Sky color http://www.nanowrimo.org/en/forums/science-fiction/threads/49934 Maydeleh Oh, this is so frivolous. But for those of you doing habitable planets, what are you doing with observed sky color? I've been doing a little reading, but can't get much of a picture of what's potentially possible. What have you selected? Mon, 06 Feb 2012 01:08:16 -0600 http://www.nanowrimo.org/en/forums/science-fiction/threads/49934?page=1#forum_thread_comment_1119282 http://www.nanowrimo.org/en/forums/science-fiction/threads/49934?page=1#forum_thread_comment_1119282 Kataja Our sky is blue due to optical effects (ärgh, now I'm not sure about the correct terms in English), so some kind of blue is almost "obligatory", if you wish to have sun shining and not a sky that is permanently covered by clouds. Of coutse if you have something in the air directly coloring it, the sky may have another colour. And a wild guess: the thicker the atmosphere, the lighter colour and vice versa. Mon, 06 Feb 2012 03:43:40 -0600 http://www.nanowrimo.org/en/forums/science-fiction/threads/49934?page=1#forum_thread_comment_1119465 http://www.nanowrimo.org/en/forums/science-fiction/threads/49934?page=1#forum_thread_comment_1119465 throughasplendour (Start of science lesson. Apologies if you already know all this.) In simple terms, when gas in the atmosphere is hit by light from the sun, the light scatters. The wavelength/colour of the light determines by how much the light is scattered. The blue part of light is scattered the most. When you see the sky as being blue, you're actually seeing blue light being scattered off the gas in the atmosphere. The red part of light is scattered the least when it hits atmospheric gas, which is why the sky goes red at sunset: this is the time of day when the light is going through the largest amount of atmosphere before it reaches your eyes, so it loses more blue light. White light minus the blue part produces red light. So re: Kataja's point, the thicker the atmosphere, the redder the sky (less and less blue light reaching your eye). At the other end of the scale, the thinner the atmosphere, the whiter (or paler blue) the sky (less and less blue light being scattered by the atmosphere to reach your eye). (End of science lesson) Assuming you care about respecting the science (why else would you be asking?) If you want to have a very earth-like planet, it's probably going to have to be blue. But if the atmosphere contains coloured gases that might absorb or reflect different components of white light, you could have different sky colours.However, you might also need to change other colours on your planet, such as having plants with differently coloured leaves. If you want to really get into it you'll probably need to read a lot around the subject. If you want to cheat, you could make the sky whatever colour you want, then say that the species of people living there have eyes that see the colour the sky should, scientifically, be as your chosen colour :) Mon, 06 Feb 2012 05:50:21 -0600 http://www.nanowrimo.org/en/forums/science-fiction/threads/49934?page=1#forum_thread_comment_1119591 http://www.nanowrimo.org/en/forums/science-fiction/threads/49934?page=1#forum_thread_comment_1119591 Kataja Hmmm. But isn't there a turning point? When there is no atmosphere, there is nothing to scatter the light, and the sky is black. Add more stuff to scatter, and you first get lighter and lighter blue and then colour getting deeper and moving towards red as blue rays start to absorb and longer waves scatter more... (disclaimer - I'm just pondering, have no time to check jthe physics just now) Although an atmosphere so thin that the sky isn't even blue, is probably far too thin for any kind of life capable of looking at it - the sky's light blue in Mars, as far as I know. Tue, 07 Feb 2012 04:24:56 -0600 http://www.nanowrimo.org/en/forums/science-fiction/threads/49934?page=1#forum_thread_comment_1121956 http://www.nanowrimo.org/en/forums/science-fiction/threads/49934?page=1#forum_thread_comment_1121956 throughasplendour You're right. Whoops. The sky's black when there's nothing to scatter light. I must have been thinking about the light, which is closer to white when there's less scattering, rather than the sky. Tue, 07 Feb 2012 09:20:14 -0600 http://www.nanowrimo.org/en/forums/science-fiction/threads/49934?page=1#forum_thread_comment_1122105 http://www.nanowrimo.org/en/forums/science-fiction/threads/49934?page=1#forum_thread_comment_1122105 Notkieran Don't forget that there will be some variation due to the light from the parent star, as well. Thu, 09 Feb 2012 21:33:30 -0600 http://www.nanowrimo.org/en/forums/science-fiction/threads/49934?page=1#forum_thread_comment_1127944 http://www.nanowrimo.org/en/forums/science-fiction/threads/49934?page=1#forum_thread_comment_1127944 Cheesypriestess I read that the sky on mars is pink, actually...but maybe I'm wrong. It just seems so cool to have a pink sky. Mon, 27 Feb 2012 01:20:33 -0600 http://www.nanowrimo.org/en/forums/science-fiction/threads/49934?page=1#forum_thread_comment_1173721 http://www.nanowrimo.org/en/forums/science-fiction/threads/49934?page=1#forum_thread_comment_1173721 Kataja I can remember some early depictions of Mars sky being pink, but it was an error in the colour handling . OK, now I found: there is so much dust that it colours the sky oddly, but it varies between violet and pink or something like that: http://en.wikipedia.org/wiki/Astronomy_on_Mars Mon, 27 Feb 2012 05:44:49 -0600 http://www.nanowrimo.org/en/forums/science-fiction/threads/49934?page=1#forum_thread_comment_1173890 http://www.nanowrimo.org/en/forums/science-fiction/threads/49934?page=1#forum_thread_comment_1173890 RobertLent From the wikipedia article: Around sunset and sunrise the Martian sky is pinkish-red in color, but in the vicinity of the setting sun or rising sun it is blue. This is the exact opposite of the situation on Earth. However, during the day the sky is a yellow-brown "butterscotch" color.[3] On Mars, Rayleigh scattering is usually a very small effect. It is believed that the color of the sky is caused by the presence of 1% by volume of magnetite in the dust particles. Twilight lasts a long time after the Sun has set and before it rises, because of all the dust in Mars's atmosphere. At times, the Martian sky takes on a violet color, due to scattering of light by very small water ice particles in clouds.[4] Wed, 29 Feb 2012 11:47:52 -0600 http://www.nanowrimo.org/en/forums/science-fiction/threads/49934?page=1#forum_thread_comment_1179481 http://www.nanowrimo.org/en/forums/science-fiction/threads/49934?page=1#forum_thread_comment_1179481