Several years ago I made the comment to a friend who happens to be a career scientist that sometimes the sky didn't seem as blue as it was when I was younger. More greenish, espeically noticeable at low sun angles. I can't remember his exact answer, but he said it had to do with the increased concentrations of carbon dioxide and other greenhouse gasses in the atmosphere, as well as certain man-made particulates. Would an increase in CO2 level (or other industrial pollutants) tend to make the atmosphere more opaque to certain wavelengths of light? Is ground-based astronomy eventually going to take a hit because of air pollution? --- Patrick Wiggins <paw@wirelessbeehive.com> wrote:
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