The motion of the air changes how light passes through the atmosphere. As the waves of air pass in front of the stars the difference in how the light passes through the air makes the stars appear to twinkle.
When you hold a lens in front of a light source, the lens makes the light either increase or decrease in brightness, depending on whether that lens is enlarging or shrinking the image.
Air varies in density from place to place because of heat and wind. As a pocket of warmer or cooler air passes between you and a distant star, that pocket acts as a lens because light is bent at the effective "surface" of that pocket. Though there is no "solid surface," a "cell" of air acts as if it has a surface, because of the changes in density. This lensing effect causes each star to brighten or dim depending on the shapes of the intervening cells of air.
Planets in our own Solar system, however, don't twinkle nearly as much because they are not point sources like stars. The planets have a measurable disk when magnified by a telescope. Because of this, one side of the planet may be experiencing a brightening while the other side experiences a dimming, effectively canceling out the overall twinkling effect.
by plinka 6 years ago
Why do anticyclones cause air-pollution problems?
by Laura Schneider 3 years ago
Are you afraid of the dark? If so, why?What is it about the dark that makes people afraid? Do you think it is culturally dependent or universal to all cultures that many people are, to some degree, afraid of the dark?
by Katina Davenport 6 years ago
Why would a wound hurt when air hits it?
by janesix 4 years ago
Please, someone who knows more about physics than me, will you help me with a few "dumb" questions? The reason I say they're dumb is because I should be able to grasp it, but can't. Here's the first one:Are inertial mass (as in p=mv where p is momentum) and "rest mass" the same...
by Randy Godwin 6 years ago
How familiar are you with the night sky?Do you live--or have you ever lived--in a place where the sky is dark enough to become familiar with the different planets, constellations, nebulae,and individuals stars?
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