Space Telescopes

Absorption Light is absorbed by solids, liquids and gases. Clear vs opaque Absorption depends on the frequency. Glass is clear to visible light, and opaque in infrared. COMSOL

Atmospheric Absorption The atmosphere absorbs radiation, except at visible light, infrared, and radio frequencies.

Adaptive Optics The moving atmosphere disturbs images. Computers can correct and reshape a mirror. Keck I and II use computer corrections of mirror panels. NGC 7469, CFHT

Charge-Coupled Device CCDs are sensitive to light from ultraviolet to infrared. Can be sensitive to individual photons Sensitivity to thermal noise and cosmic rays can blur an image. Multiple exposures are averaged to get correct image. Dark frame closed shutter Hammamatsu.com

Telescopes in Orbit Orbiting telescopes avoid the Earth’s atmosphere. Improve resolution at visible and radio (microwave) frequencies Observe other frequencies

Hubble Space Telescope The Hubble is an orbiting reflector telescope. Launched in 1990 No atmosphere to peer through Four cameras for different views and onboard computer for optical correction

Infrared Eyes The Spitzer Space Telescope views infrared light. Launched in 2003 Images are often mixed with other telescopes to give a full picture. False color Red on the left image is radio. Other colors represent different infrared wavelengths.

Ultraviolet Explorer The GALEX spacecraft measured ultraviolet light from galaxies. Flew from 2003 until 2013 Hisaki launched in 2013 by JAEA

X-ray Observatory The Chandra X-ray Observatory was launched in 1999. Originally scheduled for five years and still running X-rays are associated with super-hot material in magnetic fields or extreme gravity. optical x-ray Chandra X-ray Observatory

Fermi Space Telescope In 2008 the Fermi Gamma-ray Space Telescope was launched. CsI scintillator and silicon strip readout Large area telescope (LAT) detects hard gammas Gamma burst monitor (GBM) detects soft gammas