This month sees a penumbral eclipse of the Moon. It is the first of four eclipse this year (penumbral eclipses also occur in July and August, and there’s a Partial eclipse in December). The eclipse details are shown below. Times are in UT. The diagram (slightly reduced in size) was created with LunarPhase Pro.

In a Penumbral Eclipse the Full Moon passes into the outer shadow of the Earth and dims imperceptibly. A penumbra refers to a partially shaded outer region of a shadow that an object casts. A penumbral eclipse occurs when the moon passes through the faint penumbral portion of the earth’s shadow. The moon’s surface is not completely shadowed by the earth’s umbra (the darkest part of a shadow). Instead, observers see only the slightest dimming near the lunar limb closest to the umbra. The eclipse may be undetectable unless at least half of the moon enters the penumbra.

Many penumbral eclipses have few observable effects but the February 9 lunar eclipse will carry the moon far enough into the light gray shadow to produce a dimming of the northern lunar limb. According to NASA, this event is the deepest penumbral eclipse in 2009, with a penumbral magnitude of 0.899. It will be visible to the naked eye as dusky shading in the northern half of the moon.


Click for larger image

The eclipse’s start and end are not visible to the naked eye and no shading will be seen until about two-thirds of the moon’s disk is immersed in the penumbra.

The eastern parts of Canada and the United States (USA) will miss the eclipse because it begins after moonset. Observers in the western parts of Canada and the USA will have the best views with moonset occurring sometime after mid-eclipse. To catch the entire event, you’ll need to be in places such as Alaska, Australia, eastern Asia, Hawaii or New Zealand.

Observers in western Europe will be out of luck too, as the moon doesn’t rise until after the eclipse finishes. Those in eastern Europe will get to see part of the eclipse with the moon rising just before mid-eclipse.

The penumbral lunar eclipse on February 9, 2009, is not the only eclipse to occur during the year. The list of eclipses for 2009 includes:

  • An annular solar eclipse on January 26.
  • A penumbral lunar eclipse on February 9.
  • A penumbral lunar eclipse on July 7.
  • A total solar eclipse on July 22.
  • A penumbral lunar eclipse on August 6.
  • A partial lunar eclipse on December 31.

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Lunar Eclipse Videos:

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