Test Bank for Foundations of
Astronomy, 15th Edition
Absolute Age - answer-An age determined in years, as from radioactive dating
absolute bolometric magnitude - answer-the absolute magnitude you would observe if you
could detect all wavelengths
absoluted visual magnitude - answer-intrinsic brightness of a star; the apparent visual
magnitude the star would have if it were 10 pc away
absolute zero - answer-the lowest possible temperature; the temperature at which the particles
in a material, atoms or molecules, contain no energy of motion that can be extracted from the
body
absorption line - answer-a dark line in a spectrum; produced by the absence of photons
absorbed by atoms or molecules
absorption spectrum/dark-line spectrum - answer-a spectrum that contains absorption lines
acceleration - answer-a change in a velocity; a change in either speed or direction
acceleration of gravity - answer-a measure of the strength of gravity at a planet's surface
accretion - answer-the sticking together of solid particles to produce a larger particle
1
,accretion disk - answer-the whirling disk of gas that forms around a compact object such as a
white dwarf, neutron star, or black hole as matter is drawn in
achondrite - answer-stony meteorite containing no chondrules or volatiles
achromatic lens - answer-a telescope lens composed of two lenses ground from different kinds
of glass and designed to bring two selected colors to the same focus and correct for chromatic
aberration
active galactic nucleus (AGN) - answer-the central energy source of an active galaxy
active optics - answer-optical elements whose position or shape is continuously controlled by
computers
active galaxy - answer-a galaxy that is a source of excess radiation, usually radio waves, X rays,
gamma rays, or some combination
active region - answer-an area on the sun where sunspots, prominences, flares, and the like
occur
adaptive optics - answer-computer-controlled telescope mirrors that can at least partially
compensate for seeing
albedo - answer-the fraction of the light hitting an object that is reflected
alt-azimuth mounting - answer-a telescope mounting capable of motion parallel to and
perpendicular of the horizon
2
,amazonian period - answer-on mars, the geological era from about 3 billion years ago the
present marked by low-level cratering, wind erosion, and small amounts of water seeping from
subsurface ice
amino acid - answer-one of the carbon-chain molecules that are the building blocks of protein
angstrom - answer-a unit of measure (10^-10) used to measure the wavelength of light
angular diameter - answer-a measure of the size of an object in the sky; numerically equal to
the angle in degrees between two lines extending from the observer's eye to opposite edges of
the object
angular distance - answer-a measure of the separation between two objects in the sky;
numerically equal to the angle in degrees between two lines extending from the observer's eye
to the opposite edges of the object
angular momentum - answer-the tendency of a rotating body to continue rotating;
mathematically, the product of mass, velocity, and radius
angular momentum problem - answer-an objection to Laplace's nebular hypothesis that cited
the slow rotation of the sun
annular eclipse - answer-a solar eclipse in which the solar photosphere appears around the
edge of the moon in a bright ring, or annulus. The corona, chromosphere, and prominences
cannot be seen.
anomalous x-ray pulsars - answer-high magnetic neutron stars that emit X rays but spin slowly
3
, with periods of 5 to 10 seconds
anorthosite - answer-rock of aluminum and calcium silicates found in the lunar highlands
antimatter - answer-matter composed of antiparticles, which on colliding with a matching
particle of normal matter annihilate and convert the mass of both particles into energy. The
antiproton is the antiparticle of the proton, and the positron is the antiparticle of the electron
aphelion - answer-the orbital point of greatest distance from the sun
apogee - answer-the orbital point of greatetst distance from Earth
Apollo-Amor object - answer-Asteroid whose orbit crosses that of Earth (Apollo) and Mars
(Amor).
