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 2138005 times)
  2. What color is each planet? (viewed 926580 times)
  3. At what speed does the earth move around the sun? (viewed 595737 times)
  4. Is the Moon moving away from the Earth? When was this discovered? (viewed 574737 times)
  5. How far is each planet from Earth? (viewed 475900 times)
  6. When will Halley's Comet return? (viewed 431172 times)
  7. How long does it take for the Sun's light to reach us? (viewed 395490 times)
  8. How many stars are there in our Galaxy (Milky Way)? (viewed 390792 times)
  9. Why do the planets orbit the sun? (viewed 387192 times)
  10. What is the universe expanding into? (viewed 374609 times)
  11. How do you measure the distance between Earth and the Sun? (viewed 348102 times)
  12. Which planets have rings? (viewed 324419 times)
  13. Why do stars twinkle? (viewed 322676 times)
  14. Does the Moon rotate? Are there other moons that always keep one face toward their planet? (viewed 306466 times)
  15. How do I build a model rocket? (viewed 292313 times)
  16. Can you hear sounds in space? (viewed 280179 times)
  17. What color is Venus? (viewed 275698 times)
  18. What is a white hole? (viewed 269602 times)
  19. What is the life cycle of a star? (viewed 247199 times)
  20. What are the names of the earth, moon, sun, and solar system? (viewed 241518 times)
  21. What is that ring (or rainbow) around the moon? (viewed 238674 times)
  22. What are the different kinds of astronomers? (viewed 237423 times)
  23. What makes the Earth rotate? (viewed 236605 times)
  24. What are shooting stars? (viewed 232350 times)
  25. What is the largest star? (viewed 222432 times)
  26. How do we know the age of the Universe and the Earth? (viewed 216075 times)
  27. Can artificial gravity be created in space? (viewed 214557 times)
  28. What do astronauts eat in space? Can they grow food? (viewed 213248 times)
  29. Why do planets rotate? (viewed 211301 times)
  30. Is the universe expanding faster than the speed of light? (viewed 207333 times)
  31. How does the location of sunrise and sunset change throughout the year? (viewed 201319 times)
  32. How can we see the Milky Way if we are inside it? (viewed 187112 times)
  33. Where did the name 'Earth' come from? (viewed 181925 times)
  34. What would happen if we did not have a Moon? (viewed 178108 times)
  35. Why is a day divided into 24 hours? (viewed 175840 times)
  36. Why isn't the sky bright at night if the universe has so many stars? (viewed 175488 times)
  37. How does the position of Moonrise and Moonset change? (viewed 175061 times)
  38. How many Earths fit into the Sun? (viewed 173784 times)
  39. Who named the planets and who decides what to name them? (viewed 163891 times)
  40. Why do airplanes take longer to fly West than East? (viewed 161712 times)
  41. When was the last time all 9 planets were aligned? (viewed 161120 times)
  42. Why are the Moon and Sun sometimes orange or red? (viewed 160120 times)
  43. Is the distance from the Earth to the Sun changing? (viewed 152322 times)
  44. Is Pluto a planet? (viewed 151524 times)
  45. What is at the end of the Universe? (viewed 150416 times)
  46. How can I find the star I have "bought"? (viewed 148169 times)
  47. How much money is spent on space exploration? (viewed 145825 times)
  48. What is a nova? (viewed 138537 times)
  49. Does your weight change between the poles and the equator? (viewed 135580 times)
  50. How do astronauts take baths and use restrooms in space? (viewed 134758 times)
  51. Can we feel the Earth spin? (viewed 133337 times)
  52. Why are there both high and low tides? (viewed 131872 times)
  53. What direction do planets rotate? (viewed 131832 times)
  54. Is the Sun expanding? Will it ever explode? (viewed 129971 times)
  55. What is the largest galaxy? (viewed 127708 times)
  56. Do stars move in the sky? (viewed 127016 times)
  57. How many known galaxies are there? (viewed 126551 times)
  58. What are the advantages and disadvantages of using a telescope in space? (viewed 122687 times)
  59. Why do all the planets orbit in the same plane? (viewed 121634 times)
  60. Can I buy a star? (viewed 118774 times)
  61. How are light and heavy elements formed? (viewed 117752 times)
  62. Will the sun go supernova in six years and destroy Earth (as seen on Yahoo)? (viewed 116077 times)
  63. What is the physical difference between a star and a planet? (viewed 115721 times)
  64. Are there telescopes that can see the flag and lunar rover on the Moon? (viewed 115099 times)
  65. Why hasn't NASA gone back to the moon? (viewed 114591 times)
