ASTRON C10 Midterm: AstroC10 Midterm Review

• School: Berkeley
• Department: Astronomy
• Course: ASTRON C10
• Professor: Alex Filippenko

Document Summary

Light year is the distance light travels in one year. Astronomers are seeing back into the past because it takes light from far away planets and stars a long time to reach us. Speed of light in vacuum is constant. Light is produced by self-propagating, oscillating electric and magnetic fields perpendicular to each other and the direction of motion. Frequency (number of times per second a crest passes a fixed plane; unit is hertz) and wavelength (distance from one crest to the next) are inverses. Wavelength of electromagnetic radiation (from lowest to highest) Frequencies and energy are opposite of wavelength. Light is made of packets of photons of same wavelength that collectively make a wave. Energy of photon proportional to its frequency. Higher frequency, higher energy and lower wavelength. Electrons of a photon exist at discrete energy levels. Can"t absorb just part of a photon"s energy. Can"t absorb two photons that add up to the energy of a single photon.