Why, Do You Know, Why Reasons

Do you know the 'why' reasons, or, do the 'whys' often bother you for scientific explanations? For instance, you do know that stars twinkle, but do you know the reasons why, and how? Or, do you know the 'why' reasons behind falling in love? Or, do you know the reasons why dogs bury bones? Probably many of you don’t! Why Corner – the 'why' blog, answers these 'whys' for basic knowledge, with real reasons for the 'why' facts. So, just know them all here if you have the 'why' urge, that is!

Apr 6, 2007

Do you know why stars twinkle?

Prof. Know Why explains:

On a clear, dark night, our eyes can see about 6,000 or so stars in the sky. They seem to twinkle, or change their brightness, all the time. The scientific name for this twinkling of stars is stellar scintillation or astronomical scintillation. Stars seem to twinkle when we see them from the Earth's surface, because we are viewing them through thick layers of turbulent (moving) air in the Earth’s atmosphere.

The Earth's atmosphere comprises of layers of gases surrounding the Earth. It’s composed of 78% nitrogen, 21% oxygen, 0.9% argon, 0.03% carbon dioxide, and other gases. These gaseous layers insulate the Earth from extreme temperatures and block the Earth from much of the Sun’s incoming ultraviolet radiation.

As light of a star travels through these layers of the Earth's atmosphere, it is bent or refracted many times and in random directions (it happens whenever it hits a change in density - like a pocket of cold air or hot air). This random refraction results in the star appear to our eyes as twinkling.

Stars would not appear to twinkle if viewed from outer space or from a planet that doesn't have an atmosphere.

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