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 2103048 times)
  2. What color is each planet? (viewed 862413 times)
  3. At what speed does the earth move around the sun? (viewed 546388 times)
  4. Is the Moon moving away from the Earth? When was this discovered? (viewed 525778 times)
  5. How far is each planet from Earth? (viewed 450831 times)
  6. When will Halley's Comet return? (viewed 392233 times)
  7. How many stars are there in our Galaxy (Milky Way)? (viewed 376985 times)
  8. How long does it take for the Sun's light to reach us? (viewed 371977 times)
  9. Why do the planets orbit the sun? (viewed 357206 times)
  10. What is the universe expanding into? (viewed 354911 times)
  11. How do you measure the distance between Earth and the Sun? (viewed 322419 times)
  12. Which planets have rings? (viewed 315501 times)
  13. Why do stars twinkle? (viewed 303835 times)
  14. Does the Moon rotate? Are there other moons that always keep one face toward their planet? (viewed 291969 times)
  15. How do I build a model rocket? (viewed 282405 times)
  16. What color is Venus? (viewed 266758 times)
  17. What is a white hole? (viewed 259063 times)
  18. What is the life cycle of a star? (viewed 241468 times)
  19. What are the names of the earth, moon, sun, and solar system? (viewed 229117 times)
  20. Can you hear sounds in space? (viewed 223847 times)
  21. What is the largest star? (viewed 219825 times)
  22. What is that ring (or rainbow) around the moon? (viewed 218716 times)
  23. What makes the Earth rotate? (viewed 217468 times)
  24. What are shooting stars? (viewed 216135 times)
  25. What do astronauts eat in space? Can they grow food? (viewed 198244 times)
  26. Why do planets rotate? (viewed 193150 times)
  27. How do we know the age of the Universe and the Earth? (viewed 190505 times)
  28. Can artificial gravity be created in space? (viewed 187077 times)
  29. Is the universe expanding faster than the speed of light? (viewed 185896 times)
  30. How does the location of sunrise and sunset change throughout the year? (viewed 176150 times)
  31. Where did the name 'Earth' come from? (viewed 173754 times)
  32. How many Earths fit into the Sun? (viewed 169591 times)
  33. What would happen if we did not have a Moon? (viewed 169264 times)
  34. How can we see the Milky Way if we are inside it? (viewed 167549 times)
  35. Why is a day divided into 24 hours? (viewed 156985 times)
  36. How does the position of Moonrise and Moonset change? (viewed 151453 times)
  37. Who named the planets and who decides what to name them? (viewed 149459 times)
  38. Is Pluto a planet? (viewed 147425 times)
  39. Is the distance from the Earth to the Sun changing? (viewed 145512 times)
  40. Why are the Moon and Sun sometimes orange or red? (viewed 143537 times)
  41. When was the last time all 9 planets were aligned? (viewed 142869 times)
  42. What is at the end of the Universe? (viewed 138780 times)
  43. Why do airplanes take longer to fly West than East? (viewed 134965 times)
  44. How much money is spent on space exploration? (viewed 134219 times)
  45. What are the different kinds of astronomers? (viewed 131830 times)
  46. How can I find the star I have "bought"? (viewed 131618 times)
  47. Why are there both high and low tides? (viewed 128622 times)
  48. What is the largest galaxy? (viewed 125806 times)
  49. How many known galaxies are there? (viewed 124244 times)
  50. What direction do planets rotate? (viewed 123953 times)
  51. Is the Sun expanding? Will it ever explode? (viewed 123044 times)
  52. How do astronauts take baths and use restrooms in space? (viewed 122203 times)
  53. Can we feel the Earth spin? (viewed 121457 times)
  54. Do stars move in the sky? (viewed 117984 times)
  55. Can I buy a star? (viewed 112831 times)
  56. Does your weight change between the poles and the equator? (viewed 111967 times)
  57. Will the sun go supernova in six years and destroy Earth (as seen on Yahoo)? (viewed 110908 times)
  58. What are the advantages and disadvantages of using a telescope in space? (viewed 109786 times)
  59. What is a nova? (viewed 109576 times)
  60. What is the hottest time of day? (viewed 108036 times)
  61. Are there telescopes that can see the flag and lunar rover on the Moon? (viewed 107664 times)
  62. How are light and heavy elements formed? (viewed 106969 times)
  63. How do stars move in the Galaxy? (viewed 106888 times)
  64. Why do all the planets orbit in the same plane? (viewed 106136 times)
  65. Will the magnetic field of the Earth reverse its direction in the future? Will this cause problems? (viewed 105350 times)
  66. What happens when galaxies collide? (viewed 105261 times)
  67. Does the Sun have a scientific name? (viewed 105123 times)
  68. When is the next comet due to arrive? (viewed 104420 times)
  69. What was there before the Big Bang and what is there outside of our universe? (viewed 104010 times)
  70. What is the size of the Solar System? (viewed 103920 times)
  71. Why hasn't NASA gone back to the moon? (viewed 103141 times)
  72. How do rockets work? (viewed 102881 times)
  73. Why do planets have elliptical orbits? (viewed 102621 times)
  74. Who first measured the speed of light? (viewed 102534 times)
  75. What would happen if an impact caused Earth to stop rotating? (viewed 102209 times)
  76. How long does a solar eclipse last? (viewed 102162 times)
  77. How much money do astronomers make? (viewed 101537 times)
  78. How many constellations are there? (viewed 99955 times)
  79. What will happen to life on Earth when the Sun becomes a red giant? (viewed 99585 times)
  80. Do black holes die? If so how? (viewed 99552 times)
  81. What elements make up the Sun? (viewed 98909 times)
  82. How do you calculate the lifetime of the Sun? (viewed 98654 times)
  83. Does the Sun move around the Milky Way? (viewed 97611 times)
  84. Does the Sun rotate? (viewed 97569 times)
  85. What is the observational difference between a star and a planet? (viewed 96221 times)
  86. What is the physical difference between a star and a planet? (viewed 95800 times)
  87. What is the significance of the Tropic of Cancer, Tropic of Capricorn, Arctic Circle and Antarctic Circle? (viewed 94401 times)
  88. Does evolution contradict the second law of thermodynamics? (viewed 93626 times)
  89. What's the difference between astronomy and astrology? (viewed 92879 times)
  90. What is apparent magnitude? (viewed 92470 times)
  91. What do astronauts do all day in the International Space Station? (viewed 90752 times)
  92. Which planet is most similar to Earth? (viewed 90209 times)
  93. If Mars is only about 35-60 million miles away at close approach, why does it take 6-8 months to get there? (viewed 88628 times)
  94. How critical is the Earth-Sun distance in maintaining our average temperatures on Earth? (viewed 88528 times)
  95. Does gravity vary across the surface of the Earth? (viewed 88256 times)
  96. How many meteorites hit Earth each year? (viewed 87637 times)
  97. How do astronomers use math in their jobs? (viewed 86311 times)
  98. Have astronomers discovered Earth's second moon? (viewed 86093 times)
  99. What would happen if the gravity on Earth was suddenly turned off? (viewed 86077 times)
  100. Why are stars and planets round? (viewed 86003 times)
  101. Why do different stars appear with seasons? (viewed 85790 times)
  102. What are constellations used for? (viewed 85591 times)
  103. Is there a proof that Earth moves? (viewed 85328 times)
  104. Where did the Universe come from? (viewed 84606 times)
  105. Does the Sun orbit the Earth as well as the Earth orbiting the Sun? (viewed 84272 times)
  106. What would happen if an asteroid 10 kilometers across hit the Earth? (viewed 84258 times)
  107. Why is the Moon so bright? (viewed 83869 times)
  108. Why is the Universe flat and not spherical? (viewed 83662 times)
