why our palm doesn't turn dark even if we expose it to the sun ???
460649
lack of pigment melanin in palms and soles of feet? Dunno, just a guess.
1164007
Because of the hormone that makes your skin light or dark.  The more melatonin you have the darker the skin.  If you have light skin you should use a sunscreen or stay out of the sun.  Or in about 20 years you'll look like a prune.
1113985
Even the hightest SPF screen won't completely prevent UV rays from touching your skin. That's what tans you. The sunscreen is to help you stay in the sun longer without burning. It always needs to be reapplied every few hours. You'll tan if you're outdoors and exposed, believe me.
842958
I know it's a cultural thing, but you'd better embrace your dark skin, there's so many people who try to get your color.  I suppose that if you remain in cooler climates your skin will lighten up on its own.  Mine does without me trying.
367855
when you stand in the sun and get warm, it is because your skin absorbs the electromagnetic radiation we call light.  light is both a wave and a particle - called a photon.  photons have no mass, but they do carry energy.  when the photon is absorbed by your skin, the light energy is converted into (mostly) heat energy.\n\nanyway, it should'nt make a difference whether you are moving or not.  strictly speaking there are a few effects to consider but i would think they are very small.  for example:\n\n - the further you are from a light source, the dimmer it appears, and therefore the less light you absorb.  so if you are running away from the sun and you have a fixed effective area, then on average you will receive less solar flux than if you are just standing there.  however this is a tiny amount in terms of moving around on the surface of the earth.\n\n- conceivably if you are moving away from the sun, there will also be an effective doppler shift of the light, which will (slightly) shift the solar spectrum into the red.  since redder light has a lower energy, you should effectively absorb less energy, but the absorption spectrum of the skin should be considered.  also unless you are the flash, this effect will also be tiny because humans run so slow.\n\nthe energy that you DO absorb gets carried away from your body by several mechanisms:\n\n - radiation:  you (and all things) radiate light energy in the infrared.  this is called "blackbody radiation" and is a function of your temperature.  (blackbody radiation is why hot things glow orange, for instance.)\n\n - evaporation:  your skin sweats, and the sweat evaporates.  this evaporation requires some heat, which effectively cools down your skin.\n\n - conduction:  if you are standing perfectly still in air that is not moving, your body will warm up a layer of air molecules around your skin.  this warm air will rise, and cooler air will move in to replace it.  this is actually probably why it *feels* like you're cooler if you're running around: more wind = more cool air = more heat loss.
1039389
Its dark in your world, isn't it?  :-)
782431
Why SUN appears red in dawn? (and dusk)\n\nThis is the time when the sun's light travels through most atmosphere to reach us. The small particles of dust scatter some of the light and most of the light scattered is blue light. As the blue light gets scattered out of the original white light the light that reaches us has a bredominance of red light and so the sun appears red.\n\nThis also explains why the sky appears blue during the day as we see much of this scattered light coming at us from all directions. It also explains why when we see the sun through smoke it appears very red as well and why we see great sunsets after days with a great deal of haze or after some event such as a huge volcanic eruption somewhere on the earth gives us a long sequence of beautiful sunsets (and sunrises) as the eruption of Mt Pinatubo in the Philipines did in the 1980s
698574
First of all keep you arms covered when outside or use sun screen all year round.\nIf you do this the skin will naturally lighten on it's own. But there are a number of skin lighteners on the market available at your drug store or cosmetic counter.
319253
You mean like not being able to convert sunlight into illumination?
21830
"Dark" is not produced, per se...but it is an absence of light.  A black hole absorbs light...perhaps that is what you are looking for...\n\nLook at this website...it provides a quick overview of black holes and how they are created: \nhttp://www.damtp.cam.ac.uk/user/gr/public/bh_home.html\n\nAlso...to the person below me here...the clouds do not absorb light.  They block the sun's light and reflect it back to the atmosphere therefor cutting it off from our view.  However, some of the rays that come from the sun travel through the clouds, such as UV rays.  If the clouds absorbed light, we would see nothing during an overcast day.
1168385
Because of their skin color. I know that everyone needs to put on some sun screen. Just because your skin is dark doesn't mean you are protected form UV rays.
991413
Throw light . \nwhy, doesn't the place get any sunlight.
329179
I stand corrected, as usual.  The people below are correct in that the wavelength of the light is not correct for you to see your finger bones.  It takes a certain wavelength (e.g. X-rays), not the light that's coming from your mouse.  You probably also need the proper "background" to see it correctly.
626058
Since it is believed that people are originally from Africa, dark colored skin would have been the norm.  However, as people migrated north they weren't getting as much sun because they had to cover up to keep warm.  However, black people who get very little sun develope vitamin D deficiency because your body requires sunlight to make the last step of the synthesis go.  So, their skin needed to let more light in and it was beneficial to them to evolve lighter colored skin.  \nHave you noticed (part of it is interbreeding with white people, of course) that American blacks, who have been in the US about 200 years, are not nearly as dark black as native Africans anymore?
18414
The body is made up of many metals such as sodium from salt (sodium chloride) and iron that carries oxygen in the blood (hemoglobin).\n\nThe body may in fact light up when the sun shines on it because sunlight contains all visible and invisible wavelengths.  But you would not see the body light due to the strong glare of the sun.  You would need a special light (like ultraviolet blacklight) under dark conditions.  The black light would enter the skin and excite electrons which would in turn give off charteristic colors depending on the metals present, including the molecules they are a part of at present.  The body may even phosphoresce under certain light wavelengths if the metal phosphorus (from bananas) is present, and of course it is!
401016
because of the distance and variations of the surface temperature of the sun, plus the infrared spectrum within the sun, sun spots appear darker.Photvoltiac activity is contained within or under the suns surface, thereby hidden from our view, but detected via spectrum analyzers
318462
The sun shines for the same reason a fire radiate light.\nAnd we need the sun because without it it would be freezing cold outside. In fact the Earth and all the solar system wouldnt exist if the sun wasnt there because there wouldn't the gravitational field the sun provides to gather elements and form planets.