Rotating Question Curious About Astronomy? Ask an Astronomer

All previously answered questions (in order of times viewed)

  1. What's going to happen on December 21st 2012? (viewed 2134005 times)
  2. What color is each planet? (viewed 916074 times)
  3. At what speed does the earth move around the sun? (viewed 587563 times)
  4. Is the Moon moving away from the Earth? When was this discovered? (viewed 566591 times)
  5. How far is each planet from Earth? (viewed 470833 times)
  6. When will Halley's Comet return? (viewed 427417 times)
  7. How long does it take for the Sun's light to reach us? (viewed 392070 times)
  8. How many stars are there in our Galaxy (Milky Way)? (viewed 389089 times)
  9. Why do the planets orbit the sun? (viewed 381335 times)
  10. What is the universe expanding into? (viewed 371767 times)
  11. How do you measure the distance between Earth and the Sun? (viewed 343739 times)
  12. Which planets have rings? (viewed 323188 times)
  13. Why do stars twinkle? (viewed 320516 times)
  14. Does the Moon rotate? Are there other moons that always keep one face toward their planet? (viewed 305369 times)
  15. How do I build a model rocket? (viewed 291128 times)
  16. What color is Venus? (viewed 274357 times)
  17. Can you hear sounds in space? (viewed 268670 times)
  18. What is a white hole? (viewed 268004 times)
  19. What is the life cycle of a star? (viewed 246345 times)
  20. What are the names of the earth, moon, sun, and solar system? (viewed 239617 times)
  21. What makes the Earth rotate? (viewed 233847 times)
  22. What is that ring (or rainbow) around the moon? (viewed 233488 times)
  23. What are shooting stars? (viewed 230252 times)
  24. What are the different kinds of astronomers? (viewed 225043 times)
  25. What is the largest star? (viewed 222048 times)
  26. How do we know the age of the Universe and the Earth? (viewed 212744 times)
  27. What do astronauts eat in space? Can they grow food? (viewed 211430 times)
  28. Can artificial gravity be created in space? (viewed 210834 times)
  29. Why do planets rotate? (viewed 208397 times)
  30. Is the universe expanding faster than the speed of light? (viewed 203932 times)
  31. How does the location of sunrise and sunset change throughout the year? (viewed 196990 times)
  32. How can we see the Milky Way if we are inside it? (viewed 183378 times)
  33. Where did the name 'Earth' come from? (viewed 180777 times)
  34. What would happen if we did not have a Moon? (viewed 176747 times)
  35. Why isn't the sky bright at night if the universe has so many stars? (viewed 174785 times)
  36. Why is a day divided into 24 hours? (viewed 173274 times)
  37. How many Earths fit into the Sun? (viewed 173107 times)
  38. How does the position of Moonrise and Moonset change? (viewed 171718 times)
  39. Who named the planets and who decides what to name them? (viewed 161387 times)
  40. Why are the Moon and Sun sometimes orange or red? (viewed 158709 times)
  41. When was the last time all 9 planets were aligned? (viewed 158374 times)
  42. Why do airplanes take longer to fly West than East? (viewed 157788 times)
  43. Is the distance from the Earth to the Sun changing? (viewed 151075 times)
  44. Is Pluto a planet? (viewed 151034 times)
  45. What is at the end of the Universe? (viewed 148312 times)
  46. How can I find the star I have "bought"? (viewed 145899 times)
  47. How much money is spent on space exploration? (viewed 143673 times)
  48. What is a nova? (viewed 135140 times)
  49. How do astronauts take baths and use restrooms in space? (viewed 132561 times)
  50. Does your weight change between the poles and the equator? (viewed 131835 times)
  51. Can we feel the Earth spin? (viewed 131571 times)
  52. Why are there both high and low tides? (viewed 131334 times)
  53. What direction do planets rotate? (viewed 130710 times)
  54. Is the Sun expanding? Will it ever explode? (viewed 128895 times)
  55. What is the largest galaxy? (viewed 127405 times)
  56. How many known galaxies are there? (viewed 126270 times)
  57. Do stars move in the sky? (viewed 125015 times)
  58. What are the advantages and disadvantages of using a telescope in space? (viewed 120548 times)
  59. Why do all the planets orbit in the same plane? (viewed 118748 times)
  60. Can I buy a star? (viewed 118057 times)
  61. How are light and heavy elements formed? (viewed 115769 times)
  62. Will the sun go supernova in six years and destroy Earth (as seen on Yahoo)? (viewed 115428 times)
  63. Are there telescopes that can see the flag and lunar rover on the Moon? (viewed 113888 times)
  64. Why hasn't NASA gone back to the moon? (viewed 113014 times)
  65. Does the Sun have a scientific name? (viewed 112703 times)
  66. Why do planets have elliptical orbits? (viewed 112502 times)
  67. What is the physical difference between a star and a planet? (viewed 112132 times)
  68. How do stars move in the Galaxy? (viewed 111826 times)
  69. What is the hottest time of day? (viewed 111803 times)
  70. Who first measured the speed of light? (viewed 111778 times)
  71. What happens when galaxies collide? (viewed 111129 times)
  72. How do rockets work? (viewed 110236 times)
  73. What is the size of the Solar System? (viewed 108785 times)
  74. What is the significance of the Tropic of Cancer, Tropic of Capricorn, Arctic Circle and Antarctic Circle? (viewed 108285 times)
  75. What would happen if an impact caused Earth to stop rotating? (viewed 107847 times)
  76. How much money do astronomers make? (viewed 107776 times)
  77. Will the magnetic field of the Earth reverse its direction in the future? Will this cause problems? (viewed 107440 times)
  78. What was there before the Big Bang and what is there outside of our universe? (viewed 107146 times)
  79. When is the next comet due to arrive? (viewed 106789 times)
  80. Does evolution contradict the second law of thermodynamics? (viewed 106779 times)
  81. What will happen to life on Earth when the Sun becomes a red giant? (viewed 106264 times)
  82. How long does a solar eclipse last? (viewed 105664 times)
  83. How do you calculate the lifetime of the Sun? (viewed 105533 times)
  84. What elements make up the Sun? (viewed 104715 times)
  85. Do black holes die? If so how? (viewed 104687 times)
  86. How many constellations are there? (viewed 103827 times)
  87. What do astronauts do all day in the International Space Station? (viewed 103022 times)
  88. What is the observational difference between a star and a planet? (viewed 102893 times)
  89. What's the difference between astronomy and astrology? (viewed 101666 times)
  90. Does the Sun rotate? (viewed 101225 times)
  91. Does the Sun move around the Milky Way? (viewed 99820 times)
  92. Does gravity vary across the surface of the Earth? (viewed 99576 times)
  93. What would happen if the gravity on Earth was suddenly turned off? (viewed 98431 times)
  94. What is apparent magnitude? (viewed 96659 times)
  95. How many meteorites hit Earth each year? (viewed 96064 times)
  96. Which planet is most similar to Earth? (viewed 95806 times)
  97. What are constellations used for? (viewed 95355 times)
  98. Why do different stars appear with seasons? (viewed 93630 times)
  99. What kind of schooling is necessary to become an astronomer? (viewed 93237 times)
  100. If Mars is only about 35-60 million miles away at close approach, why does it take 6-8 months to get there? (viewed 92228 times)
  101. How do astronomers use math in their jobs? (viewed 92064 times)
  102. How critical is the Earth-Sun distance in maintaining our average temperatures on Earth? (viewed 91114 times)
  103. Is there a proof that Earth moves? (viewed 91046 times)
  104. Where did the Universe come from? (viewed 90226 times)
  105. Why are stars and planets round? (viewed 90189 times)
  106. Does the Sun orbit the Earth as well as the Earth orbiting the Sun? (viewed 89823 times)
  107. Why is the Moon so bright? (viewed 89471 times)
