Tuesday, April 15, 2014

Salmon Moon, the Lunar Eclipse of April 2014

Last night I watched and photographed the lunar eclipse from start to finish. I haven't worked on my photos much and will do that over the next few weeks in my ample spare time. My first impression is that this eclipse was a bit bland, not quite as rich as others I've seen and photographed before. You can see a little color difference in these moons, one taken at the peak of the 2007 eclipse and the other from the peak of the April 2014 eclipse:

These were taken with the same telescope and camera, the only difference is that the 2014 photo is using my camera's medium setting for file size and in 2007 I used my camera's maximum setting. The difference is their pixel densities, which I don't believe account for the 2007 eclipse appearing a stronger orange over the maria.

Here's the eclipse at it's peak:

Here are pre- and post-peak images, at time when the camera speed can be manipulated to reveal color gradients from white to purple to orange:


I believe the color gradient is caused by different layers of the atmosphere transmitting different wavelengths: e.g, the purple band is caused by ozone or other stratospheric gases and the red zone is the troposphere's scattering of all but the red light. I'm not sure about the stratosphere imparting a purple color and hope to check on this. 

The size difference between photos is a result of adding a focal reducer to my telescope. I photographed the first half using my telescope's prime focal length, focal ratio F6.3, and the second half at F5.0 with the focal reducer. I saw no appreciable difference in image quality. I used the focal reducer so I could include the star Spica in my field of view:

Early in the eclipse, I thought I was watching the moon pass in front of a star, but upon examining my photos, the star emerged from behind the moon. The eyepiece inverts and flips images, so it's easy to lose track of which way the moon is moving. I put a few images together in this animation:

I still need to sort through my photos for more discoveries that may make for good animations.


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