Very few people have been lucky enough to see the Earth from space, thanks to the incredible spacecraft that have already explored neighboring celestial objects. Modern space exploration has gifted the people of Earth to see our big blue planet like never before. One of humankind’s greatest achievements is currently in orbit around the Earth, the International Space Station.
This astonishing habitable artificial satellite is around 240 miles above our planet’s surface, traveling at about 17000 miles an hour, and has been visited by over 200 people since 2000. Most of the time, the satellite shows the blue color of the earth. Do you know why the Earth appears blue from space?
Why does the Earth look blue from space?
Mars looks red, Moon looks ashy grey, and Earth looks blue. Mother Earth is called a blue planet due to the abundant water on its surface. Earth is the only planet in our solar system that has liquid water. Unlike Sun, the Earth is not a light source. Planet Earth receives light primarily from the Sun.
Sunlight appears white, but it combines lights of several different colors. As the sunlight enters the water, the water absorbs all other colors of white light and reflects blue light. This is a scattering phenomenon.
Here are the main points explaining why the Earth looks blue from space:
Rayleigh scattering: Sunlight is a mix of different colors, and as it passes through the Earth’s atmosphere, it interacts with molecules in the air. Light scattering is more effective for shorter wavelengths, particularly blue and violet.
Small atmospheric particles: The Earth’s atmosphere contains tiny particles, such as nitrogen and oxygen molecules, as well as other pollutants and aerosols. These particles scatter short-wavelength light more effectively than longer-wavelength light, contributing to the blue color.
Longer path through the atmosphere: When sunlight passes through the Earth’s atmosphere to reach an observer in space, it travels a longer path than when it reaches an observer on the ground. This increased path length enhances the scattering of blue light, making the Earth appear predominantly blue.
Absorption by water: The Earth’s surface is mostly covered by water bodies, such as oceans, seas, and lakes. Water selectively absorbs longer-wavelength colors like red and reflects shorter-wavelength colors like blue. The reflection of blue light from water further adds to the overall bluish appearance of the Earth.
Contrast with land and clouds: While the water bodies contribute to the blue color, land areas, and clouds can introduce variations and contrast. Land masses can appear differently due to vegetation, deserts, or other geological features. Clouds composed of water droplets or ice crystals may appear white or gray, standing out against the predominantly blue background.
When we see the Earth from space, the sun’s light hits the Earth, gets reflected, and reaches our eyes. About 71% of the earth’s surface is covered with water. That is, two-thirds of the surface is covered with water. So 71% of the earth’s water cover consumes white light and reflects blue light. That means almost 71% of Earth’s surface appears blue from outer space, and the remaining 29% looks greenish-brownish. That’s why the Earth seems blue from outer space.
The color changes a lot as you go higher and higher. Also, it doesn’t change as fast; temperature also changes. The thickness of the air also changes. It’s all about the air getting thinner as the blue sky fades to black. So the sky is blue because of the thickness of the atmosphere above us, the light bounces off all the air molecules, and dust particles take away their atmosphere.
The space station orbits the planet approximately six times every 24 hours. It has enabled astronauts to capture some incredible high-resolution footage of the planet’s vast cloud cover, swooping auroras, bright blue oceans, impressive landscapes, and the magnificent nighttime glow of our city lights. On a clear night, the moon can be seen shining in the dark sky with a background of distant, glistening stars.
Over the years, many images have been captured of our planet from the moon. But the most famous one was taken by the Apollo 17 crew in 1972 during their journey to the lunar surface named Blue Marble. The picture showed a beautiful full view of the earth and was only enabled by the lucky alignment of the planets, the spacecraft, and the moon.
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