{"id":297,"date":"2022-02-11T17:10:58","date_gmt":"2022-02-11T17:10:58","guid":{"rendered":"https:\/\/pressbooks.ccconline.org\/astronomy\/?post_type=chapter&p=297"},"modified":"2022-02-11T17:10:58","modified_gmt":"2022-02-11T17:10:58","slug":"key-terms-3","status":"publish","type":"chapter","link":"https:\/\/pressbooks.ccconline.org\/astronomy\/chapter\/key-terms-3\/","title":{"raw":"Key Terms","rendered":"Key Terms"},"content":{"raw":"
\r\n \t
absorption spectrum<\/dt>\r\n \t
a series or pattern of dark lines superimposed on a continuous spectrum<\/dd>\r\n<\/dl>\r\n
\r\n \t
blackbody<\/dt>\r\n \t
an idealized object that absorbs all electromagnetic energy that falls onto it<\/dd>\r\n<\/dl>\r\n
\r\n \t
continuous spectrum<\/dt>\r\n \t
a spectrum of light composed of radiation of a continuous range of wavelengths or colors, rather than only certain discrete wavelengths<\/dd>\r\n<\/dl>\r\n
\r\n \t
dispersion<\/dt>\r\n \t
separation of different wavelengths of white light through refraction of different amounts<\/dd>\r\n<\/dl>\r\n
\r\n \t
Doppler effect<\/dt>\r\n \t
the apparent change in wavelength or frequency of the radiation from a source due to its relative motion away from or toward the observer<\/dd>\r\n<\/dl>\r\n
\r\n \t
electromagnetic radiation<\/dt>\r\n \t
radiation consisting of waves propagated through regularly varying electric and magnetic fields and traveling at the speed of light<\/dd>\r\n<\/dl>\r\n
\r\n \t
electromagnetic spectrum<\/dt>\r\n \t
the whole array or family of electromagnetic waves, from radio to gamma rays<\/dd>\r\n<\/dl>\r\n
\r\n \t
emission spectrum<\/dt>\r\n \t
a series or pattern of bright lines superimposed on a continuous spectrum<\/dd>\r\n<\/dl>\r\n
\r\n \t
energy flux<\/dt>\r\n \t
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<\/dd>\r\n<\/dl>\r\n
\r\n \t
energy level<\/dt>\r\n \t
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<\/dd>\r\n<\/dl>\r\n
\r\n \t
excitation<\/dt>\r\n \t
the process of giving an atom or an ion an amount of energy greater than it has in its lowest energy (ground) state<\/dd>\r\n<\/dl>\r\n
\r\n \t
frequency<\/dt>\r\n \t
the number of waves that cross a given point per unit time (in radiation)<\/dd>\r\n<\/dl>\r\n
\r\n \t
gamma rays<\/dt>\r\n \t
photons (of electromagnetic radiation) of energy with wavelengths no longer than 0.01 nanometer; the most energetic form of electromagnetic radiation<\/dd>\r\n<\/dl>\r\n
\r\n \t
ground state<\/dt>\r\n \t
the lowest energy state of an atom<\/dd>\r\n<\/dl>\r\n
\r\n \t
infrared<\/dt>\r\n \t
electromagnetic radiation of wavelength 103<\/sup>\u2013106<\/sup>\u00a0nanometers; longer than the longest (red) wavelengths that can be perceived by the eye, but shorter than radio wavelengths<\/dd>\r\n<\/dl>\r\n
\r\n \t
inverse square law<\/dt>\r\n \t
(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<\/dd>\r\n<\/dl>\r\n
\r\n \t
ion<\/dt>\r\n \t
an atom that has become electrically charged by the addition or loss of one or more electrons<\/dd>\r\n<\/dl>\r\n
\r\n \t
ionization<\/dt>\r\n \t
the process by which an atom gains or loses electrons<\/dd>\r\n<\/dl>\r\n
\r\n \t
isotope<\/dt>\r\n \t
any of two or more forms of the same element whose atoms have the same number of protons but different numbers of neutrons<\/dd>\r\n<\/dl>\r\n
\r\n \t
microwave<\/dt>\r\n \t
electromagnetic radiation of wavelengths from 1 millimeter to 1 meter; longer than infrared but shorter than radio waves<\/dd>\r\n<\/dl>\r\n
\r\n \t
nucleus (of an atom)<\/dt>\r\n \t
the massive part of an atom, composed mostly of protons and neutrons, and about which the electrons revolve<\/dd>\r\n<\/dl>\r\n
\r\n \t
photon<\/dt>\r\n \t
a discrete unit (or \u201cpacket\u201d) of electromagnetic energy<\/dd>\r\n<\/dl>\r\n
\r\n \t
radial velocity<\/dt>\r\n \t
motion toward or away from the observer; the component of relative velocity that lies in the line of sight<\/dd>\r\n<\/dl>\r\n
\r\n \t
radio waves<\/dt>\r\n \t
all electromagnetic waves longer than microwaves, including radar waves and AM radio waves<\/dd>\r\n<\/dl>\r\n
\r\n \t
spectrometer<\/dt>\r\n \t
an instrument for obtaining a spectrum; in astronomy, usually attached to a telescope to record the spectrum of a star, galaxy, or other astronomical object<\/dd>\r\n<\/dl>\r\n
