The moon illusion

You may have heard that the moon should appear the same size regardless of its position on the horizon, since its distance to the observer varies minimally with its position on the horizon. Therefore the fact that it appears larger when close to the horizon is an illusion.

What I did not know is that we don't fully understand the illusion. Three explanations are offered in this video.

One has to do with our brains performing a relative comparison with nearby objects of known size, such as trees, which is only possible when the moon appears on the horizon. But the explanation fails to account for the illusion also working for sailors and pilots, even though they don't have such objects to confuse them.

Another explanation involves perspective correction, where things that are far away are assumed to be bigger. The video has a nice illustration of this.

Yet a third explanation is that the brain judges distance by taking into account how much our eyes need to focus to observe something. This focus is different for the horizon and for looking at the top of the sky.

No single explanation works in all cases, so amazingly we still don't know why the moon appears larger. Check out the video for a more visual explanation of the same points.

And here is wikipedia’s take.


What would happen if we drained the Mediterranean sea?

I was reminded in the Natural History Museum in New York that the Mediterranean sea was dry at some point.

If the connection to the Atlantic Occean was cut off, it would dry again. That is why it is so salty, especially in the East, it evaporates more than it can be replenished from rivers.

It did not take too long to go from there, to this video with graphics and some speculation about the consequences of no water in the Mediterranean.

How much of Europe would be a desert, how much deeper than the Grand Kanyon would it be, and how much higher the rest of sea level would be?


Athens Portrait

Here is a nice video showing the capital of Greece. From the description in Vimeo:

The film is a homage to the capital of Greece. It features hyperlapse, timelapse and drivelapse cinematography of the urban area and the skyline of "το κλεινόν άστυ" / the glorious city. Shot almost entirely from the highest rooftops, hills and mountains at night, the film explores the urban core, the city center and beyond.

Worth watching in a 5 min break.

City of Athens - A Portrait of a Changing Metropolis from Alexandros Maragos on Vimeo.


Ronig rebetika

I recently came across Christian Ronig, a German guy who seems to love rebetika songs, i.e. Greek songs from 2 generations ago. He has translated and modified some of them to a different style, which still captures the original essense. It is quite interesting to see what a person with completely different influences sees in a different culture. I think he does a great job.

He has an album named “Greece is mine”, here is one of the songs (morning in minor). Youtube has some more which might brighten your day.

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