves the umbra at about 7:11 CST. The Moon will still be in the penumbra, the outer portion of the shadow, for another 1:11, but its departure from the penumbra may not be detectable. (Hint, to see more of the event, find a high observing site with low horizons.)

Use the diagrams on the back to draw the eclipse from sunset and every 10 minutes after. Interesting questions you may wish to address with observations include the following:

1. About how much of the Moon is visible when it finally appears? What colors are the light and shadowed portions? Do the colors change with time? What could cause the coloring, especially of the umbral portion?

2. Does the Earth's shadow appear to be a nice smooth curve or does it show angular kinks or an odd shape? What could cause the shadow to not be a smooth curve?

3. Does the Moon leave the umbra at the predicted time? Previous eclipses have been off by a couple of minutes. Why might this be so?

4. How late can you detect evidence of the penumbra on the Moon?

You can photograph the eclipse. Mount your camera and telephoto lens on a tripod and use a cable release, or brace yourself when holding them.

An adjustable camera is just about a necessity, since automatic cameras will be fooled by seeing mostly dark sky instead of exposing for the bright but small Moon. To be sure of getting pictures you should bracket your exposures, meaning that you take several at each time you want a picture. This is recommended because the darkness of the Moon in the shadow and the absorption of light near the horizon are unpredictable.

At a minimum, you should take three pictures each time. At f/16, partial phase exposures should be made at 1/(ISO rating) and at twice this value and at four times this value. For ISO 100, you would use exposures at 1/100 sec, 2 x 1/100 = 1/50 sec, and 4 x 1/100= 1/25 sec, but since most cameras don't have these shutter speeds use the closest ones: 1/125, 1/60, and 1/30 sec, respectively. Exposures during the total phase will need to be several seconds in length, spanning 5 to 30 seconds with the f/ number at its lowest value. Note that shutter times longer than about 10 seconds will show blurring due to Earth's rotation.

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