  66. Why do planets have elliptical orbits? (viewed 114491 times)
  67. Does the Sun have a scientific name? (viewed 113628 times)
  68. Who first measured the speed of light? (viewed 113349 times)
  69. How do stars move in the Galaxy? (viewed 112825 times)
  70. What happens when galaxies collide? (viewed 112149 times)
  71. What is the hottest time of day? (viewed 112053 times)
  72. How do rockets work? (viewed 111263 times)
  73. What is the significance of the Tropic of Cancer, Tropic of Capricorn, Arctic Circle and Antarctic Circle? (viewed 110299 times)
  74. What is the size of the Solar System? (viewed 109654 times)
  75. What would happen if an impact caused Earth to stop rotating? (viewed 108641 times)
  76. How much money do astronomers make? (viewed 108588 times)
  77. Does evolution contradict the second law of thermodynamics? (viewed 108394 times)
  78. Will the magnetic field of the Earth reverse its direction in the future? Will this cause problems? (viewed 107780 times)
  79. What was there before the Big Bang and what is there outside of our universe? (viewed 107648 times)
  80. What will happen to life on Earth when the Sun becomes a red giant? (viewed 107567 times)
  81. When is the next comet due to arrive? (viewed 107151 times)
  82. How do you calculate the lifetime of the Sun? (viewed 107129 times)
  83. How long does a solar eclipse last? (viewed 106033 times)
  84. What elements make up the Sun? (viewed 105748 times)
  85. What do astronauts do all day in the International Space Station? (viewed 105325 times)
  86. Do black holes die? If so how? (viewed 105272 times)
  87. How many constellations are there? (viewed 104314 times)
  88. What is the observational difference between a star and a planet? (viewed 104196 times)
  89. What's the difference between astronomy and astrology? (viewed 102607 times)
  90. Does gravity vary across the surface of the Earth? (viewed 101906 times)
  91. Does the Sun rotate? (viewed 101798 times)
  92. What would happen if the gravity on Earth was suddenly turned off? (viewed 101119 times)
  93. Does the Sun move around the Milky Way? (viewed 100144 times)
  94. What are constellations used for? (viewed 97673 times)
  95. What is apparent magnitude? (viewed 97347 times)
  96. How many meteorites hit Earth each year? (viewed 97309 times)
  97. Which planet is most similar to Earth? (viewed 96919 times)
  98. Why do different stars appear with seasons? (viewed 95532 times)
  99. What kind of schooling is necessary to become an astronomer? (viewed 95470 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 92933 times)
  101. How do astronomers use math in their jobs? (viewed 92872 times)
  102. Is there a proof that Earth moves? (viewed 92190 times)
  103. How critical is the Earth-Sun distance in maintaining our average temperatures on Earth? (viewed 91553 times)
  104. Where did the Universe come from? (viewed 91060 times)
  105. Why are stars and planets round? (viewed 90941 times)
  106. Does the Sun orbit the Earth as well as the Earth orbiting the Sun? (viewed 90850 times)
  107. Why is the Universe flat and not spherical? (viewed 90412 times)
  108. Why is the Moon so bright? (viewed 90158 times)
  109. What makes the wind? (viewed 89522 times)
  110. How can a star burn with no oxygen? (viewed 89472 times)
  111. What is the difference between a "star" and a "sun"? (viewed 89065 times)
  112. What would happen if an asteroid 10 kilometers across hit the Earth? (viewed 88836 times)
  113. What is a singularity? (viewed 88802 times)
  114. Have astronomers discovered Earth's second moon? (viewed 88191 times)
  115. What are the requirements for being a planet? (viewed 86161 times)
  116. Why does the Earth tilt back and forward once a year? (viewed 84301 times)
  117. What are RA and DEC? (viewed 84174 times)
  118. Where does the name "Milky Way" come from? (viewed 83680 times)
  119. Since Earth is spinning, why do we land in the same place when we jump or fall? (viewed 82746 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 82173 times)
  121. What would happen if Earth had more than one moon? (viewed 81902 times)
  122. How many stars are born and die each day? (viewed 81130 times)
  123. Why aren't there any green stars? (viewed 79360 times)
  124. What kind of rock is the moon made of? (viewed 78706 times)
  125. Why is the moon in a different place every night? (viewed 78415 times)
  126. Did astronauts really go to the Moon, or is it a hoax? (viewed 78142 times)
  127. How are galaxies formed? (viewed 78049 times)
  128. Will the Sun become a black hole one day? (viewed 76334 times)
