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PHYS 131
Final Exam
| Question | Answer |
|---|---|
| Constellations | groups if stars named by ancient cultures to honor gods, animals, legends, etc. |
| How many constellations are in whole sky? | 88 |
| The stars appear to rotate around _____. | Polaris |
| What causes the stars in the night sky to rotate? | The rotation of the Earth. |
| What do you call stars and constellations that never set? | circumpolar (the rotate around the pole. Circumpolar stars rotate around Polaris in the Northern Hemisphere. |
| How do the stars move at the North and South pole? | horizontally |
| How do that stars move at the equator? | Vertically. |
| How do stars move at mid-latitudes? | Diagonally,on an arc across the sky. |
| Will the sun appear to move with respect to the constellations? | Not in a day, but it will appear to have moved over the course of months or a year. |
| What are the 12 constellations the sun moves through in a year called? What is this path called? | The zodiac. Ecliptic. |
| Precession | Why your sign is wrong. Rotation of the Earth's axis itself; makes one complete circle in about 26,000 years. |
| Sidereal year | Time for Earth to orbit once around the Sun, relative to fixed stars. It follows constellations. |
| Tropical year | Time it takes for the Earth to be in the same configuration with respect to the Sun again (as opposed to distant stars). It follows seasons. |
| What will happen to the "summer triangle" in 13,000 years? | It will be a winter constellation |
| Asterism | Pattern of stars seen in Earth's sky which is not an official constellation. |
| Alpha Orionis | Second brightest star in Orion |
| Messier Catalog | An early listing of nebulae, star clusters, and deep sky objects that might have been confused with comets by users of small telescopes |
| Why don't many professional astronomers know the constellations? | Because big telescopes can only look at small portions of the sky. |
| The pattern of rotation that stars make in the sky depends on your _____. | Position. |
| What causes night and day? | The earth's rotation on its axis. |
| Solar day | Average time between consecutive "noontimes" |
| What defines a year? | The revolution of the Earth around the Sun. |
| Ecliptic | Path the Earth's motion around the Sun traces on the Celestial Sphere |
| T/F The sun is lower in the sky in the winter. | True |
| Equinoxes | Sun crosses the celestial equator (twice-- Spring & Fall) |
| Solstices | Sun's farthest northernly or southernly position. (summer or winter) |
| Ecliptic | Path that the sun follows in the sky. 23.5 degrees to the celestial equator |
| Northernmost point above the celestial equator | Summer solace |
| Southernmost point below the celestial equator | Winter solace |
| Points where paths cross celestial equator | Vernal & autumnal equinoxes |
| Time from one vernal equinox to the next | Tropical year |
| Season | combination of day length and sunlight angle |
| Moon's revolution around the earth causes: | Lunar phases, eclipses, tides |
| Synodic month | moon takes about 29.5 days to go through whole cycle of phases |
| Phases are due to | different amounts of sunlit portion being wisible from Earth |
| Lunar Eclipse | moon disapears |
| Solar Eclipse | sun disappears |
| Lunar eclipses occur when | the moon enters the shadow of the earth |
| Umbra | all sunlight blocked |
| penumbra | only some sunlight blocked |
| total eclipse | all of moon in umbra |
| partial eclipse | only part of moon in umbra |
| penumbral eclipse | moon only in penumbra |
| Solar eclipses occur when | the Earth enters the shadow of the moon (moon blocks the sun" |
| Annular eclipse | moon doesnt cover the whole sun |
| Why arent eclipses more frequent? | The moon's orbit around the Earth is tilted so the Earth's orbits and the Moon's orbits are not in the same plane. |
| # solar eclipses per year | at least 2, no more than 5 |
| #Lunar eclipses per year | maximum is 3 |
| # combined eclipses per year | maximum is 7 |
| maximum duration of Solar eclipse | 7 1/2 minutes |
| maximum duration of lunar eclipse | 1 hour 47 minutes |
| Spring tide | when tides from the sun and moon combine |
| Neap tide | when the tides from the Sun and Moon counteract eachother |
| How many high tides are there per day? | 2 |
| Lunar phases during which tides are particularly strong | New Moon & Full Moon |
| Region between Mars and Jupiter | Asteroid belt |
| Asteroids | large chunks of rock and metal left over from the formation of the solar system |
| Meteroids | small asteroids. most are less than 1mm in diameter |
| Meteors | flash you see when a meteoroid hits the Earth's atmosphere and gets burned up. |
| Meteorites | pieces of meteoroids that make it thought the Earth's atmosphere without burning up |
| Comets | Dirty snowballs. Ice and rock mixed together |
