2014-2015 Discovery Exhibit Preview
The Nature of COLOR
Welcome to the World of COLOR!
The natural world is full of plants and animals that produce pigments of a wide
variety of colors! We are able to see these colors because our eyes detect the
light that these pigments reflect!
But why do plants and animals produce the pigments that color the natural
world?
Some pigments have very important functions. For example, chlorophylls that
make plants green are needed for photosynthesis to take place (changing water
and carbon dioxide to sugars and oxygen).
Most pigments serve as signals of colorful communications from one living thing
to another. For example, a colorful flower communicates the message: "Come
pollinate me now! You can get nectar or pollen here!" Each wildflower has
evolved a color, scent, and structure to attract a specific type of pollinator.
Animals have evolved pigments that improve their chances of survival and
reproduction.
Color Begins with Light!
Light is energy that moves in tiny particles known as photons. Light waves are
very similar to sound waves, but can move much faster!
Unlike sound waves, light waves can travel through the vacuum of space. That is
how light from the sun gets to us and how we see the light from distant stars!
Light Moves Through Waves?
Light moves through wavelengths. That is the distance between the crest (high
spot) of one wave and the crest of the next wave.
Each kind of light moves with a different wavelength. Some types of light, like xrays or ultraviolet (UV) light move in short wavelengths. These wavelengths have
a large amount of energy and can be damaging in large quantities.
Visible light moves at a more medium wavelength – that is why we can see it.
But even visible light has many different wavelengths within it.
Then there are the longer wavelengths. These include radio and television waves
and also microwaves. You might have a microwave oven in your kitchen.
Longer and shorter wavelengths are not visible to our eyes without special
equipment. Only visible light, with a medium wavelength, moves in such a way
that we can see it
What does wavelength have to do with color?
Within the spectrum of visible light are still more wavelengths! Each wavelength
is perceived by our eyes as a different color. The shorter wavelengths of visible
light are violet (purple). Then as the wavelengths get longer and longer, the visible
light changes in color to blue, green, yellow, orange, and finally the longest which
is red!
What Causes a Rainbow?
When light passes through certain materials such as water droplets from a storm
or a sprinkler, the light can bend. If it bends just right, each of the different
wavelengths can be seen. Because the bending has to be just right, sometimes
you won’t see the full arch of a rainbow. Some of it may be missing or even
appear to hide inside of a cloud.
The colors in a rainbow appear to be Red on the top and progress down through
Orange, Yellow, Green, Blue, Indigo (dark blue), and Violet. Violet is another word
for purple. The colors spell out an easily remembered name: ROY G. BIV!
How do Prisms Work?
Prisms are another way that light can be bent. Prisms are made from glass or
another clear material. If placed just right in a stream of white light, they can
separate the light into its various colors. Sometimes other things can act as prisms
such as the edge of a glass, a CD or a piece of jewelry!
Reflected Light
Besides being bent by prisms or water droplets, light has the ability to change
direction. Light that hits a surface and bounces off is called reflected light. If the
surface is slightly rough, some of the light scatters or bounces off the surface. If
the surface is very smooth the light scatters less and you can see your image.
Refracted Light
As light travels through air it can move rather easily, but if it gets slowed down by
traveling through a piece of glass, it is refracted. A great example of this happens
when you have a straw in a glass of liquid. The top of the straw appears to be in a
different location than the portion of the straw that is in the drink. The glass and
the liquid are refracting the light or slowing it down. It makes the image change.
This science is used to make lenses, microscopes, telescopes and other visual
tools.
How Do We See Color?
This apple looks red because some of the light hitting it is being absorbed into the
object and some of the light is reflecting off. The red apple is absorbing all of the
colors of the white light except the red. The red color reflects off of the apple and
travels to our eyes. We see red.
What about Black & White?
If an object looks white, all of the colors are reflecting off of the object.
If an object appears black, all the colors are being absorbed into the object.
What is a Color Wheel?
The three colors known as the primary colors - red, yellow and blue - are used in
televisions to create all of the colors that you see!
If you were to mix any two of these colors, you would get the secondary colors orange, purple, and green. These six colors make up the basic color wheel. Artists,
photographers, and others use the color wheel in their work. Sometimes artists
use opposite colors from the wheel because opposites actually complement each
other. Yellow and purple will go well together and even make each other seem
brighter. Color opposites are called complementary colors!
What is an Optical Illusion?
