Did a giant impact cause the Dark Ages? (Beginner)
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Feb 11 |
63327 |
Which way does the sun travel in the southern hemisphere? (Beginner)
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Apr 05 |
96765 |
How can observations of the distant universe prove that the expansion is accelerating *now*? (Advanced)
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Dec 04 |
37545 |
Traveling at light speed, how long would it take to get to the nearest galaxy? (Beginner)
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Nov 04 |
208515 |
Is there a list of the sizes of different kinds of stars? (Beginner)
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Sep 04 |
74458 |
Are the planes of solar systems aligned with the plane of the Galaxy? (Intermediate)
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Jul 04 |
164020 |
Does Cerenkov radiation travel faster than light? (Intermediate)
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Jun 04 |
51051 |
What is the hottest time of day? (Beginner)
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Jun 04 |
169387 |
Why doesn't light from distant galaxies reach us instantaneously? (Intermediate)
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Mar 04 |
53940 |
Does the Sun rotate? (Intermediate)
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Mar 04 |
130134 |
Why is it easier to see a star if you look slightly to the side? (Intermediate)
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Feb 04 |
64813 |
When will Halley's Comet return? (Intermediate)
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Jan 04 |
526723 |
Is the Great Wall the largest galaxy cluster? (Advanced)
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Jan 04 |
66437 |
Why is the WMAP picture of the CMB an ellipse? (Intermediate)
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Jan 04 |
51097 |
Why can we see the sun's image before sunrise and after sunset? (Beginner)
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Dec 03 |
147136 |
Could someone travel the universe in his or her own lifetime? (Beginner)
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Dec 03 |
76185 |
Has anyone made a map of the Milky Way? (Beginner)
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Nov 03 |
51899 |
Did time go slower just after the Big Bang? (Advanced)
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Oct 03 |
53327 |
How long would it take for a mini-black hole to eat the Earth? (Advanced)
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Sep 03 |
74681 |
Does a photon observe other photons moving past it at the speed of light? (Intermediate)
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Sep 03 |
50935 |
Is there a "South Star"? (Intermediate)
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Sep 03 |
91119 |
Could a different theory of gravity explain the dark matter mystery? (Intermediate)
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Sep 03 |
48281 |
Could you escape from a black hole if you were able to go faster than the speed of light? (Intermediate)
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Aug 03 |
63851 |
Do unmanned spacecraft like Voyager travel in straight lines? (Intermediate)
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Jul 03 |
55718 |
How do we know that superclusters are the largest structures in the universe? (Advanced)
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Jun 03 |
52825 |
Why does the apparent density of galaxies drop off at larger distances? (Advanced)
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Jun 03 |
50267 |
Could matter-anti-matter repulsion power the expansion of the universe? (Intermediate)
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May 03 |
43657 |
Can I listen to the SETI@home radio signal? (Beginner)
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May 03 |
54434 |
No matter how fast the universe is expanding, shouldn't gravity eventually make it recollapse? (Intermediate)
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May 03 |
37843 |
Why do so many of the world's UFO sightings happen in America? (Beginner)
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Apr 03 |
69786 |
Can you use an infinite line of reflectors to send light to the edge of the Universe? (Intermediate)
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Apr 03 |
60175 |
How long does it take the Big Dipper to move in the sky? (Intermediate)
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Mar 03 |
70019 |
What would an "open geometry" for the universe look like? (Advanced)
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Mar 03 |
55600 |
What would happen if a supermassive black hole came close to the Earth? (Advanced)
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Mar 03 |
116704 |
How is it that we see farther out in space (farther back in time) than in the past? (Beginner)
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Mar 03 |
60631 |
How can the Sun have such a strong gravitational field if it's made of gases? (Beginner)
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Mar 03 |
69099 |
If the universe is "bounded" today, could it one day become "unbounded"? (Advanced)
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Mar 03 |
44311 |
Don't tachyons travel faster than light? (Intermediate)
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Mar 03 |
50445 |
Do stars' orbits in galaxies obey Kepler's Laws? (Intermediate)
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Mar 03 |
49334 |
Which American colleges teach astronomy? (Beginner)
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Jan 03 |
64468 |
Why do we assume that the universe is homogeneous? (Intermediate)
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Jan 03 |
58534 |
How do astronomers observe the Sun's interior? (Intermediate)
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Dec 02 |
55428 |
How does the Earth compare in size to the entire universe at the present epoch? (Intermediate)
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Dec 02 |
49936 |
Does the Sun have any heavy elements? (Beginner)
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Dec 02 |
55084 |
Is the Sun always up for exactly 12 hours at the equator? (Beginner)
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Dec 02 |
176743 |
What are collections of galaxies called? (Intermediate)
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Nov 02 |
72728 |
How does the Sun compare to other stars? (Beginner)
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Nov 02 |
202712 |
Do stars move in the sky? (Beginner)
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Nov 02 |
304784 |
Which planet is most similar to Earth? (Intermediate)
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Nov 02 |
244686 |
Why do supernova remnants look like rings rather than spheres? (Intermediate)
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Nov 02 |
42559 |
What percent of the time can astronomers observe without interference from the Moon? (Beginner)
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Oct 02 |
41182 |
What would the Big Crunch look like to an observer on Earth? (Advanced)
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Oct 02 |
48999 |
What kind of interference must astronomers contend with when observing? (Beginner)
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Oct 02 |
39347 |
Why does the Sun's apparent path through the sky change throughout the year? (Beginner)
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Oct 02 |
136455 |
Would a planet near the galactic center have a brighter night sky? (Intermediate)
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Oct 02 |
82198 |
Can two lunar eclipses occur in the same month? (Advanced)
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Oct 02 |
65290 |
Is the distance from the Earth to the Sun changing? (Advanced)
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Oct 02 |
343042 |
What is the approximate GPA needed in High School in Math and Science to be an astronomer? (Beginner)
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Oct 02 |
74717 |
Could our position in the universe affect our perceptions of the expansion? (Intermediate)
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Sep 02 |
51798 |