Optical Illusions
 
Why is the sky blue?
The sun shines white and black light to our planet. The white light has all the colors in it. In our upper atmosphere, we have dust particles and oxygen molecules. The white light meaning all of the colors in a rainbow shines through the upper levels of the atmosphere and the blue light scatters across the entire planet. That is why our sky is blue. Now, during sunrise and sunset, the light traveling through atmosphere is longer at the horizon, then if you were to look up high in the sky. There are more dust particles and oxygen molecules at the horizon, so that is why you see such pretty colors like red, oranges and yellows.

Blue Sky

How do we get rainbows?
Rainbows are spectacular rays of color. Sunlight looks white, but it's really made up of different colors...red, orange, yellow, green, blue, indigo, and violet. The sun makes rainbows when white sunlight passes through rain drops. The raindrops act like tiny prisms. They bend the different colors in white light, so the light spreads out into a band of colors that can be reflected back to you as a rainbow.

Rainbow

Where do you look for a rainbow?
Three conditions must be met in order for you to see a rainbow. First, it must be raining. Second, the sun must be shining. Third, the observer must be between the sun and the rain. The lower the sun is in the sky, the higher the arc of the rainbow will be.

Rainbow

Can rainbows make a full-circle?
If you could get up high enough in the sky, then you'd see that some rainbows continue below the horizon. That's because when the sun and rain combine to make a rainbow, they really make a full-circle rainbow. We can't see all of the circle, because the horizon blocks it from our view. Pilots high in the sky do sometimes report seeing genuine full-circle rainbows.
Rainbow


Are there double rainbows?
Yes, they do happen! The inner and brighter rainbow has the red on the top and the blue on the bottom side. The outer and dimmer rainbow has the color scheme reversed.
Double Rainbow


What is an upside-down rainbow?
An upside-down rainbow is an unusual phenomenon caused by sunlight shining through a thin, visible screen of tiny ice crystals high in the sky. Interestingly enough, it has nothing to do with rain. Some people refer to this as a 'smile rainbow'.

Upside-down Rainbow

Why can't you ever find the end of a rainbow?
A rainbow is an optical illusion, so you just can't catch up to it. When you move, so does it!

Rainbow

Can a rainbow appear during the night?
Yes, they're called moonbows! The nighttime rainbow is very rare and occurs only when the moon is bright enough and positioned properly with respect to falling rain to produce the beautiful effect.

Lunar Rainbow

What are the Northern Lights?

The Northern Lights, commonly referred to as the Aurora Borealis, are the result of interactions between the Sun and Earth's outer atmosphere. They are one of the most spectacular light shows to watch as vivid colors glow in the sky. In the Southern Hemisphere, it is called the Aurora Australis.
Aurora

What causes the auroras?
Most auroras occur in response to energetic particles from a solar storm, which cause the gases of the thin upper atmosphere to glow. They take place at heights between 50 to 100 miles above the Earth. The aurora can last anywhere between a few minutes to several hours. Auroras are most common in polar regions. The various colors, of which green and red predominate, are the results of various light emissions from oxygen and nitrogen gases being energized by the solar particles.
Aurora Aurora


What are crepuscular rays?
Crepuscular rays are are bands of sunlight shining through breaks in clouds on the horizon.
Crepuscular Rays

What is a halo?
A halo is a ring around the moon or sun produced by refraction of light through a thin cloud of ice crystals. The halo had red colors on the inside of the ring shifting to blue on the outside.
Halo

What are sun dogs?
Sun dogs are bright spots that appear on either side of the sun when there are thin layers of high ice crystal clouds otherwise known as Cirrus clouds. This can also happen at night. These are called moon dogs.
Sun Dogs

What are sun pillars?
Sun pillars are luminous vertical streaks of light, while or sometimes slightly reddish in color, extending from above and below the sun. They are the result of the light being reflected by the mirror-like surfaces of ice crystals. They are common to see around sunrise and sunset.
Sun Pillars

What is a blue moon?
The term is used when a full moon occurs twice in the same calendar month. It happens every 2.7 years and never in the month of February because there are not enough days. Is the moon really blue, though? It depends! Most moons are not blue, but if there is a volcanic eruption or even a forest fire, the smoke in the sky can turn the moon a blue color.
Blue Moon

What are blue jets?
The blue jet appears as a blue column of light that squirts out the top of a thunderstorm at speeds of 62 miles per second. They sometimes reach a height of 25 to 30 miles. What exactly causes blue jets is not known.

Blue Jet

What is a mirage?
A mirage is a refraction phenomena in which the image of some object appears displaced from its true position. A common example of a mirage is the appearance of water some distance down the highway on a hot summer day.

Mirage

What are sprites?
Sprites are huge blobs of light that occur briefly above thunderstorms. They can extend 55-60 miles high into the ionosphere and can be 100 or more miles wide. Most are invisible to the naked eye on the ground. The best way to see them is from a high-flying aircraft.

Sprites

What are elves?
Elves are bright flashes of light in the night sky resulting from lightning within thunderstorms. The thin upper atmosphere gives off a brief glow as the electromagnetic pulse from a lightning bolt passes through on its way to outer space. Elves are too fast to be seen with the naked eye, last less than one-thousandth of a second.

Elves

RainbowOptical Illusion ActivitiesRainbow
Lesson Plan: Here is a great lesson plan on rainbows. In this activity, kids see that white light is composed of all the colors in the rainbow.

Rainbow Experiment: Here is a great experiment that allows kids to make a rainbow indoors.

Rainbow Experiment: Here is a great experiment that allows the kids to make a rainbow.

Examining Colors Experiment: Here is a great experiment that allows kids to understand what the primary colors are and how to mix them together to get the secondary colors.

Blue Sky Experiment: Here is a great experiment that allows kids to visually see and understand why the sky is blue.


Science Fair Project Ideas: Here is a complete list of science fair project ideas. Discover the science behind the weather that impacts us every day.
 
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