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Sunlight reaches Earth's atmosphere and is scattered in all directions by all the gases and particles in the air. Blue light is scattered in all directions by the tiny molecules of air in Earth's atmosphere. Blue is scattered more than other colors because it travels as shorter, smaller waves. This is why we see a blue sky most of the time

As the light from our Sun shines into the atmosphere, most of the colors are able to reach the Earth’s surface uninterrupted. However, because blue light has a wavelength that is the same size as the particulates in the air, this light is scattered in every direction. This blue light bounces from particulate to particulate until it eventually reaches your eyes. For this reason, no matter what direction you look in the sky, it appears to be blue. This blue light originated with the Sun, was bounced around in the sky many times, and then eventually reached your eyes.

ARE YOU A SUPERTASTER? To find out, put blue food coloring on your tongue. Blue dye doesn't stick to taste papillae, so if your tongue doesn't get very blue, you're probably a supertaster. The bluer it gets, the greater the chance you are a subtaster. More hot sauce!

People who have a lot of papillae—the bumps on our tongue, most of which house our taste buds—often find flavors overwhelming. They're "supertasters," and as such they add cream to their coffee and order food mild instead of spicy. Subtasters, on the other hand, have low papillae density and prefer their chicken wings "atomic."

Most toxic plants taste bitter, and nomadic groups that came into contact with a variety of plants would have, over time, developed a variety of receptors. People from malaria-infested parts of the world tend to carry a gene that makes them less sensitive to some bitter compounds, specifically those that contain cyanide.

The wavelength of the blue light scatters better than the rest, predominates over the other colors in the light spectrum, and makes the sky appear blue to us.

The sky is blue because of the “scattering” of sunlight. The color blue has a shorter wavelength and greater energy than the other colors. As a result, blue is selectively absorbed by air molecules, then given off again in all directions. The other colors are less scattered, and therefore not usually seen.

s is pretty uncommon, just 11 out of every 1,000 Americans. This uncanny trait is caused by several factors, and can actually develop over tim

Sometimes, though, the concentration and distribution of melanin isn't uniform, which leads to a condition known as heterochromia. This condition can present itself in different ways. There's complete heterochromia, when each eye is a distinctly different color, say, one blue and one brown. Central heterochromia is when the eyes show various colors, such as a blue iris with a golden-brown ring around the pupil. And sectoral heterochromia is when one iris has a splash of color that's different from its overall hue, a trait that actress Kate Bosworth has.

Cats and dogs are just like color blind humans, seeing some colors but not all of them. For the bright daytime light, cells known as cones are needed. Humans have three kinds of cones, enabling them to see blue, red and green.

Cats and dogs, on the other hand, have just two kinds of cone cells (blue and green sensitive), allowing them to see only partial color.

while we’re on the subject, contrary to the legend that cats can see perfectly in total darkness, they do not have those superpowers. But cats require only about one-sixth of the light that humans do, making their night vision a whole lot better than ours

Eye color is the result of variations in the amount of melanin, a pigment found in the front part of the iris of the eye.  The lack of this pigment results in blue eyes, some pigment gives green and lots of pigment gives brown eyes.   So light brown eyes just have a bit less melanin than darker brown eyes.  All of the different shades of eye color happen the same way.  Blue-green eyes have an amount of melanin between green and blue, hazel eyes have an amount of pigment between green and brown, etc.  

During a sunrise, the sun is lower in the sky, which lengthens the angle at which light reaches the Earth. As a result, the shorter violet, blue and green light never reaches the eye, so only the yellow, orange and red light is visible. Because red has the longest wavelength, the first light of dawn often appears pink or red--depending on the particles in the atmosphere. As the sun moves further up the sky, the reds and yellows fade as the scattered blue light becomes more visible.

The planet that Voyager uncovered is a stormy, windswept world with a vivid blue hue. Its highly active atmosphere is surprising, since it receives so little sunlight to power its weather systems. Like the other giant outer planets, Neptune has no solid surface. It also has a system of rings and more than a dozen moons.

Neptune is the smallest of the four giant outer planets. The diameter at its equator is about 30,775 miles (49,528 kilometers), as measured at a level of the atmosphere where the pressure is 1 bar (the pressure at sea level on Earth). This makes it slightly smaller than Uranus but nearly four times as big as Earth. Neptune’s mass is about 1.2 times greater than Uranus’, however, and more than 17 times greater than Earth’s. It is the third most massive planet in the solar system, after Jupiter and Saturn. Like the other outer planets, Neptune has a low density—only about 1.6 times the density of water. However, it is the densest of the four, being roughly 25 percent denser than Uranus.

In space, there is no air. Because there is nothing for the light to bounce off, it just goes straight. None of the light gets scattered, and the "sky" looks dark and black.

For starters, cats’ visual fields are broader than ours, spanning roughly 200 degrees instead of 180 degrees, and their visual acuity isn’t as good. So, the things humans can sharply resolve at distances of 100-200 feet look blurry to cats, which can see these objects at distances of up to 20 feet. That might not sound so great, but there’s a trade-off: Because of the various photoreceptors parked in cats’ retinas, they kick our asses at seeing in dim light. Instead of the color-resolving, detail-loving cone cells that populate the center of human retinas, cats (and dogs) have many more rod cells, which excel in dim light and are responsible for night-vision capability. The rod cells also refresh more quickly, which lets cats pick up very rapid movements — like, for example, the quickly shifting path a marauding laser dot might trace. Lastly, cats see colors differently than we do, which is why the cat-versions of these images look less vibrant than the people-versions. Scientists used to think cats were dichromats — able to only see two colors — but they’re not, exactly. While feline photoreceptors are most sensitive to wavelengths in the blue-violet and greenish-yellow ranges, it appears they might be able to see a little bit of green as well. In other words, cats are mostly red-green color blind, as are many of us, with a little bit of green creeping in.

1. Tears help us see. Starting with the most basic function of tears, they enable us to see. Literally. Tears not only lubricate our eyeballs and eyelids, they also prevent dehydration of our various mucous membranes. No lubrication, no eyesight. Writes Bergman: “Without tears, life would be drastically different for humans–in the short run enormously uncomfortable, and in the long run eyesight would be blocked out altogether.”

2. Tears kill bacteria. No need for Clorox wipes. We’ve got tears! Our own antibacterial and antiviral agent working for us, fighting off all the germs we pick up on community computers, shopping carts, public sinks, and all those places the nasty little guys make their homes and procreate. Tears contain lysozyme, a fluid that the germ-a-phobic dreams about in her sleep, because it can kill 90 to 95 percent of all bacteria in just five to 10 minutes! Which translates, I’m guessing, to three months’ worth of colds and stomach viruses.

3. Tears remove toxins. Biochemist William Frey, who has been researching tears for as long as I’ve been searching for sanity, found in one