  129. How do we weigh objects in space? (viewed 76312 times)
  130. What is the density of a black hole? (viewed 75835 times)
  131. How are black holes made? Could one be made close to us? (viewed 75683 times)
  132. What would happen if a supermassive black hole came close to the Earth? (viewed 75385 times)
  133. Who has landed on the moon? (viewed 73904 times)
  134. How do rockets move in space? (viewed 73511 times)
  135. Can moons have moons? (viewed 73468 times)
  136. What happens to a substance if its speed is more than the speed of light? (viewed 73257 times)
  137. Do most astronomers believe in God based on the available scientific evidence? (viewed 73218 times)
  138. What would you see from inside a black hole? (viewed 73083 times)
  139. Why can't you see stars during the day? (viewed 73020 times)
  140. Does the Mediterranean sea have tides? (viewed 72686 times)
  141. What would happen if you took off your helmet in space? (viewed 72654 times)
  142. How often does the Sun pass through a spiral arm in the Milky Way? (viewed 72517 times)
  143. How do astronomers measure the brightness of stars? (viewed 72362 times)
  144. When the Sun converts mass to energy, do the orbits of the planets change? (viewed 72321 times)
  145. What are some of the effects of solar flares on Earth? (viewed 71840 times)
  146. How can the Universe expand faster than the speed of light during inflation? (viewed 71766 times)
  147. Can you fire a gun on the Moon? (viewed 71633 times)
  148. What is the evidence supporting the nebula theory of Solar System formation? (viewed 71581 times)
  149. How do we know the mass of the Earth and the Moon? (viewed 71216 times)
  150. Why do we not have eclipses every month? (viewed 70696 times)
  151. How is astronomy impacted by trigonometry? (viewed 70617 times)
  152. Is it possible to measure the temperature of the Sun? (viewed 70060 times)
  153. How do you measure a planet's mass? (viewed 69894 times)
  154. How does the Moon stay "suspended" in the air? (viewed 69384 times)
  155. Why do stars change colour when they twinkle? (viewed 69329 times)
  156. How does the Sun compare to other stars? (viewed 69038 times)
  157. How are elements heavier than iron formed? (viewed 68820 times)
  158. What are the "dog days of summer"? (viewed 67454 times)
  159. Does quantum entanglement imply faster than light communication? (viewed 66350 times)
  160. What kinds of jobs do astronomers do? (viewed 66285 times)
  161. If the universe is infinite does that mean there is an infinite number of "me"s? (viewed 65472 times)
  162. How long would it take the Earth to fall into the Sun? (viewed 64841 times)
  163. Where does the name "Moon" come from? (viewed 64734 times)
  164. How did the stars get named? (viewed 64678 times)
  165. How do you measure the mass of a star? (viewed 64670 times)
  166. How does light pollution affect astronomers? (viewed 64656 times)
  167. What are black holes made of? (viewed 64485 times)
  168. Where did the matter in the universe come from? (viewed 64200 times)
  169. Why doesn't the earliest sunset occur on the shortest day of the year? (viewed 64078 times)
  170. What causes seasons? (viewed 64035 times)
  171. Are there stars outside of galaxies? (viewed 63933 times)
  172. How did asteroids form and what is the difference between an asteroid and a comet? (viewed 63874 times)
  173. Traveling at light speed, how long would it take to get to the nearest galaxy? (viewed 63873 times)
  174. What are Altitude and Azimuth? (viewed 63869 times)
  175. How fast is the Universe expanding? (viewed 63273 times)
  176. When can I see the Moon through the hole in the Pantheon? (viewed 63173 times)
  177. Why do planets not twinkle? (viewed 62436 times)
  178. What's the best college for astronomy? (viewed 62346 times)
  179. Where, in relation to the entire universe, is the Milky Way located? (viewed 62327 times)
  180. What would happen to us if the sun went out for an hour? (viewed 61893 times)
  181. What's the difference between dark matter and dark energy? (viewed 61769 times)
  182. Why doesn't the length of each day change much around the solstices? (viewed 61742 times)
  183. What is the mass of the Universe? (viewed 60860 times)
  184. Why does the Sun's apparent path through the sky change throughout the year? (viewed 60789 times)
  185. How does astronomy benefit humankind? (viewed 60415 times)
  186. Why is looking out into space the same as looking back in time? (viewed 60282 times)
  187. How can I calculate the position or path of the Sun for a given time and location? (viewed 60025 times)
