I love illusions, and I love astronomy. So what could be better than combining the two? If you’ve ever seen the Moon rising over the horizon, looking so fat and looming that you felt like you could fall right into it, then you’ve been a victim of the famous Moon Illusion.

The Space Shuttle orbiter was the reusable spaceplane component of. Challenger established a modified marking scheme for the shuttle fleet that would be matched. Space Shuttle Fleet V4.5 for Orbiter 2010 now. I have removed the Shuttle Fleet V4.5 until I can resolve an issue with the attachments that has occurred since.

And it is an illusion, a pervasive and persuasive one. So, how does this thing work? Ah, step right up.

One of my favorite brain-benders is the Ponzo Illusion. You’ve seen it: the simplest case is with two short horizontal lines, one above the other, between two slanting but near-vertical lines. The upper line looks longer than the lower line, even though they’re the same length. The illusion works because our brains are a bit wonky.

The slanted lines make us think that anything near the top is farther away; the lines force our brain to think those lines are parallel but receding in the distance (like railroad tracks). The two horizontal lines are physically the same length, but our brain thinks the upper one is farther away. If it’s farther away, then duh, our brain says to itself, it must be bigger than the lower one. So we perceive it that way. While procrastinating on reddit, (you do look at reddit, don’t you, especially?) I found this beautiful example of Ponzo: Heehee! You’d swear up and down that the red vertical line on the right is much longer than the one on the left, wouldn’t you? It looks almost twice as long to me.

It’s a very powerful perception. But they’re not! I cut out the two red lines and put them side by side. Solidworks 2010 Windows 7 64 Bit. They’re pretty much exactly the same length (well, they’re off by a bit due to resolution issues in the image, but not by nearly as much as your brain likes to think). This example is a great one because it uses a real-life image. You can see the wall tiles getting smaller with distance, and the horizontal layout of them, complete with the lines between them, forces your brain to see the line on the right as farther away. This illusion plays out all the time including when the Moon is rising (you were wondering when I’d get back to that, weren’t you?).

The Moon Illusion is in part due to this same effect, but weirdly, you also need to understand how we perceive the sky. If I were to ask you what shape the sky is above your head, you’d probably answer 'a hemisphere'. But in fact, almost everyone perceives it as an inverted bowl, flattened at the top.

Put it this way: if the sky were a hemisphere above you, you’d say the horizon was as far away as the zenith. But in fact most people perceive the horizon being farther away than the point straight over their heads; test after test has shown this. This isn’t too surprising; think of a cloudy day. The clouds over your head are maybe two or three kilometers above, but near the horizon they may be 100 kilometers away!