Tuesday, December 13, 2011

The December 10, 2011 lunar eclipse

Any hobby usually requires some "sacrifice". In my case, astronomy normally requires that I be awake and up while it's dark outside (the exception is when I'm using my telescopes to look [safely] at the Sun). A lunar eclipse always takes place when the Moon is full; the Moon is always exactly opposite the Sun then. At this time of year, the Sun rises low in the SE. That means that the Moon sets high in the NW.

This month's lunar eclipse occurred a couple of hours before sunrise, and I could watch it through my west-facing office window. I set up one of my cameras (a Canon Rebel XT SLR) and took some pictures through the double-paned window, and through breaks in the clouds. Before the eclipse started, the sky had been absolutely clear, but, just around the start of the eclipse, heavy clouds began to roll in. This is Vancouver, after all. Midway through the eclipse they totally obliterated any view of the eclipsed Moon. I got only one good picture through the last cloud break. These clouds kept the day dark and gray right through the next night, until the next morning.

Here are some of the pictures:

From the top down:

The Moon before entering Earth's shadow. The area at "11 o'clock" is getting darker.
Clouds are rolling in.
Three quarters into the Earth's shadow. Picture taken through a break in the clouds.

About 5 minutes before "totality" (again a break in the clouds). The star under the Moon is Iota Tauri (Iota in the constellation of Taurus, the bull)
The last "hole" in the clouds. The clouds to the right of the dark tree covered the Moon a short time later.
Midway through totality. This picture was taken just after the one above. About half-way through totality - the Moon has moved, so now is totally covered by the Earth's shadow. The brighter part of the Moon is closer to the edge of the shadow. Notice that the star Iota Tauri is now farther away from the Moon - it's a consequence of the Moon's motion in its orbit.

This is my last picture of this eclipse. A minute later, the Moon was completely covered by clouds and no longer visible.

The orange colour of the Moon in the Earth's shadow is due the sunlight being "refracted" by the Earth's atmosphere onto the Moon's surface. If you were on the Moon, you'd see the dark disk of the Earth surrounded by a reddish-orange ring (a circular sunset). From the Moon, this event is a total eclipse of the Sun. You'd have an awe-inspiring sight.

 The top picture was taken about two hours before the bottom one. It was a cold morning outside. This kind of thing did not bother me in the past, but now, in my old age, I enjoy creature comforts much more. I was glad to witness this in my nice, warm office.