Light and Atmospheres
• Greenhouse gases absorb infrared light
• Scattering of visible wavelengths depends on wavelength
• Molecular dissociation by ultraviolet light
• Ionization by X-rays
Atmospheric Layers
Greenhouse Effect
Blue Sky: Scattered Light
UV and X-ray Light
• Ozone (O3) in stratosphere of Earth absorbs ultraviolet light.– Chemical balance between O3 and O2
– Chlorofluorocarbons (CFCs) destroy ozone
• X-rays ionize the upper layers of the atmosphere (ionosphere)– Charged particles reflect low frequency radio
waves (e.g., AM radio)
Atmospheric Windows
• Certain wavelengths require orbiting telescopes• Radio and visible light can be done from ground
Seeing: Atmospheric Effect
Why Put a Telescope in Orbit?
• The only reason to put a telescope in space is to eliminate atmosphere!
• a) ground-based b) damaged Hubblec) enhanced image d) repaired Hubble
Mauna Kea
