Astronomy Unit 1 Flashcards
a series or pattern of dark lines superimposed on a continuous spectrum
absorption spectrum
an idealized object that absorbs all electromagnetic energy that falls onto it
blackbody
a spectrum of light composed of radiation of a continuous range of wavelengths or
colors, rather than only certain discrete wavelengths
continuous spectrum
separation of different wavelengths of white light through refraction of different amounts
dispersion
the apparent change in wavelength or frequency of the radiation from a source due to its
relative motion away from or toward the observer
Doppler effect
radiation consisting of waves propagated through regularly varying electric and
magnetic fields and traveling at the speed of light
electromagnetic radiation
the whole array or family of electromagnetic waves, from radio to gamma rays
electromagnetic spectrum
a series or pattern of bright lines superimposed on a continuous spectrum
emission spectrum
the amount of energy passing through a unit area (for example, 1 square meter) per second; the
units of flux are watts per square meter
energy flux
a particular level, or amount, of energy possessed by an atom or ion above the energy it
possesses in its least energetic state; also used to refer to the states of energy an electron can have in an atom
energy level
the process of giving an atom or an ion an amount of energy greater than it has in its lowest energy
(ground) state
excitation
he number of waves that cross a given point per unit time (in radiation)
frequency
photons (of electromagnetic radiation) of energy with wavelengths no longer than 0.01
nanometer; the most energetic form of electromagnetic radiation
gamma rays
he lowest energy state of an atom
ground state
electromagnetic radiation of wavelength 103–106 nanometers; longer than the longest (red)
wavelengths that can be perceived by the eye, but shorter than radio wavelength
infrared
(for light) the amount of energy (light) flowing through a given area in a given time
decreases in proportion to the square of the distance from the source of energy or light
inverse square law
an atom that has become electrically charged by the addition or loss of one or more electrons
ion
the process by which an atom gains or loses electrons
ionization
any of two or more forms of the same element whose atoms have the same number of protons but different numbers of neutrons
isotope
electromagnetic radiation of wavelengths from 1 millimeter to 1 meter; longer than infrared but
shorter than radio waves.
microwave
the massive part of an atom, composed mostly of protons and neutrons, and about
which the electrons revolve
nucleus
a discrete unit (or “packet”) of electromagnetic energy
photon
motion toward or away from the observer; the component of relative velocity that lies in the
line of sight
radical velocity
all electromagnetic waves longer than microwaves, including radar waves and AM radio waves
radio waves