  188. How does the parachute in a model rocket work? (viewed 59470 times)
  189. Why does the Earth have only one moon? (viewed 59403 times)
  190. Does the Moon rotate? (viewed 59371 times)
  191. Could there be life in the galaxies nearest to the Milky Way? (viewed 59270 times)
  192. What can we learn from the color of a star? (viewed 59082 times)
  193. What is the origin of spiral structure in galaxies? (viewed 59063 times)
  194. Can any galaxies be seen with the naked eye? (viewed 59025 times)
  195. How close was the Moon to the Earth when it formed? (viewed 58769 times)
  196. How long does the supernova stage of a star last? (viewed 58216 times)
  197. What makes up most of the Universe? (viewed 58117 times)
  198. How do the astronauts communicate in space if sound cannot travel in a vacuum? (viewed 57109 times)
  199. What is the shape of the universe? (viewed 56849 times)
  200. If gravity is a "curvature of space" rather than a force, why do a ball and bullet follow different paths? (viewed 56512 times)
  201. Why isn't the summer solstice the hottest day of the year? (viewed 56350 times)
  202. How do astronauts use math in their jobs? (viewed 56316 times)
  203. What is a star's "spectrum"? (viewed 56189 times)
  204. What is the largest structure in the universe? (viewed 55939 times)
  205. What is the size of a black hole? (viewed 55526 times)
  206. Where are stars born? (viewed 55441 times)
  207. How do we measure the size of the Moon and of the Sun? (viewed 55395 times)
  208. How do you calculate the azimuth and altitude of an object? (viewed 55267 times)
  209. What happens to a bullet fired on the moon? (viewed 55250 times)
  210. 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 54997 times)
  211. Which constellation does our Sun belong to? (viewed 54976 times)
  212. Are names given to black holes? (viewed 54905 times)
  213. Can you see satellites? (viewed 54548 times)
  214. How can I find the distance to the Sun on any given day? (viewed 54173 times)
  215. What other careers involve Astronomy besides Astronomer? (viewed 53764 times)
  216. Why do we see stars? (viewed 53489 times)
  217. Which hemisphere has the best view of the Milky Way? (viewed 53467 times)
  218. Are aliens or UFOs real? (viewed 53276 times)
  219. Where did all the water in the universe come from? (viewed 53174 times)
  220. How can I measure the distance of a star? (viewed 53126 times)
  221. Why is twilight short near the equator? (viewed 52869 times)
  222. Is the speed of light constant? (viewed 52809 times)
  223. Are meteorites hot or cold when they hit Earth? (viewed 52443 times)
  224. Are there any asteroids on a collision course with Earth? (viewed 52327 times)
  225. Why is the sky blue and not blue & purple? (viewed 52313 times)
  226. How long has there been water on Earth? (viewed 52231 times)
  227. What do a galaxy's colors mean? Are they its true colors? (viewed 52073 times)
  228. What are some astronomy science fair projects? (viewed 51958 times)
  229. What would happen if the Moon fell out of its orbit around Earth? (viewed 51896 times)
  230. Would your weight change as you go underground? (viewed 51732 times)
  231. Can we look back far enough in time to see the Big Bang? (viewed 51126 times)
  232. Is time travel possible? (viewed 51018 times)
  233. Why does the Moon look big on the horizon? (viewed 50874 times)
  234. Who discovered each planet? (viewed 50850 times)
  235. How is the time of sunrise calculated? (viewed 50606 times)
  236. What skills do astronomers need? (viewed 50549 times)
  237. If the Earth's rotation period is less than 24 hours, why don't our clocks fall out of sync with the Sun? (viewed 50545 times)
  238. Are the planes of solar systems aligned with the plane of the Galaxy? (viewed 50381 times)
  239. How do we know what other planets (and stars, galaxies, etc.) are made of? (viewed 50302 times)
  240. What is the difference between nutation and precession of the Earth? (viewed 50059 times)
  241. Why is it difficult to understand the expansion of the universe? (viewed 49920 times)
  242. What's the difference between astronomy and astrophysics? (viewed 49680 times)
  243. What is a graviton? (viewed 49509 times)
  244. If light has no mass, then what draws it into a black hole? (viewed 49094 times)
  245. Why do the size and brightness of the full moon change? (viewed 47864 times)
  246. Why are most months 30 or 31 days long? (viewed 47651 times)
  247. Do supermassive black holes cause galaxy rotation? (viewed 47558 times)
  248. What do I need to do to become an astronomer? (viewed 47496 times)
