blamski Posted October 23, 2012 Report Share Posted October 23, 2012 hi all i'm wondering if anyone can help me out with a little research i'm trying to do for one of my projects. i'm trying to find out the strength and colour temperature of sunlight that arrives on the surfaces of earth, venus, the moon and mars. i know that there are certain modifying factors related to inconsistent cloud cover, atmospheric densities and distances from the sun but something near enough to the mean would be usable. i've been googling for days - NASA pages, wikipedia, all sorts of science blogs etc etc but have so far been able to come up with anything so far. if anyone already has this kind of information or knows where to point me i'd really appreciate it. cheers Quote Link to comment Share on other sites More sharing options...
Guest Aemilius Posted October 23, 2012 Report Share Posted October 23, 2012 What's the project? Quote Link to comment Share on other sites More sharing options...
blamski Posted October 23, 2012 Author Report Share Posted October 23, 2012 its one of a series of projects i've been doing that reference astrobiology and the use of model organisms in space based bio-science. in this instance i want to grow some arabidopsis seeds under light conditions found on other planets in the solar system (ones that we believe, or have believed, might one day be settled by humans). i'm using the NW67 photomorphogenic mutant as it is shown to develop differently under different percentages of red or blue light. just in case you didn't get this from other posts of mine, i'm coming at this as an artist not a scientist. Quote Link to comment Share on other sites More sharing options...
Chewbalka Posted October 23, 2012 Report Share Posted October 23, 2012 Try this out, hopefully it helps!I was just looking at this a few days ago! http://en.wikipedia.org/wiki/Apparent_magnitude#Calculations Quote Link to comment Share on other sites More sharing options...
blamski Posted October 23, 2012 Author Report Share Posted October 23, 2012 yeah, the apparent magnitude page is interesting and i lost myself in it, and some of the links from it, for a while. its not quite what i need though. i'm looking for light intensity and colour temperature at the surface, not as perceived from another body at great distance. cheers all the same... Quote Link to comment Share on other sites More sharing options...
Chewbalka Posted October 24, 2012 Report Share Posted October 24, 2012 http://en.wikipedia.org/wiki/Venus#Atmosphere_and_climatehttp://en.wikipedia.org/wiki/Mars#ClimateI dont even know if this is gonna help and i am sure ya all ready got this anyway... Its a real tough project ya got there... Maybe do a little photosynthesis research with filters to try and match the lack of sunlight... Quote Link to comment Share on other sites More sharing options...
blamski Posted October 24, 2012 Author Report Share Posted October 24, 2012 wikipedia is pretty much always my first port of call when i'm researching stuff, not so much for the quality of information in any article but more for the links and references that a well written article will provide. thanks again for sending links, but... i've already seen them and they don't really help. ;) if i continue with a lack of definitive, or even ball park, data about the light intensity and colour temperature (no apologies for the english spellings, by the way) then i'm considering even grabbing some NASA 'real colour' images and checking the colour data with photoshop. and this despite knowing that there is ongoing controversy about whether NASA's 'real colour' images are actually 'real colour' or not. that's a whole other conversation in itself. Quote Link to comment Share on other sites More sharing options...
blamski Posted October 30, 2012 Author Report Share Posted October 30, 2012 in case anybody is actually interested in this question about the quality of light on other planets, i found this wikipedia link. so... while i was busy trying all sorts of clever scientific search terms about colour temperatures and so on, all i really had to do was type in 'extraterrestrial skies' <_< its still not quite what i was looking for.... but was kinda interesting and kinda helpful all the same Chewbalka 1 Quote Link to comment Share on other sites More sharing options...
Chewbalka Posted October 31, 2012 Report Share Posted October 31, 2012 (edited) Thats a cool read! I would not have expected the jupiter and saturn responses! Wonder if they are correct? One day we will know for sure! Hopefully i am still alive to find out lol Edited October 31, 2012 by Chewbalka Quote Link to comment Share on other sites More sharing options...
blamski Posted October 31, 2012 Author Report Share Posted October 31, 2012 yeah... given the choice i'm not sure i'd prefer to be looking at Mars from Phobos, where Mars fills a quarter of the sky, or looking at Saturn from Pan, seeing the rings all around you and an enormous Saturn hanging above. both sound pretty spectacular. Quote Link to comment Share on other sites More sharing options...
