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Rainbow

✨ The Bridge of Colors

A rainbow is an optical phenomenon that appears when sunlight shines through countless tiny water droplets suspended in the air, usually after a rain shower. As light enters each droplet, it slows down and bends, a process called refraction. Inside the droplet, the light is reflected from the inner surface before leaving the droplet and bending again.

Because each color of light bends by a slightly different amount, white sunlight separates into a spectrum of colors. The main rainbow is usually seen with red on the outer edge and violet on the inner edge. To observe a rainbow, the Sun must be behind the observer while the raindrops are in front. Since every observer receives light from a different set of droplets, no two people see exactly the same rainbow.

A second, fainter rainbow sometimes appears outside the primary one when light is reflected twice inside the water droplets. In this secondary rainbow, the order of the colors is reversed. Rainbows can also form in the mist of waterfalls, sea spray or garden sprinklers whenever sunlight and water droplets are present at the right angle.

Although they seem to occupy a fixed place in the sky, they have no physical location and cannot be approached. Scientists study rainbows to better understand how light behaves when it passes through transparent materials. This phenomenon is also an everyday demonstration of refraction, reflection and the dispersion of light.

💡 Did you know?

Did you know that a rainbow is actually a complete circle? From the ground, we only see the top half (the arc), but if you were in a high-flying plane or at the top of a mountain, you could see a magnificent colored circle surrounding the shadow of the plane! This is what's called a 'pilot's glory'.

You may have already seen a double rainbow! That's what happens when light bounces twice inside raindrops. The second arc is a bit less bright and, incredibly, all its colors are reversed compared to the first: red is on the inside and violet is on the outside. It's like a mirror reflection!

There are also rainbows created by the moon! They are called 'moonbows'. They are much rarer and appear at night when the full moon is very bright and it rains. They are often a bit pale and white because our eyes have trouble seeing colors in low light, but a camera can reveal all their colors!