AST 1002 Lecture Notes - Lecture 3: Photon, Tella, Black-Body Radiation
Document Summary
We can only measure the light of stars. The wave travels by points on the surface going only up and down. All light travels at the same speed: c=300,000 km/s. Galileo stood on a hill with lantern and his assistant stood on another hill with a lantern to try to measure light. This experiment failed because the light travel time was only ~. 00001 seconds. Accelerated charges (electrons, protons) produce: ripples in the electromagnetic field. Visible light ranges in wavelength from 400-700 nanometers. Water droplets act like prisms, bending and reflecting light. (cid:862)white(cid:863) light f(cid:396)o(cid:373) the u(cid:374) is di(cid:448)ided i(cid:374)to colors and reflected. We see droplets in an arc ~42 degrees away from the direction opposite the sun. Radio infrared visible uv x ray gamma ray (most energetic) It (cid:271)lo(cid:272)ks (cid:373)ost of the u(cid:374)"s (cid:396)adiatio(cid:374) (cid:271)ut lets a little bit through. O(cid:374)l(cid:455) (cid:448)isi(cid:271)le a(cid:374)d (cid:396)adio full(cid:455) pe(cid:374)et(cid:396)ate ea(cid:396)th"s at(cid:373)osphe(cid:396)e. Blackbody radiation: idealized radiation that absorbs all radiation.