  109. What makes the wind? (viewed 82908 times)
  110. What is a singularity? (viewed 82588 times)
  111. Where does the name "Milky Way" come from? (viewed 80059 times)
  112. What kind of schooling is necessary to become an astronomer? (viewed 79967 times)
  113. Why does the Earth tilt back and forward once a year? (viewed 79571 times)
  114. How can a star burn with no oxygen? (viewed 79485 times)
  115. What would happen if Earth had more than one moon? (viewed 79126 times)
  116. What are RA and DEC? (viewed 78830 times)
  117. Considering the motion of the Earth, the solar system, and the galaxy, how fast am I moving while lying in bed asleep? (viewed 77980 times)
  118. What kind of rock is the moon made of? (viewed 76815 times)
  119. Why isn't the sky bright at night if the universe has so many stars? (viewed 75853 times)
  120. Did astronauts really go to the Moon, or is it a hoax? (viewed 75235 times)
  121. Why aren't there any green stars? (viewed 74605 times)
  122. Since Earth is spinning, why do we land in the same place when we jump or fall? (viewed 74547 times)
  123. How are galaxies formed? (viewed 74356 times)
  124. How many stars are born and die each day? (viewed 73480 times)
  125. What is the difference between a "star" and a "sun"? (viewed 72940 times)
  126. Who has landed on the moon? (viewed 72414 times)
  127. How are black holes made? Could one be made close to us? (viewed 72379 times)
  128. Will the Sun become a black hole one day? (viewed 71706 times)
  129. What would happen if a supermassive black hole came close to the Earth? (viewed 71509 times)
  130. What is the density of a black hole? (viewed 70931 times)
  131. What are the requirements for being a planet? (viewed 70839 times)
  132. What would you see from inside a black hole? (viewed 69607 times)
  133. Do most astronomers believe in God based on the available scientific evidence? (viewed 68381 times)
  134. Can you fire a gun on the Moon? (viewed 67935 times)
  135. Can moons have moons? (viewed 67895 times)
  136. How do astronomers measure the brightness of stars? (viewed 67741 times)
  137. How do rockets move in space? (viewed 67396 times)
  138. What happens to a substance if its speed is more than the speed of light? (viewed 67300 times)
  139. Why can't you see stars during the day? (viewed 67253 times)
  140. How often does the Sun pass through a spiral arm in the Milky Way? (viewed 67156 times)
  141. What are some of the effects of solar flares on Earth? (viewed 66831 times)
  142. Why is the moon in a different place every night? (viewed 66752 times)
  143. How can the Universe expand faster than the speed of light during inflation? (viewed 66526 times)
  144. How do we weigh objects in space? (viewed 66483 times)
  145. Is it possible to measure the temperature of the Sun? (viewed 66170 times)
  146. How is astronomy impacted by trigonometry? (viewed 65856 times)
  147. How do we know the mass of the Earth and the Moon? (viewed 65740 times)
  148. When the Sun converts mass to energy, do the orbits of the planets change? (viewed 65548 times)
  149. How does the Sun compare to other stars? (viewed 65351 times)
  150. What are the "dog days of summer"? (viewed 65123 times)
  151. What would happen if you took off your helmet in space? (viewed 65056 times)
  152. Why do stars change colour when they twinkle? (viewed 64056 times)
  153. How do you measure a planet's mass? (viewed 64026 times)
  154. How does the Moon stay "suspended" in the air? (viewed 63960 times)
  155. What kinds of jobs do astronomers do? (viewed 63826 times)
  156. Does the Mediterranean sea have tides? (viewed 63527 times)
  157. How are elements heavier than iron formed? (viewed 63243 times)
  158. What are black holes made of? (viewed 62484 times)
  159. What causes seasons? (viewed 62273 times)
  160. What is the evidence supporting the nebula theory of Solar System formation? (viewed 61997 times)
  161. If the universe is infinite does that mean there is an infinite number of "me"s? (viewed 61944 times)
  162. Does quantum entanglement imply faster than light communication? (viewed 61881 times)
  163. When can I see the Moon through the hole in the Pantheon? (viewed 61866 times)
  164. Why do we not have eclipses every month? (viewed 61268 times)
  165. Why doesn't the earliest sunset occur on the shortest day of the year? (viewed 61125 times)
  166. How did the stars get named? (viewed 60970 times)
  167. How did asteroids form and what is the difference between an asteroid and a comet? (viewed 60511 times)
  168. How fast is the Universe expanding? (viewed 60463 times)
  169. Where does the name "Moon" come from? (viewed 60296 times)
  170. What's the best college for astronomy? (viewed 60167 times)
  171. Why doesn't the length of each day change much around the solstices? (viewed 59908 times)
  172. Why do planets not twinkle? (viewed 59753 times)
  173. What are Altitude and Azimuth? (viewed 59633 times)
  174. What would happen to us if the sun went out for an hour? (viewed 59464 times)
  175. Traveling at light speed, how long would it take to get to the nearest galaxy? (viewed 59384 times)
  176. How do you measure the mass of a star? (viewed 59366 times)
  177. How long would it take the Earth to fall into the Sun? (viewed 59283 times)
  178. Where did the matter in the universe come from? (viewed 59138 times)
  179. Are there stars outside of galaxies? (viewed 58703 times)
  180. What is the mass of the Universe? (viewed 58644 times)
  181. Where, in relation to the entire universe, is the Milky Way located? (viewed 57854 times)
  182. How does light pollution affect astronomers? (viewed 57818 times)
  183. Does the Moon rotate? (viewed 57589 times)
  184. Could there be life in the galaxies nearest to the Milky Way? (viewed 57232 times)
  185. How can I calculate the position or path of the Sun for a given time and location? (viewed 56758 times)
  186. Why does the Earth have only one moon? (viewed 56555 times)
  187. Why does the Sun's apparent path through the sky change throughout the year? (viewed 56026 times)
  188. Can any galaxies be seen with the naked eye? (viewed 55895 times)
  189. What's the difference between dark matter and dark energy? (viewed 55514 times)
  190. What is the shape of the universe? (viewed 55329 times)
  191. What is the largest structure in the universe? (viewed 55119 times)
  192. How does the parachute in a model rocket work? (viewed 54690 times)
  193. What is the origin of spiral structure in galaxies? (viewed 54677 times)
  194. Where are stars born? (viewed 54307 times)
  195. How long does the supernova stage of a star last? (viewed 54054 times)
  196. How close was the Moon to the Earth when it formed? (viewed 53895 times)
  197. How does astronomy benefit humankind? (viewed 53840 times)
  198. Are names given to black holes? (viewed 53718 times)
  199. What makes up most of the Universe? (viewed 53698 times)
  200. What is the size of a black hole? (viewed 53237 times)
  201. Can you see satellites? (viewed 53093 times)
  202. What is a star's "spectrum"? (viewed 52882 times)
  203. How do astronauts use math in their jobs? (viewed 52852 times)
  204. Why isn't the summer solstice the hottest day of the year? (viewed 52823 times)
  205. Which constellation does our Sun belong to? (viewed 52188 times)
  206. How do you calculate the azimuth and altitude of an object? (viewed 51964 times)
  207. What can we learn from the color of a star? (viewed 51891 times)
  208. How do we measure the size of the Moon and of the Sun? (viewed 51830 times)
  209. Are aliens or UFOs real? (viewed 51672 times)
  210. Why do we see stars? (viewed 51140 times)
  211. Why is looking out into space the same as looking back in time? (viewed 51089 times)
  212. How can I find the distance to the Sun on any given day? (viewed 50999 times)
