Let’s say you’re an astronomer. You’ve built yourself a gigantic new observatory to study the heavens above. You look through the eyepiece (or more accurately, the computer screen), expecting the glory of space to reveal itself to you. Instead, to your frustration, you find only a blurry, wiggly mess.
Earth’s atmosphere is pretty good when it comes to
keeping living things alive, but pretty terrible when it comes to astronomy. No matter how
big your telescope is, how sophisticated, and how powerful, as long as it’s on the ground it has to contend with all those miles of thick atmosphere.
The problem is the ever-shifting turbulent motions of hot and cold air as they struggle to evenly distribute heat throughout the globe. Warm and cold air have different indices of refraction, meaning that they bend the path of light differently. So light from a distant star doesn’t follow a straight line on its way through our atmosphere – it constantly shifts, zigging and zagging as the air moves.
It’s exactly the same process that makes stars twinkle. It’s pretty, but annoying.
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