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46 Cards in this Set
- Front
- Back
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Electromagnetic Radiation
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Radiation consisting of waves propagated through regularly varying electric and magnetic fields; includes radio, infrared, visible light, ultraviolet, x-rays and gamma rays
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Wavelength
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The distance from one crest to another between two waves
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Frequency
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The number of wave cycles that pass per second
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Photons
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Packets of electromagnetic energy
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Inverse-Square Law
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The amount of energy (light) flowing through a given area in a given time (flux) decreases in proportion to the square of the distance from the source of energy or light
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Electromagnetic Spectrum
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The whole array or family of electromagnetic waves from radio to gamma rays
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Gamma Rays
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Electromagnetic radiation with the shortest wavelengths
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X-rays
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Electromagnetic radiation with wavelengths between 0.01 nm and 20 nm; used for medical purposes
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Ultraviolet
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Radiation intermediate between x-rays and visible light; mostly blocked by ozone layer
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Visible Light
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Electromagnetic Radiation with wavelengths between roughly 400 and 700 nm
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Radio Waves
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All electromagnetic waves longer than infrared; divided into several sub-categories (microwaves, radar, FM & TV waves, AM)
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Wien's Law
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Formula that relates the temperature of a blackbody to the wavelength at which it emits the greatest intensity of radiation
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Energy Flux
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The power emitted per square meter
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Stefan-Boltzman Law
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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
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Dispersion
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Separation of the different wavelengths of white light through being refracted by different amounts
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Spectrometer
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An instrument for obtaining a spectrum; in astronomy, usually attaced to a telescope to record the spectrum of a star, galaxy, or other astronomical object
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Continuous Spectrum
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An array of all wavelengths or colors of the rainbow
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Absorption Line Spectrum
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A series or pattern of dark lines
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Emission Line Spectrum
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A spectrum consisting of emission lines (discrete bright lines in the spectrum)
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Isotopes
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Types of elements that have the same number of protons but differring numbers of neutrons
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Energy Level
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A particular level, or amount, of energy possessed by an atom or ion above the energy it posesses in its least energetic state; also used to refer to the states of energy an electron can have in an orbit
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Ground State
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When an atom is in the state of lowest possible energy
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Excited State
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When an atom or an ion gets an amount of energy greater than it has in its least-energy state
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Ionized
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When an atom becomes electrically charged by the addition or loss of one or more electrons
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Doppler Effect
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Apparent change in wavelength or frequency of the radiation from a source due to its relative motion away from or toward the observer
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Radial Velocity
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The component of relative velocity that lies in the line of sight; motion toward or away from the observer
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Detector
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A device that can sense the radiation in the wavelength regions chosen
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Aperatures
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The diameter of an opening, or of the primary lens or mirror of a telescope
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Refracting Telescope
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A telescope in which the principal light collectro is a lens or system of lenses
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Focus
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Point where the rays of light converged by a mirror or lens meet
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Reflecting Telescope
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A telescope in which the principal light collector is a concave mirror
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Resolution
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The fineness of detail present in an image
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Adaptive Optics
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Systems used with telescopes that change to compesnate for distortions in an image introduced by the atmosphere, thus producing sharper images
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Charge-Coupled Devices
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An array of high-sensitivity electronic detectors of electromagnetic radiation, used at the focus of a telescope (or camera lens) to record an image or spectrum
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Interferometer
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An instrument that combines electromagnetic radiation (or gravitational waves)from one or more telescopes to obtain a resolution equivalent to what would be obtained with a single telescope with a diameter equal to the baseline separating the individual separate telescopes
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Radar
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The technique of transmitting radio waves to an object in our solar system and then detecting the radio radiation that the object reflects back
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Terrestrial Planets
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The four planets closest to the Sun
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Asteroids
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Rocky bodies that orbit the Sun like miniature planets, mostly in the space between Mars and Jupiter
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Comets
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A class of small bodies that are composed of ice (made of frozen gases such as water, carbon dioxide, carbon monoxide, and methyl alcohol)
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Meteor
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A flash of light observed when a small piece of solid matter enters the Earth's atmosphere and burns up; popularly called a "shooting star"
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Meteorite
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A portion of a meteriod that survives passage through the atmosphere and strikes the ground
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Differentiation
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The name given to the process by which gravity helps separate a planet's interior into layers of different compositions and densities
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Radioactivity
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The process by which certain kinds of atmoic nuclei naturally decompose, with the sponataneous emission of subatomic particles and gamma rays
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Half-life
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The time required for half of the radioactive atoms in a sample to disintegrate
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Solar Nebula
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The cloud of gas and dust from which the solar system formed
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Planetesimals
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Objects, from tens to hundreds of kilometers in diameter, that formed in the solar nebula as an intermediate step between tiny grains and the large planetary objects we see today; the comets and some asteroids may be leftover planetesimals
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