Pictures of the conjunction!
Published on Dec 1, 2008 at 7:05 pm.
3 Comments.
Filed under astrophotography.
A little while ago I took these photos of the conjunction that I blogged about a few hours ago. As before, click on the image to get a bigger sized view.
Both photos were taken with a Nikon D70, ISO 1600. The upper one was an 0.5 second exposure, and the lower one was a 2 second exposure. The longer exposure photo obviously over exposed the planets and the brightly lit surface of the Moon. However, the longer exposure also brought out the more dimly lit side of the Moon. The Moon does not shine by its own visible light. It reflects visible light, which is how we see it. So, the phases are the result of the direction that the Sun is shining on the Moon. But, sometimes you can see some of the non-sunlit side of the Moon. This is because the Sun also shines on the Earth, which reflects a large amount of that sunlight back into space. In fact, the Earth is far more reflective than the Moon, and a fair bit larger in the sky. So, if you were on the Moon tonight looking back towards Earth, you’d see a nearly full (gibbous) Earth. That would be much brighter than a nearly full Moon. All of that light falls on the Moon, and some of it reflects back into space. This reflected light which lights the “dark” side of the Moon is called earthshine.
When you see the Moon lit by earthshine like this, you are seeing doubly reflected light. Each reflection is only a fraction as bright as the Sun, which is why it is so dim. Your eye has a much more dynamic range than a camera, though. Thus, when you look at the earthshine lit Moon, your eye can adapt to the wide range of brightness and you can see both the bright part and the dim part. A camera, though, does not have the same range, so it will normally have either the bright part or the dim part with the proper exposure. Where the earthshine lit part is visible, the bright part is way over exposed. But, where the bright part is more properly exposed, then the dim part is too dim to see. Even here, the lit part of the Moon is overexposed, but if I got that exposed right, then even Jupiter would be too dim to see. That is also why you do not see stars in the photos taken from the surface of the Moon. In order for the interesting things (the lunar surface, itself) not to be overexposed, the exposure is too short for the stars to be visible.
So, for those of you who missed looking for yourself tonight, I thought that I’d post these photos.
-Astroprof
Keith on December 1, 2008 at 10:32 pm: 1
Thanks for sharing. We were clouded out here in LA.
Jeff on December 2, 2008 at 10:43 am: 2
Those are great. We were cloudy in St. Louis too. I literally only got to see it for 3 seconds on my drive home from work. Thanks!
Sonnenschutz on December 12, 2008 at 10:46 am: 3
Thank you for the picture, I don`t saw it in Germany