Home / TIL: The sky is black and the sun is white  
0
Image of TIL: The sky is black and the sun is white

Today I learned that the sky isn't blue and the sun isn't yellow. The sky is actually black and the sun is white. It's only because we have an atmosphere (which is made of gas molecules and dust) that we see colors. Because there's no air in space, there's nothing for the light to bounce off.

FTA:

On a clear sunny day, the sky above us looks bright blue. In the evening, the sunset puts on a brilliant show of reds, pinks and oranges. Why is the sky blue? What makes the sunset red?

To answer these questions, we must learn about light, and the Earth's atmosphere...

The blue color of the sky is due to Rayleigh scattering. As light moves through the atmosphere, most of the longer wavelengths pass straight through. Little of the red, orange and yellow light is affected by the air.

However, much of the shorter wavelength light is absorbed by the gas molecules. The absorbed blue light is then radiated in different directions. It gets scattered all around the sky. Whichever direction you look, some of this scattered blue light reaches you. Since you see the blue light from everywhere overhead, the sky looks blue...

On Earth, the sun appears yellow. If you were out in space, or on the moon, the sun would look white.

In space, there is no atmosphere to scatter the sun's light. On Earth, some of the shorter wavelength light (the blues and violets) are removed from the direct rays of the sun by scattering. The remaining colors together appear yellow.

Why is the sky blue?

What did you learn today?

DISCUSS!

Original posting by Braincrave Second Life staff on Nov 16, 2010 at http://www.braincrave.com/viewblog.php?id=384

You need to be logged in to comment.
search only within braincrave

About braincrave

relationships/dating/braincravebraincrave

We all admire beauty, but the mind ultimately must be stimulated for maximum arousal. Longevity in relationships cannot occur without a meeting of the minds. And that is what Braincrave is: a dating venue where minds meet. Learn about the thoughts of your potential match on deeper topics... topics that spawn your own insights around what you think, the choices you make, and the actions you take.

We are a community of men and women who seek beauty and stimulation through our minds. We find ideas, education, and self-improvement sexy. We think intelligence is hot. But Braincrave is more than brains and I.Q. alone. We are curious. We have common sense. We value and offer wisdom. We experiment. We have great imaginations. We devour literacy. We are intellectually honest. We support and encourage each other to be better.

You might be lonely but you aren't alone.

Sep, 2017 update: Although Braincrave resulted in two confirmed marriages, the venture didn't meet financial targets. Rather than updating our outdated code base, we've removed all previous dating profiles and retained the articles that continue to generate interest. Moving to valME.io's platform supports dating profiles (which you are welcome to post) but won't allow typical date-matching functionality (e.g., location proximity, attribute similarity).

The Braincrave.com discussion group on Second Life was a twice-daily intellectual group discussions typically held at 12:00 PM SLT (PST) and 7:00 PM SLT. The discussions took place in Second Life group chat but are no longer formally scheduled or managed. The daily articles were used to encourage the discussions.

Latest Activity