  108. Why is the Universe flat and not spherical? (viewed 89433 times)
  109. What makes the wind? (viewed 88844 times)
  110. What would happen if an asteroid 10 kilometers across hit the Earth? (viewed 88210 times)
  111. Have astronomers discovered Earth's second moon? (viewed 87945 times)
  112. How can a star burn with no oxygen? (viewed 87879 times)
  113. What is a singularity? (viewed 87266 times)
  114. What is the difference between a "star" and a "sun"? (viewed 86890 times)
  115. What are the requirements for being a planet? (viewed 83690 times)
  116. Why does the Earth tilt back and forward once a year? (viewed 83585 times)
  117. What are RA and DEC? (viewed 83463 times)
  118. Where does the name "Milky Way" come from? (viewed 83165 times)
  119. What would happen if Earth had more than one moon? (viewed 81550 times)
  120. Considering the motion of the Earth, the solar system, and the galaxy, how fast am I moving while lying in bed asleep? (viewed 81465 times)
  121. Since Earth is spinning, why do we land in the same place when we jump or fall? (viewed 81361 times)
  122. How many stars are born and die each day? (viewed 79918 times)
  123. Why aren't there any green stars? (viewed 78654 times)
  124. What kind of rock is the moon made of? (viewed 78382 times)
  125. Did astronauts really go to the Moon, or is it a hoax? (viewed 77683 times)
  126. How are galaxies formed? (viewed 77512 times)
  127. Why is the moon in a different place every night? (viewed 76542 times)
  128. Will the Sun become a black hole one day? (viewed 75560 times)
  129. How are black holes made? Could one be made close to us? (viewed 75239 times)
  130. What is the density of a black hole? (viewed 75126 times)
  131. What would happen if a supermassive black hole came close to the Earth? (viewed 74788 times)
  132. How do we weigh objects in space? (viewed 74314 times)
  133. Who has landed on the moon? (viewed 73685 times)
  134. Do most astronomers believe in God based on the available scientific evidence? (viewed 72561 times)
  135. Can moons have moons? (viewed 72517 times)
  136. What would you see from inside a black hole? (viewed 72410 times)
  137. What happens to a substance if its speed is more than the speed of light? (viewed 72275 times)
  138. How do rockets move in space? (viewed 72262 times)
  139. Why can't you see stars during the day? (viewed 72226 times)
  140. Does the Mediterranean sea have tides? (viewed 71911 times)
  141. How often does the Sun pass through a spiral arm in the Milky Way? (viewed 71719 times)
  142. How do astronomers measure the brightness of stars? (viewed 71490 times)
  143. What would happen if you took off your helmet in space? (viewed 71341 times)
  144. Can you fire a gun on the Moon? (viewed 71197 times)
  145. What are some of the effects of solar flares on Earth? (viewed 71084 times)
  146. How can the Universe expand faster than the speed of light during inflation? (viewed 71044 times)
  147. When the Sun converts mass to energy, do the orbits of the planets change? (viewed 70977 times)
  148. How do we know the mass of the Earth and the Moon? (viewed 70195 times)
  149. What is the evidence supporting the nebula theory of Solar System formation? (viewed 70112 times)
  150. How is astronomy impacted by trigonometry? (viewed 69908 times)
  151. Is it possible to measure the temperature of the Sun? (viewed 69510 times)
  152. Why do we not have eclipses every month? (viewed 69350 times)
  153. How do you measure a planet's mass? (viewed 68832 times)
  154. Why do stars change colour when they twinkle? (viewed 68640 times)
  155. How does the Sun compare to other stars? (viewed 68465 times)
  156. How does the Moon stay "suspended" in the air? (viewed 68302 times)
  157. How are elements heavier than iron formed? (viewed 67753 times)
  158. What are the "dog days of summer"? (viewed 67206 times)
  159. What kinds of jobs do astronomers do? (viewed 66028 times)
  160. Does quantum entanglement imply faster than light communication? (viewed 65901 times)
  161. If the universe is infinite does that mean there is an infinite number of "me"s? (viewed 64969 times)
  162. What are black holes made of? (viewed 64145 times)
  163. How did the stars get named? (viewed 64120 times)
  164. Where does the name "Moon" come from? (viewed 63993 times)
  165. How long would it take the Earth to fall into the Sun? (viewed 63829 times)
  166. What causes seasons? (viewed 63761 times)
  167. How do you measure the mass of a star? (viewed 63642 times)
  168. How does light pollution affect astronomers? (viewed 63590 times)
  169. Why doesn't the earliest sunset occur on the shortest day of the year? (viewed 63578 times)
  170. Where did the matter in the universe come from? (viewed 63496 times)
  171. What are Altitude and Azimuth? (viewed 63359 times)
  172. How did asteroids form and what is the difference between an asteroid and a comet? (viewed 63250 times)
  173. Traveling at light speed, how long would it take to get to the nearest galaxy? (viewed 63076 times)
  174. When can I see the Moon through the hole in the Pantheon? (viewed 63021 times)
  175. Are there stars outside of galaxies? (viewed 62979 times)
  176. How fast is the Universe expanding? (viewed 62873 times)
  177. Why do planets not twinkle? (viewed 62132 times)
  178. What's the best college for astronomy? (viewed 62086 times)
  179. Where, in relation to the entire universe, is the Milky Way located? (viewed 61845 times)
  180. What would happen to us if the sun went out for an hour? (viewed 61504 times)
  181. Why doesn't the length of each day change much around the solstices? (viewed 61470 times)
  182. What's the difference between dark matter and dark energy? (viewed 60941 times)
  183. What is the mass of the Universe? (viewed 60569 times)
  184. Why does the Sun's apparent path through the sky change throughout the year? (viewed 59797 times)
  185. How can I calculate the position or path of the Sun for a given time and location? (viewed 59536 times)
  186. How does astronomy benefit humankind? (viewed 59382 times)
  187. Does the Moon rotate? (viewed 59065 times)
  188. Why does the Earth have only one moon? (viewed 58976 times)
  189. Could there be life in the galaxies nearest to the Milky Way? (viewed 58927 times)
  190. How does the parachute in a model rocket work? (viewed 58700 times)
  191. Can any galaxies be seen with the naked eye? (viewed 58540 times)
  192. Why is looking out into space the same as looking back in time? (viewed 58523 times)
  193. What is the origin of spiral structure in galaxies? (viewed 58421 times)
  194. How close was the Moon to the Earth when it formed? (viewed 58177 times)
  195. What can we learn from the color of a star? (viewed 57666 times)
  196. How long does the supernova stage of a star last? (viewed 57601 times)
  197. What makes up most of the Universe? (viewed 57519 times)
  198. What is the shape of the universe? (viewed 56653 times)
  199. Why isn't the summer solstice the hottest day of the year? (viewed 56042 times)
  200. How do astronauts use math in their jobs? (viewed 55840 times)
  201. What is the largest structure in the universe? (viewed 55831 times)
  202. What is a star's "spectrum"? (viewed 55652 times)
  203. How do the astronauts communicate in space if sound cannot travel in a vacuum? (viewed 55390 times)
  204. If gravity is a "curvature of space" rather than a force, why do a ball and bullet follow different paths? (viewed 55378 times)
  205. Where are stars born? (viewed 55302 times)
  206. What is the size of a black hole? (viewed 55139 times)
  207. Are names given to black holes? (viewed 54774 times)
  208. How do you calculate the azimuth and altitude of an object? (viewed 54768 times)
  209. How do we measure the size of the Moon and of the Sun? (viewed 54735 times)
  210. Which constellation does our Sun belong to? (viewed 54613 times)