  213. How can I measure the distance of a star? (viewed 50832 times)
  214. What are some astronomy science fair projects? (viewed 50776 times)
  215. What other careers involve Astronomy besides Astronomer? (viewed 50676 times)
  216. If gravity is a "curvature of space" rather than a force, why do a ball and bullet follow different paths? (viewed 50486 times)
  217. What happens to a bullet fired on the moon? (viewed 50413 times)
  218. Is the speed of light constant? (viewed 50388 times)
  219. 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 49798 times)
  220. Are there any asteroids on a collision course with Earth? (viewed 49649 times)
  221. How long has there been water on Earth? (viewed 49577 times)
  222. Is time travel possible? (viewed 49505 times)
  223. How do the astronauts communicate in space if sound cannot travel in a vacuum? (viewed 49284 times)
  224. Who discovered each planet? (viewed 49214 times)
  225. Which hemisphere has the best view of the Milky Way? (viewed 49210 times)
  226. What would happen if the Moon fell out of its orbit around Earth? (viewed 48741 times)
  227. If the Earth's rotation period is less than 24 hours, why don't our clocks fall out of sync with the Sun? (viewed 48731 times)
  228. Why does the Moon look big on the horizon? (viewed 48463 times)
  229. Why is the sky blue and not blue & purple? (viewed 48365 times)
  230. Would your weight change as you go underground? (viewed 48297 times)
  231. Can we look back far enough in time to see the Big Bang? (viewed 48075 times)
  232. Why is it difficult to understand the expansion of the universe? (viewed 47923 times)
  233. Are meteorites hot or cold when they hit Earth? (viewed 47733 times)
  234. What do a galaxy's colors mean? Are they its true colors? (viewed 47354 times)
  235. What is a graviton? (viewed 47338 times)
  236. Why is twilight short near the equator? (viewed 47100 times)
  237. If light has no mass, then what draws it into a black hole? (viewed 47062 times)
  238. What is the difference between nutation and precession of the Earth? (viewed 46942 times)
  239. Are the planes of solar systems aligned with the plane of the Galaxy? (viewed 46353 times)
  240. How is the time of sunrise calculated? (viewed 46142 times)
  241. Where did all the water in the universe come from? (viewed 46109 times)
  242. What's the difference between astronomy and astrophysics? (viewed 46031 times)
  243. What skills do astronomers need? (viewed 45945 times)
  244. What do I need to do to become an astronomer? (viewed 45472 times)
  245. Do dead stars still shine? (viewed 45311 times)
  246. Where is the nearest black hole? (viewed 44800 times)
  247. How do gravitons escape black holes to tell the universe about their gravity? (viewed 44605 times)
  248. Do supermassive black holes cause galaxy rotation? (viewed 44505 times)
  249. Why do the size and brightness of the full moon change? (viewed 44361 times)
  250. Will we get sucked into the black hole at the center of the Milky Way? (viewed 44282 times)
  251. What is a wormhole? (viewed 44175 times)
  252. How are black holes discovered? (viewed 44024 times)
  253. How do we know what other planets (and stars, galaxies, etc.) are made of? (viewed 43992 times)
  254. Why can't we see Venus at night when it is an inner planet? (viewed 43807 times)
  255. Can I calculate the size of the Universe by converting light years to kilometres? (viewed 43756 times)
  256. How do galaxies collide in an expanding universe? (viewed 43588 times)
  257. The Moon slows the Earth's rotation, but how fast was it spinning billions of years ago? (viewed 43355 times)
  258. Is the Earth slowly getting larger? (viewed 43106 times)
  259. Why does the Sun appear larger on the horizon than overhead? (viewed 43068 times)
  260. Why are there stars? (viewed 43049 times)
  261. Why does Barnard 68 appear dark? (viewed 42972 times)
  262. Can we find the place where the Big Bang happened? (viewed 42581 times)
  263. What is the biggest crater recorded on Earth? (viewed 41871 times)
  264. Was the Sun made in a supernova? (viewed 41670 times)
  265. Why are most months 30 or 31 days long? (viewed 41115 times)
  266. How much longer will the Earth last? (viewed 41103 times)
  267. Are Kuiper Belt Objects asteroids? Are large Kuiper Belt Objects planets? (viewed 41022 times)
  268. Why does the location of sunrise change? (viewed 40916 times)
  269. Has there been an experiment that measured speed faster than the speed of light in vacuum? (viewed 40905 times)
  270. Can I buy land on the Moon? (viewed 40861 times)
  271. Could the Universe have expanded faster than the speed of light at the Big Bang? (viewed 40781 times)
  272. Are there eclipses on other planets? (viewed 40713 times)
  273. Why doesn't dark matter fall into a black hole? (viewed 40676 times)
  274. Is there a "South Star"? (viewed 40614 times)
  275. Is the Moon hollow? (viewed 40549 times)
  276. What is the best way to see the Milky Way? (viewed 40476 times)
  277. What happens when two black holes get too close? (viewed 40396 times)
  278. What's the biggest meteorite? (viewed 40337 times)
  279. How would the weather on Earth be different if it were a cube? (viewed 40332 times)
  280. What happens to spacetime inside a black hole? (viewed 40158 times)
  281. What is the difference between the "Doppler" redshift and the "gravitational" or "cosmological" redshift? (viewed 40113 times)
  282. What is time dilation? (viewed 40082 times)
  283. Why does the Earth only see one side of the Moon? (viewed 40048 times)
  284. Why don't people walk upside-down on the bottom of the Earth? (viewed 39989 times)
  285. Did life originate on Earth, or did it come from somewhere else? (viewed 39917 times)
  286. What color would Mars be if you were standing on it? (viewed 39852 times)
  287. What is the most distant known galaxy? (viewed 39759 times)
  288. How does Astronomy involve Chemistry? (viewed 39677 times)
  289. How can two moons of Saturn share the same orbit? (viewed 39266 times)
  290. How long could life on Earth survive if the Sun stopped shining? (viewed 39006 times)
  291. How much can the location of sunset differ from due West? (viewed 38937 times)
  292. What are the names of the three stars in Orion's belt? (viewed 38830 times)
  293. How long would it take for a mini-black hole to eat the Earth? (viewed 38751 times)
  294. Can terrestrial planets have rings? (viewed 38711 times)
  295. How many Astronauts have been in space? (viewed 38498 times)
  296. Could someone travel the universe in his or her own lifetime? (viewed 38433 times)
  297. What if the Earth rotated twice as fast? (viewed 38326 times)
  298. Why do pictures of distant galaxies have higher resolution than those of nearby planets? (viewed 38290 times)
  299. What are "blue stragglers" in globular clusters? (viewed 37888 times)
  300. What is the typical size of a visible shooting star? (viewed 37797 times)
  301. Does Mt. Everest cast a shadow on the moon? (viewed 37708 times)
  302. Why do people draw stars with five points? (viewed 37705 times)
  303. If a white dwarf is a "dead" star, why is it so hot? (viewed 37493 times)
  304. Can the acceleration of the Universe be analogous to apparent acceleration in a airplane? (viewed 37427 times)
  305. Is it possible to see the full Moon and the Sun simultaneously in high northern latitudes when the Sun doesn't set? (viewed 37316 times)
  306. Is the Great Wall the largest galaxy cluster? (viewed 37295 times)
  307. How do we know that nuclear fusion is still going on in the Sun? (viewed 37213 times)
  308. How does night and day work? (viewed 37193 times)
  309. What is the speed of gravity? (viewed 37113 times)
  310. How do we feel heat? (viewed 37031 times)
  311. What can I use for fuel in my homemade rocket? (viewed 36968 times)
  312. Can a person go into a black hole and come out alive? (viewed 36945 times)
