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147 Cards in this Set
- Front
- Back
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1. In the ancient geocentric view of the Universe, the Earth was surrounded by a celestial sphere that |
rotated from East to West every day |
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2. Over a night, as seen from the surface of the Earth, the stars generally appear to move in what way? |
appear to rise in the east and set in the west |
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3. As seen from here in Texas, stars close to the celestial north pole |
can be seen all night |
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4. As seen here from Texas, stars close to the celestial south pole |
cant be seen at all |
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5. The ecliptic is a circle half way between the celestial poles |
False |
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6. Seasons are caused by |
the tilt of the Earth's orbit relative to it's orbit around the sun |
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7. What is the greatest distance a star can be from Polaris and still be circumpolar as seen from College Station (latitude 30.6 N)? |
30.6 |
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8. If earth's axis were tilted by 45 degrees instead of 23.5 degrees |
we would have more extreme seasons |
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9. If the moon were twice its present distance from earth, |
we would never see a total solar eclipse |
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10. a lunar eclipse occurs when the moon |
passes through the Earth's shadow |
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11. A solar eclipse occurs when the Earth |
passes through the Moon's shadow |
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12. ancient greek astronomers knew the sun was bigger than the moon because |
they knew the sun was farther than the moon, but appears the same size |
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13. Lunar phases change as we see more or less of |
the moon's sunlit half |
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14. Kepler also showed that the period of a planet's orbit (P) and the size of its orbit (a) are related. What is that functional relation? |
P^2=a^3 |
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15. If you could observe Earth through a telescope from mars, earth would |
go through all the phases from crescent to full |
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16. Galileo was the first person to notice retrograde motion of all the planets, since it takes a telescope to observe such a small effect |
False |
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17. People in ancient times distinguished the planets from the stars because the planets |
move in the sky differently than stars |
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18. Looking at Tycho's data on the positions of planets relative to stars, Kepler determined that planetary orbits are |
ellipses with the sun at one focus |
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19. Keplers 2nd law of planetary motion says that a line connecting the planet and what body sweeps out equal areas in equal times? |
Sun |
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20. Suppose a new planet was found in the soalr system that was 4 AU from the sun. how long would it take that planet to complete one orbit around the Sun? |
8 years |
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21. Galileo's telescopic observations supported a heliocentric model of the solar system |
true |
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22. If an object is accelerated, what must change? |
either it's speed, direction, or both
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23. according to Newton, an object at rest in space will only move if |
it is acted upon by an outside force |
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24. Two objects with the same mass travel through space, one moving twice as fast as the other. According to Newton's laws of motion, if the same force is applied to both objects, which one accelerates more? |
they accelerate the same amount |
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25. If the distance between two objects increases, what will happen to the force of the gravity between two objects? |
it decreases |
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26. When you step on a scale to measure the attractive force of Earth's gravity |
your gravity attracts the Earth with equal force |
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27. Stone A has a mass twice that of stone B. They are dropped from the same height above the Earth at the same time. What statement is NOT true? |
The gravitational force on A is twice that on B |
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28. Visible light is only one form of electromagnetic radiation; other examples include |
radio waves, x-rays, and microwaves |
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29. The color your eyes see depends on what property of the light? |
the wavelength; red is longer and blue is shorter |
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30. Which of the following types of photons has the greatest energy? |
x-ray |
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31. We can identify the type of atom in a gas by noting: |
at what wavelength the spectral lines appear |
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32. If a star is much hotter than our sun, we would expect it to emit most of its energy in |
ultraviolet light |
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33. Our sun emits most of it's light at a wavelength of 550 nm. if a star were twice as hot as our sun, at what wavelength would it emit most of its radiation? |
275 nm |
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34. When a light is redshifted, what changes? |
The light's wavelength |
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35. Measurements of the Doppler effect from distant galaxies tells us that the Universe is expanding. If the Universe were shrinking rather than expanding, which of the following would be observed from Earth? |
The light from the most of the stars and galaxies would be blueshifted. |
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36. the gravitational force due to the sun on a hypothetical planet in our solar system is 16 times smaller than the gravitational force on the earth. what is the orbital radius of the planet in AU? |
4 |
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37. What is the orbital period of the planet in years? |
