Timeline for How many times brighter would full-earth-shine appear to people standing on the moon, than full-moon-shine does to people on earth?
Current License: CC BY-SA 4.0
24 events
| when toggle format | what | by | license | comment | |
|---|---|---|---|---|---|
| May 5, 2022 at 6:25 | comment | added | nanoman | The log measure should be stated as "four magnitudes brighter", not "four times brighter". Likewise, in a comment, you said "a factor of two in terms of perceived brightness", but that should be "an difference of two magnitudes in terms of perceived brightness". Once you have taken the log, the comparison is additive, not multiplicative. If A is three magnitudes brighter than B and B is three magnitudes brighter than C, then A is six magnitudes brighter than C. Your phrasing like "perceived as three 'times' brighter" would lead to thinking that A is perceived as nine 'times' brighter than C. | |
| Feb 22, 2021 at 10:00 | vote | accept | Constantthin | ||
| Feb 18, 2021 at 13:38 | history | bounty ended | Constantthin | ||
| Feb 13, 2021 at 23:01 | comment | added | David Hammen | @Constantthin No, it is not. Both luminosity and magnitude are valid measures of the concept of "brightness". | |
| Feb 13, 2021 at 22:26 | comment | added | Constantthin | Is it not clear on my question which of the two I am asking for? | |
| Feb 13, 2021 at 19:39 | comment | added | David Hammen | @Constantthin It depends on what one means by "brighter". If it's luminosity, then the answer is 41 (better, 42, because that's the answer to life, the universe, and everything). If it's magnitude, then the answer is 4 because magnitude is a $\log_{2.5}$ function. | |
| Feb 13, 2021 at 12:08 | comment | added | Constantthin | So your answer is 4 times brighter, not 41 times? | |
| Feb 10, 2021 at 15:30 | comment | added | PM 2Ring | Well, I did originally think of titanium dioxide, but I settled on chalk because it's less dense and a lot cheaper. :) Hopefully, I'd get a bulk discount on 94.8 billion (metric) tons of chalk: that'd give 1 mm depth over the whole Moon. But of course I can ignore most of the far side. | |
| Feb 10, 2021 at 13:16 | comment | added | David Hammen | @PM2Ring Chalk dust? Why not titanium dioxide? That would raise the Moon's albedo to nearly 1, or a factor of eight increase in luminosity. But that's only a bit over a factor of two in terms of perceived brightness; the human eye has a logarithmic response. I updated by answer to reflect the difference between luminosity and magnitude. | |
| Feb 10, 2021 at 13:14 | history | edited | David Hammen | CC BY-SA 4.0 |
added 179 characters in body
|
| Feb 10, 2021 at 12:06 | comment | added | PM 2Ring | Now I'm wondering how bright the Full Moon would be if the Moon had a high albedo, eg if we covered it in chalk dust... | |
| Feb 10, 2021 at 2:33 | comment | added | Constantthin | @David Hammen. I suppose that temperature must have played a (small?) part in their choice also, considering temperature swings between +200 and -200? | |
| Feb 9, 2021 at 20:36 | comment | added | David Hammen | @Luris: I added a linked question on this site in which an answer by uhoh contains this very image. I added the link under the question. | |
| Feb 9, 2021 at 20:34 | comment | added | David Hammen | @Constantthin All Apollo missions occurred under sunlit conditions. Landing occurred an Earth day or two after sunrise had occurred at the landing site (think of roughly an hour or two after sunrise on the Earth) to enhance the crew's ability to see shadows, and launch occurred an Earth day or two before lunar noon to avoid extreme lunar heating. The longest mission on the Moon was a bit over three Earth days long. | |
| Feb 9, 2021 at 19:10 | comment | added | Luris | @Constantthin The photo is from Apollo 12. I couldn't 100% confirm the information (I probably didn't search for the right term), but they were lit by the sun at least at some point while on the moon (that's how the color video camera got destroyed), and given the length of a lunar day, I assume the whole mission (and that picture) was lit by the sun. It seems it was the case for every Apollo mission? I'm surprised I didn't find a question about that on the stack. | |
| Feb 9, 2021 at 11:23 | comment | added | Constantthin | Nice. Is the venue lit up by the earth, or the sun, in that picture? | |
| Feb 9, 2021 at 10:25 | comment | added | David Hammen | @jcaron - i.sstatic.net/OVZLJ.jpg | |
| Feb 9, 2021 at 9:22 | comment | added | jcaron | Wow. The moon looks sooo bright in the night sky (much brighter that "slightly aged asphalt"), so is that just an optical illusion due to the black background? | |
| Feb 9, 2021 at 1:27 | comment | added | Constantthin | @Ruslan. Thx. I had to read the word “sunglint” a few times before I realised that it says “sunglint”, and not “sunlight” :) | |
| S Feb 8, 2021 at 17:54 | history | suggested | costrom | CC BY-SA 4.0 |
Edited question quote since typo was fixed in prompt; minor edits
|
| Feb 8, 2021 at 15:41 | review | Suggested edits | |||
| S Feb 8, 2021 at 17:54 | |||||
| Feb 8, 2021 at 14:46 | comment | added | Ruslan | Given that we have full Earth, sunglint should increase albedo considerably. | |
| Feb 8, 2021 at 11:00 | comment | added | Constantthin | +1. Would the moon's lack of atmosphere be an influencing factor in the light reaching the moon surface at night, from a full earth? In other words, would it be easier, or more difficult, to read a newspaper under a full earth, if a moon atmosphere was in place? | |
| Feb 8, 2021 at 9:07 | history | answered | David Hammen | CC BY-SA 4.0 |