  313. How fast does the Earth go at perihelion and aphelion? (viewed 36924 times)
  314. How big is the universe? (viewed 36879 times)
  315. Where is the supernova remnant that led to our solar system? (viewed 36729 times)
  316. What is Earthrise over the Moon? (viewed 36693 times)
  317. What is a dimension? (viewed 36679 times)
  318. Can I communicate faster than light? (viewed 36640 times)
  319. Where do planetary rings come from, and what are they made of? (viewed 36515 times)
  320. Can you see the future as you fall into a black hole? (viewed 36387 times)
  321. On which days can I see the Moon in the evening / morning and why is this so? (viewed 36367 times)
  322. What is the approximate GPA needed in High School in Math and Science to be an astronomer? (viewed 36177 times)
  323. Why are Saturn's rings flat? (viewed 36169 times)
  324. Does the Sun have an iron surface? (viewed 36029 times)
  325. Is there really a 10th planet? (viewed 36021 times)
  326. Are all stars the same? (viewed 35893 times)
  327. Why can we see the sun's image before sunrise and after sunset? (viewed 35856 times)
  328. Why is sea water salty, and not lake water? (viewed 35838 times)
  329. What would happen to the Earth if an asteroid hit the Moon? (viewed 35811 times)
  330. How many stars can I see? (viewed 35776 times)
  331. How do I tell which planet is which? (viewed 35707 times)
  332. Do you think it's possible to maintain life on other planets? (viewed 35682 times)
  333. How do we determine the age of the universe? (viewed 35636 times)
  334. Does the Coriolis force determine which way my toilet drains? Does it affect black holes? (viewed 35625 times)
  335. Who (and when) discovered that the earth's axis is on a 23 degree tilt? (viewed 35612 times)
  336. What companies or businesses can astronomers work for? (viewed 35512 times)
  337. Do the Sun's or Earth's magnetic field reverse? (viewed 35265 times)
  338. Is the Sun always up for exactly 12 hours at the equator? (viewed 35176 times)
  339. Is there a beginning and an end to a galaxy's life? (viewed 35042 times)
  340. If the universe is 15 billion years old, how can it be larger than 15 billion light years across? (viewed 34994 times)
  341. How can I find my age on another planet? (viewed 34639 times)
  342. Is Andromeda part of the Milky Way? Where can I find them in the sky? (viewed 34461 times)
  343. How do we know the Milky Way is a spiral galaxy? (viewed 34419 times)
  344. Why do clocks turn in the opposite direction from the Earth and Moon? (viewed 34374 times)
  345. How do we define distance in an expanding universe? (viewed 34294 times)
  346. Why have star signs shifted by one constellation? (viewed 34177 times)
  347. What was that really big falling star that I saw? (viewed 34143 times)
  348. How can the universe be "flat"? We're 3D! (viewed 33917 times)
  349. How are photons created and destroyed? (viewed 33850 times)
  350. How does the brightness of a star depend on its distance from us? (viewed 33500 times)
  351. When we look back to the Big Bang, why don't we see the universe as a tiny speck of matter? (viewed 33494 times)
  352. Who came up with the name "black hole"? (viewed 33442 times)
  353. Why do humans want to go in space? (viewed 33430 times)
  354. Is the Earth at the centre of the Universe? (viewed 33396 times)
  355. What would happen if two stars collided? (viewed 33388 times)
  356. What is the pattern to the distances between each planet and the sun? (viewed 33359 times)
  357. Why don't astronomers use everyday units to measure distances (what is an AU or a pc)? (viewed 33317 times)
  358. How can we estimate the number of Earth-like planets in the Galaxy? (viewed 33259 times)
  359. What is the significance of the second focus of elliptical orbits of planets in our Solar System? (viewed 33233 times)
  360. Is there a simple formula to calculate solar eclipse timings from any position on Earth? (viewed 33212 times)
  361. How do astronauts communicate with their families from space? (viewed 33172 times)
  362. Can a lunar and a solar eclipse happen in the same month? When will this happen next? (viewed 33150 times)
  363. How are planets detected around other stars? (viewed 33123 times)
  364. Are Earth and the Moon "twin planets"? (viewed 32933 times)
  365. How is it that we see farther out in space (farther back in time) than in the past? (viewed 32909 times)
  366. Will the Moon be invisible in 500 million years? (viewed 32880 times)
  367. Will we ever stop having solar eclipses because of the moon's motion away from the Earth? (viewed 32735 times)
  368. Which American colleges teach astronomy? (viewed 32704 times)
  369. How dangerous are the asteroids? (viewed 32693 times)
  370. Why are there blue shifted galaxies? (viewed 32551 times)
  371. Why is our solar system so different from all the others we've found? (viewed 32527 times)
  372. Can we colonize other planets? (viewed 32474 times)
  373. What kind of eyepieces do I need to look at planets? (viewed 32343 times)
  374. Why is Uranus tipped on its side? (viewed 32275 times)
  375. How do I become both an astronaut and an astronomer? (viewed 31894 times)
  376. How can I calculate distances between stars? (viewed 31735 times)
  377. What are quasars made of? (viewed 31706 times)
  378. Why doesn't gravity change the speed of light? (viewed 31451 times)
  379. Why do constellations look the same after several years even though all the stars are moving? (viewed 31287 times)
  380. Is it possible to count the stars? (viewed 31230 times)
  381. Is time travel possible using merging black holes? (viewed 31205 times)
  382. Why do astronauts in space need to exercise? (viewed 31126 times)
  383. Why are there no craters on Earth? Did all the meteorites miss us? (viewed 31086 times)
  384. How do sunrise and sunset times change with altitude? (viewed 31085 times)
  385. What is happening just around the black hole in the center of the Milky Way? (viewed 30987 times)
  386. Is the gravitational force exerted by the Earth on the Moon equal to the centripetal force acting on the Moon? (viewed 30926 times)
  387. What is dark matter? (viewed 30859 times)
  388. How hot is each one of the layers of the sun? (viewed 30830 times)
  389. Did the speed of light change over the history of the universe? (viewed 30673 times)
  390. How can we distinguish a star's "real" color from the change in color that we observe due to the star's motion? (viewed 30645 times)
  391. Can we see dead stars with the naked eye? (viewed 30611 times)
  392. How big a change in the Earth's orbit would be required to destroy all life? (viewed 30605 times)
  393. Is the universe really like an expanding balloon? (viewed 30472 times)
  394. How do we measure distances to other stars? (viewed 30447 times)
  395. Can superheavy elements (such as Z=116 or 118) be formed in a supernova? Can we observe them? (viewed 30436 times)
  396. Is it true that the Sun burns off a billion tons of gas every 5 seconds? (viewed 30434 times)
  397. Are time machines possible? (viewed 30350 times)
  398. What happens when an antimatter black hole collides with a matter blackhole? (viewed 30319 times)
  399. How do I make a scale model of the Solar System? (viewed 30193 times)
  400. How many moles of stars are in the known universe? (viewed 29887 times)
  401. Is there any limitation to what a black hole can "suck" in? (viewed 29688 times)
  402. Can you describe a day on the job as an astronomer? (viewed 29630 times)
  403. How are galaxy distances inferred from their recessional velocities? (viewed 29516 times)
  404. What's that dark spot on the Sun? (viewed 29298 times)
  405. What is the farthest in space that we have gone? (viewed 29148 times)
  406. How can we tell what the interiors of planets are like? (viewed 29066 times)
