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Eclipse

Entry 597, on 2007-08-29 at 16:28:48 (Rating 1, Activities)

Last night I observed a total eclipse of the Moon which was the last one visible from New Zealand for about three years. Unfortunately the weather rapidly deteriorated as the time of the eclipse approached, but I was still able to observe it through patches of cloud. Then as totality approached the sky cleared and I got some excellent views after that, so the weather was quite friendly after all (apart from the cold temperature and annoying wind).

I took a series of photographs of the eclipse which I have included with this blog entry. Its surprisingly difficult to get the exposure just right because the part of the Moon still lit by the Sun is so much brighter than the area in the umbra. Maybe this shouldn't be surprising because its only light refracted through the Earth's atmosphere which prevents the areas of the Moon in shadow being completely dark.

The astronomy program I use on my Mac laptop (Starry Night) was very helpful and interesting during this event. It showed me when different parts of the event would begin and end and it also revealed some interesting phenomena. For example, because the Moon's orbit isn't circular it was getting about 1 kilometer closer to the Earth every second I was watching it! Another interesting thing was the program's rendition of the Earth as seen from the Moon, with a thin red atmosphere surrounding it.

So I didn't finish until after 1 am and I got fairly cold and I didn't get the programming work done that I was supposed to, but when you're an amateur astronomer these are sacrifices you have to make!

Comment 1 (913) by Star Man on 2007-10-11 at 19:59:27:

What type of equipment did you use for these pictures and what settings did you use on the camera? Do you have a telescope or just a camera?

Comment 2 (916) by OJB on 2007-10-14 at 11:33:52:

I used my Canon EOS 350D digital SLR with a Canon 75-300 mm lens at 300 mm on a camera tripod (this was before I got my driven telescope). Exposures ranged from 1" to 1/320" depending on how much of the Moon was in shadow. I also changed the f/ratio from f/11 to f/5.6 and the speed from 200 to 800 iso.

The difference in light form the fully illuminated to fully eclipsed Moon is a lot more than you might think, that's why its so hard to get the half eclipsed Moon (image 4th from left above) right. Notice that when the exposure is correct for the illuminated area (image 2nd from left) the eclipsed area is totally dark. Next time I will do multiple exposures at different speeds and combine them in Photoshop.

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