Full Lunar Eclipse Feb 20/21 / Earth picture |
Full Lunar Eclipse Feb 20/21 / Earth picture |
Feb 7 2008, 10:26 PM
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Newbie Group: Members Posts: 2 Joined: 23-January 08 Member No.: 4025 |
I see we have a full lunar eclipse coming on Feb 20/21 (depending where you live).
I know that even during a full eclipse the Moon is still visible with a coppery hue, due to the refraction of light around the Earth. Now that we have a bunch of probes in orbit of the Moon, is there any plan / is it possible to take an image of the Earth from the Moon during totality? (or has this already been done?) I would think that a picture of the Earth surrounded by a red ring would be amazing! |
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Dec 17 2015, 08:46 PM
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Senior Member Group: Members Posts: 1649 Joined: 5-March 05 From: Boulder, CO Member No.: 184 |
Thanks for the Celestia view. This provides a reminder that it would be nice to add in a representation of the solar corona, as the brightness range of the rendered image allows.
I mentioned this model in passing to Emily at the AGU conference and she posed the question of whether Earth city lights would be visible on the moon during totality. As an example, I found a web site where it states Tokyo would appear +23.7 magnitude from 30AU away. This translates to about magnitude +9.8 as seen from the moon, below naked eye visibility. Additionally I believe there would be significant glare from the ring of light refracting through Earth's atmosphere making this more difficult to see in practice, depending on how deeply immersed the observer is in the umbra. The apparent magnitude of the developing ring is about -20 for an observer on the edge of the umbra and -15 for an observer in the center (about the full moon seen from Earth). The latter value is somewhat tricky to specify due to the deep red color, meaning the apparent magnitude can deviate from the "visual" V-band magnitude. Here is an image similar to post #27 with some of the antialiasing measures applied: In this view around the edge of the umbra the brightness is scaled so the unattenuated (and non-limb darkened) sun is white with 255 RGB counts. When we go to the center of the umbra the red ring faintly shows up with 17 counts in the red channel, somewhat more than 100 times surface brightness reduction in the red channel. This looks pretty dim even when I crank up my monitor brightness. So it's barely possible to show the full dynamic range involved. The second image shows this as a blinking comparison between edge of umbra and center of umbra views. This is a good test of one's monitor contrast. It's also possible to scale up the brightness of the image while you're displaying it to see the red ring better. (UPDATED Jan 3, 2016) -------------------- Steve [ my home page and planetary maps page ]
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