Optical Illusions can use color, light and patterns to create images that are
deceptive or misleading to our brains. The information is gathered by the eye and
processed by the brain, creating a perception that in reality, does not match the
true image. Optical illusions occur because our brain is trying to interpret what we
see and make sense of the world around us. Optical illusions simply trick our
brains into seeing things which may or may not be real.
COLORS in Nature
Daylight is a mix of all colors. All the colors of nature come from light!
However, with electric lighting, we don't need all the colors to make white. We
only need light’s primary colors - red, green, and blue. The amazing human visual
system "fills in," and our perception takes care of the rest.
White is Colorful?
White is not a true color but a combination of all the colors in the visible
spectrum. Sir Isaac Newton, a 17th century scientist and mathematician, was the
first to prove this when he experimented with prisms. Prisms bend light and
separate it into a rainbow of colors! When the colors are passed through a
second prism, they combine again and create white light!
Try It! Mix Colored Pigments
Combine these colored films to create new colors! What’s happening?
As colored pigments are mixed together, more and more colors of light are
removed from the white light combination. When all the colored pigments are
mixed, no color can be seen, and the surface looks black.
Try It! Mix Colored Light
When the red, green, and blue lights combine they create white light! What’s
happening?
The primary colors of light are red, blue, and green. They can be added together
to produce every color. If you look closely at your TV screen while it is on, you will
see tiny dots of red, blue and green light. In various combinations, these colors
produce all the other colors you see on TV or a computer. Mixing all three of the
primary colors of light together produces white!
How does light act?
When light hits an object it is reflected, refracted, or absorbed.
Reflection
Did you know? Every object we see has many rays of light coming from it either
by reflection or because it is a light source such as a light bulb, the Sun, a star, etc!
Benham’s Disk
Benham's disk was invented by a nineteenth-century toymaker who noticed
colors in a black-and-white pattern he had mounted on a spinning top!
Different people see different amounts of colors on this spinning disk. Why
people see color here is not fully understood, but the illusion involves color vision
cells in your eyes called cones.
There are three types of cones. One is most sensitive to red light, one to green
light, and one to blue light. Each type of cone takes a different amount of time to
respond to a color. Blue cones, for example, are the slowest to respond, and keep
responding the longest.
When you gaze at one place on the spinning disk, you are looking at alternating
flashes of black and white. When a white flash goes by, all three types of cones
respond. But your eyes and brain see the color white only when all three types of
cones are responding equally. The fact that some types of cones respond more
quickly than others leads to an imbalance that partly explains why you see colors.
The colors vary across the disk because at different positions on the disk the black
arcs have different lengths, so the flashing speed they produce on the retina is
also different.
Meet Sir Isaac Newton
Our current understanding of light and color begins with a scientist named Sir
Isaac Newton (1642-1726).
He is the first to understand the rainbow by refracting (or bending) white light
with a prism, which separates it into individual colors:
red, orange, yellow, green, blue and violet.
Newton set up a prism near his window, and projected a beautiful rainbow of
colors onto a wall 22 feet away. Further, to prove that the prism was not coloring
the light, he refracted the light back together to make white!
Color Vision: Animals vs. Human
Many animal species can see light with frequencies outside the human "visible
spectrum". Bees and many other insects can detect ultraviolet light, which helps
them find nectar in flowers. Birds also can see ultraviolet colors and some have
markings on their feathers that are visible only in the ultraviolet range.
Mammals in general have color vision of a limited type, and usually have redgreen color blindness, with only two types of cones. Humans, some primates, and
some marsupials see an extended range of colors, but only by comparison with
other mammals. Many species of birds, fish, reptiles, amphibians, and some
invertebrates, have more than three cone types and probably superior color
vision to humans.
Color in your campfire?
The light of the flames in a campfire reveal the temperature of the glowing wood.
The coals of a fire begin to glow red at 1,300 degrees F. The flames glow orangeyellow at 2,700 degrees F.
Star Color
The constellation of Orion, the Hunter, is a good place to look to see stars of
different colors. A star's color reflects its surface temperature. The star that
forms Orion's right shoulder is Betelgeuse, a red supergiant star with a surface
temperature of about 5,400 degrees F. The star that forms Orion's left foot is
Rigel, a blue supergiant with a surface temperature of over 54,000 degrees F. The
central bright point of Orion's dagger is the Orion Nebula, a giant gas cloud
illuminated by a star.