apparent visual magnitude - answer-the brightness of a star as seen by human eyes on Earth
archaeoastronomy - answer-the study of the astronomy of ancient cultures
association - answer-group of widely scattered stars moving together through space; not
gravitationally bound into a cluster
asterism - answer-a named group of stars not identified as a constellation
asteroid - answer-a small rocky world; most asteroids lie between mars and jupiter in the
asteroid belt
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Astronomy, 15th Edition
Absolute Age - answer-An age determined in years, as from radioactive dating
absolute bolometric magnitude - answer-the absolute magnitude you would observe if you
could detect all wavelengths
absoluted visual magnitude - answer-intrinsic brightness of a star; the apparent visual
magnitude the star would have if it were 10 pc away
absolute zero - answer-the lowest possible temperature; the temperature at which the particles
in a material, atoms or molecules, contain no energy of motion that can be extracted from the
body
absorption line - answer-a dark line in a spectrum; produced by the absence of photons
absorbed by atoms or molecules
absorption spectrum/dark-line spectrum - answer-a spectrum that contains absorption lines
acceleration - answer-a change in a velocity; a change in either speed or direction
acceleration of gravity - answer-a measure of the strength of gravity at a planet's surface
accretion - answer-the sticking together of solid particles to produce a larger particle
1
,accretion disk - answer-the whirling disk of gas that forms around a compact object such as a
white dwarf, neutron star, or black hole as matter is drawn in
achondrite - answer-stony meteorite containing no chondrules or volatiles
achromatic lens - answer-a telescope lens composed of two lenses ground from different kinds
of glass and designed to bring two selected colors to the same focus and correct for chromatic
aberration
active galactic nucleus (AGN) - answer-the central energy source of an active galaxy
active optics - answer-optical elements whose position or shape is continuously controlled by
computers
active galaxy - answer-a galaxy that is a source of excess radiation, usually radio waves, X rays,
gamma rays, or some combination
active region - answer-an area on the sun where sunspots, prominences, flares, and the like
occur
adaptive optics - answer-computer-controlled telescope mirrors that can at least partially
compensate for seeing
albedo - answer-the fraction of the light hitting an object that is reflected
alt-azimuth mounting - answer-a telescope mounting capable of motion parallel to and
perpendicular of the horizon
2
,amazonian period - answer-on mars, the geological era from about 3 billion years ago the
present marked by low-level cratering, wind erosion, and small amounts of water seeping from
subsurface ice
amino acid - answer-one of the carbon-chain molecules that are the building blocks of protein
angstrom - answer-a unit of measure (10^-10) used to measure the wavelength of light
angular diameter - answer-a measure of the size of an object in the sky; numerically equal to
the angle in degrees between two lines extending from the observer's eye to opposite edges of
the object
angular distance - answer-a measure of the separation between two objects in the sky;
numerically equal to the angle in degrees between two lines extending from the observer's eye
to the opposite edges of the object
angular momentum - answer-the tendency of a rotating body to continue rotating;
mathematically, the product of mass, velocity, and radius
angular momentum problem - answer-an objection to Laplace's nebular hypothesis that cited
the slow rotation of the sun
annular eclipse - answer-a solar eclipse in which the solar photosphere appears around the
edge of the moon in a bright ring, or annulus. The corona, chromosphere, and prominences
cannot be seen.
anomalous x-ray pulsars - answer-high magnetic neutron stars that emit X rays but spin slowly
3
, with periods of 5 to 10 seconds
anorthosite - answer-rock of aluminum and calcium silicates found in the lunar highlands
antimatter - answer-matter composed of antiparticles, which on colliding with a matching
particle of normal matter annihilate and convert the mass of both particles into energy. The
antiproton is the antiparticle of the proton, and the positron is the antiparticle of the electron
aphelion - answer-the orbital point of greatest distance from the sun
apogee - answer-the orbital point of greatetst distance from Earth
Apollo-Amor object - answer-Asteroid whose orbit crosses that of Earth (Apollo) and Mars
(Amor).
apparent visual magnitude - answer-the brightness of a star as seen by human eyes on Earth
archaeoastronomy - answer-the study of the astronomy of ancient cultures
association - answer-group of widely scattered stars moving together through space; not
gravitationally bound into a cluster
asterism - answer-a named group of stars not identified as a constellation
asteroid - answer-a small rocky world; most asteroids lie between mars and jupiter in the
asteroid belt
4
