IB Physics Astrophysics Definitions – Flashcards
Unlock all answers in this set
Unlock answersquestion
planet
answer
orbits star elliptically with constant period
question
asteroid
answer
rocky object smaller than planet orbiting star
question
meteoroid
answer
asteroid on collision course with planet
question
meteor
answer
object that has entered earth's atmosphere
question
meteorite
answer
object that has reached earth's surface
question
comet
answer
rocky and icy object with very elliptical orbit around star, whose tail points away from star due to radiation pressure
question
constellation
answer
collection of stars forming pattern as viewed on earth, not necessarily close together
question
stellar cluster
answer
group of stars of similar age and size, held together by mutual gravitational attraction
question
luminosity
answer
power emitted by star (total energy per unit time)
question
apparent brightness
answer
power per unit area received on earth
question
apparent magnitude
answer
measure of brightness as viewed on earth
question
absolute magnitude
answer
apparent magnitude if star was 10 parsecs away from earth
question
Newton's Steady State Theory
answer
universe is infinite in time and space, uniform (homogeneous, mass equally distributed, same in all directions), static
question
Hubble's Law
answer
recessional velocity of distant galaxy is proportional to distance from earth
question
Cosmic background radiation
answer
black body radiation uniform in all directions and not linked to source, cooled since big bang to temp of 3K
question
open universe
answer
universe continues to expand forever, gravity slows expansion but unable to stop it
question
closed universe
answer
universe stops expanding and contracts due to gravity
question
flat universe
answer
universe expansion rate slows to zero after infinite amount of time, but never reverses