  211. What happens to a bullet fired on the moon? (viewed 54511 times)
  212. Can you see satellites? (viewed 54379 times)
  213. Is the Moon seen as a crescent (and not a "boat") all over the world? Is the same phase of the moon visible from the Northern and Southern hemispheres? (viewed 54309 times)
  214. How can I find the distance to the Sun on any given day? (viewed 53618 times)
  215. What other careers involve Astronomy besides Astronomer? (viewed 53380 times)
  216. Why do we see stars? (viewed 53195 times)
  217. Are aliens or UFOs real? (viewed 53046 times)
  218. Which hemisphere has the best view of the Milky Way? (viewed 52946 times)
  219. How can I measure the distance of a star? (viewed 52826 times)
  220. Is the speed of light constant? (viewed 52394 times)
  221. Where did all the water in the universe come from? (viewed 52176 times)
  222. Why is twilight short near the equator? (viewed 52027 times)
  223. Are there any asteroids on a collision course with Earth? (viewed 51997 times)
  224. Why is the sky blue and not blue & purple? (viewed 51855 times)
  225. How long has there been water on Earth? (viewed 51805 times)
  226. What are some astronomy science fair projects? (viewed 51781 times)
  227. Are meteorites hot or cold when they hit Earth? (viewed 51714 times)
  228. What would happen if the Moon fell out of its orbit around Earth? (viewed 51421 times)
  229. What do a galaxy's colors mean? Are they its true colors? (viewed 51338 times)
  230. Would your weight change as you go underground? (viewed 51190 times)
  231. Is time travel possible? (viewed 50789 times)
  232. Can we look back far enough in time to see the Big Bang? (viewed 50713 times)
  233. Who discovered each planet? (viewed 50568 times)
  234. Why does the Moon look big on the horizon? (viewed 50549 times)
  235. If the Earth's rotation period is less than 24 hours, why don't our clocks fall out of sync with the Sun? (viewed 50318 times)
  236. What skills do astronomers need? (viewed 49998 times)
  237. How is the time of sunrise calculated? (viewed 49883 times)
  238. Are the planes of solar systems aligned with the plane of the Galaxy? (viewed 49738 times)
  239. What is the difference between nutation and precession of the Earth? (viewed 49680 times)
  240. Why is it difficult to understand the expansion of the universe? (viewed 49679 times)
  241. How do we know what other planets (and stars, galaxies, etc.) are made of? (viewed 49233 times)
  242. What's the difference between astronomy and astrophysics? (viewed 49229 times)
  243. What is a graviton? (viewed 49207 times)
  244. If light has no mass, then what draws it into a black hole? (viewed 48714 times)
  245. Why do the size and brightness of the full moon change? (viewed 47265 times)
  246. What do I need to do to become an astronomer? (viewed 47183 times)
  247. Do supermassive black holes cause galaxy rotation? (viewed 47026 times)
  248. How do gravitons escape black holes to tell the universe about their gravity? (viewed 46858 times)
  249. Do dead stars still shine? (viewed 46766 times)
  250. Why are most months 30 or 31 days long? (viewed 46741 times)
  251. Why does the Sun appear larger on the horizon than overhead? (viewed 46533 times)
  252. What is a wormhole? (viewed 46514 times)
  253. How are black holes discovered? (viewed 46491 times)
  254. Can we find the place where the Big Bang happened? (viewed 46288 times)
  255. The Moon slows the Earth's rotation, but how fast was it spinning billions of years ago? (viewed 46035 times)
  256. Will we get sucked into the black hole at the center of the Milky Way? (viewed 45619 times)
  257. Why are there stars? (viewed 45586 times)
  258. Where is the nearest black hole? (viewed 45568 times)
  259. Is the Earth slowly getting larger? (viewed 45567 times)
  260. Why can't we see Venus at night when it is an inner planet? (viewed 45517 times)
  261. Can the acceleration of the Universe be analogous to apparent acceleration in a airplane? (viewed 45278 times)
  262. How do galaxies collide in an expanding universe? (viewed 45245 times)
  263. Can I calculate the size of the Universe by converting light years to kilometres? (viewed 44956 times)
  264. Why don't people walk upside-down on the bottom of the Earth? (viewed 44667 times)
  265. Why does Barnard 68 appear dark? (viewed 44529 times)
  266. Are Kuiper Belt Objects asteroids? Are large Kuiper Belt Objects planets? (viewed 44249 times)
  267. Did life originate on Earth, or did it come from somewhere else? (viewed 44148 times)
  268. Are there eclipses on other planets? (viewed 43634 times)
  269. What is the best way to see the Milky Way? (viewed 43251 times)
  270. How does Astronomy involve Chemistry? (viewed 43190 times)
  271. Could the Universe have expanded faster than the speed of light at the Big Bang? (viewed 43161 times)
  272. Is there a "South Star"? (viewed 43152 times)
  273. Why does the location of sunrise change? (viewed 43028 times)
  274. Has there been an experiment that measured speed faster than the speed of light in vacuum? (viewed 42952 times)
  275. How long could life on Earth survive if the Sun stopped shining? (viewed 42892 times)
  276. What is the difference between the "Doppler" redshift and the "gravitational" or "cosmological" redshift? (viewed 42863 times)
  277. Was the Sun made in a supernova? (viewed 42701 times)
  278. How much can the location of sunset differ from due West? (viewed 42632 times)
  279. What is the biggest crater recorded on Earth? (viewed 42611 times)
  280. How would the weather on Earth be different if it were a cube? (viewed 42518 times)
  281. Why doesn't dark matter fall into a black hole? (viewed 42359 times)
  282. How much longer will the Earth last? (viewed 42284 times)
  283. What happens to spacetime inside a black hole? (viewed 42128 times)
  284. Can I buy land on the Moon? (viewed 41636 times)
  285. Why does the Earth only see one side of the Moon? (viewed 41565 times)
  286. Is the Moon hollow? (viewed 41405 times)
  287. What are the names of the three stars in Orion's belt? (viewed 41370 times)
  288. What happens when two black holes get too close? (viewed 41353 times)
  289. What's the biggest meteorite? (viewed 40932 times)
  290. What color would Mars be if you were standing on it? (viewed 40901 times)
  291. What is time dilation? (viewed 40891 times)
  292. What if the Earth rotated twice as fast? (viewed 40849 times)
  293. What is the most distant known galaxy? (viewed 40621 times)
  294. How can two moons of Saturn share the same orbit? (viewed 40500 times)
  295. Why do people draw stars with five points? (viewed 40361 times)
  296. How do we feel heat? (viewed 40295 times)
  297. Could someone travel the universe in his or her own lifetime? (viewed 40278 times)
  298. Is it possible to see the full Moon and the Sun simultaneously in high northern latitudes when the Sun doesn't set? (viewed 40074 times)
  299. Can terrestrial planets have rings? (viewed 40050 times)
  300. Why can we see the sun's image before sunrise and after sunset? (viewed 39964 times)
  301. How long would it take for a mini-black hole to eat the Earth? (viewed 39749 times)
  302. What are "blue stragglers" in globular clusters? (viewed 39708 times)
  303. How many Astronauts have been in space? (viewed 39625 times)
  304. How fast does the Earth go at perihelion and aphelion? (viewed 39387 times)
  305. How do we know that nuclear fusion is still going on in the Sun? (viewed 39343 times)
  306. Why do pictures of distant galaxies have higher resolution than those of nearby planets? (viewed 39184 times)
  307. Is the Sun always up for exactly 12 hours at the equator? (viewed 39086 times)
  308. What is the typical size of a visible shooting star? (viewed 38968 times)
  309. If a white dwarf is a "dead" star, why is it so hot? (viewed 38968 times)
  310. Does the Sun have an iron surface? (viewed 38953 times)
