Astronomy 1021 Lecture 12: Oct 18 - Astronomy

• School: Western University
• Department: Astronomy
• Course: Astronomy 1021
• Professor: Robert Cockcroft

Document Summary

Constellation of the week: draco: lati(cid:374) fo(cid:396) (cid:862)d(cid:396)ago(cid:374)(cid:863, between uma and umi, circumpolar constellation, used to contain pole star (thuban) Motivation: all mater emits and absorbs light, but at different wavelengths depending on composition and temperature, visible light vs. Infrared: the sun and moon also look quite different at different wave lengths. How do light & matter interact: reflection/scattering, absorption, transmission, emission, usually a combination of all. Transmission: light (maybe partially) passing through a medium transmission. Ast(cid:396)o(cid:374)o(cid:373)(cid:455) e(cid:454)a(cid:373)ple: light th(cid:396)ough the ea(cid:396)th"s at(cid:373)osphe(cid:396)e: the light ofte(cid:374) (cid:862)(cid:271)e(cid:374)t(cid:863) i(cid:374) the p(cid:396)o(cid:272)ess refraction. Astronomy example: oval sun shape at sunset. Red sunset: blue light more easily scattered than red, light stakes a longer oath through the atmosphere at sunset, more blue light gets scattered out at sunset, also season why skies are blue. Absorption: light may also be absorbed, an object that absorbs all light is opaque, an object that only partially absorbs is translucent, often different for different colours.