  249. How do gravitons escape black holes to tell the universe about their gravity? (viewed 47228 times)
  250. What is a wormhole? (viewed 47108 times)
  251. Why does the Sun appear larger on the horizon than overhead? (viewed 47049 times)
  252. Can we find the place where the Big Bang happened? (viewed 46986 times)
  253. Do dead stars still shine? (viewed 46974 times)
  254. How are black holes discovered? (viewed 46936 times)
  255. The Moon slows the Earth's rotation, but how fast was it spinning billions of years ago? (viewed 46517 times)
  256. Can the acceleration of the Universe be analogous to apparent acceleration in a airplane? (viewed 46514 times)
  257. Why are there stars? (viewed 46108 times)
  258. Is the Earth slowly getting larger? (viewed 45965 times)
  259. Will we get sucked into the black hole at the center of the Milky Way? (viewed 45916 times)
  260. Why can't we see Venus at night when it is an inner planet? (viewed 45802 times)
  261. Where is the nearest black hole? (viewed 45694 times)
  262. Why don't people walk upside-down on the bottom of the Earth? (viewed 45640 times)
  263. How do galaxies collide in an expanding universe? (viewed 45534 times)
  264. Can I calculate the size of the Universe by converting light years to kilometres? (viewed 45117 times)
  265. Did life originate on Earth, or did it come from somewhere else? (viewed 44886 times)
  266. Are Kuiper Belt Objects asteroids? Are large Kuiper Belt Objects planets? (viewed 44750 times)
  267. Why does Barnard 68 appear dark? (viewed 44683 times)
  268. Are there eclipses on other planets? (viewed 44094 times)
  269. Could the Universe have expanded faster than the speed of light at the Big Bang? (viewed 43609 times)
  270. How does Astronomy involve Chemistry? (viewed 43580 times)
  271. What is the best way to see the Milky Way? (viewed 43539 times)
  272. Is there a "South Star"? (viewed 43535 times)
  273. Why does the location of sunrise change? (viewed 43458 times)
  274. How long could life on Earth survive if the Sun stopped shining? (viewed 43431 times)
  275. What is the difference between the "Doppler" redshift and the "gravitational" or "cosmological" redshift? (viewed 43372 times)
  276. Has there been an experiment that measured speed faster than the speed of light in vacuum? (viewed 43315 times)
  277. How much can the location of sunset differ from due West? (viewed 43215 times)
  278. What happens to spacetime inside a black hole? (viewed 42933 times)
  279. How would the weather on Earth be different if it were a cube? (viewed 42883 times)
  280. Was the Sun made in a supernova? (viewed 42833 times)
  281. What is the biggest crater recorded on Earth? (viewed 42713 times)
  282. Why doesn't dark matter fall into a black hole? (viewed 42630 times)
  283. How much longer will the Earth last? (viewed 42507 times)
  284. Why does the Earth only see one side of the Moon? (viewed 41800 times)
  285. What are the names of the three stars in Orion's belt? (viewed 41788 times)
  286. Can I buy land on the Moon? (viewed 41774 times)
  287. What happens when two black holes get too close? (viewed 41514 times)
  288. Is the Moon hollow? (viewed 41506 times)
  289. What if the Earth rotated twice as fast? (viewed 41295 times)
  290. What is time dilation? (viewed 41075 times)
  291. What color would Mars be if you were standing on it? (viewed 41068 times)
  292. What's the biggest meteorite? (viewed 41015 times)
  293. Why do people draw stars with five points? (viewed 40855 times)
  294. How do we feel heat? (viewed 40753 times)
  295. What is the most distant known galaxy? (viewed 40738 times)
  296. How can two moons of Saturn share the same orbit? (viewed 40711 times)
  297. Could someone travel the universe in his or her own lifetime? (viewed 40673 times)
  298. Why can we see the sun's image before sunrise and after sunset? (viewed 40663 times)
  299. Is it possible to see the full Moon and the Sun simultaneously in high northern latitudes when the Sun doesn't set? (viewed 40508 times)
  300. Can terrestrial planets have rings? (viewed 40340 times)
  301. What are "blue stragglers" in globular clusters? (viewed 39952 times)
  302. How fast does the Earth go at perihelion and aphelion? (viewed 39944 times)
  303. How long would it take for a mini-black hole to eat the Earth? (viewed 39903 times)
  304. Is the Sun always up for exactly 12 hours at the equator? (viewed 39863 times)
  305. How do we know that nuclear fusion is still going on in the Sun? (viewed 39815 times)
  306. How many Astronauts have been in space? (viewed 39789 times)