  311. Do you think it's possible to maintain life on other planets? (viewed 38909 times)
  312. Why are Saturn's rings flat? (viewed 38804 times)
  313. Why do clocks turn in the opposite direction from the Earth and Moon? (viewed 38772 times)
  314. Is the Great Wall the largest galaxy cluster? (viewed 38708 times)
  315. Does Mt. Everest cast a shadow on the moon? (viewed 38667 times)
  316. On which days can I see the Moon in the evening / morning and why is this so? (viewed 38512 times)
  317. What is a dimension? (viewed 38489 times)
  318. How does night and day work? (viewed 38481 times)
  319. Can you see the future as you fall into a black hole? (viewed 38450 times)
  320. Who (and when) discovered that the earth's axis is on a 23 degree tilt? (viewed 38427 times)
  321. Can a person go into a black hole and come out alive? (viewed 38281 times)
  322. Where do planetary rings come from, and what are they made of? (viewed 38143 times)
  323. Can I communicate faster than light? (viewed 38087 times)
  324. What is the speed of gravity? (viewed 37897 times)
  325. Are all stars the same? (viewed 37873 times)
  326. What is Earthrise over the Moon? (viewed 37786 times)
  327. What companies or businesses can astronomers work for? (viewed 37711 times)
  328. How do we define distance in an expanding universe? (viewed 37696 times)
  329. How do we determine the age of the universe? (viewed 37625 times)
  330. What is the approximate GPA needed in High School in Math and Science to be an astronomer? (viewed 37567 times)
  331. Where is the supernova remnant that led to our solar system? (viewed 37545 times)
  332. What can I use for fuel in my homemade rocket? (viewed 37484 times)
  333. How big is the universe? (viewed 37454 times)
  334. Why is sea water salty, and not lake water? (viewed 37176 times)
  335. Is there really a 10th planet? (viewed 37170 times)
  336. Is there a beginning and an end to a galaxy's life? (viewed 36984 times)
  337. How can the universe be "flat"? We're 3D! (viewed 36965 times)
  338. If the universe is 15 billion years old, how can it be larger than 15 billion light years across? (viewed 36832 times)
  339. Does the Coriolis force determine which way my toilet drains? Does it affect black holes? (viewed 36828 times)
  340. How do we know the Milky Way is a spiral galaxy? (viewed 36673 times)
  341. What would happen to the Earth if an asteroid hit the Moon? (viewed 36637 times)
  342. How many stars can I see? (viewed 36578 times)
  343. How are photons created and destroyed? (viewed 36572 times)
  344. How do I tell which planet is which? (viewed 36424 times)
  345. Why are there blue shifted galaxies? (viewed 36094 times)
  346. Do the Sun's or Earth's magnetic field reverse? (viewed 35985 times)
  347. How can I find my age on another planet? (viewed 35792 times)
  348. Can a lunar and a solar eclipse happen in the same month? When will this happen next? (viewed 35612 times)
  349. How are planets detected around other stars? (viewed 35461 times)
  350. Is Andromeda part of the Milky Way? Where can I find them in the sky? (viewed 35397 times)
  351. Why have star signs shifted by one constellation? (viewed 35391 times)
  352. How does the brightness of a star depend on its distance from us? (viewed 35390 times)
  353. Why can't a plane fly slowly and let the Earth pass underneath? (viewed 35378 times)
  354. What is the pattern to the distances between each planet and the sun? (viewed 35332 times)
  355. Why do humans want to go in space? (viewed 35328 times)
  356. What kind of eyepieces do I need to look at planets? (viewed 35309 times)
  357. Will we ever stop having solar eclipses because of the moon's motion away from the Earth? (viewed 35177 times)
  358. What is the significance of the second focus of elliptical orbits of planets in our Solar System? (viewed 35033 times)
  359. Who came up with the name "black hole"? (viewed 34757 times)
  360. What was that really big falling star that I saw? (viewed 34713 times)
  361. How can we estimate the number of Earth-like planets in the Galaxy? (viewed 34694 times)
  362. How do astronauts communicate with their families from space? (viewed 34689 times)
  363. What would happen if two stars collided? (viewed 34677 times)
  364. Is there a simple formula to calculate solar eclipse timings from any position on Earth? (viewed 34424 times)
  365. Is the Earth at the centre of the Universe? (viewed 34401 times)
  366. How hot is each one of the layers of the sun? (viewed 34377 times)
  367. When we look back to the Big Bang, why don't we see the universe as a tiny speck of matter? (viewed 34315 times)
  368. Can you describe a day on the job as an astronomer? (viewed 34222 times)
  369. How is it that we see farther out in space (farther back in time) than in the past? (viewed 34218 times)
  370. Why don't astronomers use everyday units to measure distances (what is an AU or a pc)? (viewed 34206 times)
  371. Will the Moon be invisible in 500 million years? (viewed 33935 times)
  372. How do I become both an astronaut and an astronomer? (viewed 33914 times)
  373. Is the Local Group expanding along with the entire Universe? (viewed 33588 times)
  374. Are Earth and the Moon "twin planets"? (viewed 33552 times)
  375. Why is our solar system so different from all the others we've found? (viewed 33511 times)
  376. How dangerous are the asteroids? (viewed 33498 times)
  377. Which American colleges teach astronomy? (viewed 33445 times)
  378. Why is Uranus tipped on its side? (viewed 33408 times)
  379. How do sunrise and sunset times change with altitude? (viewed 33316 times)
  380. Can we colonize other planets? (viewed 33101 times)
  381. Why do constellations look the same after several years even though all the stars are moving? (viewed 32843 times)
  382. Is it true that the Sun burns off a billion tons of gas every 5 seconds? (viewed 32653 times)
  383. Why are there no craters on Earth? Did all the meteorites miss us? (viewed 32644 times)
  384. Is the universe really like an expanding balloon? (viewed 32613 times)
  385. Why do astronauts in space need to exercise? (viewed 32448 times)
  386. What are quasars made of? (viewed 32434 times)
  387. Is the gravitational force exerted by the Earth on the Moon equal to the centripetal force acting on the Moon? (viewed 32419 times)
  388. How can I calculate distances between stars? (viewed 32413 times)
  389. Can superheavy elements (such as Z=116 or 118) be formed in a supernova? Can we observe them? (viewed 32158 times)
  390. Why doesn't gravity change the speed of light? (viewed 32123 times)
  391. What is dark matter? (viewed 32027 times)
  392. Is it possible to count the stars? (viewed 31837 times)
  393. How big a change in the Earth's orbit would be required to destroy all life? (viewed 31707 times)
  394. Is time travel possible using merging black holes? (viewed 31684 times)
  395. What is happening just around the black hole in the center of the Milky Way? (viewed 31599 times)
  396. Can we see dead stars with the naked eye? (viewed 31525 times)
  397. Did the speed of light change over the history of the universe? (viewed 31513 times)
  398. How do we measure distances to other stars? (viewed 31429 times)
  399. How can we distinguish a star's "real" color from the change in color that we observe due to the star's motion? (viewed 31395 times)
  400. Why is the time between two successive full moons different from the lunar synodic month? (viewed 31344 times)
  401. How do I make a scale model of the Solar System? (viewed 31325 times)
  402. What happens when an antimatter black hole collides with a matter blackhole? (viewed 31167 times)
  403. Are time machines possible? (viewed 30995 times)
  404. How many moles of stars are in the known universe? (viewed 30812 times)
  405. How can we tell what the interiors of planets are like? (viewed 30801 times)