\r\n \t
Stefan-Boltzmann law<\/dt>\r\n \t
a formula from which the rate at which a blackbody radiates energy can be computed; the total rate of energy emission from a unit area of a blackbody is proportional to the fourth power of its absolute temperature:\u00a0F<\/em>\u00a0= \u03c3T<\/em>4<\/sup><\/dd>\r\n<\/dl>\r\n
\r\n \t
ultraviolet<\/dt>\r\n \t
electromagnetic radiation of wavelengths 10 to 400 nanometers; shorter than the shortest visible wavelengths<\/dd>\r\n<\/dl>\r\n
\r\n \t
visible light<\/dt>\r\n \t
electromagnetic radiation with wavelengths of roughly 400\u2013700 nanometers; visible to the human eye<\/dd>\r\n<\/dl>\r\n
\r\n \t
wavelength<\/dt>\r\n \t
the distance from crest to crest or trough to trough in a wave<\/dd>\r\n<\/dl>\r\n
\r\n \t
Wien\u2019s law<\/dt>\r\n \t
formula that relates the temperature of a blackbody to the wavelength at which it emits the greatest intensity of radiation<\/dd>\r\n<\/dl>\r\n
\r\n \t
X-rays<\/dt>\r\n \t
electromagnetic radiation with wavelengths between 0.01 nanometer and 20 nanometers; intermediate between those of ultraviolet radiation and gamma rays<\/dd>\r\n<\/dl>\r\n
This book was adapted from the following: Fraknoi, A., Morrison, D., & Wolff, S. C. (2016). Key Terms. In Astronomy<\/i>. OpenStax. https:\/\/openstax.org\/books\/astronomy\/pages\/5-key-terms under a Creative Commons Attribution License 4.0<\/a><\/div>\r\n
Access the entire book for free at https:\/\/openstax.org\/books\/astronomy\/pages\/1-introduction<\/a><\/div>","rendered":"
\n
absorption spectrum<\/dt>\n
a series or pattern of dark lines superimposed on a continuous spectrum<\/dd>\n<\/dl>\n
\n
blackbody<\/dt>\n
an idealized object that absorbs all electromagnetic energy that falls onto it<\/dd>\n<\/dl>\n
\n
continuous spectrum<\/dt>\n
a spectrum of light composed of radiation of a continuous range of wavelengths or colors, rather than only certain discrete wavelengths<\/dd>\n<\/dl>\n
\n
dispersion<\/dt>\n
separation of different wavelengths of white light through refraction of different amounts<\/dd>\n<\/dl>\n
\n
Doppler effect<\/dt>\n
the apparent change in wavelength or frequency of the radiation from a source due to its relative motion away from or toward the observer<\/dd>\n<\/dl>\n
\n
electromagnetic radiation<\/dt>\n
radiation consisting of waves propagated through regularly varying electric and magnetic fields and traveling at the speed of light<\/dd>\n<\/dl>\n
\n
electromagnetic spectrum<\/dt>\n
the whole array or family of electromagnetic waves, from radio to gamma rays<\/dd>\n<\/dl>\n
\n
emission spectrum<\/dt>\n
a series or pattern of bright lines superimposed on a continuous spectrum<\/dd>\n<\/dl>\n
\n
energy flux<\/dt>\n
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<\/dd>\n<\/dl>\n
\n
energy level<\/dt>\n
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<\/dd>\n<\/dl>\n
\n
excitation<\/dt>\n
the process of giving an atom or an ion an amount of energy greater than it has in its lowest energy (ground) state<\/dd>\n<\/dl>\n
\n
frequency<\/dt>\n
the number of waves that cross a given point per unit time (in radiation)<\/dd>\n<\/dl>\n
\n
gamma rays<\/dt>\n
photons (of electromagnetic radiation) of energy with wavelengths no longer than 0.01 nanometer; the most energetic form of electromagnetic radiation<\/dd>\n<\/dl>\n
\n
ground state<\/dt>\n
the lowest energy state of an atom<\/dd>\n<\/dl>\n
\n
infrared<\/dt>\n
electromagnetic radiation of wavelength 103<\/sup>\u2013106<\/sup>\u00a0nanometers; longer than the longest (red) wavelengths that can be perceived by the eye, but shorter than radio wavelengths<\/dd>\n<\/dl>\n
\n
inverse square law<\/dt>\n
(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<\/dd>\n<\/dl>\n
\n
ion<\/dt>\n
an atom that has become electrically charged by the addition or loss of one or more electrons<\/dd>\n<\/dl>\n
\n
ionization<\/dt>\n
the process by which an atom gains or loses electrons<\/dd>\n<\/dl>\n
\n
isotope<\/dt>\n
any of two or more forms of the same element whose atoms have the same number of protons but different numbers of neutrons<\/dd>\n<\/dl>\n
\n
microwave<\/dt>\n