Iridescent Beauty!
The mother-of-pearl coating that lines the inside of an abalone shell is made up of
alternating layers of calcium carbonate and water. Light waves reflecting from
these layers interfere with each other, producing iridescent colors!
Brilliant Calling Card
The male peacock displays his tail to attract the attention of a mate. The brilliant
colors of his tail are important to his success in finding a mate.
The Colors of Water
Deep ocean waters look blue because water molecules absorb red light and
scatter blue light back to your eyes. In shallow water, light reflecting from yellow
sand combines with the blue of the water to make a greenish hue.
Green water usually means there is algae growing underneath.
Lakes formed by melting glaciers are sometimes a brilliant turquoise blue. The
water contains tiny particles of rock, known as rock flour or glacial milk, formed
by the movement of the glacier.
Polar Bear Secret
The fur of a polar bear scatters all colors of light in all directions, reflecting white
to your eyes. The polar bear's hair also acts like a fiber-optic cable. Some of the
light that shines on the hair is channeled through the fur to the bear's dark skin,
allowing the bear to absorb the warmth of the sunlight.
Who has super color vision?
Bees and butterflies can see colors that we can't see. The range of bees and
butterflies color vision extends into the ultraviolet. The leaves of the flowers they
pollinate have special ultraviolet patterns which guide the insects deep into the
flower.
Animal Kingdom Color
For land animals, good color vision helps them tell the difference between ripe
red fruit and unripe green fruit. Colors can also make animals more attractive to
each other when they mate. The ability to see colors helps animals identify
predators (animals who may attack them).
This snake “sees” by feel!
A pit viper “sees” by sensing the heat in an object.
Think about the last time you were really sick. Did you check your forehead to see
if you were running a temperature? That "fever-heat" is what gives a pit viper a
different kind of vision. This is called "thermal vision."
Night Color Pro?
Did you know? Geckos and some frogs can see some colors even when it’s dark!
They can tell the difference between blue and grey at night… can you?
Kaleidoscopes!
Light travels in a straight line through empty space, but when it bumps into an
object, it changes direction. In a kaleidoscope, the mirrors and inside of the tube
reflect light back to your eye and create multiple images that you can move with a
turn of the kaleidoscope wheel!
Color for survival
Poison dart frogs wear some of the most brilliant and beautiful colors on Earth.
They live in Central and South America and their coloring can be yellow, gold,
copper, red, green, blue, and/or black. Their bright colors are helpful in warding
off potential predators and are sometimes called “warning colors” because they
warn predators that they are not good to eat.
Poison dart frogs are usually only about two inches long, but their skin can be very
toxic, depending on the species. The Golden Poison Dart Frog has enough venom
to kill 10 grown men. Indigenous Emberá people of Colombia have used its
powerful venom for centuries to tip their blowgun darts when hunting!
Scientists are unsure of the source of the frogs' poison, but it is possible they pick
up plant poisons which are carried by their prey (including ants, termites and
beetles). Poison dart frogs raised in captivity and isolated from insects in their
native habitat are not toxic at all.
The medical research community has been exploring possible medicinal uses for
some poison dart frog venom. They have already developed a synthetic version of
one compound that shows promise as a painkiller.
“I’m an Axolotl!”
Axolotl (Mexican Salamander) Pronunciation: (ax·o·lotl)
Salamanders are attracting renewed interest from biomedical researchers
because of their amazing ability to regenerate (re-grow) entire organ systems. A
salamander can regenerate its limbs, its tail, parts of its brain and spinal cord,
damaged parts of its heart and lungs, and almost any other part of its body.
Understanding how this works could help doctors treat human trauma, disease,
and aging.
Although it is considered an endangered animal, the use of the Axolotl as a
laboratory animal should ensure the species' survival, if only in captivity. It has
long been known that the Axolotl is a worthy study due to its amazing healing and
regeneration abilities.
Ordinarily, amphibians undergo metamorphosis from egg to larva (the tadpole of
a frog is a larva), and finally to adult form. The Axolotl however, remains in its
larval form throughout its life. This means that it retains its gills and fins, and it
doesn't develop the protruding eyes, eyelids and characteristics of other adult
salamanders. It grows much larger than a normal larval salamander, and it
reaches sexual maturity in this larval stage. The animal is completely aquatic, and
although it does possess rudimentary lungs, it breathes primarily through its
feathery gills and to a lesser extent, its skin.