8 |
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38. What is the orbital speed of the planet compared to earth? |
slower |
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39. What is the orbital speed of earth compared to the planet? |
twice as fast |
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40. the planet mongo emits a continuous blackbody spectrum with a maximum brightness occuring at wavelength 29,000 nm (in the infrared). Using Wien's law, what is Mongo's approximate surface temperature? |
100K |
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41. Using stefan-boltzmann's law, how much energy is emitted per second per area by mongo compared to the earth? |
Less |
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42. Using stefan-bltzmann law, how much energy is emitted per second per area by mongo compared to the earth? |
about 81 times less |
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43. you observe a spectral line at a wavelength o 510 nm in a distant calaxy. the rest wvelength of this line is 500 nm. what is the radial velocity of this galaxy in kilometers per second? |
.02 times the speed of light |
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44. is the galaxy moving away from us or towards us? |
away |
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45. one of the hottest stars known has a surface temperature of 100,000K. in what part of the electromagnetic spectrum does the blackbody radiation from the star peak? |
x-ray |
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46. can the peak of the emission of the star in question 45 be seen from the surface of the earth? |
no |
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47. if the nearest star similar to the sn is roughly 500,000 AU away, what is the gravitational force on that star from jupiter compared to the force from the sun? |
about 1000 times less |
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48. you observe an emission line from a distant object that you identify as from oxygen atoms,which has a rest wavelength of 441.49nm. the observed wavelength is 550.7nm. what is the velocity of the object you observed? |
74159.5 km/sec |
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49. was it possible that there was a total solar eclipse last week somewhere on earth? (ull moon was last week) |
no |
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50. was it possible ther was a total solar eclipse somewhere on earth last week? |
yes |
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51. imagine we lived on the moon. how frequent would there be a total solar eclipse? |
more frequently than on earth |
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52. what is the weakest force in nature on sufficient small scales? |
gravity |
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53. here on earth matter is mostly neutral (atoms have the same number of protons and electrons, so the net electric charge is zero). The reason for this is that |
the electromagnetic force brings opposite charges together strongly |
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54. why dont the protons in the nucleus of an atom fly apart from their like charges? |
the nuclear forces overwhelm electromagnetic forces on small scales. |
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55. what causes a prism to break light into the spectrum that you see? |
different colors of light have different wavelengths, which are refracted at different angles |
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56. you see (with your eyes) through "pupils" that are only ~5mm in diameter. This means |
you will see much more sharply with even a small telescope |
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57. One of isaac newton's triumphs was to realize |
his rules about motion and gravity apply everywhere in the Universe |
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58. two identical spacefract are launched by nasa. the first is inserted into a circular orbit 20,000 Km from the center of the earth, while the second flies to the planet mongo and is inserted into a circular orbit that is 20,000KM from the center of mongo. the orbital period of this space craft is 4.58 times the period of the spacecraft orbiting earth. what is the mass of mongo |
much less than the earth |
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newton is more famous than kepler because newton explained why the planets moved while kepler just how they moved |
true |
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an element is known by the nuber of what particles in its nucleus |
protons |
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TEST 2 |
TEST 2 |
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1. Why do the stars shine? |
they are hot |
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2. distances are difficult to measure to most astronomical objects, but crucial for understanding some physical characteristics like luminosity and mass |
True |
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3. the parallax to a tar is measured to be much less than .01 arcseconds. is this star... |
further than 100 parasecs distant |
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4. consider two stars with different parallaxes. star A has a parallax of .5 arcsecodns; star B has a parallax of .1 arcseconds. which statement is true? |
star A is closer to us than star B A= 1/.5 = 2 B= 1/.1 = 10 |
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5. stars far away; nonetheless they have obvious parallaxes that were easily measured by ancient astronomers |
false |
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6. the luminosity of an object is |
the total energy output |
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7. consider two objects with the same luminosity, but a different distances, what statement is true? |
one object would appear brighter |
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8. stars in the sky appear to be of different apparent brightness. this is because |
stars are at a range of distances and have various luminosities. |
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9. all stars have the same color |
false |
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10. the correct sequency of spectral types for stars (hot to cold) is |
OBAFGKMLT |
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11. true binary stars are |
A pair of stars bound together by gravity |
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12. binary stars are useful because |
they allow us to measure the masses of stars |
