What makes the earth look blue?

Answer 1

lol the water

Answer 2

Because of the chemicals gasses that make up the Earth's atmosphere, which is mostly nitrogen. Gaseous molecules refract light at different frequencies. Nitrogen will give off a different color than hydrogen, and oxygen different from both. When sunlight passes through and into these gasses, the combined molecules give off a blue appearance, similarly as looking at a rainbow. Each planet that has an atmosphere will give off a color that corresponds to the gaseous makeup of it's atmosphere. Examples are Jupiter and Neptune.

Answer 3

The oceans combined with the atmosphere make the Earth LOOK blue! :) Has the Earth Always Looked Blue From Space?
We have all seen the photographs of the Earth take from space. The Earth has a brilliant blue color? Has that always been true? NO!
In order to consider this question, we need to first establish just why the Earth appears blue now! We know it's not because of the land areas, and the photographs usually clearly show that the ocean areas are the parts with the blue color.

Is water blue? No! It is clear, and colorless. If it should have ANY color on its own, it would probably be greenish, because of the algae and seaweed and other green vegetative matter that live in the oceans near its surface. But it's NOT green, it's clearly blue!

The oceans (and lakes and large rivers) appear blue because of the way sunlight is selectively scattered as it goes through our atmosphere. It turns out that the SIZE of oxygen molecules and nitrogen molecules are almost the same and they are comparable in size to the wavelength of blue light. In simple terms, this makes it so waves of blue light effectively run into the oxygen and nitrogen molecules in the atmosphere and are then bounced off in all directions. Scientists call this scattering.

The wavelengths of red light are somewhat bigger, and they tend to be able to get past the oxygen and nitrogen molecules without being entirely blocked. This allows the red light part of sunlight to more easily pass through the atmosphere, while blue light doesn't get very far before being scattered.

When you're on the ground looking up at the sky, you are looking at an area where sunlight has already passed by (cross-ways to you). You see a good amount of scattered blue light and much less scattered red light. So the sky looks blue to you.

By the way, this also explains why the Sun looks reddish at sunset, because the sunlight had to pass through much more of the Earth's atmosphere on its way to you, so it lost nearly all the blue light it contained. Primarily only red light remains by the time the light gets to you.

All this is a LOT more complicated than this, of course, but this is the general reason why the sky looks blue to us.

When sunlight passes through the sky over an ocean, the same scattering of blue light occurs. Some of that scattered blue light goes downward. That light then becomes reflected off the surface of the ocean, which would give a bluish tint to the oceans. At the same time, some of the original scattered light is scattered UPWARD toward space! The two effects add together, to create a very distinct and brilliant blue color for the oceans from space.

Over land, by the way, the UPWARD scattering still occurs, so there IS a bluish contribution to the overall color even over the continents. But the intensities of the colors of the browns and greens of the mountains and grasslands are much greater, and they make the blue contribution generally unnoticeable. Over the oceans, where there IS no actual background color, the blue seems to predominate, mostly because there is no competition!


Our Question
So! Has the Earth always looked blue? No!
Early in the Earth's existence, there was no atmosphere and there were no oceans. The Earth probably looked generally brownish or reddish, like Mars or Mercury. Later, an atmosphere of methane and carbon dioxide and some other simple chemicals probably existed. At this point, the Earth may have had faint colored stripes or banding like we see on Jupiter, but FAR less noticeable. Later yet, volcanoes spewed out a lot of stuff from the inside of the Earth. The two most obvious color affectors would be smoke/volcanic ash, which would likely make the Earth look black or dark gray, and water vapor, which when condensed into droplets would likely make the earth look while like steam!

LONG after these activities had occurred, plant life developed, which generally had the effect of converting the carbon dioxide in the atmosphere into oxygen. As this oxygen content increased, the bluish color of the Earth would have increased, as described above.

We have not mentioned the nitrogen in the atmosphere. At whatever point nitrogen became prominent in the atmosphere, this also would have enhanced the bluish color. There seem to be different opinions about where and when the nitrogen got into the atmosphere. One popular opinion was that it came out of the volcanoes at the much earlier time, so the Earth may have been somewhat bluish soon after the oceans formed, and well before there was much free oxygen in the atmosphere.


Other Planets
Some day, if we ever discover a planet orbiting some other star, that happens to have oceans on it, it may not look blue! If their star emits a different distribution of colors in its starlight, that could affect it. If the planet's atmosphere is composed of different molecules than our oxygen and nitrogen, it may look a VERY different color, ranging from nearly white to nearly black!
Conclusion
OK! These are somewhat irrelevant subjects! Who cares?
The point is, most people just ASSUME that a planet with oceans will look blue, because the Earth does, now! I just wanted to bring thinking people to realize the many hidden assumptions we tend to make in many of the things we investigate. Rather than being sloppy and blindly accepting such assumptions, we need to cautiously think about all matters that might alter the findings we are seeking!



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C Johnson, Physicist, Physics Degree from Univ of Chicago

Answer 4

Accually it is because of the water vapor in the atmosphere and is a simular event such as moisture in the air that causes rainbows, this spectrum of light ("Blue in the sky") is the color that we see, there are other factors that effect the sky color but I do not want to write a book about it here and now.
(check NASA or U.S.M.I. web sites for more detailed onfo)

Answer 5

Water

Answer 6

I'm inclined to believe that the blue appearance of our planet is caused by the refractive index of our particular atmosphere, since this is what makes our sky appear blue usually. Other planets photographed in "true" color have their own distinctive colors.

Answer 7

the sky makes it look blue

Answer 8

The color is caused by the coloration of the atmosphere, which is mostly nitrogen. Other prominent gases include carbon monoxide and oxygen.

These gases also give our sky its blue color.

Answer 9

Its more water, than land mass. Hence the blue.

Answer 10

the sky reflecting on the water

Answer 11

The ocean!!! Well thats my best guess... Thats what my mom always said LOL Jeff