“Barely There” Lunar Eclipse

Last night's full Moon was accompanied by a lunar eclipse — but no one noticed! Even amateurs who were aware of the event couldn't tell by eye that something was going on.

That's because the Moon skirted through the outermost fringe of Earth's shadow, the penumbra, and only about half of the lunar disk was involved.

Penumbral lunar eclipse
Identical exposures taken before and during the lunar eclipse of August 5-6, 2009, reveal a very slight penumbral shading at lower left.
© 2009 Tunç Tezel
Photography proved the only sure way to confirm that an eclipse occurred, as these two images by Turkish amateur astronomer Tunç Tezel show. He took identical 1/500-second pictures at ISO 100 using a Meade 8-inch LX10 telescope and a Canon EOS 5D camera. One was snapped well before the eclipse began and the other at mid-eclipse. You can see a subtle change in shading at lower left.

Meanwhile, the Moon appears to nod noticeably between the two frames, mostly due to Tezel's changing perspective as Earth rotated through the night.

This weak lunar eclipse comes just two weeks after a spectacularly deep and long total solar eclipse on July 22nd, which was preceded by another weak penumbral eclipse on July 7th. And these two barely there events continue an extended drought of lunar eclipses. The last total lunar eclipse occurred in February 2008 (the third of its kind within a 12-month span), and the next won't happen until late December 2010.

Observers in the Eastern Hemisphere can look forward to a partial lunar eclipse this coming New Year's Eve. It won't be much of a visual treat either — but at least it'll be noticeable! Click here to keep tabs on all of this year's solar and lunar eclipses.