October 27, 2015

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Eclipse Preview

Originally published October 26, 2004


Image Credit: Eric Jamison

Eclipse Preview

There are usually 1-2 lunar eclipses each year, and the nice thing is that each one is visible from half the Earth. This image of the November 8, 2003 eclipse shows the Moon at maximum eclipse, but as you can see the lunar south polar area was quite bright. This was because it was just barely a total eclipse - the south pole of the Moon skimmed along the edge of the umbral (or darkest) shadow. The October 27, 2004 (28th in Europe) eclipse should be darker because the Moon passes well within the umbra. During totality on the 27th, the north pole will be the brighter side because it will be closest to the edge of the umbra. Despite the fact that the lunar orbit is very predictable, the color and darkness of eclipses are not. The problem is that these hues depend upon the clarity of the Earth's atmosphere, but of course that varies with time and place. The atmosphere can be full of debris (that blocks sunlight and darkens eclipses) from forest fires, volcanic eruptions or even recent meteor showers. For the October 27th eclipse none of these atmospheric perturbations should be severe so a bright eclipse is expected. Visit the Sky & Telescope web site to learn the Danjon Scale for eclipse brightnesses and then you can judge how bright totality actually is. Clear skies!

Chuck Wood

Technical Details:
Nov. 8, 2003. mid-eclipse using an AP 7.1" f/9 on AP 800 equatorial mount. Exposure 12 seconds on ASA 400 speed film using my trusty Olympus OM-1 camera. 

Related Links:
Oct 27 Eclipse Information
Sky & Telescope Eclipse Info (and Danjon Scale)
Eric's web site

Yesterday's LPOD: Modeling Domes

Tomorrow's LPOD: The Moon by Day

Author & Editor:
Charles A. Wood



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