Astronomy Picture of the Day (or APOD for short) is a website run by NASA’s Goddard Space Flight Center and Michigan Tech University. It displays an astronomy-related picture daily. The majority of these pictures are pictures taken from telescopes, most notably the Hubble Space Telescope and the Spitzer Space Telescope (an infrared telescope). These pictures tend to range from modestly interesting to awe-inspiring. I will often use pictures I see on that site as wallpaper on my laptop. In fact, my current wallpaper is a cropped, resized version of this Hubble image of the Carina Nebula (though the credit for finding it goes to Phil Plait, not APOD).
However, APOD sometimes runs pictures or diagrams that relate to an aspect of astronomical science in a more abstract way. Today’s was one such example:
This is a classic illusion where because of other visual cues, A appears to be a significantly darker shade of gray than B when in actuality, they are the same color. The point made by this graphic in relation to astronomy is that human vision is biased and thus affects our perception of the world. The article notes that the advent of CCDs among other automated measuring devices has allowed for less biased observation in astronomy and other sciences.
This is the part that caught my interest. I had already seen this illusion a few times before but while interesting, it is also the same as it was the last few times I saw it. The part I found interesting was the mention of CCDs, which are part of the system by which most digital cameras work.
As it just so happens, earlier today, I was taking some pictures of the sunrise over Lake Winnebago with my new camera. Here is one of the pictures:
While I think it is a lovely picture, it fails to capture one of the best parts of the scene: the deep red-orange hue of the sun.
You see, as a result of the same biases in human perception that created the illusion above, we are able to see both the deep-red hues of the sun and the reflections from the clouds, where the digital camera, in attempting to adjust to to the overall brightness of the scene, mimicked my vision pretty well for the area around the sun, it show the sun as an off-white spot with a red-orange hue around the rim, because it is significantly brighter than anything else in the scene.
So, while our visual perception is biased, this bias is not without use. In this case, it allows us to catch more visual beauty in a scene that is caught in an automated measuring device such as the CCD of my digital camera. While it has it’s drawbacks in science, human vision’s quirks are not without reward.