Term
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Definition
| the distance light travels in one year |
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Term
| Why does the sun appear to move approximately one degree per day against the background stars? |
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Definition
| because the Earth moves about one degree per day in its revolution about the sun |
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Term
| The nearest star to the sun is about 4.2 light years away. This means that |
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Definition
| we see a that star as it was 4.2 years ago, the nearest star is thousands of times farther away than the planets in our solar system, the light from that star took 4.2 years to reach us, if some event occurred on that star, we would not know about it until 4.2 years after the event. |
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Term
| How is the boundary of the observable universe determined? |
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Definition
| It is a boundary that is determined by how far we can potentially see, given the finite age of the universe. |
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Term
| Where on the Earth would you have to be to see the North Celestial Pole on your horizon? |
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Definition
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Term
| Why is it hotter in the summer than in the winter? |
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Definition
| because your hemisphere of Earth is tilted towards the sun in the summer, casing the sun to be higher in the sky |
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Term
| Where on the Earth would you have to be to see the celestial equator go directly overhead? |
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Definition
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Term
| Where on the Earth would you have to be to see the North Celestial Pole at your zenith? |
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Definition
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Term
| The spring equinox occurs when the sun |
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Definition
| crosses the celestial equator, on its way north |
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Term
| If the moon is full when it rises, what phase will it be when it sets? |
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Definition
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Term
| Relative to the background of the stars, what causes the outer planets to appear to move backwards(east to west) in the sky? |
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Definition
| As Earth passes the planet, it appears to move backwards due to parallax |
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Term
| When will the full moon be the highest in the sky for an observer in the Northern Hemisphere? |
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Definition
| at midnight near the winter solstice |
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Term
| If the moon is on the ecliptic when it is new, what will happen? |
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Definition
| There will be a solar eclipse somewhere on Earth |
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Term
| Which of the following would increase the parallax angle of a star, thereby making it easier to calculate its distance? |
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Definition
| observing the star from Mars, rather than Earth |
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Term
| Why are some constellation in our night sky visible only in the summer, while others are visible only during the winter? |
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Definition
| Since Earth revolves around the sun, the part of the sky we see at night changes |
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Term
| When a planet is directly opposite from the sun in the sky, what time will it cross the meridian? |
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Definition
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Term
| Which of the following is a consequence of the Earth's precession? |
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Definition
| The north star will not always be Polaris |
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Term
| As the moon orbits the Earth, it always keeps the same side pointed toward Earth. This means that the moon |
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Definition
| rotates once per revolution |
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Term
| What time does the moon rise when its full? |
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Definition
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Term
| Kepler's second law implies that |
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Definition
| a planet should move at its greatest speed when it is closest to the sun |
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Term
| Astronauts in orbit around Earth appear to be weightless because |
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Definition
| they are in continuous free-fall around Earth |
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Term
| What time will a planet in retrograde motion rise? |
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Definition
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Term
| Given that Earth is closest to the sun during the first week of January... |
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Definition
| Winter in the northern hemisphere is slightly shorter than summer |
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Term
| According to Kepler's 3rd law, a planet's orbital period is related to |
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Definition
| the average distance from the sun |
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Term
| Consider two objects separated by distance R. Suppose the distance between the objects is doubled. The gravitational force between the object is |
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Definition
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Term
| Kepler's 1st law implies that |
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Definition
| the distance between the planet and sun changes as the planet orbits the sun |
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Term
| Galileo's observation of the moons of Jupiter proved that |
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Definition
| not all objects in the universe orbited Earth |
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Term
| Suppose a comet orbits the Sun on a highly eccentric orbit with an average(semimajor axis) distance of 1AU. How long does it take to complete each orbit and how do we know? |
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Definition
| 1 year, we know from Kepler's 3rd Law |
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Term
| Evidence that the moon was formed as a result of a giant impact? |
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Definition
| The moon has very little volatile(easily vaporized) material, Earth's tilt may be a result of the collision that formed the moon, Earth's outer layers and the moon are similar in composition. |
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Term
| The age of the solar system is thought to be approx. 4.6 billion years old based on |
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Definition
| radioactive dating on meteorites |
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Term
| Which of the following objects is most like the primitive planetesimals that formed in the solar nebula? |
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Definition
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Term
| based on temperature predictions with the solar nebula.....should have condensed closest to the newly formed sun. |
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Definition
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Term
| The surface of Jupiter's moon Io has impact craters because |
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Definition
| evidence of impacts are quickly erased by resurfacing processes |
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Term
