From the sky and the sea to the Earth and other planets

(ORDO NEWS) — You’ve probably wondered before: why is the sky blue? And have heard the wrong answers: because it reflects the ocean; because oxygen is a blue gas; because sunlight has a blue tint. In truth, the sky looks blue for three simple reasons.

First, sunlight is composed of different wavelengths. Second, the Earth’s atmosphere is made up of particles that scatter light of different wavelengths in different ways. Third, our eyes react in interesting ways to different colors.

What is sunlight made of?

The entire range of the light spectrum consists of visible rays, infrared rays and ultraviolet rays. Visible light energy accounts for approximately 50% of solar radiation energy. Visible light is the only region of the electromagnetic spectrum that can be seen with the naked eye, while ultraviolet and infrared rays are invisible to the human eye.

Visible sunlight is composed of red, orange, yellow, green, blue, and purple.

Purple light (like blue) has the shortest wavelength and therefore the highest vibration frequency in the visible spectrum. Since frequency is directly proportional to energy, violet light also has the most energy. On the other hand, red light has the longest wavelength, lowest vibration frequency, and lowest energy.

How does light travel on Earth?

Sunlight is scattered in all directions by all gases and particles present in the Earth’s atmosphere.

The tiny invisible particles that make up our atmosphere – the molecules of nitrogen, oxygen, water, carbon dioxide, and argon atoms – scatter light of all wavelengths. However, they scatter the shorter wavelengths much more efficiently.

What is Rayleigh scattering that makes the sky blue?

The blue sky is due to a phenomenon called Rayleigh scattering. It is the scattering of light or other electromagnetic radiation by particles much smaller than the wavelength of the radiation.

Solar radiation that reaches the Earth’s surface after being scattered in the atmosphere is called scattered celestial radiation. The shortest wavelengths of light are easily scattered, in particular blue light waves, so we see the sky in blue.

Why isn’t the sky purple?

If purple has the shortest wavelength and diffuses easily, why is the sky blue and not purple?

The reason lies in the sensitivity of our eyes to light. Although purple is the dominant color in the atmosphere around us, the retina of the human eye is not sensitive enough to this color, unlike blue.

More violet light is emitted from the atmosphere than blue, but our eyes are more responsive to the wavelengths of blue, blue, and green light than to violet. Thus, although there is a lot of violet light, it is not enough to overcome the strong blue signal that our brains transmit.

But if we can see ultraviolet rays, the sky will probably turn more violet.

If the sky were purple, our eyes would see it more like purple, but because the violet and blue light overlap, we see the sky as pale blue.

And if human eyes were like dogs’ eyes, we would see the blue sky during the day, but we would not be able to see the red, orange and yellow colors at sunset.

What’s the secret to orange twilight?

At sunset and sunrise, the angle of penetration of sunlight into the atmosphere changes dramatically. Most of the blue and green light waves are scattered even before they reach the lower atmosphere, so we see more orange and red hues in the sky.

Does the ocean reflect the color of the sky?

Many people think that the ocean is blue because it reflects the sky, but it is not. In fact, water appears to be blue because its molecules absorb red light.

As light penetrates deep into the water, waves of different lengths are successively filtered out. Water molecules absorb red light but reflect blue.

For this reason, shallow bodies of water tend to appear less blue than deep ones.

For example, there are not enough molecules in a cup of water to absorb photons, so light penetrates it through and through, and we see that the water is colorless.

Why does the Earth appear blue from space?

When we look at the Earth from space, it looks like a blue ball due to the predominance of seas and oceans (70.8%) over land (29.2%).

The number of bodies of water is one of the reasons why the Earth is the brightest planet in the solar system. Reservoirs on its surface reflect sunlight, making the planet look like a bright blue pearl.

Is the sun yellow or orange?

Young children usually paint the sun in yellow, orange, or even red. The cultural factor also plays a role in this. For example, American children usually paint the sun in yellow and Japanese children in red. But the sun is actually white.

The sun is all colors blended together. They appear white to our eyes. This is easily confirmed by photographs of the Sun taken in space.

Does the sky also appear blue on other planets?

The color of the sky on a planet depends on the composition of its atmosphere. For example, the atmosphere on rocky planets similar to Earth contains a certain amount of gases, the combination of which gives the planet’s atmosphere the appropriate color.

The shell of Mars is composed primarily of carbon dioxide and small dust particles that scatter light differently than gases and particles in the Earth’s atmosphere.

NASA photographs showed that what is happening on Mars is exactly the opposite of what is happening on Earth. The sky on Mars takes on an orange or reddish tint during the day, and turns gray-blue at sunset.

The atmosphere of the two ice giants, Neptune and Uranus, has incredible shades of blue due to the high methane content.

Uranus’ atmosphere contains some ammonia, which makes the planet slightly greener than the dark blue Neptune.

Saturn, on the other hand, has a pale yellow hue due to the ammonia crystals present in the upper layers of its atmosphere.

In the atmosphere of Jupiter there are characteristic crimson and orange stripes – this is due to gases, which include phosphorus and sulfur, and maybe more complex chemical substances – carbohydrates.


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