August 15, 2013
I know this has been written about and also taught to many students, except me (that I can recall). Did you know that when you see the sun at the horizon, as it’s about to leave our view, that you are not seeing the actual sun? I was watching a video from the Teaching Company about astronomy and learned something that seems like I should have been taught in optometry school. The sun is already below the horizon when we see it above the horizon due to the way light is refracted in the atmosphere. Look at the picture below and see if you can figure out what I’m talking about.
I hope I didn’t ruin what you thought of the beautiful sunsets we see. But think of it this way. You have a more profound understanding of how things work in our world if you get the picture. There are a lot of interesting things that happen to the sun at or near the horizon besides it being a mirage. There are all kinds of crazy possible effects when the sun goes down. One simple way to explain the mirage of the sun is to think of the atmosphere above us as a thick lens. Just like someone who wears glasses, light from the sun has to go through it. When the sun is straight up over our heads, light rays are coming in straight through the lens without bending, just like glasses. When that sun gets to the very edge of the lens, the rays are bent. That’s how glasses work, rays are bent to bring the image into your eyes.
There are some interesting names that have been given to the effects of the atmosphere on the suns rays. How about these, sun dogs, sun pillars and sun halos! If you go to the website below you will find some AMAZING pictures. I mean AMAZING! And the site is not just about sunsets.
Go here! NOW! http://www.atoptics.co.uk/
To explain the picture a little bit, the orange sun is what we see (perceive) but the yellow sun is the actual sun. If you follow the curve line from the yellow sun to the little observer on the earth, the last part of the curved line goes into the observers eyes and that observer then thinks the line came from above the horizon (we don’t see curves!). That’s the mirage that we see (the sunset).