  407. How can I tell if the rock I found is a meteorite? (viewed 29038 times)
  408. What happens when you change the mass of a White Dwarf or Neutron Star? (viewed 29001 times)
  409. What are the closest and/or brightest stars? (viewed 28945 times)
  410. How can we know that there are other galaxies if we cannot leave ours? (viewed 28925 times)
  411. Is the Local Group expanding along with the entire Universe? (viewed 28902 times)
  412. Can astronauts produce water in space? (viewed 28731 times)
  413. Could an astronaut or satellite fall into a black hole that we didn't know about? (viewed 28718 times)
  414. Will the seasons change due to precession? (viewed 28704 times)
  415. What are the facts about the Star of Bethlehem? (viewed 28640 times)
  416. Why is the time between two successive full moons different from the lunar synodic month? (viewed 28640 times)
  417. Did I see the Aurora Borealis as a child? (viewed 28638 times)
  418. Don't tachyons travel faster than light? (viewed 28601 times)
  419. Do astronomers believe in astrology? (viewed 28575 times)
  420. Why do most moons orbit their planets at the equator? (viewed 28563 times)
  421. Aren't jobs in astronomy scarce? (viewed 28501 times)
  422. What are the atmospheres of Mars and Pluto like? (viewed 28460 times)
  423. How long does it take the Big Dipper to move in the sky? (viewed 28457 times)
  424. How was the starting point for the Julian Date system chosen? (viewed 28440 times)
  425. What do "homogeneity" and "isotropy" mean? (viewed 28406 times)
  426. Why does the SETI project search for radio signals? (viewed 28389 times)
  427. When are there 5 Sundays in February? (viewed 28248 times)
  428. Has anyone made a map of the Milky Way? (viewed 28226 times)
  429. Why do we study black holes? (viewed 28194 times)
  430. How do we know if the universe will keep expanding forever? (viewed 28192 times)
  431. Wouldn't the Big Bang theory be considered a hypothesis and not a theory? (viewed 28184 times)
  432. Was I hit by a meteorite? (viewed 28158 times)
  433. How are galaxies named? (viewed 28044 times)
  434. What does the term "visible universe" mean? (viewed 27930 times)
  435. Why can't a plane fly slowly and let the Earth pass underneath? (viewed 27928 times)
  436. What colors are visible through an amateur telescope? (viewed 27875 times)
  437. How can geometry be different in space? (viewed 27820 times)
  438. Does the Milky Way spin counter-clockwise? If so, do all spiral galaxies spin in this direction and why? (viewed 27773 times)
  439. Could you tell me about the life cycle of galaxies? (viewed 27579 times)
  440. Can you use an infinite line of reflectors to send light to the edge of the Universe? (viewed 27546 times)
  441. Why are the compositions of comets and asteroids different? (viewed 27478 times)
  442. Do you believe in UFOs? (viewed 27476 times)
  443. How do asteroids, meteors and comets disappear? (viewed 27302 times)
  444. Will winter and summer constellations change due to abnormal warmth or cold on Earth? (viewed 27298 times)
  445. How much time do astronomers spend looking through telescopes? (viewed 27177 times)
  446. How will the two black holes that are going to collide affect Earth? (viewed 27166 times)
  447. Have there been other Big Bangs before? (viewed 27078 times)
  448. What's the best thing about being an astronomer? (viewed 26961 times)
  449. Do we see the same stars from above and below the equator? (viewed 26950 times)
  450. How can we see galaxies if their stars are so faint? (viewed 26945 times)
  451. Can life exist on the recently discovered extrasolar planets? (viewed 26914 times)
  452. How do astronomers measure the radius of a star? (viewed 26778 times)
  453. How close do you have to come to the Earth to be influenced by its gravity? (viewed 26743 times)
  454. Is the Milky Way a collision of two galaxies? (viewed 26648 times)
  455. Can two lunar eclipses occur in the same month? (viewed 26601 times)
  456. How do I explain to my children why the Moon has phases? (viewed 26600 times)
  457. How are galaxies and solar systems similar? (viewed 26574 times)
  458. Is there a project I can do on black holes? (viewed 26574 times)
  459. How can we measure distances to more stars? (viewed 26535 times)
  460. Why do so many of the world's UFO sightings happen in America? (viewed 26408 times)
  461. Could you escape from a black hole if you were able to go faster than the speed of light? (viewed 26406 times)
  462. How do scientists slow light down? (viewed 26296 times)
  463. Is infinite temperature possible? (viewed 26289 times)
  464. Do we know everything about the Sun? (viewed 26270 times)
  465. How close does a supernova need to be to damage the Earth's environment? (viewed 26151 times)
  466. Do the magnitudes and colors of stars ever change? (viewed 26087 times)
  467. Can one star orbit another? (viewed 26028 times)
  468. Can "tired light theory" explain the observed redshifts of galaxies? (viewed 25977 times)
  469. How far does a galaxy extend? (viewed 25852 times)
  470. Is it worthwhile to continue the search for extraterrestrial life? (viewed 25851 times)
  471. What supernova created the Crab nebula? (viewed 25801 times)
  472. How do I polar align my telescope? (viewed 25780 times)
  473. Is there such a thing as hyperspace? (viewed 25716 times)
  474. What is the origin of the stellar classification system "OBAFGKM"? (viewed 25704 times)
  475. Can double stars have planets? (viewed 25703 times)
  476. What happens to the material that has been sucked into a black hole? (viewed 25650 times)
  477. What causes gamma ray bursts? (viewed 25647 times)
  478. Do asteroids hit the sun? (viewed 25626 times)
  479. What type of energy does a black hole have? (viewed 25605 times)
  480. What will happen to the Milky Way in the future? (viewed 25549 times)
  481. Why do the explosions of Type Ia supernovae have a more predictable spectrum than those of regular Type II supernovae? (viewed 25529 times)
  482. What is the farthest Northern Latitude in which the Magellanic Clouds can be seen? (viewed 25519 times)
  483. Can astronauts play musical instruments in space? (viewed 25500 times)
  484. What is sidereal time? (viewed 25451 times)
  485. Which way does the sun travel in the southern hemisphere? (viewed 25405 times)
  486. How will a change in the speed of light affect the evolution of the Universe? (viewed 25340 times)
  487. Is there oxygen in the atmospheres of other planets? (viewed 25160 times)
  488. How do we know what parameters to use when simulating the collision of the Milky Way and Andromeda? (viewed 25159 times)
  489. What's the object I saw that moved across the sky and then got very bright? (viewed 25119 times)
  490. What is "nothing", from a scientific point of view? (viewed 25064 times)
  491. Why did the Pioneer and Voyager take only 2 years to reach Jupiter, while Galileo and Cassini took more than 5 years? (viewed 25016 times)
  492. How do we know that sunspots are associated with the Sun's magnetic field? (viewed 25009 times)
  493. What is a Cepheid variable? (viewed 24979 times)
  494. How different would the night sky have looked in 40,000 B.C.? (viewed 24964 times)
  495. Why do we assume that the universe is homogeneous? (viewed 24893 times)
  496. Are there any dark stars or dark galaxies made of dark matter? (viewed 24866 times)
  497. Is there sound coming from the Sun? (viewed 24831 times)
  498. Was Stonehenge built to mark solar phenomena? (viewed 24802 times)
  499. What calculations go into predicting eclipses? (viewed 24776 times)
  500. Why is the shadow on the Moon the shape it is? (viewed 24729 times)
  501. Is there a list of the sizes of different kinds of stars? (viewed 24724 times)
  502. When unmanned spacecraft accelerate in space, what causes them to slow down? (viewed 24687 times)
