Lunar Eclipse  (December 21, 2010)

Fig. 1.  Composite photograph of fully eclipsed Moon as it appeared to the naked eye in the southwestern sky on 2010 December 21 from the driveway of our house in Cockeysville, Maryland.  The Moon appeared as a small, dim, sharply demarcated orange disk among the stars.  (Canon 5D Mark II camera with 50 mm f/1.4 lens set at f/2.8, ISO 400, composite of 0.5- and 8-second exposures.) Fig. 2.  Photograph through telescope taken at lunar eclipse's midpoint on 2010 December 21 at 03:17 EST (08:17 UT), when the Moon passed through the darkest part of Earth's shadow along the Moon's path. Fig. 3.  Time-lapse movie (1.1 Mb) covering the beginning and middle of the lunar eclipse, demonstrating passage of Earth's shadow over the Moon.  In this time-lapse sequence, time has been sped up by a factor of 360.  During the beginning of the eclipse, the camera was set to show the part of the Moon not yet covered by Earth's shadow.  During the middle of the eclipse, the camera was set to show the part of the Moon covered by Earth's shadow.  The telescope tracks the Moon so that it appears motionless in the frame, but it is actually moving relative to the stars, a few of which are visible in the background toward the end of the movie.  Playing this movie requires web browser support of HTML5 video. Fig. 4.  Our setup for tracking and photographing the lunar eclipse.  The main components are telescope, motorized tracking mount, digital SLR camera, and laptop computer.  The air temperature was 23°F as we huddled around the computer in front of our darkened house at 3 am.  This was not the first late winter night activity that neighbors have noticed in front of the Engs' house.  (Canon G11 camera, 13 seconds at f/2.8.)

Rare Triple Coincidence During a full moon, the Sun and Moon are on opposite sides of Earth.  Therefore, if a full moon happens during a winter solstice, when the Sun is at its lowest height above the horizon, the Moon will be at its greatest height.    Lunar eclipses can only occur during a full moon.  If a lunar eclipse happens during the winter solstice, the eclipsed moon will be at its highest possible position in the sky.  The combination of full moon, winter solstice, and lunar eclipse is quite rare.  Prior to 2010, such an event occurred 372 years ago in 1638, the only other time since the year 1 AD.  The next one will occur in the year 2094.    This was the third lunar eclipse we have been able to observe and photograph from our driveway (Figs. 1-3).  More details about lunar eclipses in general can be found on our lunar eclipse pages from 2004 and 2008.  Observing the entire 2010 lunar eclipse would have required staying up almost an entire weeknight, so we had to stop photographing before the eclipse ended.    We photographed the eclipse using a setup to capture full-frame images of the Moon (Fig. 4). GPS location:  N 39° 28.274', W 76° 35.681', elevation 520 ft Telescope:  Celestron C9.25 Schmidt-Cassegrain with f/6.3 focal reducer lens (235 mm aperture, 1480 mm effective focal length) Camera:  Canon EOS 5D Mark II (21-megapixel resolution, full-frame 35 mm format) mounted at telescope's prime focus with 2-inch diameter coupling system Telescope mount:  Losmandy GM-8 equatorial mount with digital clock drive to compensate for Earth's rotation; manual corrections to compensate for Moon's motion against the stars Exposure:  Ranged from 1/500 second at ISO 400 during beginning of eclipse to 4 seconds at ISO 800 during middle of eclipse Camera control:  Telescope focus and camera settings adjusted via USB connection with Canon EOS Utility software running on Apple MacBook Pro laptop; time lapse frames triggered by Canon TC-80N3 timer remote control Image processing:  Frames aligned and sharpened using Adobe Photoshop CS4 and custom JavaScript program; assembled frames into movie using Apple QuickTime Pro 7 ( back to home page)

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