 Greetings and welcome to the Astronomy Picture of the Day podcast. Today's picture for December 18, 2023 is titled The Same Color Illusion. So what do we see here? Well let's go ahead and zoom in and take a look at our image and what we see is what looks like a checkerboard with alternating light and dark spaces and in addition we see a green cylinder sitting on it. Now the question is looking at squares labeled A and B and whether they are the same color. So are A and B the same color? Well at first glance you would say they are definitely not the same color. It looks like that A is among the darker here and that B is among the lighter colored. So they look very distinctly different. However we can connect these two with a bar that is exactly the same color all the way along it and see how it goes from A to B and note that yes it matches exactly that A and B this bar matches exactly with both colors. This is of course an example of an optical illusion and these occur. We've seen many different of these before. This is one example of them where different the way things are set up can play tricks on our brain and make us think we see things that we really don't see. Now how does this tie in to astronomy? Because just looking at this you wouldn't think this has any astronomical implications at all. But it is very true and one of the things that it shows is that our mind does play tricks on us and that the human eye is not a very good detector of light for detecting for examining the stars. Now that doesn't mean not looking at pictures of it but if we think about this going back less than 200 years photography had not really been developed yet and did not really apply to astronomy. So how did we record our studies of the stars and galaxies? Well people would draw them and of course there is an inherent bias in what we see. So there was not a very good way to be able to record them because let's just say we're sketching Mars. Well five people could sketch Mars and may see some light in dark areas but they'd never be exactly the same. So why would you want then you could take a picture of Mars and you can see that everybody is then seeing exactly the same thing. We also have some other illusions. We can look at the moon when it's close to the horizon, sometimes called the moon illusion and that is that the moon looks very large when it's close to the horizon and it really is not. It's not any bigger. You can make measurements and find out that even when the moon is close to the horizon it is exactly the same angular size as it is when it's high in the sky. So that's one other astronomical example that we can look at and of course we always put shapes to astronomical objects. We have things like the horse head nebula and other objects that we name after something that they may vaguely resemble but for the most part of course that is all just optical illusion as well where our minds just want to put some kind of order to the randomness of patterns in various astronomical objects. So here we get to see one example of that with the same color illusion that we looked at for our picture today. So that was our picture of the day for December 18th of 2023. It was titled the same color illusion. We'll be back again tomorrow for the next picture. So until then have a great day everyone and I will see you in class.