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View Full Version : Lunar eclipse, Tenerife, 21st December



Perikles
2010-Dec-20, 10:03 AM
Nothing special about a lunar eclipse, you will say, but the one reported here (http://www.eclipsesolar.es/index_en.html)is unusual in that the eclipse coincides with the rising sun in Tenerife. This happened in 2001, and the link shows a photo of the shadow of the pointy volcanic cone of Tenerife stretching out towards the full moon.

It does seem strange that you can see both the sun and the moon at the same time during a lunar eclipse, but I seem to be the only person I know who finds this slightly disconcerting.

megrfl
2010-Dec-20, 01:57 PM
The article below was printed in our paper today, it doesn't mention Tenerife, but it sounds awesome.

Sun Sentinel

FORT LAUDERDALE — The last eclipse of the year promises to be a doozy: Legend has it that an event very much like it inspired a 1935 song that put Miami on the map.

“It’s going to be a ‘Moon Over Miami’ eclipse,” said Arnold Pearlstein, former planetarium director for Miami-Dade County schools and an astronomy columnist for the Sun Sentinel.

The show will happen Tuesday, the first day of winter, when the moon is at its northernmost point, directly above South Florida, he said.

Starting at 1:33 a.m., the silvery moon will begin to appear in shades of orange. By 2:41 a.m., the moon will be completely covered. It will b egin changing back by 3:53 a.m., Pearlstein said. The next total lunar eclipse will occur in 2014, but the next to coincide with the first day of winter won’t come until 2094.

Locals can grab their favorite blankets and enjoy the sight. The period when the moon will be completely covered will offer prime star-gazing skies, Pearlstein said, and no equipment is needed to view it.

NGCHunter
2010-Dec-20, 03:01 PM
It does seem strange that you can see both the sun and the moon at the same time during a lunar eclipse, but I seem to be the only person I know who finds this slightly disconcerting.
Atmospheric refraction is the reason; it makes things appear to above the horizon that have actually set in a pure geometric sense. Atmospheric refraction of objects on the horizon makes them appear to be approximately 34 arcminutes higher than they actually are; as you can see, that's a value large enough to fit the apparent diameter of the sun or moon, making it possible to observe both above the horizon simultaneously during an eclipse if your location and timing is just right.

Perikles
2010-Dec-20, 04:04 PM
Atmospheric refraction is the reason; it makes things appear to above the horizon that have actually set in a pure geometric sense. Atmospheric refraction of objects on the horizon makes them appear to be approximately 34 arcminutes higher than they actually are; as you can see, that's a value large enough to fit the apparent diameter of the sun or moon, making it possible to observe both above the horizon simultaneously during an eclipse if your location and timing is just right.Thanks for that. I was aware of the refraction, but didn't know the exact amount involved. My comment was rather a sociological one, in that a lot of people I know are aware of this coming eclipse and know they could see both sun and moon simultaneously. Nobody I know has actually raised the question as to how this is possible when the sun, earth and moon are in line.

Something in the back of my mind tells me that Aristotle also mentions a lunar eclipse when the sun is visible, but I can't find the reference. All I can find is in Meteorologica II viii where he explains why earthquakes sometime occur at an eclipse of the moon. Not his best moment.

RickJ
2010-Dec-21, 03:44 AM
Also when up high as on a mountain or in a plane, the horizon is lowered gaining several degrees more than refraction gives you. One night many years ago flying about 10,000 feet I watched the moon rise as we approached the airport. We decided to see if we could descend fast enough to make the now risen moon set. Turned out to be easy. In fact we were gassing the plane when the moon rose for us a second time that night. There was no eclipse that night though the moon was close to full. A couple days past full as the sun had set and the sky rather dark when the moon began to rise for the first time.

I should add it is rather neat to watch the moon set in the east! A fast descent can do just that we learned that night.

Rick

Chuck
2010-Dec-21, 05:42 AM
Too cloudy in Phoenix, Arizona. That never happens.

Hernalt
2010-Dec-21, 10:53 AM
No. 1 (http://www.flickr.com/photos/cydar/5279454021/) , No. 2 (http://www.flickr.com/photos/cydar/5280058816/) , 12/21 eclipse, Tucson, 8 inch Celestron, Canon Eos Rebel XSI

baric
2010-Dec-21, 02:25 PM
Here's a close-up shot of my nephew watching the eclipse. The angle was such that the moon looks particularly large and almost pinkish.

http://sphotos.ak.fbcdn.net/hphotos-ak-snc4/hs1357.snc4/162905_1489252710871_1220577279_31124671_1698410_n .jpg