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78 Cards in this Set
- Front
- Back
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feild of view
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the area visible in an image
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astronomical unit (AU)
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average distance from the earth to the sun.
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star
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a globe of gas held together by its own gravity and supported by the internal pressure of its hot gases, which generate energy by nuclear fusion
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planet
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a small nonluminous body formed by accertion in the disk around a protostar
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solar system
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the sun ands its planets, asteroids, comets and so on
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asterium
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a named grouping of stars that is not a recognized constellation
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angular distance
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the angle formed by the lines extending from the observer to two locations
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apparent visual magnitude
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the brightness of the star as seen by the human's eyes on earth
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absolute visual magnitude
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instrinsic brightness of a star
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constellation
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one of the stellar patterns identified by name, usually of mythological gods, people, animals, or objects.
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angular diameter
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the angle formed by lines extending from the observer to the opposite sides of an object
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minute of an arc
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an angular measure, one sixtieth of a degree
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second of an arc
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an angulard measure, one sixieth of a minute of an arc
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apogee
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the point farthest fromt eh earth in the orbit of the body encircling the earth
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dark line spectrum
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a spectrum that contains absorbtion lines
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accretion disk
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the whirling disk of the gas that forms around a compact object such as a white dwarf, nuetron star or black hole as matter is drawn in
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achromatic lense
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a telescope lens composed of two lensess ground from different kinds of glass and designed to bring two selected colors to the same focus and correct for chromatic aberration
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active optics
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thin telescope mirrors that are controlled by computers to maintain proper shape as telescopic moves
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annular eclispe
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a solar eclispe in which the solar photosphere appears around the edge of the moon in a bright ring or annulus
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atmospheric window
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wavelength region in which our atmosphere is transparent at visual, infrared, and radio wavelengths.
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balmer series
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a series of spectral lines produced by hydrogen in the near ultraviolet and visible parts of the spectrum. the three longest wavelength balmer lines are visible to the human eye
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barred spiral galaxy
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a spiral galaxy with an elongated nucleus resembling a bar from which the arms originate
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binary stars
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pair of stars that orbit around their common center of mass
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black dwarf
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the end state of a white dwarf that has cooled to a low temp
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black hole
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a mass that has collasped to such a small volume that it's gravity prevents the escape of all radiation. also, the volume and space from whcih radtiation may not escape
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blueshift
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a doppler shift towards shorter wavelengths caused by a velocity of aproach
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CNO Cycle
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carbon-nitrogen-oxygen cycle : a series of nuclear reactions that use carbon as a catalyst to combine four hydrogen atoms to make one helium atom plus energy, effective in stars more massive than the sun
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big bang
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the high density, high temperature state from which the expanding universe began
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big rip
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the fate of the universe if the dark energy increases over time, the universe will be torn apart by accellerating exspansion
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cosmology
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the study of the nature, origin, and evolution of the universe
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differtial rotation
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the rotation pof a body in which different parts of the body have different periods of rotation; example the sun.
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doppler effect
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the change in the wavelength of radiation due to relative radical motion of the source and observer
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ecliptic
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the apparent path of the sun
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emission line
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a bright line in a spectrum caused by the emission of photons from atoms
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bright-line spectrum
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emission spectrum : a spectrum containing emission lines
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geosynchronous satellite
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a satellite that orbits eastward around the earth with a period of 24 hours and remains in about the same spot on the earth's surface
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H-R Diagram
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Hertssprung-Russell Diagram
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intersteller dust
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microscopic solid grains in the intersteller medium
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interstellar medium
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the gas and dust distrubuted between the stars
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interstellar reddening
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the process in which dust scatters blue light out of the startlight and makes the stars look redder
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joule
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unit of energy
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luminousity
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the total amount of energy a star radiates in 1 second
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luminousity class
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a catergory of stars of simular luminousity deteremined by the widths of lines in their spectra
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magnitude scale
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the astronomical brightness scale. the larger the number the fainter the star
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main sequence
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the region of the HR diagram running from upper left to lower right which includes roughly 90% of stars
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mass-luminousity relation
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the more massive a star is, the more luminous it is
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nebula
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a glowing cloud of gas or a cloud of dust reflecting the light of nearby stars
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neutron star
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a small highly dense star with a radius about 10 km composed almost entirely of tightly packed nuetrons
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parallax
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the apparent chang ein position of an object due to a change in the location of the observer. astronomical parallax is measured in seconds of an arc
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parsec
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the distance to a hyothetical star whose distance is one second of an arc
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planetary nebula
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an exspanding shell of gas ejected from a star during the latter stages of it's evolution
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population 1
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stars rich in atoms heavier than helium, relatively young stars found in the disk of the galaxy
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population 2
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star poor in atoms heavier than helium, relatively old and found in halo, globular clusters, or the nuclear bulge
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protostar
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a collapsing cloud of gas and dust destined to become a star
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radical velocity
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that componet of an objects velocity directed away from or toward the earth
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resolving power
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the ability of a telescope to reveal fine detail, depends on the diameter of the telescopes objective
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reflecting telescope
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a telescope using a concave mirror to focus light into an image
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spectral class
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a star's position in the temperature class system based on the appearance of the star's spectrum
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spectroscopic paralllax
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the method of determing a star's distance y comparing its apparent magnitude with it's absolute magnitude as estimated by its spectrum
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stellar parallax
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a measure of stellar distance
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supergiant
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exceptionally luminous star whose diamter is 10 to 1000 times the sun
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supernova
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the explosion of a star in which it increases its brightness factor by a factor of about a million
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white dwarf
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dying star in the lower left of the hr diagram that has collasped into the size of the eart and is cooling off
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what are the phases of the moon
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new moon, waxing cresent, first quarter, wawing gibbous, full moon, waning gibbous, third quarter, waning cresent, new again
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the moon cycle takes how long
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about a month long
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kepler is famous for?
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keplers 3 laws of planetary motion
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keplers first law
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the planets orbits around the sun are eclispes
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who believed that the earth was not geocentric but heliocentric
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copernicus
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who worked with tycho brahe
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kepler
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keplers second law says
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a line from the planet to the sun sweeps over equal areas in equalervals of time
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who discovered the four moons of jupiter
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galileo
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who discovered that the moon had mountains
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galileo
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who discovered the milky way has many stars that you cannot see with an unaided eye
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galileo
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radio telescope
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a device that measures the strength of radio waves coming from a small spot in the sky at specific wavelength
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what are the avantages of radio telescopes
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1.radio telescopes can show spots of cool hydrogen between stars. 2.radio signals are relatively long wavelengths and can penetrate clouds of dust that visual wavelengths can't
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are bigger stars less dense or more dense then smaller stars
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less dense
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stars generate energy by?
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fusion of hydrogen into helium
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stages of a star
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protostar, zeroage main sequence star, main sequence star, white dwarf, nova
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