maddog Posted November 1, 2012 Report Share Posted November 1, 2012 (edited) hi all i'm wondering if anyone can help me out with a little research i'm trying to do for one of my projects. i'm trying to find out the strength and colour temperature of sunlight that arrives on the surfaces of earth, venus, the moon and mars. i know that there are certain modifying factors related to inconsistent cloud cover, atmospheric densities and distances from the sun but something near enough to the mean would be usable. i've been googling for days - NASA pages, wikipedia, all sorts of science blogs etc etc but have so far been able to come up with anything so far. if anyone already has this kind of information or knows where to point me i'd really appreciate it.The answer to your question is in two parts:1) The first part is easy. This is just color (frequencies) of light from the sun. Our sun being a G2 IV main sequence star with the central wavelength around 580 nm or so (yellow).2) The hard part is what would the color you would see somewhere (another planet). This depends on many things: the absorption properties of the atmosphere of the planet you are on (assuming there is one). This depends on the atmospheric density which is likely dependent on elevation and how thick the atmosphere is. If the atmosphere is thick enough to support vapor suspension then yes, clouds may form which can attenuate light depending upon frequency. Humidity is also relevant as is the current local temperature and pressure. Know what the atmosphere is composed of will help to determine what wavelengths of light might be absorbed. I know this didn't really answer it other than give you some ideas upon which to enhance your search. Good Luck! :D maddog Edited November 1, 2012 by maddog freeztar 1 Quote Link to comment Share on other sites More sharing options...
blamski Posted November 3, 2012 Author Report Share Posted November 3, 2012 thanks, maddog. the thing is that we know quite a lot about the conditions you mention on mars, the moon, venus, and titan. we've sent probes and orbiters there and measured things, taken pictures and poked around in all sorts of fascinating ways. we know reasonably well what the sky looks like in these places, and what the atmosphere is made of. all this data is easily accessed in half an hour on the internet. the thing we don't have, or that i haven't discovered, is the actual quality of light that reaches the surface - or that would fall on the leaves of my hypothetical plant. actually, as you infer, given the spectrum of sunlight and the absorption properties of planetary atmospheres combined with their distance from the sun, there must be some math that could work out what i'm looking for. surely its out there somewhere.... Quote Link to comment Share on other sites More sharing options...
Moontanman Posted November 8, 2012 Report Share Posted November 8, 2012 I remember reading some place that in a methane atmosphere the sky would appear green to a human, color perception is tied to human eyesight and human eyes are a very poor judge of light intensity. From a strictly c wave length perspective the sun should appear the same color at any distance. I was once involved in approximating sunlight to grow plants, coral really, but the same values work for higher plants as well. Distance shouldn't matter in color just intensity. The atmosphere is the deciding factor, in my case water filters out the red quite soon, 33 feet and you have no red at all. Blood appears green at that depth... I know, i was cut while diving, really weird to see green stuff coming out of your skin... Quote Link to comment Share on other sites More sharing options...
freeztar Posted November 8, 2012 Report Share Posted November 8, 2012 I remember reading some place that in a methane atmosphere the sky would appear green to a human, color perception is tied to human eyesight and human eyes are a very poor judge of light intensity. From a strictly c wave length perspective the sun should appear the same color at any distance. I was once involved in approximating sunlight to grow plants, coral really, but the same values work for higher plants as well. Distance shouldn't matter in color just intensity. The atmosphere is the deciding factor, in my case water filters out the red quite soon, 33 feet and you have no red at all. Blood appears green at that depth... I know, i was cut while diving, really weird to see green stuff coming out of your skin... Actually, the wavelength of light stretches over distance due to dark energy. This is why we see a Doppler Effect in the universe. Of course, this is imperceptible to the human eye within the solar system. As for the intial question, I think Maddog outlined it pretty well. If you want *exact* colours for the human eye on the planet's surface, then you would have to go there yourself. But a close approximation can be had from using the data that probes have provided. It might be better to approach this subject one planet/moon at a time. The ground-observed sunlight on The Moon is going to look a lot different to the light on Venus or Titan. And as Maddog points out, elevation can be a big factor. If I were writing a scientific paper on this, I would first delineate all of the variables that influence colour (mean cloud cover, mean cloud composition, ground temperature, atmospheric temperature profile, etc. One avenue that might prove fruitful is to study papers relating to phytoplankton growth on extraterrestial bodies (astrobiology). Here is a starting point: http://plankt.oxfordjournals.org/content/23/12/1373.full Quote Link to comment Share on other sites More sharing options...
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