  406. Does the Milky Way spin counter-clockwise? If so, do all spiral galaxies spin in this direction and why? (viewed 30712 times)
  407. What would happen if a human were exposed to space without wearing a spacesuit? (viewed 30677 times)
  408. How are galaxy distances inferred from their recessional velocities? (viewed 30623 times)
  409. Do we see the same stars from above and below the equator? (viewed 30610 times)
  410. What happens when you change the mass of a White Dwarf or Neutron Star? (viewed 30586 times)
  411. What do "homogeneity" and "isotropy" mean? (viewed 30533 times)
  412. What is the farthest in space that we have gone? (viewed 30305 times)
  413. Will the seasons change due to precession? (viewed 30158 times)
  414. Is there any limitation to what a black hole can "suck" in? (viewed 30144 times)
  415. Can astronauts produce water in space? (viewed 30050 times)
  416. How can we know that there are other galaxies if we cannot leave ours? (viewed 30010 times)
  417. How was the starting point for the Julian Date system chosen? (viewed 29979 times)
  418. What are the closest and/or brightest stars? (viewed 29938 times)
  419. Aren't jobs in astronomy scarce? (viewed 29866 times)
  420. How can I tell if the rock I found is a meteorite? (viewed 29819 times)
  421. How do we know if the universe will keep expanding forever? (viewed 29803 times)
  422. What's that dark spot on the Sun? (viewed 29791 times)
  423. Why does the SETI project search for radio signals? (viewed 29655 times)
  424. How long does it take the Big Dipper to move in the sky? (viewed 29624 times)
  425. Do astronomers believe in astrology? (viewed 29607 times)
  426. Did I see the Aurora Borealis as a child? (viewed 29505 times)
  427. Why do we study black holes? (viewed 29493 times)
  428. Why do most moons orbit their planets at the equator? (viewed 29355 times)
  429. When are there 5 Sundays in February? (viewed 29332 times)
  430. What are the facts about the Star of Bethlehem? (viewed 29309 times)
  431. Don't tachyons travel faster than light? (viewed 29228 times)
  432. Wouldn't the Big Bang theory be considered a hypothesis and not a theory? (viewed 29199 times)
  433. What are the atmospheres of Mars and Pluto like? (viewed 29187 times)
  434. Do you believe in UFOs? (viewed 29126 times)
  435. Could an astronaut or satellite fall into a black hole that we didn't know about? (viewed 29126 times)
  436. Can you use an infinite line of reflectors to send light to the edge of the Universe? (viewed 29032 times)
  437. What does the term "visible universe" mean? (viewed 28874 times)
  438. Does the Moon look different in the northern and southern hemispheres? (viewed 28866 times)
  439. Could you tell me about the life cycle of galaxies? (viewed 28860 times)
  440. What colors are visible through an amateur telescope? (viewed 28765 times)
  441. Has anyone made a map of the Milky Way? (viewed 28674 times)
  442. Was I hit by a meteorite? (viewed 28658 times)
  443. How are galaxies named? (viewed 28646 times)
  444. How can geometry be different in space? (viewed 28612 times)
  445. Why are the compositions of comets and asteroids different? (viewed 28462 times)
  446. Why do so many of the world's UFO sightings happen in America? (viewed 28430 times)
  447. What's the best thing about being an astronomer? (viewed 28264 times)
  448. Can two lunar eclipses occur in the same month? (viewed 28220 times)
  449. How do astronomers measure the radius of a star? (viewed 28099 times)
  450. How do asteroids, meteors and comets disappear? (viewed 28093 times)
  451. What is the origin of the stellar classification system "OBAFGKM"? (viewed 27895 times)
  452. How much time do astronomers spend looking through telescopes? (viewed 27887 times)
  453. Will winter and summer constellations change due to abnormal warmth or cold on Earth? (viewed 27767 times)
  454. How can we see galaxies if their stars are so faint? (viewed 27711 times)
  455. How do I explain to my children why the Moon has phases? (viewed 27690 times)
  456. How will the two black holes that are going to collide affect Earth? (viewed 27601 times)
  457. Have there been other Big Bangs before? (viewed 27598 times)
  458. How are galaxies and solar systems similar? (viewed 27570 times)
  459. Is there a project I can do on black holes? (viewed 27331 times)
  460. How close do you have to come to the Earth to be influenced by its gravity? (viewed 27320 times)
  461. Can life exist on the recently discovered extrasolar planets? (viewed 27309 times)
  462. Do the magnitudes and colors of stars ever change? (viewed 27283 times)
  463. Is the Milky Way a collision of two galaxies? (viewed 27213 times)
  464. Do asteroids hit the sun? (viewed 27170 times)
  465. How can we measure distances to more stars? (viewed 27165 times)
  466. Could you escape from a black hole if you were able to go faster than the speed of light? (viewed 27076 times)
  467. How do scientists slow light down? (viewed 27052 times)
  468. How close does a supernova need to be to damage the Earth's environment? (viewed 26868 times)
  469. Is infinite temperature possible? (viewed 26862 times)
  470. Is it worthwhile to continue the search for extraterrestrial life? (viewed 26832 times)
  471. What supernova created the Crab nebula? (viewed 26826 times)
  472. Can "tired light theory" explain the observed redshifts of galaxies? (viewed 26783 times)
  473. Do we know everything about the Sun? (viewed 26781 times)
  474. Can double stars have planets? (viewed 26729 times)
  475. What causes gamma ray bursts? (viewed 26684 times)
  476. Can a human give birth in space? (viewed 26669 times)
  477. Can one star orbit another? (viewed 26605 times)
  478. Is there oxygen in the atmospheres of other planets? (viewed 26470 times)
  479. How far does a galaxy extend? (viewed 26460 times)
  480. Which part of the sky did the famous 'wow' signal originate from? (viewed 26433 times)
  481. What will happen to the Milky Way in the future? (viewed 26346 times)
  482. Can astronauts play musical instruments in space? (viewed 26312 times)
  483. How do I polar align my telescope? (viewed 26288 times)
  484. What is sidereal time? (viewed 26244 times)
  485. Which way does the sun travel in the southern hemisphere? (viewed 26224 times)
  486. What type of energy does a black hole have? (viewed 26179 times)
  487. Why did the Pioneer and Voyager take only 2 years to reach Jupiter, while Galileo and Cassini took more than 5 years? (viewed 26157 times)
  488. Is there such a thing as hyperspace? (viewed 26148 times)
  489. What is the farthest Northern Latitude in which the Magellanic Clouds can be seen? (viewed 26146 times)
  490. What happens to the material that has been sucked into a black hole? (viewed 26086 times)
  491. What is a Cepheid variable? (viewed 26075 times)
  492. What is "nothing", from a scientific point of view? (viewed 26047 times)
  493. Is there sound coming from the Sun? (viewed 26046 times)
  494. What's the object I saw that moved across the sky and then got very bright? (viewed 26034 times)
  495. Why do the explosions of Type Ia supernovae have a more predictable spectrum than those of regular Type II supernovae? (viewed 26023 times)
  496. How different would the night sky have looked in 40,000 B.C.? (viewed 26002 times)
  497. When did people discover that the Sun is a star? (viewed 25942 times)
  498. How will a change in the speed of light affect the evolution of the Universe? (viewed 25876 times)
  499. Are planetary nebulae the result of supernovae? (viewed 25781 times)
  500. Why is the shadow on the Moon the shape it is? (viewed 25762 times)
  501. Why do we assume that the universe is homogeneous? (viewed 25689 times)
  502. How do we know what parameters to use when simulating the collision of the Milky Way and Andromeda? (viewed 25622 times)
  503. If we invented special suits could we ever go to the sun? (viewed 25604 times)
