Lunar Eclipse: The Starry Messenger, Vol. 1 Issue 1

-- Fist Quarter, November 2003 --

FRONT PAGE

Volume 1, Issue 1

Now You See it, Now You Don't

by Mary Bongiovi
What were you doing on Saturday, November 8th? Unless you were living under a rock, you probably noticed that the moon underwent an eclipse. To get a better view of this event, some students in our Astronomy class braved the cold to view the eclipse at Lincoln field. Armed with cider and a really large telescope, we got to see a celestial phenomenon that will not occur again for another year.

Eclipses are when a shadow cuts off the light from one celestial body by another. There are two kinds of eclipses, lunar and solar. On Saturday, the Moon passed through the shadow of the earth. While the Moon is at its fullest and the Earth lies between the Sun and the Moon, a lunar eclipse occurs. Since the Earth's shadow is in the way, the Moon, which would normally be brightened with the Sun's light, is now mostly dark. As the Moon passes into the Earth's umbra, the darkest part of the shadow, we could see it begin to darken much like it would during its normal phases, except now it was occurring in a much shorter time span. An eclipse differs from the Moon's phases because the shadow is caused by the Earth itself during an eclipse, while the phases of the Moon are not. There still is some sunlight visible in the Earth's atmosphere which can reach the Moon even during a solar eclipse, giving it the red hue you may have noticed on Saturday. For those of you who may have missed it, the next lunar eclipse that we can observe here in North America occurs October 28, 2004.

A total solar eclipse is a bit more noticeable to the average observer than a lunar eclipse. The Sun actually goes completely dark, save for the solar corona which is visible at totality, which is the time when the object being eclipsed has been completely covered over. Totality can last for up to seven and a half minutes.

To see the most of this eclipse, the viewer must be within the eclipse path, otherwise he or she will only see a partial solar eclipse. The size of the eclipse path varies depending on the Moon's distance to the Earth at the time of the eclipse. If the Moon is at perigree, the point in its orbit when it is the closest to Earth, then the path will be at its widest. If the Moon is at apogee, its furthest point from Earth, then it will not appear large enough to completely cover up the Sun. If this is the case, an annular solar eclipse will occur, and a ring of the Sun will be seen surrounding the Moon.


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