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Telescopes. Discussion. If you had a Coke bottle and you wished to fill it with rainwater falling from the sky, how would you do it?. Telescopes Serve 3 Functions. To collect light To resolve fine detail To magnify the image. Discussion.
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Discussion If you had a Coke bottle and you wished to fill it with rainwater falling from the sky, how would you do it?
Telescopes Serve 3 Functions • To collect light • To resolve fine detail • To magnify the image
Discussion Of the three telescope functions which do you think is the most important in astronomy and why?
Refraction(Marching Band Analogy) What happens to the marching band if it hits a muddy part which causes the individual band members to slow?
Speed of light in glass Light moves slower in glass than in a vacuum Speed of light through glass is different for different frequencies and each frequency has a slightly different focus.
Resolution The ability to separate two closely spaced objects, such as a double star. The bigger your telescope objective the better your resolution will be.
Resolution and the atmosphere Atmospheric turbulence limits the resolution of even the largest telescopes on Earth to about that of a 6 inch telescope.
Points of light Stars are so far away that they appear as points of light no matter how big a telescope you observe them with. Bigger stars in photographs are simply brighter.
“Seeing” The apparent size of the stars as viewed through the telescope. Good seeing is typically 1 arcsec.
Discussion What can astronomers do to try and improve resolution of their observations?
Adaptive optics Actuators deform the primary mirror hundreds of times a second to try and remove atmospheric distortion.
Discussion Adaptive optic telescopes work best in the infrared region of the spectrum and not in the visible. Why do you think that is?
Discussion What do you think happens when very high energy gamma rays from space hit the Earth’s atmosphere?
Discussion Why can’t the very long wavelength radio waves make it to Earth’s surface?
Discussion Why does the Sun emit light?
Discussion How do you know the Sun is hot?
The setting Sun is red because • The Earth is rotating away from the Sun, so it is redshifted. • The setting Sun is cooler at sunset, so Wien’s law says the frequency of maximum emission shifts to lower frequencies thus appears redder. • At sunset the light has to travel through more of the Earth’s atmosphere, which has lots of absorption lines in the blue portion of the spectrum. • None of the above
Solar Data Radius: 109 Earth radii Mass: 333,000 Earth masses Mean density: 1.41 g/cm3 Composition: 74% hydrogen 25% helium Luminosity: 3.86 1026 Watts
The Sun as a big cosmic light bulb Suppose every human being on Earth turned on 1000 100-watt light bulbs. With about 6 billion people this would only be 6 1014 watts. We would need 670 billion more Earth’s doing the same thing to equal the energy output of the Sun.