| 2 comet tails | Ion tail & dust tail. Point away from the sun. |
| 2 primary reservoirs of comets | Kuiper Belt & Oort Cloud |
| Kuiper Belt | Flattened disk of solar system remnants out past Pluto. |
| Oort Cloud | Spherical distribution of material even darther |
| The “Terrestrial Planets” include | Earth, Mercury, Mars, Venus |
| Astronomers like to describe distances between planets in terms of | AU |
| Planet that spins backwards | Venus |
| Mercury and Venus exhibit ________________, much like our Moon. | Craters |
| Mercury has extreme temperature differences from night to day, but is still _________than Venus, despite being closer to the Sun. | Cooler |
| A day on Mercury takes ______ years, while undergoing _________ rotations. | 2 years 3 rotations |
| Venus is so hot because of its very strong _______________ effect. | Greenhouse |
| Oddly, the Earth’s _______________ north is not quite at the same place as the North Pole. | Magnetic North |
| The Earth’s ___________________ protects us from the Solar Wind. | Magnetosphere |
| Some particles get trapped in the _________________ Belts. | Van Allen |
| When these overflow, we see _______________. | an Aurora |
| Craters on the Moon are made by the same sort of ________________ impacts that we find on Earth. | Meteor |
| Largest volcano in the Solar System. | Olympus Mons |
| While the Sun has no surface, the outer layer that we see is called the | Photosphere |
| Chromosphere | layer just above the photosphere. Sort of the “lower atmosphere” |
| Corona | above the chromosphere. Sort of a hot upper atmosphere |
| Sunspots | Dark blotches ont he surface of the sun |
| Sunspots are linked by | Pairs of magnetic field lines |
| What causes kinks? | the rotation of the sun drags magnetic field lines around with it |
| Number of sunspots | varies with time. 11 year cycle |
| What happens when the sun's magnetic field prevents hot, ionized material from rising? | Dark sunspots result |
| When does the Sun's northern magnetic pole become the southern magnetic pole? | after 11 years |
| Solar Flares | eruptions in the Sun's atmosphere that cause energetic particles to escape from the sun |
| Coronal mass ejection | emits charged particles that can affect the Earth |
| How do stars shine? | nuclear fusion |
| Nuclear fusion | the extra mass is converted to energy according the Einsteins famous formula, E=mc2 |
| Hydrostatic Equilibrium | Fusion keeps stars from collapsing under their own weight. Pressure from the outflowing hot gas balances the pressure of gravity |
| Stellar evolution | big bang |
| A stars brightness is effected by | its distance from the Earth |
| Inverse square Law | Move 2x as far from a light and it gets 4x dimmer |
| Temperature of stars | Color of a star is indicative of its temperature. Red- cool Blue- Hot |
| Hertzsprung-Russell (H-R) diagram | any plot of brightness vs. color or temperature is and HR diagram |
| Percent of stars on "main sequence" | 90% |
| Percent of stars are red giants | 9% |
| Percent of stars are white dwarfs | 1% |
| Main sequence stars are also called | dwarfs |
| Red Giants | much bigger than the sun, coolest |
| Supergiants | bigger and brighter then the average giants |
| White Dwarfs | Much smaller than the sun, very hot but not very bright, remnants of dead or dying stars |
| supernova | star blown into smithereens |
| nebula | supernova remnant |
| Pulsars | type of neutron star emitting regular pulses of light |
| What happens when compressed gas from stars collides? | New stars form |
| Galactic Cannicalism | when two unequal size galaxies collide and merge |
| Quasars | Active galaxies |
| Most big galaxies have supermassive _______ in their centers | black holes |
| During a merger, what happens when fuel is fed into a black hole? | A hot disk of material that spirals into the black hole. the disk shines brighter than the galaxy itself |
| Energy source of a Quasar | black hole surrounded by an accretion disk |
| When did the universe begin? | about 13.7 billion years ago |
| Cosmology | study of the origin, structure, and evolution of the universe |
| Universe | all matter, energy, and spacetime |
| Homogeneity | Matter is uniformly spread throughout space |
| Isotrophy | Universe looks the same in every direction |
| cosmological principle | any observer in any part of the universe sees the same general features |
| Olber's Paradox | If the universe is homogeneous, isotropic, infinite, and unchanging, the entire sky should be as bright as the surface of the Sun |
| Why is it dark at night? | The universe is homogeneous and isotropic, it must not be infinite or unchanging |
| Hubble Flow | The universe is not unchanging, it is expanding |
| Doppler effect | motion through space-time |
Created by:
Jaz33
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