ASTRON 0087: EXAM 2
58 Cards in this Set
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Least massive atomic particle
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electron
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least massive atom
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Hydrogen
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measured the speed of light using lanterns atop hills
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Galileo
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Ole Romer accurate meaurment of the speed of light 1676
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used the delay in eclipses of jupiter's moon when the earth is on the opposite side of the sun as jupiter
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most energetic light photons
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The most energetic light photons is blue visible light
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number of wave repetitions passing an observer each second is defined as
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Frequency in hertz
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energy is released in the form of light when electrons
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move from higher orbital energy levels to lower energy levels
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Radiation with the shortest wave length
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Gamma rays
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An ion is....
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a charged particle, more electrons than protons or vis a versa
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the spectrum of a star can reveal
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its chemical composition
its surface temp
whether or not it is moving away from us
how fast it is moving either away or towards us
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compared to visible light radio waves have
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lower energy and longer wavelength
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the doppler effect detects the speed of a star by
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measuring the shift in wavelength of a particular spectral line
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a sound passing by a source at a constant speed does.... (firetruck)
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has a higher pitch when a approaching and a lower pitch as it recedes
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different elements have unique spectral lines because
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each element has a unique set of electron orbits due to the unique number of protons attracting the electrons
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if a hot object is partially blocked by a could of cold gas then we will see
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absorption lines
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what is the resolving power of a telescope
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the ability to distinguish objects close together in the sky
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500 light years= how many real years
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500
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2 stars have equal luminosity one is twice as far away as the other how much brighter/ dimmer is the further one
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1/4 as bright as the closer one
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if one star is 10 time further away, how much more luminosity must the further one have for them to appear equally as bright to an observer on the earth
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100 times brighter
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two stars have equal luminosity one is twice as far away as the other, how much brighter/dimmer does the further one appear than the closer one
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the further one is 1/4 as bright as the closer
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refracting telescopes are not commonly employed because
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chromatic aberration
large lenses causing sagging in the middle
large lenses cause the telescope to be difficult to maneuver
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a telescopes spatial resolution is determined by
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the objective diameter
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Telescope A has a 4 inch objective diameter, telescope B has an 8 inch objective diameter how much more powerful is telescope B?
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4 times
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professional astronomers use large telescopes because
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to gather more light
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Intergalactic UV light must be observed with telescopes in space because
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UV light is absorbed by the o-zone and does not penetrate to the ground
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atmospheric blurring (aka "seeing") effects the quality of an image. Poor seeing makes a telescopes resolution....
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worse
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large telescopes are typically placed on high mountains/in space because...
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the attempt to eliminate atmospheric blurring and to improve seeing.
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Why is there no atmosphere on the moon?
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Because its low mass is not enough to hang on to its atmosphere at its temperature.
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Lunar Rotation
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rotates on its axis with the same period as its revolution about the earth
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during a single night the moon moves
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East to West across the sky
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Trans neptunian object
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Any object too small to be classified as a planet that orbits the sun at a greater average distance than Neptune.
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Asteroid
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Rocky bodies smaller than a planet often found between the orbits of Mars and jupiter.
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Venus
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Planet that can be in the Easter sky at sunrise
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Composition of Jupiter
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the composition of Jupiter is closest to the composition of the sun
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Planets that cant be seen at Opposition
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Planets that have a smaller radius than the earth cannot be seen at opposition
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Energy produced by the sun
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Comes from nuclear fusion, similar to energy produced in a hydrogen bomb
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The suns position within the milky way
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The sun is located in the disk, slightly more then halfway out from the center
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Approximate number of stars in the MIlky Way galaxy
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100,000,000,000 one hundred billion
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Absorption Nebulae
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should appear redder than Reflection nebulae
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Extinction
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known as the dimming of distant objects in the plane of the milky way
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Immanuel Kent
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Philosopher of the 18th century who proposed that the milky way was a flattened disk of stars and that spiral nebulae were "island universes" similar to the milky way
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Thomas Wright
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pictured the milky way as a spherical shell of stars
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Herschel
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Discovered Uranus
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Bessel's first measurement of parallax importance
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important for many reasons and connects back to the ancient renaissance astronomers because measurement of parallax is one proof that the earth moves about the sun that was not measurable previously.
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Jacobus Kapteyn
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the first to use star counts to develop a detailed model with the sun at the center of a disk-like distribution of stars.
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Harlow Shapley
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Used the positions of globular clusters to deduce that the sun does not lie near the center of the milky way galaxy
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Herber Curtis
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he was a former director of the Allegheny Observatory
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Harlow Shapley Great Debate point
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argued that the spiral nebulae usually appear bluer in color than the milky way does
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Heber Curtis Great debate point
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Argued that bright novae are often seen in andromeda, so there must be many stars in Andromeda
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Henrietta Leavitt
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showed that cepheid variable stars follow a distinct relationship between dimming and brightening period and peak luminosity.
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Edwin Hubble
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Resolved the Great Debate by measuring the distances to external galaxies and resolving individual stars in the andromeda galaxy
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Age of the universe
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14 billion years.
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A spiral galaxy
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shows substantial rotation, interstellar gas, and interstellar dust
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Vesto Slipher
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Measured the spectra of external galaxies noting that they were nearly always redshifted
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Luminosity
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an effective way to estimate the distances to other galaxies
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Einstein's theory or relativity
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a theory that has been tested experimentally
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Sir Arthur Eddington
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organized expeditions to verify the gravitational lensing prediction of general relativity by observing stars near the sun during an eclipse
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According to special relativity
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Time and space are inseparably linked and observers have a perspective on spacetime that is determined by their state of relative motion
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ASTRON 0087: EXAM 1