* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Light, radiation, telescopes
Survey
Document related concepts
X-ray astronomy detector wikipedia , lookup
Arecibo Observatory wikipedia , lookup
Hubble Space Telescope wikipedia , lookup
Leibniz Institute for Astrophysics Potsdam wikipedia , lookup
Lovell Telescope wikipedia , lookup
Allen Telescope Array wikipedia , lookup
James Webb Space Telescope wikipedia , lookup
Optical telescope wikipedia , lookup
Spitzer Space Telescope wikipedia , lookup
International Ultraviolet Explorer wikipedia , lookup
Reflecting telescope wikipedia , lookup
Transcript
Light, radiation, telescopes Tools of the trade Electromagnetic Radiation from distant sources Telescopes Detectors Computers Lots of hard work Electromagnetic Radiation Characterized by Wavelength Frequency All types travel at same speed… 300,000 km/s = c f c f = frequency = wavlength c = speed of light Electromagnetic spectrum Click on images to go to Physics 2000 site! Lower frequency waves are caused by oscillating charges What frequency do electrons in your car antenna oscillate at? Telescopes and detectors First detector: The Eye The Bending of Light Focus – to bend all light waves coming from the same direction to a single point Light rays which come from different directions converge at different points to form an image. Angular Resolution The ability to separate two objects. The angle between two objects decreases as your distance to them increases. The smallest angle at which you can distinguish two objects is your angular resolution. Types of Telescopes • • What’s the difference between a refracting telescope and a reflecting telescope? What are the two most important properties of a telescope? Refractor Yerkes 40-inch telescope; largest refractor in the world Reflecting Telescope Lick Observatory 2.4 m Planet Finder Gemini 8 m telescope Hawaii Different Reflector designs Best type to buy? Dobsonian! Most Bang for buck Large aperature Relatively light Relatively cheap Easy to maneuver Easy to fix College scopes 14” Schmidt Cassegrain Corrector plate Compact design Tracking Not cheap Build your own scope? Chabot Science Center Telescope makers workshop: http://www.chabotspace.org/visit/tel escopeworkshop.asp Space telescopes 1. 2. Why bother? To improve resolving power (seeing) Observe non visible wavelengths Seeing Due to turbulence in atmosphere Limits resolving power to size of seeing disk About ½ arc second maximum for “normal” observing (no adaptive optics) With no atmosphere, seeing is about .01 arc seconds for 10 m telescope D =wavelength, D = Diameter of objective (mirror) Seeing Disks of Binary Stars above are what two binary stars separated by 1 degree would look like if photographed by Different sized telescopes…largest on left, smallest on right. Hubble images on right More Hubble images .1 arc second Seeing! Spitzer IR telescope 85 cm aperture Trails earth in orbit Cooled Wavelength between 3 – 180 microns Multi-wavelength images Combine light from visible and IR telescopes! How to improve Resolving power At 1m, telescopes on ground are already “diffraction limited” by size of seeing disk So…Build bigger telescope in space Or correct for atmospheric distortion Use adaptive optics Next Generation James Web space telescope 6.5 meter Aperture Launch 2011 Note large sun shield Adaptive optics Taking out the twinkle! Image of a star “dancing” on detector due to motion of air Laser Guide star system Laser “scintillates” atoms in ionosphere Optical system brings artificial star into focus. other wavelength astronomy Radio Astronomy Uses much larger aperatures—why? Ultraviolet, X-Ray, Gamma Ray In future Gigantic Earth based optical telescopes with adaptive optics systems More Interferometers