Christmas Eclipse

(This column was first published in the December 25, 2000 Buffalo News.)

    The timing could not be more perfect. You exchange and open your gifts, clear up the mess of wrappings, enjoy a holiday breakfast and then -- assuming we have a break in the clouds to the south -- join family or friends at midday to watch a solar eclipse.

    Today as this millennial year 2000 draws to a close we have a very rare Christmas Day solar eclipse. This hasn't happened in North America on this holiday for over 300 years and it will not happen again for centuries to come.

    Although this will be only a partial eclipse, the Niagara Frontier will enjoy just about the best opportunity to observe it in the United States. Here almost exactly half of the sun will be hidden by the encroaching moon. Because the moon is so much closer to the earth, it will appear in the sky as though it is the same size as the sun. (In fact, the moon is near its farthest point of its elliptical path around the earth so it would not have completely covered the sun even if it passed directly in front of it. What we would have seen then would have been a ring-like or annular eclipse.)

    Here is today's eclipse schedule:

    At 10:59 a.m. in the southern sky, the moon will appear tangent to the sun's upper right arc and the eclipse will begin. The apparent bite out of this corner of the sun will increase over the next hour and a half as the moon crosses between us and the upper half of the sun's face.

    At 12:36 p.m. the eclipse will be at its maximum. The moon will appear directly over the top half of the sun and what we see of the sun will take on a bowl-like appearance. It will replicate the mouth of the widely grinning Cheshire Cat in the Disney movie version of Alice in Wonderland. At this time the planet Mercury, invisible to us in the daytime sky, is just below the sun at about where the Cheshire Cat's belly-button would be.

    After this the moon will pass slowly off to the upper left of the sun and the eclipse will end for us at 2:11 p.m.

    It is very important to note that an eclipse SHOULD NOT be observed directly. I am especially sensitive to this issue as I injured my eyes when, as a youngster I foolishly stared at the sun. Although there are lenses available for watching, I urge caution. Arc-welder's glass of shade 13 or 14 is necessary to give adequate protection. Don't use sunglasses or smoked glass.

    Because the sun is so low in the sky at this time of year, a much better way to observe is available. Place a sheet of paper with a single paper-punch-size hole in it against a south-facing window through which the sun is shining. Now hold another sheet of paper far across the room to obtain the sun's image. You'll want to adjust the distance to get sharpest focus.

    You can, of course, get a clearer and much larger image by replacing the paper in the window with a telescope or binocular lens. You have to aim your optical instrument carefully by trial and error -- NOT by looking through it -- in order to get the best image.

    In the past my luck has not been good in recommending astronomical observations. If once again clouds intervene and you cannot get a pilot friend to fly you above those clouds, you'll just have to try out your new sled, skis or snowshoes.

Happy holidays.-- Gerry Rising