  503. What is a Dyson Sphere? (viewed 24664 times)
  504. What's so exciting about the new planet around 55 Cancri? (viewed 24649 times)
  505. What process would bring about a quark star? (viewed 24645 times)
  506. Which part of the sky did the famous 'wow' signal originate from? (viewed 24645 times)
  507. What is the difference between homogeneity and isotropy? (viewed 24576 times)
  508. Did a giant impact cause the Dark Ages? (viewed 24554 times)
  509. Have gravitational waves been proven to exist? (viewed 24550 times)
  510. If we invented special suits could we ever go to the sun? (viewed 24531 times)
  511. When did people discover that the Sun is a star? (viewed 24516 times)
  512. Are planetary nebulae the result of supernovae? (viewed 24459 times)
  513. How many sunspots can the Sun have at once? (viewed 24448 times)
  514. Can I see a quasar? (viewed 24432 times)
  515. Can I see details on Venus? (viewed 24375 times)
  516. What is our galaxy's halo made of, and how was it formed? (viewed 24350 times)
  517. How are asteroid compositions and classifications determined? (viewed 24337 times)
  518. Can any comparison be made between spiral galaxies and hurricanes? (viewed 24305 times)
  519. Why are there active volcanos on Io? (viewed 24234 times)
  520. Is there any possibility that the Solar System or the Universe is in a black hole? (viewed 24153 times)
  521. What equipment do I need for astrophotography? (viewed 24128 times)
  522. Does Cerenkov radiation travel faster than light? (viewed 24111 times)
  523. Can a human give birth in space? (viewed 24079 times)
  524. How is it proved that the Universe is expanding? (viewed 24050 times)
  525. How big was the Sun when it first "fired up"? (viewed 23942 times)
  526. What happened to all the black holes that were around in the early universe? (viewed 23925 times)
  527. Why are there more maria on the near side of the Moon? (viewed 23904 times)
  528. If clocks run slow in a gravitational field, how can we know the true age of the Solar System and Universe? (viewed 23825 times)
  529. How can we compare dark matter and dark energy? (viewed 23823 times)
  530. Could we send a space mission to a comet? (viewed 23782 times)
  531. What caused Shoemaker-Levy 9 to split up? (viewed 23774 times)
  532. Why are telescopes kept in cold conditions? (viewed 23743 times)
  533. Could we be seeing dead stars? (viewed 23713 times)
  534. Why do photos of space taken from space never show any stars? (viewed 23670 times)
  535. If the Universe was infinitely dense at the Big Bang, why didn't time stand still? (viewed 23618 times)
  536. How are sunspots formed? (viewed 23603 times)
  537. How long do supernova remnants last? (viewed 23597 times)
  538. How do solar flares affect airline pilots? (viewed 23533 times)
  539. Would the biggest airplanes cause tsunamis if they crashed? (viewed 23508 times)
  540. Why doesn't light from distant galaxies reach us instantaneously? (viewed 23493 times)
  541. How many comets are currently orbiting our sun? (viewed 23404 times)
  542. As the universe expands, why don't galaxies get stretched out? (viewed 23396 times)
  543. What happened to the girl who named Pluto? (viewed 23396 times)
  544. Why is the Hubble Space Telescope in space? (viewed 23363 times)
  545. Could a different theory of gravity explain the dark matter mystery? (viewed 23328 times)
  546. How does the Earth compare in size to the entire universe at the present epoch? (viewed 23296 times)
  547. How do we know that superclusters are the largest structures in the universe? (viewed 23253 times)
  548. Can you tell time by the Big Dipper? (viewed 23222 times)
  549. Why doesn't NASA build rotating spacecraft to simulate gravity? (viewed 23210 times)
  550. How powerful are quasars? (viewed 23119 times)
  551. Can you give me advice on buying a telescope? (viewed 23109 times)
  552. Would extraterrestrial civilizations know that there is life on Earth? (viewed 23070 times)
  553. Can I build an instrument to measure the size of the Sun and of the Moon? (viewed 22983 times)
  554. Where does the kinetic energy of infalling bodies come from? (viewed 22940 times)
  555. How is the Cepheid yardstick validated? (viewed 22903 times)
  556. Did I really hear a meteor? (viewed 22876 times)
  557. Can supernovae hinder the formation of life in galaxies? (viewed 22828 times)
  558. What would happen if there was a collision between two white dwarfs? (viewed 22808 times)
  559. Are there any new craters on the moon? (viewed 22762 times)
  560. Do unmanned spacecraft like Voyager travel in straight lines? (viewed 22761 times)
  561. Why are stars of different masses? (viewed 22729 times)
  562. Why is it important to study meteorites? (viewed 22695 times)
  563. How do planets capture satellites? (viewed 22686 times)
  564. How big is the Hubble Ultra Deep Field image? (viewed 22686 times)
  565. Did time go slower just after the Big Bang? (viewed 22665 times)
  566. Do galaxies orbit around anything? (viewed 22625 times)
  567. Do similar laws of physics throughout the Universe imply that all life must be like life on Earth? (viewed 22617 times)
  568. What kind of instruments are used to detect extrasolar planets? (viewed 22606 times)
  569. How do I become an astronomical artist? (viewed 22553 times)
  570. Why are telescopes located in remote places? (viewed 22549 times)
  571. Does the Moon look different in the northern and southern hemispheres? (viewed 22377 times)
  572. Could there have been multiple Big Bangs at different places in the universe? (viewed 22348 times)
  573. How can I contribute to science as an amateur astronomer? (viewed 22315 times)
  574. Are the asteroids the remains of a planet which broke apart? (viewed 22274 times)
  575. Do the Earth's magnetic poles ever change places? (viewed 22269 times)
  576. What kind of telescope should I use for astrophotography? (viewed 22261 times)
  577. Are the properties of extrasolar planets known? (viewed 22225 times)
  578. How could galaxies have gotten so far away in only 15 billion years? (viewed 22208 times)
  579. What would happen if a human were exposed to space without wearing a spacesuit? (viewed 22204 times)
  580. How are astronomy and poetry linked? (viewed 22183 times)
  581. Why is NASA shutting down the Hubble Space Telescope? (viewed 22158 times)
  582. Can I listen to the SETI@home radio signal? (viewed 22156 times)
  583. How can you tell if a crescent moon is preceding or following a new-moon phase? (viewed 22146 times)
  584. Could dark energy come from matter anti-matter pairs forming spontaneously and then annihilating? (viewed 22126 times)
  585. Does the Sun have any heavy elements? (viewed 22115 times)
  586. What month was it when Odysseus saw Orion in 1000BC? (viewed 21997 times)
  587. Will we discover an 11th planet? What would it be called? (viewed 21993 times)
  588. Can the theory of formation of the solar system explain all the observables? (viewed 21972 times)
  589. How do unmanned space probes avoid running into things? (viewed 21881 times)
  590. Why can't relative velocities add up to more than the speed of light? (viewed 21847 times)
  591. What class of spiral galaxy is the Milky Way? (viewed 21804 times)
  592. 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 21800 times)
  593. Why does one side of Mars look more catastrophic than the other? (viewed 21725 times)
  594. Why does the apparent density of galaxies drop off at larger distances? (viewed 21658 times)
  595. What makes a satellite geosyncronise itself with Earth's orbit? (viewed 21646 times)
  596. Would a planet near the galactic center have a brighter night sky? (viewed 21615 times)
  597. What is the solar cycle? (viewed 21551 times)
  598. Is it possible for amateurs to do optical interferometry? (viewed 21417 times)