  504. How do we know that sunspots are associated with the Sun's magnetic field? (viewed 25595 times)
  505. When unmanned spacecraft accelerate in space, what causes them to slow down? (viewed 25592 times)
  506. What is the difference between homogeneity and isotropy? (viewed 25474 times)
  507. What calculations go into predicting eclipses? (viewed 25447 times)
  508. What is our galaxy's halo made of, and how was it formed? (viewed 25447 times)
  509. Are there any dark stars or dark galaxies made of dark matter? (viewed 25437 times)
  510. Was Stonehenge built to mark solar phenomena? (viewed 25294 times)
  511. Can I see a quasar? (viewed 25284 times)
  512. How many sunspots can the Sun have at once? (viewed 25259 times)
  513. Is there a list of the sizes of different kinds of stars? (viewed 25237 times)
  514. How are asteroid compositions and classifications determined? (viewed 25215 times)
  515. What process would bring about a quark star? (viewed 25208 times)
  516. Can any comparison be made between spiral galaxies and hurricanes? (viewed 25113 times)
  517. What's so exciting about the new planet around 55 Cancri? (viewed 25111 times)
  518. Can I see details on Venus? (viewed 25104 times)
  519. Did a giant impact cause the Dark Ages? (viewed 25092 times)
  520. Why are there more maria on the near side of the Moon? (viewed 25039 times)
  521. What is a Dyson Sphere? (viewed 25022 times)
  522. What happened to the girl who named Pluto? (viewed 25000 times)
  523. Have gravitational waves been proven to exist? (viewed 24996 times)
  524. Would the biggest airplanes cause tsunamis if they crashed? (viewed 24899 times)
  525. What happened to all the black holes that were around in the early universe? (viewed 24892 times)
  526. What equipment do I need for astrophotography? (viewed 24859 times)
  527. Why are telescopes kept in cold conditions? (viewed 24826 times)
  528. How is it proved that the Universe is expanding? (viewed 24822 times)
  529. How big is the Hubble Ultra Deep Field image? (viewed 24815 times)
  530. Does Cerenkov radiation travel faster than light? (viewed 24750 times)
  531. Why are there active volcanos on Io? (viewed 24727 times)
  532. Is there any possibility that the Solar System or the Universe is in a black hole? (viewed 24642 times)
  533. If clocks run slow in a gravitational field, how can we know the true age of the Solar System and Universe? (viewed 24523 times)
  534. If the Universe was infinitely dense at the Big Bang, why didn't time stand still? (viewed 24467 times)
  535. How can we compare dark matter and dark energy? (viewed 24430 times)
  536. How big was the Sun when it first "fired up"? (viewed 24409 times)
  537. How long do supernova remnants last? (viewed 24367 times)
  538. What caused Shoemaker-Levy 9 to split up? (viewed 24286 times)
  539. Why do photos of space taken from space never show any stars? (viewed 24250 times)
  540. Could we send a space mission to a comet? (viewed 24248 times)
  541. How do solar flares affect airline pilots? (viewed 24248 times)
  542. Can you give me advice on buying a telescope? (viewed 24205 times)
  543. Why doesn't light from distant galaxies reach us instantaneously? (viewed 24161 times)
  544. How are sunspots formed? (viewed 24112 times)
  545. Could we be seeing dead stars? (viewed 24032 times)
  546. How does the Earth compare in size to the entire universe at the present epoch? (viewed 24027 times)
  547. Could a different theory of gravity explain the dark matter mystery? (viewed 23999 times)
  548. Can I build an instrument to measure the size of the Sun and of the Moon? (viewed 23979 times)
  549. How can I contribute to science as an amateur astronomer? (viewed 23973 times)
  550. Why doesn't NASA build rotating spacecraft to simulate gravity? (viewed 23951 times)
  551. Why is it important to study meteorites? (viewed 23949 times)
  552. Where does the kinetic energy of infalling bodies come from? (viewed 23946 times)
  553. As the universe expands, why don't galaxies get stretched out? (viewed 23905 times)
  554. How many comets are currently orbiting our sun? (viewed 23845 times)
  555. Why are telescopes located in remote places? (viewed 23833 times)
  556. Can you tell time by the Big Dipper? (viewed 23756 times)
  557. Did I really hear a meteor? (viewed 23747 times)
  558. Why is the Hubble Space Telescope in space? (viewed 23716 times)
  559. Are the asteroids the remains of a planet which broke apart? (viewed 23710 times)
  560. How do unmanned space probes avoid running into things? (viewed 23679 times)
  561. How do we know that superclusters are the largest structures in the universe? (viewed 23605 times)
  562. Would extraterrestrial civilizations know that there is life on Earth? (viewed 23561 times)
  563. How powerful are quasars? (viewed 23560 times)
  564. How is the Cepheid yardstick validated? (viewed 23500 times)
  565. Do the Earth's magnetic poles ever change places? (viewed 23457 times)
  566. Do unmanned spacecraft like Voyager travel in straight lines? (viewed 23431 times)
  567. Did time go slower just after the Big Bang? (viewed 23377 times)
  568. Do galaxies orbit around anything? (viewed 23330 times)
  569. Can supernovae hinder the formation of life in galaxies? (viewed 23323 times)
  570. Why are stars of different masses? (viewed 23312 times)
  571. Are there any new craters on the moon? (viewed 23310 times)
  572. Why can't relative velocities add up to more than the speed of light? (viewed 23275 times)
  573. How could galaxies have gotten so far away in only 15 billion years? (viewed 23270 times)
  574. What would happen if there was a collision between two white dwarfs? (viewed 23258 times)
  575. What kind of instruments are used to detect extrasolar planets? (viewed 23250 times)
  576. Do similar laws of physics throughout the Universe imply that all life must be like life on Earth? (viewed 23212 times)
  577. How do I become an astronomical artist? (viewed 23211 times)
  578. How do planets capture satellites? (viewed 23182 times)
  579. How are astronomy and poetry linked? (viewed 23097 times)
  580. Could there have been multiple Big Bangs at different places in the universe? (viewed 23090 times)
  581. What kind of telescope should I use for astrophotography? (viewed 23061 times)
  582. Could dark energy come from matter anti-matter pairs forming spontaneously and then annihilating? (viewed 22944 times)
  583. Why is NASA shutting down the Hubble Space Telescope? (viewed 22844 times)
  584. Can I listen to the SETI@home radio signal? (viewed 22840 times)
  585. How can you tell if a crescent moon is preceding or following a new-moon phase? (viewed 22803 times)
  586. Does the Sun have any heavy elements? (viewed 22734 times)
  587. Are the properties of extrasolar planets known? (viewed 22627 times)
  588. How do astronomers observe the Sun's interior? (viewed 22627 times)
  589. What class of spiral galaxy is the Milky Way? (viewed 22609 times)
  590. A line drawn perpendicular to a line through the tips of the horns of the crescent moon doesn't point to the Sun! Why not? (viewed 22598 times)
  591. Can the theory of formation of the solar system explain all the observables? (viewed 22589 times)
  592. Will we discover an 11th planet? What would it be called? (viewed 22551 times)
  593. What month was it when Odysseus saw Orion in 1000BC? (viewed 22436 times)
  594. Where was the water in the big bang? (viewed 22260 times)
  595. What makes a satellite geosyncronise itself with Earth's orbit? (viewed 22206 times)
  596. Is it possible for amateurs to do optical interferometry? (viewed 22179 times)
  597. Could we send a manned mission to the outer planets? (viewed 22154 times)
  598. Why does the apparent density of galaxies drop off at larger distances? (viewed 22146 times)
  599. Why does one side of Mars look more catastrophic than the other? (viewed 22139 times)
