Monday, December 9, 2013
By Bernie Reim
This is usually a month of transition as the foliage slowly fades away before the snow starts flying in earnest. The terrestrial landscape will turn bleaker as the nights keep getting longer and the cold begins to settle in.
SKY GUIDE: This chart represents the sky as it appears over Maine during November. The stars are shown as they appear at 10:30 p.m. early in the month, at 8:30 p.m. at midmonth and at 7:30 p.m. at month’s end. No planets are visible at chart times. To use the map, hold it vertically and turn it so that the direction you are facing is at the bottom.
Chart prepared by George Ayers
But as soon as you look up from Earth, you will see that this will be a rich, exciting and unpredictable month for celestial treasures. Conjunctions and eclipses are predictable for thousands of years into the future, but meteor showers can be a surprise in their detailed unfolding. The real surprise this month and especially next month will be the exact nature of how the event called Comet ISON unfolds.
Discovered just over a year ago on Sept. 24, 2012 by two Russian astronomers using a 15.7-inch telescope named the International Scientific Optical Network, which was designed to detect, monitor and track near-Earth asteroids and comets, this faint fuzzy object was only 18 magnitude, or 63,000 times fainter than anything the naked eye can detect when it was first spotted. Now it can be seen glowing at about 10th magnitude just above Mars in the early morning sky in the constellation of Leo. It could become visible with the naked eye by the end of this month.
This is probably Comet ISON’s first trip in from the Oort cloud, where all the new comets originate. Located 50,000 astronomical units away, or nearly one light year, this is 1,000 times farther away than Pluto and the other Kuiper Belt objects.
There is a theory that Comet ISON is related to the Great Comet of 1680 because it is following nearly the same path. That was the first comet discovered with a telescope and then it became bright enough to see in the daytime, but nothing dramatic happened on Earth.
ISON will reach perihelion, or its closest approach to the sun, on the 28th, which happens to be Thanksgiving this year. It will pass very close to our sun, less than one solar diameter away, which is 865,000 miles. Since its nucleus is relatively small at only three miles across (Comet Hale-Bopp’s nucleus was more than 10 miles across) it may get torn apart by the sun’s enormous gravity, which is much stronger than the nucleus’s weak self-gravity. The surface of the comet will also be fried to about 5,000 degrees, hot enough to melt iron. No one knows if the comet will even survive its dramatic and dangerous close encounter with our life-giving sun but if it does, it will provide a tremendous show in early December in the morning sky. Recent comets that survived close encounters with the sun and became quite spectacular were Comet West in 1976 and Comet Lovejoy in 2011.
Before all the drama and uncertainty around this great comet starts to unfold, there will be a nice little partial solar eclipse visible all along the Eastern Seaboard. We will get one of the best views in this country, since 55 percent of the sun will be covered by the new moon right at sunrise, which will be 6:20 a.m. Don’t forget to set your clocks back one hour that Sunday or you will miss the whole event. You should predetermine a good spot for this event, preferably overlooking the ocean, and get there by 6 a.m. so you can be prepared if you plan to photograph it. Make sure you use safe solar filters for your eyes, and cameras and binoculars. A Number 14 welder’s glass is safe, as are aluminized mylar filters.
If you could travel to Africa that day, you would witness a very rare hybrid solar eclipse, which means that it will be an annular eclipse for a while with a brilliant ring of sunlight left around the moon, then a total solar eclipse for a while when the beautiful streamers in the solar corona become visible for a minute or so. Most of us won’t go to Africa but it’s not too early to prepare for the Aug. 21, 2017 total solar eclipse visible in a narrow path across this country from Oregon to Georgia. Standing in the moon’s shadow as its shadow cone gently brushes across Earth will be an experience you will never forget.
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