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On September 17th, 1998 the Ithaca Journal ran its first "Ask A Scientist!" article in which Professor Neil Ashcroft , who was then the director of CCMR, answered the question "What is Jupiter made of?" Since then, we have received over 1,000 questions from students and adults from all over the world. Select questions are answered weekly and published in the Ithaca Journal and on our web site. "Ask A Scientist!" reaches more than 21,000 Central New York residents through the Ithaca Journal and countless others around the world throught the "Ask a Scientist!" web site.

Across disciplines and across the state, from Nobel Prize winning scientist David Lee to notable science education advocate Bill Nye, researchers and scientists have been called on to respond to these questions. For more than seven years, kids - and a few adults - have been submitting their queries to find out the answer to life's everyday questions.

Previous Week's Question Published: 13 March, 2003 Next Week's Question
Some animals have ability to "see" in dark, but not humans
Question
Can humans ever see in the dark with no night vision glasses or other aids?

Question
Humans (and most animals) can see in the "dark" only if there is some starlight or, better, moonlight. It takes some time (10 to 30 minutes) for your eyes to become dark adapted to see in such low-light conditions. Best conditions are on a night with no clouds and a full moon (try it!). When dark adapted, you can see only in black and white (no color). If there is no light at all - say in a deep cave - you cannot see anything.

A few animals have infrared "vision", which works by detecting heat. Heat produces infrared radiation, which is invisible to the human eye. In some snakes (for example, rattle snakes, that hunt mainly at night), this infrared vision is well developed. This vision only works when there is a temperature difference between objects, say between a warm blooded rodent and the background.

Night vision goggles allow to us see the infrared radiation with reasonable clarity, if there is a temperature difference between objects, but the sharpness of the view is not as high as with our usual daylight vision.

Infrared radiation and visible light are all part of the electromagnetic spectrum. They are waves of different frequency. Radio waves, microwaves, infrared and visible radiation, ultraviolet rays (which give sun burns) and X-rays are all part of that spectrum - each at different frequencies. These waves interact with matter (including us) in different ways depending on their frequencies.

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