If expected cloudy skies clear in time, Midcoast sky watchers will have a special treat Tuesday, Dec. 21, as the winter solstice coincides with a full lunar eclipse. As of noon Dec. 16, the National Weather Service was predicting mostly cloudy skies for Tuesday.

According to the Web site eclipse.gsfc.nasa.gov, the earth’s shadow will begin to cross the moon at around midnight in Maine’s time zone, with the instant of greatest eclipse at 3:53 a.m. eastern time. At that point, the moon will lie near the zenith for observers in southern California and Baja, Mexico.

Locally, the eclipse will end at around 6 a.m.

While the moon is totally dark, winter constellations will appear brighter and viewers should be able to observe Pollux to the east of the eclipsed moon, Betelgeuse to the south, Aldebaran to the west, and Capella to the north.

Meanwhile, the winter solstice, that moment at which the earth’s axial tilt is farthest from the sun, will take place at about 6:30 p.m. From that moment on, residents of the earth’s Northern Hemisphere will experience increasing hours of daylight and shorter nights, through the spring equinox on March 20, continuing until the process reverses at the summer solstice on June 21.

The December solstice occurs annually on a day between Dec. 20 and Dec. 23, when the sun is directly overhead on the Tropic of Capricorn in the Southern Hemisphere.

During 2011, there will be four partial solar eclipses and two total lunar eclipses:

  • Jan. 4 — Partial solar eclipse
  • June 1 — Partial solar eclipse
  • June 15 — Total lunar eclipse
  • July 1 — Partial solar eclipse
  • Nov. 25 — Partial solar eclipse
  • Dec. 10 — Total lunar eclipse

The Herald Gazette Reporter Shlomit Auciello can be reached at 236-8511 or by e-mail at sauciello@villagesoup.com.