  599. How do astronomers observe the Sun's interior? (viewed 21351 times)
  600. Can other terrestrial moons be (or have been) stable? (viewed 21316 times)
  601. Can a black hole come back to the visual universe through a "little bang"? (viewed 21287 times)
  602. How are supernovae discovered? (viewed 21284 times)
  603. Why was the Platonic year named after Plato? (viewed 21264 times)
  604. Do stars' orbits in galaxies obey Kepler's Laws? (viewed 21246 times)
  605. Could we send a manned mission to the outer planets? (viewed 21190 times)
  606. Where was the water in the big bang? (viewed 21173 times)
  607. What would the Big Crunch look like to an observer on Earth? (viewed 21162 times)
  608. Does inflation allow for an infinite number of universes? (viewed 21129 times)
  609. Could our position in the universe affect our perceptions of the expansion? (viewed 21104 times)
  610. What is meant by "stopping down a telescope"? (viewed 21004 times)
  611. Why doesn't the hydrogen on Jupiter explode? (viewed 20924 times)
  612. Why are accretion disks flat? (viewed 20892 times)
  613. Does a photon observe other photons moving past it at the speed of light? (viewed 20763 times)
  614. Did I find a rock that came from the Moon? (viewed 20724 times)
  615. Can gravitational lensing from intervening galaxies cause the observed ripples in the Cosmic Microwave Background? (viewed 20689 times)
  616. Have astronomers observed any phenomena that could be produced by extraterrestrial civilizations? (viewed 20650 times)
  617. What is the SU(3) quark model? (viewed 20600 times)
  618. Why do spacecraft need heat shields coming back to Earth but not leaving? (viewed 20593 times)
  619. How can water be chemically trapped in rocks? (viewed 20587 times)
  620. How can the Sun have such a strong gravitational field if it's made of gasses? (viewed 20526 times)
  621. What's new with the Big Bang? (viewed 20425 times)
  622. Is it possible to build a cheap device to measure declination? (viewed 20265 times)
  623. If comets are boiling away, why are there any left? (viewed 20253 times)
  624. Could photons be dark matter? (viewed 20245 times)
  625. Will I be able to see the shadow of the Moon streaking towards me in a total solar eclipse? (viewed 20233 times)
  626. Why can we have solar eclipses? (viewed 20228 times)
  627. Why do some eclipses take longer than others? (viewed 20217 times)
  628. How fast do particles travel in space? (viewed 20162 times)
  629. Why search for only Earth-like life on other planets? (viewed 20145 times)
  630. How can we find galaxies behind the Milky Way? (viewed 20119 times)
  631. Where can I find information on the moons of other planets? (viewed 20086 times)
  632. Why is pressure broadening greater in low mass stars than in high mass stars? (viewed 19929 times)
  633. How much power is contained in a beam of light? (viewed 19918 times)
  634. What would an "open geometry" for the universe look like? (viewed 19862 times)
  635. What are the boundaries of the constellations? (viewed 19826 times)
  636. Why is the Cosmic Microwave Background not absorbed by interstellar hydrogen? (viewed 19786 times)
  637. How do astronomers come up with their facts? (viewed 19766 times)
  638. Why aren't discoveries of extrasolar planets reported on the news? (viewed 19734 times)
  639. Did the Sumerians measure precession? (viewed 19696 times)
  640. What kinds of star clusters are there? (viewed 19665 times)
  641. How do bars form in spiral galaxies? (viewed 19657 times)
  642. Why is the WMAP picture of the CMB an ellipse? (viewed 19657 times)
  643. Can HST see the Oort cloud? (viewed 19630 times)
  644. Why don't astronauts sublimate in space? (viewed 19578 times)
  645. Do electrons age? (viewed 19520 times)
  646. Can the Space Shuttle abort and return to Earth before reaching orbit? (viewed 19470 times)
  647. How do photons from distant objects maintain enough energy to reach us? (viewed 19470 times)
  648. Can we make a movie of the Milky Way galaxy's rotation? (viewed 19396 times)
  649. How long is twilight on the Moon? (viewed 19304 times)
  650. Does the shuttle worry about space junk? (viewed 19219 times)
  651. How does melting a material reset its radioactive clock? (viewed 19121 times)
  652. Why do supernova remnants look like rings rather than spheres? (viewed 19118 times)
  653. How did Mars get so dusty? (viewed 19111 times)
  654. How do you classify galaxies? (viewed 19015 times)
  655. Where can I see Newton's original reflecting telescope? (viewed 19005 times)
  656. What is the best time of the year to see eclipses? (viewed 18958 times)
  657. Why doesn't SETI concentrate its observations to the nearby stars and the solar systems that we are discovering? (viewed 18910 times)
  658. Do constellations looks the same from space? (viewed 18901 times)
  659. Will the next generation telescope OWL be able to detect an Earth like extrasolar planet? (viewed 18829 times)
  660. Will astronauts ever be able to go ice-skating on Europa? (viewed 18817 times)
  661. How can we understand the meaning of large numbers like "a million million?" (viewed 18768 times)
  662. What causes a particle to decay? (viewed 18766 times)
  663. Why don't all neutron stars become pulsars? (viewed 18760 times)
  664. Can planets collide with one another? (viewed 18758 times)
  665. Will the Leonid meteor shower go away? (viewed 18748 times)
  666. How can I nominate myself for a Nobel Prize in Physics? (viewed 18733 times)
  667. How long has humanity known that we live in a galaxy similar to others in the Universe? (viewed 18705 times)
  668. What are collections of galaxies called? (viewed 18660 times)
  669. Is light of different colors affected differently by gravity? (viewed 18629 times)
  670. What are "curled" dimensions? (viewed 18587 times)
  671. What was that eclipse I saw in the sky? (viewed 18545 times)
  672. How does interferometry work? (viewed 18433 times)
  673. How do we find out about the star formation histories of galaxies? (viewed 18339 times)
  674. Does the temperature of matter increase as it is accelerated to relativistic speeds? (viewed 18316 times)
  675. How do distant galaxies differ from those nearby? (viewed 18312 times)
  676. Do asteroids ever do anything good in the Solar System? (viewed 18269 times)
  677. Can astronomers observe anything when the moon is full? (viewed 18268 times)
  678. Wouldn't the vast distances of space distort SETI signals into unintelligeble forms? (viewed 18070 times)
  679. Do we really observe the edges of galaxies at different epochs? (viewed 18044 times)
  680. Can you tell me the characteristics of W, R, N and S type stars? (viewed 18020 times)
  681. Why is it called astronomy when all the other sciences end in -ology? (viewed 18014 times)
  682. What do stellar classifications mean? (viewed 18000 times)
  683. What kind of interference must astronomers contend with when observing? (viewed 17969 times)
  684. Why will fusion wait until hydrogen is gone before starting to fuse heavier atoms? (viewed 17958 times)
  685. How are astronauts trained for weightlessness? (viewed 17899 times)
  686. What would happen if you went back in time and killed your grandmother? (viewed 17891 times)
  687. If nothing can escape a black hole, why do some black holes have jets? (viewed 17891 times)
  688. How can I watch the Perseid meteor shower? (viewed 17882 times)
  689. Are black holes spherical? (viewed 17813 times)
  690. How does the color index of a star relate to its actual color? (viewed 17770 times)
  691. Will the diameter of a cluster of galaxies change with redshift? (viewed 17620 times)
  692. Why aren't accretion disks around giant stars as hot as accretion disks around black holes? (viewed 17614 times)
  693. If the universe is "bounded" today, could it one day become "unbounded"? (viewed 17583 times)
