ASTR-1010 Lecture Notes - Lecture 5: Light Pollution, Radiography
6 Oct 2016
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Document Summary
The wavelengths of radio waves are long. So the dishes which reflect them must be very large to achieve any reasonable angular resolution. Q: the largest telescopes are designed to have. A: large collecting area and high angular resolution; magnification doesn"t really matter. Bad weather makes it impossible to observe the night sky. Air turbulence in the atmosphere distorts light: that is why the stars appear to twinkle , angular resolution is degraded. Man-made light is reflected by the atmosphere, thus making the night sky brighter: light pollution. Earth"s atmosphere absorbs most types of light: good thing it does, or we would be dead! Only visible, radio, and certain ir and uv light make it to the ground. Interferometry: two or more radio dishes observe the same object. Has the angular resolution one would get from a dish the size of the distance between them. The light-collecting area is still only the sum of the areas.