| Although Saturn's moon Titan is considerably less massive than Earth, its atmosphere is thicker than Earth's because Titan |
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Definition
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Term
| Upon analyzing the spectrum of a distant star, suppose you found that a spectral line normally found in the visible part of the spectrum shows up in the infrared part of the spectrum. What can you conclude? |
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Definition
| The star is moving away from the Earth |
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Term
| What must we be known in order to determine the density of an extrasolar planet? |
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Definition
| We must determine its mass from the Doppler technique and its size from the amount of light it blocks during a transit |
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Term
| What is a possible explanation of why "hot Jupiters" orbit so close to their parent stars? |
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Definition
| they migrated inward due to gravitational interactions with other objects. |
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Term
| In terms of density and composition, which of the following objects do the moons of the outer solar systems resemble |
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Definition
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Term
| Why is the Doppler technique of detecting extrasolar planets more likely to find "hot Jupiters" than any other type of planet? |
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Definition
| these massive planets are close to their stars, thus causing the stars to move considerably |
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Term
| Jupiter and Saturn consist primarily of |
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Definition
| hydrogen and helium in a liquid state |
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Term
| What type of radiation contains the most energy per photon? |
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Definition
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Term
| What evidence do we have that some giant stars are at least 100 times larger than our Sun? |
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Definition
| We know of other G type stars(like our Sun) that are at least 10,000 times more luminous than our Sun, so they must have greater surface area, implying at least 100 times larger radius |
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Term
| What kind of spectrum does the sun produce? |
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Definition
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Term
| Compared to low-mass stars, high-mass stars are |
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Definition
| less common because they have shorter life spans |
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Term
| nuclear fusion releases or gives off energy because |
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Definition
| mass is being converted into energy |
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Term
| stars on the main sequence are stable because |
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Definition
| the outward pressure from nuclear fusion balances the inward pressure due to gravity |
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Term
| sunspots are dark because |
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Definition
| the strong magnetic field inhibits the currents of hot gas rising from below |
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Term
| Suppose you observe two stars and you know they have the same luminosity. If one star is ten times closer than the other, the closer star will appear how many times brighter? |
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Definition
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Term
| the total mass of a binary system can be calculated from |
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Definition
| The distance between the two stars and their orbital period |
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Term
| Why is there a mass limit for white dwarf stars? |
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Definition
| electrons cannot move faster than the speed of light |
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Term
| What causes planetary nebula to produce different colors? |
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Definition
| The star has blown of gases that emit specific wavelengths of light, creating the colors we see |
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Term
| A star in which helium is being fused to carbon in its core is called a |
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Definition
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Term
| suppose you observed a cluster of stars and plotted its members on an H-R diagram. If the turn-off point from the main sequence is at the sun's current position on the main sequence, approx how old is the cluster? |
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Definition
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Term
| the periodic pulses of radiation from a pulsar come from |
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Definition
| continuous beams of radiation emanating from the magnetic poles of the star |
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Term
| Younger stars have more heavy elements than older stars because |
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Definition
| the heavy elements were made in previous generations of stars |
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Term
| a type II supernova is triggered by the collapse of a massive star's |
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Definition
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Term
| Compared to open star clusters found in the disk, globular clusters have found fewer heavy elements. This is because |
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Definition
| open clusters formed after the globulars |
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Term
| Stars that have the lowest heavy element content in the galaxy are found in the |
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Definition
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Term
| Why did Shapley conclude that our solar system was not near the center of the Milky Way? |
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Definition
| The distribution of globular clusters indicated the galactic center is thousands of light years from our position. |
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Term
| The first atomic nuclei to exist in the very earliest moments of the universe were |
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Definition
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Term
| according to the big band theory, where did all the matter in the universe initially come from? |
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Definition
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Term
| In which cosmological model will the universe's expansion eventually stop and reverse direction |
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Definition
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Term
| which discovery revealed the expansion of the universe |
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Definition
| the greater redshift of galaxies at successively greater distances |
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Term
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Definition
| a change in a living cell's DNA |
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Term
| In general, how does the size and location of a star's habitable zone depend on the star's mass? |
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Definition
| the smaller (less massive) the s tar, the smaller and closer-in the habitable zone |
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Term
| How does the habitable zone aroudn a star of spectral type M compare to that around a star of spectral type G? |
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Definition
| The habitable zone around the M star is closer to the star. |
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