  694. Is cosmic expansion happening on microscopic scales? (viewed 17490 times)
  695. What is the three-body problem? (viewed 17461 times)
  696. How can I find out if the new moon has been sighted? (viewed 17395 times)
  697. Do we have to worry about relativity when studying galactic objects? (viewed 17201 times)
  698. Could neutrinos be dark matter? (viewed 17036 times)
  699. What kinds of cancer research have been done in space? (viewed 16992 times)
  700. How does a star take mass from another star? (viewed 16928 times)
  701. How can you tell the difference between single and multiple extrasolar planets? (viewed 16721 times)
  702. Could the Universe's dark matter be made up of black holes? (viewed 16612 times)
  703. What is Hot Dark Matter theory? (viewed 16611 times)
  704. Does lunar gardening really work? (viewed 16231 times)
  705. How does libration allow us to see more than 50% of the Moon? (viewed 16166 times)
  706. If photons have zero mass, why do they feel the effects of gravity? (viewed 16162 times)
  707. Is it a coincidence that we can have total solar eclipses? Are there other planets which also have them? (viewed 16093 times)
  708. How can observations of the distant universe prove that the expansion is accelerating *now*? (viewed 16089 times)
  709. Is light blueshifted when it is gravitationally lensed? (viewed 15979 times)
  710. Do binary or triple star systems form together? (viewed 15972 times)
  711. When measuring the expansion of the universe, do astronomers consider that they're seeing how galaxies moved long ago, not today? (viewed 15913 times)
  712. No matter how fast the universe is expanding, shouldn't gravity eventually make it recollapse? (viewed 15910 times)
  713. Is the green flash real? (viewed 15798 times)
  714. What is the photoelectric effect? Why can't multiple low-frequency photons free an electron? (viewed 15738 times)
  715. What percent of the time can astronomers observe without interference from the Moon? (viewed 15722 times)
  716. How do we know the density of some extrasolar planets? (viewed 15677 times)
  717. What do meteorites tell us about life on other planets? (viewed 15623 times)
  718. How do supernovae show us that the Universe's expansion is accelerating? (viewed 15513 times)
  719. Could matter-anti-matter repulsion power the expansion of the universe? (viewed 15434 times)
  720. Why is it easier to see a star if you look slightly to the side? (viewed 15421 times)
  721. Why doesn't the ammonia and methane in Jupiter's atmosphere sink into the core? (viewed 15018 times)
  722. Are there any 'lonely galaxies'? (viewed 15013 times)
  723. If the sun went out and our atmosphere froze solid, what color would it be? (viewed 14928 times)
  724. Can we prove that the Moon isn't hollow? (viewed 14826 times)
  725. How do we detect incoming meteorites? (viewed 14715 times)
  726. What was different on Mars in the past to allow liquid water to be present? (viewed 14605 times)
  727. During close approaches, can Mars appear in our sky as large as the Moon? (viewed 14386 times)
  728. When will Hale-Bopp return? (viewed 14366 times)
  729. Why don't skydivers burn up like meteors? (viewed 14174 times)
  730. How are planets affected by the Hot Ionised Medium? (viewed 14125 times)
  731. Has anyone ever seen a star "turn on"? (viewed 14045 times)
  732. What happens to the helium formed in the sun? (viewed 13996 times)
  733. Why was Mir burnt up in the atmosphere? (viewed 13652 times)
  734. What are the largest radio wavelengths observed from radio sources in the sky? (viewed 13599 times)
  735. How can we discern different galaxies/clusters along the same line of sight? (viewed 13582 times)
  736. Can the sun rise from the west on Mars? (viewed 13429 times)
  737. How has light from 13 billion years ago not passed us by? (viewed 13369 times)
  738. Why are craters round? (viewed 13338 times)
  739. What is the relationship between the width of a star trail on a photo and the star's intensity? (viewed 13158 times)
  740. Can we harvest H & O from space to make water? (viewed 12317 times)
  741. What is between the Oort cloud and the closest star? (viewed 12193 times)
  742. Why does Titan, in spite of being smaller than Mars, have an atmosphere more dense than Earth's? (viewed 11753 times)
  743. Does weightlessness affect hunger? (viewed 11336 times)
  744. Are there solar tides? (viewed 11304 times)
  745. Could a planetary system survive if its star merged with another, or if its star went supernova? (viewed 11296 times)
  746. What time is sunrise/sunset or moonrise/moonset at my location? (viewed 10552 times)
  747. Do planets radiate noise? (viewed 10494 times)
  748. Is Earth-moon tidal friction causing global warming? (viewed 10440 times)
  749. Is the moon spherical? (viewed 10151 times)
  750. What would happen if a nuclear-powered shuttle exploded? (viewed 10101 times)
  751. Is dark energy affected by black holes? (viewed 9845 times)
  752. What happens to the Earth as the moon gets farther away and will it ever go away entirely? (viewed 9510 times)
  753. Did the Moon or planets form in a manner similar to that of Earth? (viewed 9255 times)
  754. Do more meteorites fall at low latitudes? (viewed 9166 times)
  755. Is it sensible to consider terraforming Mars? (viewed 9014 times)
  756. Why is the Moon higher in the sky in winter and lower in the summer? (viewed 9006 times)
  757. If there are infinity universes, will every thing that is possible happen? (viewed 8942 times)
  758. Will Comet Elenin (C/2010 X1) affect the Earth on its close approach in Fall 2011? (viewed 8924 times)
  759. What are the possible ends of the universe? (viewed 8906 times)
  760. Where are the protons and electrons in a Neutron Star? (viewed 8891 times)
  761. 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 8822 times)
  762. Will the Pioneer and Voyager probes ever leave the Milky Way? (viewed 8784 times)
  763. What color are meteors? (viewed 8456 times)
  764. Wait, I'm still confused why information can't travel faster than the speed of light. (viewed 8424 times)
  765. Is the Moon always visible during winter on the North Pole? (viewed 8286 times)
  766. Where is everybody? (viewed 8254 times)
  767. Why does Mars have a dusty atmosphere? (viewed 7618 times)
  768. If I were traveling through space, could I see distant galaxies with my own eyes? (viewed 7569 times)
  769. The naming of Mars (viewed 7560 times)
  770. Does the singularity in a black hole create a new Universe? (viewed 7437 times)
  771. Is the reddish dust of Mars biogenic? (viewed 7246 times)
  772. Where is the Spitzer Space Telescope? (viewed 6828 times)
  773. When will humans travel to Mars and revisit the Moon? (viewed 6826 times)
  774. Does the particles involved in a star's final core collapse travel faster than the speed of light? (viewed 6166 times)
  775. When is the best time to observe zodiacal light? (viewed 5880 times)
  776. How likely is it for a planet to transit its star? (viewed 5299 times)
  777. Why do astronomers use telescopes? (viewed 4906 times)
  778. What causes the aurora? (viewed 4624 times)
  779. How did a transit of Venus provide astronomers with the first measurement of the Earth-Sun distance? (viewed 4398 times)
  780. Can the Sun be closer to the Earth than any planet is to Earth? (viewed 3569 times)
  781. Can we hear sound on Titan? (viewed 3387 times)
  782. Cosmologists say the expansion of the universe is accelerating, what is driving this? (viewed 3300 times)
  783. Does the direction of the moon's crescent change through the night? (viewed 3136 times)
  784. What do all the angles in a table for a planet's orbit mean? (viewed 2881 times)
  785. How do I maximize my chances of seeing shooting stars? (viewed 2123 times)
  786. Are exoplanets real? (viewed 1878 times)
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