Some scientists say that this trait (of remaining in larval form) is a "backward"
step in evolution, because the Axolotl is descended from what were once
terrestrial (land) salamanders, like the closely related species, the Tiger
Salamander.
Learn more about the University of Kentucky’s Axolotl Research Lab here:
https://www.youtube.com/watch?v=FTZ2wUUQO30
What is a Pigment?
A pigment is any dry coloring matter that can be mixed with a liquid to produce
paint! Many pigments are made from chemicals, but you can peek into history to
see how pigments have been made from the natural world too!
The Color of Soil
The color of soil can tell scientists a lot about it. Geologists have studied over 170
different soil colors. Most of these are shades of black, brown, red, gray, and
white. Most times, the darker a soil is, the more nutrient rich it is. The darker
color often indicates an increase in decomposed organic matter known as humus.
How do eyes detect Color?
We have two main types of photoreceptors called rods and cones. They are called
rods and cones because of their shapes. These cells are located in a layer at the
back of the eye called the retina. Rods are used to see in very dim light and only
show the world to us in black and white.
This is why you see only black and white when you are outside in the evening or in
a dimly lit room. The other type of photoreceptors, the cones, allow us to see
colors. They are not as sensitive as the rods so they only work in bright light.
There are three types of cones, one for each of the three main colors we see, red,
green and blue.
Colors Vision Evolution
Primates, including humans, have relatively good color vision compared to a lot of
other animals, which probably gave us and our primate cousins an evolutionary
advantage in hunting and in finding wild fruit and other plant-based food.
Pictures Made of Dots?
Have you ever looked at a magazine picture through a magnifying glass? You will
find that it is made up of cyan, magenta, yellow, and black dots! Here is a picture
of a baby as if it were a magazine photo, blown up 200, 400, and 800 times!
Star Color?
When astronomers pass the light of a star through a spectrograph, they get a
spectrum of the star. The spectrum looks like a regular rainbow, except that there
are occasional dark lines in it.
Here is a spectrum of our sun:
Each element in a star absorbs light of a particular frequency (a particular color).
Each element has a specific "signature”, a specific set of line.
Here are spectra for some elements common in the atmospheres of stars:
“I’m a Tamatave Panther Chameleon!”
Distribution and Habitat
Tamatave Panther Chameleons are found in the eastern and northern parts of
Madagascar in a tropical forest biome. They are arboreal, preferring to live in
trees, bushes, or shrubs.
Diet in the Wild
Chameleons are insectivores. It may also eat leaves as a source of water during
the dry seasons.
Interaction with Mates
They are primarily solitary and males are very territorial. Males and females
tolerate each other only during breeding.
Misconceptions
It is a common misconception that chameleons of any kind can change color to
match any color of their environments. All chameleons have a natural color range
with which they are born, and is dictated by their species. Color change is, for the
most part, subconscious. It is affected by temperature, mood, and light. If, for
example, the color purple is not within the range of colors to which their
particular species can change, then they will never turn purple.
Sticky Tongues?
Chameleons are known for their long, sticky tongues that they use to catch prey.
The tongue can be more than 1.5 times the length of their body. They "shoot"
their prey with a tongue that can be projected in the blink of an eye.
Color Changing Chameleon
Chameleons are famous for their ability to change color. The color change serves
only partly for camouflage. Although chameleons at rest tend to assume colors
similar to their surroundings, color change is most often used to signify emotional
state. Many chameleons are some shade of green or brown at rest, but can
become far more brightly colored when frightened, courting, or defending a
territory against another chameleon. When startled or threatened, chameleons
may darken in color and "play possum."
Chameleon Eyes
Chameleon eyes can move independently of one another and look in two
directions at once, as well as swivel nearly 180 degrees. They are able to look in
any direction, and even follow moving objects, without turning their heads or
shifting body position. When a prey animal is spotted, both eyes will focus on the
insect in order to perceive depth.
Hands and Tail
Chameleons are highly arboreal (tree-living). They have grasping hands that work
much like human hands. Three fingers are fused together and face toward the
inside. They also have a prehensile tail that they use as a fifth appendage.
Tree Dwellers
Chameleons are specialized tree-living lizards that catch insect prey. Their bodies
are flattened from side to side, and more or less leaf-shaped. They remain still,
concealed for long periods of time as they wait for their prey to come near. When
they move, they do so slowly, and rock their bodies from side to side like a leaf in
the wind.