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71 Cards in this Set
- Front
- Back
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Why can't we use visible light to study most of our Milky Way galaxy?
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Interstellar dust in the galaxy blocks visible light.
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According to modern cosmology, where did most of the helium in the universe come from?
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It was created in the first minute or so after the Big Bang.
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What is a MACHO?
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MAssive Compact Halo Objects
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True or False: most astronomers believe the universe is flat.
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True-- what does flat mean?
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A Population I Star is a star that is
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relatively young, hot, and in the spiral arms of a spiral galaxy.
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We have estimates of distances to far away galaxies from
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Hubble's Law
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The light from a distant star passes through a lot of interstellar dust before it gets to us. An effect this has on our observation is it
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makes the star appear to be further away than it actually is, reddens the color of the starlight that reaches us, and makes the star appear to be cooler than it actually is.
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An IRR galaxy is one that is
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irregular
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An emission nebula is characteristically
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red in color
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The interstellar medium is mostly composed of
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hydrogen
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About 400,000 years after the Big Bang was the
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last scattering epoch
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Following the last scattering epoch the
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universe became transparent.
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When astronomers refer to the galactic "halo" they mean the
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spherically-shaped distribution of stars surrounding the galaxy.
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If you see a galaxy classified as SBa, you know that it is
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barred spiral with closely wound arms.
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Which is more spherical, an E0 or E7 galaxy?
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the E0
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In a quantum fluctuation, energy can become matter. This has to produce
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matter and antimatter in equal amounts.
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True or False – Of the many individual “stars” that we see with the naked eye, many of these are actually distant galaxies, so far away that they look like single points of light.
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False
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True or False - Einstein’s Special Theory of Relativity says that nothing can move through space at a speed greater than the speed of light.
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True
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If matter and antimatter have to be created in equal amounts, how can there be only (mostly) matter today and no (little) antimatter?
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Antimatter seems to be able to decay in a manner that matter doesn’t.
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Omega (Ω) greater than 1.0 would mean that the
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universe has enough matter to stop the expansion of the universe and pull everything back together in a Big Crunch.
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The very sudden expansion of the universe from when it was smaller than a proton to when it was the size of a basketball is called
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inflation.
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True or False – The expansion of the universe refers to the spreading motion of galaxies through space.
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False
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True or False – The Planck Time is the time over which inflation is believed to have occurred in the early universe.
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False
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What is a quasar?
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a very bright, star-like object that is very far away from us
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The flatness of a galaxy’s rotation curve is evidence of which of the following?
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Dark matter
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In Einstein’s General Theory of Relativity
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gravitational fields warp or bend space
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The “failure” of the Michelson-Morley experiment proved that
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the speed of light is a constant value (in a vacuum).
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A white dwarf is gaining mass at a high rate due to accretion of material from a companion star in a binary system. What happens when the mass reaches the 1.4 solar mass limit?
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The star explodes in a Type Ia supernova.
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A neutron star is so-named because
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most all of the particles in the star are neutrons.
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A neutron is formed from the joining of
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An electron and a proton
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A neutron star is incredibly dense because
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all of the inner-atomic space has been removed as the electrons joined the protons.
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What is the upper mass limit for a neutron star?
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3 solar masses
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Big Bang theory predicts that around __% of the matter in the universe is helium, which matches what we measure today.
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24%
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Physics as we know it ceases to function at 10-43 seconds after the BB, a time called the
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Plank Time.
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What is the Plank Time?
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Where physics as we know it ceases to function at 10-43 seconds after the BB.
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A plot of rotation speed vs. distance is a
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rotation curve
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What does Hubble's Law tell us?
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The farther away a galaxy is, the faster it is receding from the Milky Way.
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What is the cosmological principle?
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The lack of a preferred location in the Universe.
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What is nova?
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nova (new as in new star.) If a white dwarf is in orbit around a red giant companion star, it can pull material off the companion and into an accretion diskaround itself.
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What is the Chandrasekhar Limit?
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The 1.4 solar masses limit of a White Dwarf.
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What is the limit of a White Dwarf?
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1.4 solar masses
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What is a Type 1A Supernova?
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Type Ia: The explosion that results from a white dwarf exceeding the Chandrasekhar limit (1.4 solar masses)
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What is a type II Supernova?
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Type II: Supernovae resulting from massive star core collapse. leaves behind the collapsed core of neutrons that started the explosion, a neutron star. If the neutron star is massive enough, it can collapse into a black hole.
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What are pulsars?
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pulsating radio sources. Usually are rotating neutron stars with jets of electromagnetic radiation.
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What is the triple-alpha process?
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The triple-alpha process(helium fusing at core) provides a new energy source for giant stars.
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What is a variable star?
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Variable starschange their brightness over time, dimming and brightening again.
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What is the life path of the Sun?
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1. Main sequence
2. Red giant 3. Yellow giant 4. Red supergiant 5. Planetary nebula 6. White dwarf |
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What is a white dwarf?
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At the center of the planetary nebula lies the core of the star, a white dwarf. This is the corpse.
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When a white dwarf cools, it becomes a
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Cools slowly, until it fades from sight –a black dwarf.
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The Stefan-Boltzmann Law links a star’s _______ to ________.
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The Stefan-Boltzmann Law links a star’s temperature to the amount of light the star emits.
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What is the Stefan-Boltzmann Law?
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The Stefan-Boltzmann Law links a star’s temperature to the amount of light the star emits.
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Why isn't Jupiter a star?
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Jupiter is about 75 times too small to have become a star.
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What's the upper limit of a star's size?
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Upper limit 150 MSun
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What's the lower limit of a star's size?
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Lower limit 0.08 MSun
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What are brown dwarfs?
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The smallest stars: 0.016 MSun to 0.08 MSun are brown dwarfs.
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Population I Stars vs Population II?
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Population I younger, bluer stars are in the disk of galaxies and population II are older, redder stars in the bulge and halo.
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What is Olber's paradox?
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If the universe extends forever and has existed forever, the night sky should be blazingly bright.
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Special vs general relativity?
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General relativity is a theory of gravity--gravity stretches space and time. Special relativity is a theory about how motion changes how space and time behave. Says that nothing can travel faster than the speed of light.
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If the moon is in tidal lock, what does that mean?
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Tidal lock means tidal forces cause a body to rotate at a rate close to its orbital period. The moon always keeps the same face toward the earth.
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One result of the precession of the Earth's rotational axis is that
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our North Star hasn't always been and won't always be Polaris.
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What causes retrograde motion?
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The Earth passing another planet in its orbit.
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How many constellations are there?
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There are 88 official constellations.
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What "star" is Venus?
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Evening star or morning star.
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What is opposition?
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When a planet is on the opposite side of the Earth as the Sun.
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When do spring tides occur?
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At the new and full moons.
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During the course of the year, the Sun appears to pass through the constellations of the Zodiac. These constellations lie in a belt called the
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Ecliptic
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What does the word "zodiac" mean?
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Comes from Greek for "animals," same root as "zoo" and "dia" as in diameter as in circle.
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Is the Big Dipper a constellation?
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No; it's an asterism.
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What is an asterism?
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An easily-identified group of stars, sometimes a part of a larger constellation.
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What is a constellation?
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An officially recognized grouping of stars on the night sky. Astronomers divide the sky into 88 constellations.
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The Sun's volume is _______x that of Earth's.
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1 million.
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