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13. analysis of binary star orbits must make use of newton's form of kepler's third law because |
the rotational velocities are very different for the who stars |
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14. it is difficult to measure the orbits o nearby visual binary stars because |
the timesscales (periods) of the orbits can be thousands of years |
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15. eclipsing binaries are most useful because |
the orientation of the orbital plane is known, even if the distance is not |
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16. the luminosity of a star van be determined from what parameters? |
apparent brightness and parallax |
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17. why is the solar system generally flat (i.e all planetary orbits are roughly in the one plane)? |
the rotating solar nebula flattened into a disk around its rotation axis |
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18. assuming our best model of the formation of the solar system is correct, Jovian planets have more icy constituents than the terrestrial planets because |
the terrestrial planets were too close to the sun for that material to condense |
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19. terrestrial planets are primarily made of rock and metal |
true |
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20. the composition of terrestrial planets probably reflects where they formed in the early disk around the sun |
true |
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21. jovian planets are primarily made of hydrogen and helium, but also have relatively large amounts of |
water, ammonia and methane |
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22. there is nothing else in the solar system other than the terrestrial planets and the jovian planets |
false |
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23. which stellar property requires knowing the distance to the star |
mass |
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24. a "hot jupiter" named Osiris has been found around a solar-mass star, HD209458. it orbits the star in only .36525 days. what is the orbial radius of the extrasolar planet? |
.01 AU |
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25. consisder two stars with different parallaxes. Star A has a parallax ofo .4 arcseconds; star B has a parallax of .1 arcseconds. what is the difference in distance of the two stars? |
a factor of 4 |
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26. rougly how far away is the star in question 25 with the smaller parallax? |
10 parasecs |
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27. two of the apparently brightest stars in the sky are the sun and sirius. n either is particularly luminous intrinsically, but both are nearby. sirius has a surface temperature of about 10,000K and an intristic luminosity about 25 times that of the sun. which star is bluer in color? |
sirius |
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28. the earth, mercury, venus, and mars are all similar in that they |
are composed mostly of rock and iron/nickle |
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29. the moons of jovian planets are |
a mixture of objects that hve been captured and formed in place |
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30. if a large comet or asteroid hit the earth then |
it would be a terrible disaster |
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31. why can we not use trigonometric parallax to measure the distance to stars in distant galaxies |
the stars are too far away, so the angle would be too small to measure. |
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32. What is the spectral type and luminosity class of the sun? |
G2 |
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33. spectral differences between stars are mostly due to |
temperature differences in the stellar photosphere |
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34. the sun and planets in our solar system probably formed from a large cool cloud of gas and dust |
true |
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35. small particles collide with each other to make larger particles in a process known as |
accretion |
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36. planets found around other stars would be called |
exoplanets or extrasolar planets |
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37. planets outside of the solar system have been known for thousands of years, since they are very easy to see |
false |
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38. the NASA Kepler mission |
looks for transiting planets around other stars |
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39. the nebular theory of how our solar system formed |
is probably correct for our stem but not all others. |
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40. all known planets around other stars |
have significant differences compared to our planets |
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41. suppose you found a tar withe he same mass as the sun moving back and forth with a period of 16 months. what could you conclude? |
the star has a planet orbiting at more than 1 AU |
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42. if the moon formed from a collision in the early solar system that it stripped off the some of the mantle of the earth, then the moon density should be |
lower than the mean density of the earth |
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43. the largest volcano in the solar system is on mars. why? |
surface gravity of mars is low, so mountains can grow higher |
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44. mercury has no atmosphere because |
its surface is hot (high thermal velocity) and escape speed is low (low surface gravity) |
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45. would it be easier to measure parallax for a specific star from jupiter than from the earth? (jupiter 5 AU from the sun and it is easierto meaure a large angle than a small one) |
yes |
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TEST 3 |
TEST 3 |
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1. The perfect gas law states that the _____ in a gas should be proportional to __________ |
pressure; temperature x density |
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2. the principle of hydrostatic equilibrium means that in the interiors of stars |
gravity and thermal pressure balance each other to make the star stable |
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3. just as in a pool of water, the deeper into a star you travel, the |