electromagnetic radiation of wavelengths from 1 millimeter to 1 meter; longer than infrared but shorter than radio waves<\/dd>\n<\/dl>\n
\n
nucleus (of an atom)<\/dt>\n
the massive part of an atom, composed mostly of protons and neutrons, and about which the electrons revolve<\/dd>\n<\/dl>\n
\n
photon<\/dt>\n
a discrete unit (or \u201cpacket\u201d) of electromagnetic energy<\/dd>\n<\/dl>\n
\n
radial velocity<\/dt>\n
motion toward or away from the observer; the component of relative velocity that lies in the line of sight<\/dd>\n<\/dl>\n
\n
radio waves<\/dt>\n
all electromagnetic waves longer than microwaves, including radar waves and AM radio waves<\/dd>\n<\/dl>\n
\n
spectrometer<\/dt>\n
an instrument for obtaining a spectrum; in astronomy, usually attached to a telescope to record the spectrum of a star, galaxy, or other astronomical object<\/dd>\n<\/dl>\n
\n
Stefan-Boltzmann law<\/dt>\n
a formula from which the rate at which a blackbody radiates energy can be computed; the total rate of energy emission from a unit area of a blackbody is proportional to the fourth power of its absolute temperature:\u00a0F<\/em>\u00a0= \u03c3T<\/em>4<\/sup><\/dd>\n<\/dl>\n
\n
ultraviolet<\/dt>\n
electromagnetic radiation of wavelengths 10 to 400 nanometers; shorter than the shortest visible wavelengths<\/dd>\n<\/dl>\n
\n
visible light<\/dt>\n
electromagnetic radiation with wavelengths of roughly 400\u2013700 nanometers; visible to the human eye<\/dd>\n<\/dl>\n
\n
wavelength<\/dt>\n
the distance from crest to crest or trough to trough in a wave<\/dd>\n<\/dl>\n
\n
Wien\u2019s law<\/dt>\n
formula that relates the temperature of a blackbody to the wavelength at which it emits the greatest intensity of radiation<\/dd>\n<\/dl>\n
\n
X-rays<\/dt>\n
electromagnetic radiation with wavelengths between 0.01 nanometer and 20 nanometers; intermediate between those of ultraviolet radiation and gamma rays<\/dd>\n<\/dl>\n
This book was adapted from the following: Fraknoi, A., Morrison, D., & Wolff, S. C. (2016). Key Terms. In Astronomy<\/i>. OpenStax. https:\/\/openstax.org\/books\/astronomy\/pages\/5-key-terms under a Creative Commons Attribution License 4.0<\/a><\/div>\n
Access the entire book for free at https:\/\/openstax.org\/books\/astronomy\/pages\/1-introduction<\/a><\/div>\n","protected":false},"author":33,"menu_order":11,"template":"","meta":{"pb_show_title":"on","pb_short_title":"","pb_subtitle":"","pb_authors":[],"pb_section_license":""},"chapter-type":[48],"contributor":[],"license":[],"class_list":["post-297","chapter","type-chapter","status-publish","hentry","chapter-type-numberless"],"part":253,"_links":{"self":[{"href":"https:\/\/pressbooks.ccconline.org\/astronomy\/wp-json\/pressbooks\/v2\/chapters\/297","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/pressbooks.ccconline.org\/astronomy\/wp-json\/pressbooks\/v2\/chapters"}],"about":[{"href":"https:\/\/pressbooks.ccconline.org\/astronomy\/wp-json\/wp\/v2\/types\/chapter"}],"author":[{"embeddable":true,"href":"https:\/\/pressbooks.ccconline.org\/astronomy\/wp-json\/wp\/v2\/users\/33"}],"version-history":[{"count":1,"href":"https:\/\/pressbooks.ccconline.org\/astronomy\/wp-json\/pressbooks\/v2\/chapters\/297\/revisions"}],"predecessor-version":[{"id":298,"href":"https:\/\/pressbooks.ccconline.org\/astronomy\/wp-json\/pressbooks\/v2\/chapters\/297\/revisions\/298"}],"part":[{"href":"https:\/\/pressbooks.ccconline.org\/astronomy\/wp-json\/pressbooks\/v2\/parts\/253"}],"metadata":[{"href":"https:\/\/pressbooks.ccconline.org\/astronomy\/wp-json\/pressbooks\/v2\/chapters\/297\/metadata\/"}],"wp:attachment":[{"href":"https:\/\/pressbooks.ccconline.org\/astronomy\/wp-json\/wp\/v2\/media?parent=297"}],"wp:term":[{"taxonomy":"chapter-type","embeddable":true,"href":"https:\/\/pressbooks.ccconline.org\/astronomy\/wp-json\/pressbooks\/v2\/chapter-type?post=297"},{"taxonomy":"contributor","embeddable":true,"href":"https:\/\/pressbooks.ccconline.org\/astronomy\/wp-json\/wp\/v2\/contributor?post=297"},{"taxonomy":"license","embeddable":true,"href":"https:\/\/pressbooks.ccconline.org\/astronomy\/wp-json\/wp\/v2\/license?post=297"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}