If skies are clear on the evening of Sept. 26 we shall be treated to our second total lunar eclipse of the year. This eclipse begins late enough for us to be able to view it in its entirety, unlike April's eclipse when totality had begun before moonrise. And it doesn't begin so late that we have to stay up exceptionally late in order to view the eclipse from beginning to end. We can safely gaze at lunar eclipses with no harm to our eyes, so no eye protection is required to view this celestial phenomenon.

         First penumbral contact, when moon begins to move into the penumbra, the outer part of Earth's shadow, occurs at 8:12 p.m. Moonrise is at 6:58 p.m. for us in Morgantown, so Moon will be well up in the sky, and sunset is 7:10 p.m., so the sky will be pretty dark. Since the outer part of the penumbra is not a very deep shadow, no evidence of this part of the eclipse will be seen until shortly before the partial phase begins. You might try watching this part of the eclipse to see when you first note a difference in brightness between the east and west sides of Moon's disk. The difference may be noticeable as early as about 8:40 p.m.

         The partial phase begins when Moon begins to enter the umbra of Earth's shadow, the dark, inner part of the shadow where the entire disk of Sun is blocked by Earth. First contact of Moon with Earth's umbra occurs at 9:12 p.m. For the next hour and 7 minutes Moon will move deeper and deeper into the umbra of our shadow until, at 10:19 p.m., totality begins with Moon completely inside Earth's shadow.

         Although Moon is entirely within Earth's shadow, sunlight still reaches Moon because of light's refraction, or bending, by Earth's atmosphere. Since our atmosphere scatters blue light more effectively than red light, the light reaching Moon is mostly red, giving a faint copper or orange cast to Moon during totality. The actual color depends on the amount of dust in Earth's atmosphere. During April's eclipse, the totally eclipsed Moon was a fairly bright reddish-orange, indicating that our atmosphere was relatively clear of dust. This is in contrast to total lunar eclipses in the early part of this decade when our atmosphere was contaminated with dust particles from relatively recent volcanic eruptions.

         At 10:54 p.m. Moon will be closest to the center of Earth's umbra, but still north of its center, so the northern, or upper edge of the eclipsed orb may be brighter than its lower edge. Totality ends at 11:29 p.m. as Moon begins to move out of Earth's umbra, and the partial phase we viewed between 9:12 p.m. and 10:19 p.m. will be repeated in reverse. This partial phase will end at 12:36 a.m. on the morning of Sept. 27 as Moon leaves the umbra of Earth's shadow.

         You may be able to observe a slight difference between the eastern and western sides of Moon's disk until as late as 1:05 a.m. as it moves outward in the penumbra, exposing Moon to more and more of Sun. The penumbral phase ends at 1:36 a.m., marking the very end of this total lunar eclipse.

          Saturn, at +0.5 magnitude, is less than 3 degrees south of Moon as the eclipse takes place. A total lunar eclipse with a near-by bright object is relatively rare. Such an event occurred last in 1968 when the near-by object was the +1.0-magnitude star Spica, and the next occurrence of such an event will take place on Feb. 21, 2008, when Saturn, shining then at +0.2 magnitude, and +1.4-magnitude Regulus will be within 3.5 degrees of eclipsed Moon.

         The next total lunar eclipse visible to us in Morgantown will not take place until January of 2000, so let's hope for clear skies on Sept. 26.