higher the pressure |
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4. the major source of energy in the Sun and other similar stars is the conversion of |
4 hydrogen atoms into 1 helium atoms and energy |
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5. neutrinos have never been observed from the sun |
false |
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6. stars like the sun generate energy (heat) in their cores, which moves to the surface typically by which main transport mechanisms? |
convection and radiation |
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7. the CNO cycle does not add any significant C, N, or O to the elemental mix in a star over the long term. however it does t |
transform hydrogen atoms into helium
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8. approximately what percentage of stars in the milky way are main sequence stars? |
85% |
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9. what does the abundance of a star's heavy elements (metals) tell us about the age of the star? |
stars with the highest concentration of the heaviest elements are younger stars that have been born after many generations of stars have seeded the interstellar medium with those elements |
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10.. it the spectral type of sirius is A1 and its luminosity is roughly 25 times that of the sun, what is sirius' luminosity class? |
Main sequence |
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11. the spectral type of arcturus is K2 and its luminosity is roughly 100 times that of the sun, what is its luminosity class? |
red giant |
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12. when will a star reach the end of its main sequence life? |
when the hydrogen in the core has been turned into helium |
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13. the core temperature of a red giant is ____ compared to the core temperature during the stars' main sequence phase. |
much hotter |
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14. what is the primary thermonuclear reaction that happens in stars on the main sequence less massive than the sun? |
the P-P chain |
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15. a white dwarf is |
a slowly cooling object supported by degenerate electron pressure |
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16. the sun is roughly through its main sequence evolution |
true |
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17. the larger the mass of a main sequence star, the higher its luminosity |
true |
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18. the larger the mass of a red giant star, the higher its luminosity |
true |
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19. an Hr diagram is a plot of |
luminosity versus surface temperature of a star |
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20. consider two groups of stars (all of the stars in a group formed together initially have the same distribution of stellar types). The brightest stars observed are blue in cluster A and are red in cluster B. which statement is correct? |
Cluster A is younger than cluster b |
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21. what evolutionary phases will the sun go through over the next 10 billion years (in order)? |
main sequence, red giant, horizontal branch, asymptotic giant branch, white dwarf |
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22. black holes can be seen due to their effects on their surroundings, even though nothing can escape from them directly |
true |
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23. the most stable atomic nucleus (the one where energy is not generated when it is split apart or added to) is |
iron |
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24. a supernova can be the end of a life of what type of star? |
O-type main sequence star |
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25. The main source of heavy elements in the Universe are |
supernovae |
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26. while on the horizontal branch, stars make energy by fusing |
helium in their cores and hydrogen in sells near their cores |
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27. a white dwarf cannot have a mass larger than roughly 1.4 times the mass of the sun. |
true |
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28. the primary energy generation mechanism in a white dwarf is |
nothing; white dwarfs do not generate any new energy |
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29. if the sun were to become a red giant, then the fate of the earth would be |
to warm substantially and become impossible for humans to live on |
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30. planetary nebulae are related to planets and part of the solar system |
false |
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31. supernovae have been speculated to exist, but have never been seen observationally |
false |
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32. some galaxies have had very little star formation for 5 billion years. consequently, if you made an HR diagram of all the stars in such a galaxy you would find |
a large fraction of stars were redder than the sun |
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33. most stars in the milky way galaxy are giant and supergiant stars |
false |
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34. the final collapse to a supernova in the evolution of a massive star happens |
very rapidly and blows the star apart |
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35. the larger the mass of a main sequence star, the _______ the lifetime on the main sequence |
shorter |
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36. a consequence of hydrostatic equillibrium inside a main sequence star is that |
the core of the star is hotter and denser than the surrounding evelope |
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37. jupiter creates a relatively small amount of energy via gravitational collapse. this process cannot be what is powering the sun, however, because |
the process cannot generate adequate energy to explain the present day luminosity of the sun |
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38. the proton-proton chain and the CNO cycle |
are different reactions for converting 4 H in to 1 He plus energy |
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39. stars shine in he sky because they are ______; they need an _______ source to stay that way |
hot, energy |
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40. __________ is a poor energy transport mechanism in all main sequence stars |
conduction |