  600. Would a planet near the galactic center have a brighter night sky? (viewed 22064 times)
  601. How can water be chemically trapped in rocks? (viewed 21999 times)
  602. Do stars' orbits in galaxies obey Kepler's Laws? (viewed 21932 times)
  603. Why do spacecraft need heat shields coming back to Earth but not leaving? (viewed 21913 times)
  604. What is the solar cycle? (viewed 21797 times)
  605. Can other terrestrial moons be (or have been) stable? (viewed 21773 times)
  606. Why was the Platonic year named after Plato? (viewed 21764 times)
  607. Why are accretion disks flat? (viewed 21716 times)
  608. What would the Big Crunch look like to an observer on Earth? (viewed 21669 times)
  609. How are supernovae discovered? (viewed 21660 times)
  610. What is meant by "stopping down a telescope"? (viewed 21562 times)
  611. Can a black hole come back to the visual universe through a "little bang"? (viewed 21554 times)
  612. Does inflation allow for an infinite number of universes? (viewed 21524 times)
  613. How can the Sun have such a strong gravitational field if it's made of gasses? (viewed 21464 times)
  614. Why doesn't the hydrogen on Jupiter explode? (viewed 21462 times)
  615. Could our position in the universe affect our perceptions of the expansion? (viewed 21456 times)
  616. Did I find a rock that came from the Moon? (viewed 21230 times)
  617. Have astronomers observed any phenomena that could be produced by extraterrestrial civilizations? (viewed 21223 times)
  618. What is the SU(3) quark model? (viewed 21189 times)
  619. Can gravitational lensing from intervening galaxies cause the observed ripples in the Cosmic Microwave Background? (viewed 21151 times)
  620. Does a photon observe other photons moving past it at the speed of light? (viewed 21080 times)
  621. Will I be able to see the shadow of the Moon streaking towards me in a total solar eclipse? (viewed 21052 times)
  622. What's new with the Big Bang? (viewed 20869 times)
  623. Could photons be dark matter? (viewed 20834 times)
  624. How can we find galaxies behind the Milky Way? (viewed 20833 times)
  625. How fast do particles travel in space? (viewed 20781 times)
  626. Why can we have solar eclipses? (viewed 20746 times)
  627. Why is the WMAP picture of the CMB an ellipse? (viewed 20742 times)
  628. Is it possible to build a cheap device to measure declination? (viewed 20737 times)
  629. Why search for only Earth-like life on other planets? (viewed 20726 times)
  630. If comets are boiling away, why are there any left? (viewed 20677 times)
  631. Where can I find information on the moons of other planets? (viewed 20661 times)
  632. Why do some eclipses take longer than others? (viewed 20616 times)
  633. How much power is contained in a beam of light? (viewed 20598 times)
  634. Can planets collide with one another? (viewed 20527 times)
  635. Do constellations looks the same from space? (viewed 20520 times)
  636. Why is pressure broadening greater in low mass stars than in high mass stars? (viewed 20463 times)
  637. What are the boundaries of the constellations? (viewed 20350 times)
  638. Did the Sumerians measure precession? (viewed 20326 times)
  639. What would an "open geometry" for the universe look like? (viewed 20323 times)
  640. What kinds of star clusters are there? (viewed 20232 times)
  641. Why is the Cosmic Microwave Background not absorbed by interstellar hydrogen? (viewed 20108 times)
  642. Why aren't discoveries of extrasolar planets reported on the news? (viewed 20101 times)
  643. How do astronomers come up with their facts? (viewed 20098 times)
  644. Why don't astronauts sublimate in space? (viewed 20088 times)
  645. How do photons from distant objects maintain enough energy to reach us? (viewed 20088 times)
  646. How do bars form in spiral galaxies? (viewed 20077 times)
  647. How did Mars get so dusty? (viewed 20054 times)
  648. What are collections of galaxies called? (viewed 20024 times)
  649. Can HST see the Oort cloud? (viewed 19925 times)
  650. Do electrons age? (viewed 19918 times)
  651. Can we make a movie of the Milky Way galaxy's rotation? (viewed 19828 times)
  652. Can the Space Shuttle abort and return to Earth before reaching orbit? (viewed 19777 times)
  653. How long is twilight on the Moon? (viewed 19773 times)
  654. Will astronauts ever be able to go ice-skating on Europa? (viewed 19688 times)
  655. How does melting a material reset its radioactive clock? (viewed 19675 times)
  656. Does the shuttle worry about space junk? (viewed 19632 times)
  657. Why don't all neutron stars become pulsars? (viewed 19584 times)
  658. Where can I see Newton's original reflecting telescope? (viewed 19567 times)
  659. Why do supernova remnants look like rings rather than spheres? (viewed 19564 times)
  660. How do you classify galaxies? (viewed 19547 times)
  661. If photons have zero mass, why do they feel the effects of gravity? (viewed 19507 times)
  662. How can we understand the meaning of large numbers like "a million million?" (viewed 19460 times)
  663. What is the best time of the year to see eclipses? (viewed 19405 times)
  664. Why doesn't SETI concentrate its observations to the nearby stars and the solar systems that we are discovering? (viewed 19394 times)
  665. What causes a particle to decay? (viewed 19338 times)
  666. Will the next generation telescope OWL be able to detect an Earth like extrasolar planet? (viewed 19316 times)
  667. Why is it called astronomy when all the other sciences end in -ology? (viewed 19273 times)
  668. How does the color index of a star relate to its actual color? (viewed 19208 times)
  669. How can I nominate myself for a Nobel Prize in Physics? (viewed 19197 times)
  670. How long has humanity known that we live in a galaxy similar to others in the Universe? (viewed 19167 times)
  671. Will the Leonid meteor shower go away? (viewed 19122 times)
  672. What are "curled" dimensions? (viewed 19028 times)
  673. If nothing can escape a black hole, why do some black holes have jets? (viewed 18957 times)
  674. Is light of different colors affected differently by gravity? (viewed 18937 times)
  675. How does interferometry work? (viewed 18866 times)
  676. Do asteroids ever do anything good in the Solar System? (viewed 18844 times)
  677. What was that eclipse I saw in the sky? (viewed 18830 times)
  678. How do distant galaxies differ from those nearby? (viewed 18789 times)
  679. Does the temperature of matter increase as it is accelerated to relativistic speeds? (viewed 18782 times)
  680. What kind of interference must astronomers contend with when observing? (viewed 18772 times)
  681. Are black holes spherical? (viewed 18772 times)
  682. What would happen if you went back in time and killed your grandmother? (viewed 18763 times)
  683. Wouldn't the vast distances of space distort SETI signals into unintelligeble forms? (viewed 18709 times)
  684. How do we find out about the star formation histories of galaxies? (viewed 18703 times)
  685. Why will fusion wait until hydrogen is gone before starting to fuse heavier atoms? (viewed 18616 times)
  686. Can astronomers observe anything when the moon is full? (viewed 18593 times)
  687. How can I watch the Perseid meteor shower? (viewed 18565 times)
  688. What do stellar classifications mean? (viewed 18520 times)
  689. Do we really observe the edges of galaxies at different epochs? (viewed 18483 times)
  690. Can you tell me the characteristics of W, R, N and S type stars? (viewed 18442 times)
  691. How are astronauts trained for weightlessness? (viewed 18386 times)
  692. Why aren't accretion disks around giant stars as hot as accretion disks around black holes? (viewed 18366 times)
  693. What is the three-body problem? (viewed 18364 times)
  694. If the universe is "bounded" today, could it one day become "unbounded"? (viewed 18139 times)
  695. Will the diameter of a cluster of galaxies change with redshift? (viewed 18098 times)
