ELI5: Explain Like I'm 5

Astronomical seeing

Astronomical seeing is when the Earth's atmosphere makes far away stars and planets look a bit wobbly and blurry instead of sharp and clear. This happens because the air is moving around and shaking, which makes it hard for light to go through it all the way to us. It's like when you put your hand in front of your eyes and then move it back and forth - the image of your hand looks jumpy and blurry.