  696. Is cosmic expansion happening on microscopic scales? (viewed 17958 times)
  697. How can I find out if the new moon has been sighted? (viewed 17754 times)
  698. When measuring the expansion of the universe, do astronomers consider that they're seeing how galaxies moved long ago, not today? (viewed 17717 times)
  699. Could neutrinos be dark matter? (viewed 17647 times)
  700. Do we have to worry about relativity when studying galactic objects? (viewed 17597 times)
  701. How do supernovae show us that the Universe's expansion is accelerating? (viewed 17490 times)
  702. Does lunar gardening really work? (viewed 17473 times)
  703. What happens to the helium formed in the sun? (viewed 17440 times)
  704. What kinds of cancer research have been done in space? (viewed 17430 times)
  705. How does a star take mass from another star? (viewed 17298 times)
  706. Could the Universe's dark matter be made up of black holes? (viewed 17210 times)
  707. How can you tell the difference between single and multiple extrasolar planets? (viewed 17086 times)
  708. What is Hot Dark Matter theory? (viewed 17045 times)
  709. Is it a coincidence that we can have total solar eclipses? Are there other planets which also have them? (viewed 16815 times)
  710. How do we know the density of some extrasolar planets? (viewed 16750 times)
  711. Is the green flash real? (viewed 16685 times)
  712. What is the photoelectric effect? Why can't multiple low-frequency photons free an electron? (viewed 16676 times)
  713. How does libration allow us to see more than 50% of the Moon? (viewed 16517 times)
  714. How can observations of the distant universe prove that the expansion is accelerating *now*? (viewed 16493 times)
  715. Is light blueshifted when it is gravitationally lensed? (viewed 16368 times)
  716. Do binary or triple star systems form together? (viewed 16325 times)
  717. No matter how fast the universe is expanding, shouldn't gravity eventually make it recollapse? (viewed 16289 times)
  718. What do meteorites tell us about life on other planets? (viewed 16104 times)
  719. Why is it easier to see a star if you look slightly to the side? (viewed 16057 times)
  720. What percent of the time can astronomers observe without interference from the Moon? (viewed 16045 times)
  721. Can we prove that the Moon isn't hollow? (viewed 15985 times)
  722. If the sun went out and our atmosphere froze solid, what color would it be? (viewed 15917 times)
  723. Could matter-anti-matter repulsion power the expansion of the universe? (viewed 15801 times)
  724. What time is sunrise/sunset or moonrise/moonset at my location? (viewed 15722 times)
  725. How has light from 13 billion years ago not passed us by? (viewed 15647 times)
  726. Why doesn't the ammonia and methane in Jupiter's atmosphere sink into the core? (viewed 15615 times)
  727. How do we detect incoming meteorites? (viewed 15526 times)
  728. What was different on Mars in the past to allow liquid water to be present? (viewed 15427 times)
  729. Are there any 'lonely galaxies'? (viewed 15411 times)
  730. When will Hale-Bopp return? (viewed 15363 times)
  731. Why don't skydivers burn up like meteors? (viewed 15307 times)
  732. Has anyone ever seen a star "turn on"? (viewed 15102 times)
  733. The Moon and Sun are the same apparent size in the sky. The Moon is moving away from us at 3.8 centimeters/year. Isn't it improbable that we live in an epoch in which they appear the same size in the sky? (viewed 15014 times)
  734. Why are craters round? (viewed 14754 times)
  735. During close approaches, can Mars appear in our sky as large as the Moon? (viewed 14659 times)
  736. How are planets affected by the Hot Ionised Medium? (viewed 14470 times)
  737. Can the sun rise from the west on Mars? (viewed 14283 times)
  738. What are the largest radio wavelengths observed from radio sources in the sky? (viewed 14052 times)
  739. Why was Mir burnt up in the atmosphere? (viewed 14024 times)
  740. How can we discern different galaxies/clusters along the same line of sight? (viewed 13913 times)
  741. What is the relationship between the width of a star trail on a photo and the star's intensity? (viewed 13480 times)
  742. Can we harvest H & O from space to make water? (viewed 13324 times)
  743. Why does Titan, in spite of being smaller than Mars, have an atmosphere more dense than Earth's? (viewed 12988 times)
  744. What is between the Oort cloud and the closest star? (viewed 12778 times)
  745. Could a planetary system survive if its star merged with another, or if its star went supernova? (viewed 11949 times)
  746. Are there solar tides? (viewed 11853 times)
  747. What happens to the Earth as the moon gets farther away and will it ever go away entirely? (viewed 11795 times)
  748. Does weightlessness affect hunger? (viewed 11647 times)
  749. Is Earth-moon tidal friction causing global warming? (viewed 11465 times)
  750. Do planets radiate noise? (viewed 11237 times)
  751. Is the moon spherical? (viewed 11177 times)
  752. Is dark energy affected by black holes? (viewed 10925 times)
  753. Why is the Moon higher in the sky in winter and lower in the summer? (viewed 10888 times)
  754. What would happen if a nuclear-powered shuttle exploded? (viewed 10646 times)
  755. Where are the protons and electrons in a Neutron Star? (viewed 10534 times)
  756. Is the Moon always visible during winter on the North Pole? (viewed 10240 times)
  757. Wait, I'm still confused why information can't travel faster than the speed of light. (viewed 9961 times)
  758. Do more meteorites fall at low latitudes? (viewed 9701 times)
  759. Did the Moon or planets form in a manner similar to that of Earth? (viewed 9657 times)
  760. Will the Pioneer and Voyager probes ever leave the Milky Way? (viewed 9616 times)
  761. Will Comet Elenin (C/2010 X1) affect the Earth on its close approach in Fall 2011? (viewed 9615 times)
  762. What are the possible ends of the universe? (viewed 9590 times)
  763. If there are infinity universes, will every thing that is possible happen? (viewed 9425 times)
  764. Is it sensible to consider terraforming Mars? (viewed 9370 times)
  765. What color are meteors? (viewed 9047 times)
  766. Where is everybody? (viewed 8629 times)
  767. Why does Mars have a dusty atmosphere? (viewed 8262 times)
  768. Does the singularity in a black hole create a new Universe? (viewed 8127 times)
  769. The naming of Mars (viewed 8124 times)
  770. If I were traveling through space, could I see distant galaxies with my own eyes? (viewed 8077 times)
  771. Is the reddish dust of Mars biogenic? (viewed 7916 times)
  772. Where is the Spitzer Space Telescope? (viewed 7360 times)
  773. When will humans travel to Mars and revisit the Moon? (viewed 7124 times)
  774. Why do astronomers use telescopes? (viewed 6901 times)
  775. How likely is it for a planet to transit its star? (viewed 6559 times)
  776. Does the particles involved in a star's final core collapse travel faster than the speed of light? (viewed 6467 times)
  777. What causes the aurora? (viewed 6424 times)
  778. When is the best time to observe zodiacal light? (viewed 6300 times)
  779. How did a transit of Venus provide astronomers with the first measurement of the Earth-Sun distance? (viewed 5275 times)
  780. Can the Sun be closer to the Earth than any planet is to Earth? (viewed 4680 times)
  781. Cosmologists say the expansion of the universe is accelerating, what is driving this? (viewed 4091 times)
  782. Can we hear sound on Titan? (viewed 3852 times)
  783. Does the direction of the moon's crescent change through the night? (viewed 3701 times)
  784. What do all the angles in a table for a planet's orbit mean? (viewed 3558 times)
  785. How do I maximize my chances of seeing shooting stars? (viewed 2934 times)
  786. Are exoplanets real? (viewed 2527 times)
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