  307. How do we define distance in an expanding universe? (viewed 39575 times)
  308. Do you think it's possible to maintain life on other planets? (viewed 39549 times)
  309. Why do clocks turn in the opposite direction from the Earth and Moon? (viewed 39501 times)
  310. Does the Sun have an iron surface? (viewed 39421 times)
  311. Why do pictures of distant galaxies have higher resolution than those of nearby planets? (viewed 39363 times)
  312. Why are Saturn's rings flat? (viewed 39315 times)
  313. If a white dwarf is a "dead" star, why is it so hot? (viewed 39257 times)
  314. What is the typical size of a visible shooting star? (viewed 39161 times)
  315. Can you see the future as you fall into a black hole? (viewed 39013 times)
  316. Can a person go into a black hole and come out alive? (viewed 38975 times)
  317. On which days can I see the Moon in the evening / morning and why is this so? (viewed 38884 times)
  318. Who (and when) discovered that the earth's axis is on a 23 degree tilt? (viewed 38873 times)
  319. Is the Great Wall the largest galaxy cluster? (viewed 38867 times)
  320. Does Mt. Everest cast a shadow on the moon? (viewed 38827 times)
  321. What is a dimension? (viewed 38807 times)
  322. How does night and day work? (viewed 38616 times)
  323. Where do planetary rings come from, and what are they made of? (viewed 38469 times)
  324. Are all stars the same? (viewed 38378 times)
  325. Can I communicate faster than light? (viewed 38316 times)
  326. What is the speed of gravity? (viewed 38063 times)
  327. How do we determine the age of the universe? (viewed 38033 times)
  328. What companies or businesses can astronomers work for? (viewed 38009 times)
  329. What is Earthrise over the Moon? (viewed 37997 times)
  330. What is the approximate GPA needed in High School in Math and Science to be an astronomer? (viewed 37787 times)
  331. Where is the supernova remnant that led to our solar system? (viewed 37683 times)
  332. How can the universe be "flat"? We're 3D! (viewed 37594 times)
  333. What can I use for fuel in my homemade rocket? (viewed 37554 times)
  334. How big is the universe? (viewed 37525 times)
  335. Why is sea water salty, and not lake water? (viewed 37344 times)
  336. Is there a beginning and an end to a galaxy's life? (viewed 37322 times)
  337. Is there really a 10th planet? (viewed 37293 times)
  338. If the universe is 15 billion years old, how can it be larger than 15 billion light years across? (viewed 37155 times)
  339. How do we know the Milky Way is a spiral galaxy? (viewed 37068 times)
  340. Does the Coriolis force determine which way my toilet drains? Does it affect black holes? (viewed 37027 times)
  341. How are photons created and destroyed? (viewed 37021 times)
  342. What would happen to the Earth if an asteroid hit the Moon? (viewed 36774 times)
  343. Why can't a plane fly slowly and let the Earth pass underneath? (viewed 36731 times)
  344. How many stars can I see? (viewed 36677 times)
  345. Why are there blue shifted galaxies? (viewed 36614 times)
  346. How do I tell which planet is which? (viewed 36519 times)
  347. Do the Sun's or Earth's magnetic field reverse? (viewed 36090 times)
  348. How can I find my age on another planet? (viewed 36077 times)
  349. How are planets detected around other stars? (viewed 35957 times)
  350. Can a lunar and a solar eclipse happen in the same month? When will this happen next? (viewed 35893 times)
  351. How does the brightness of a star depend on its distance from us? (viewed 35865 times)
  352. What kind of eyepieces do I need to look at planets? (viewed 35843 times)
  353. What is the pattern to the distances between each planet and the sun? (viewed 35766 times)
  354. Why do humans want to go in space? (viewed 35739 times)
  355. Why have star signs shifted by one constellation? (viewed 35633 times)
  356. Will we ever stop having solar eclipses because of the moon's motion away from the Earth? (viewed 35586 times)
  357. Is Andromeda part of the Milky Way? Where can I find them in the sky? (viewed 35559 times)
  358. What is the significance of the second focus of elliptical orbits of planets in our Solar System? (viewed 35399 times)
  359. How hot is each one of the layers of the sun? (viewed 35059 times)
  360. Can you describe a day on the job as an astronomer? (viewed 35054 times)
  361. Who came up with the name "black hole"? (viewed 35015 times)
  362. How do astronauts communicate with their families from space? (viewed 35003 times)
  363. How can we estimate the number of Earth-like planets in the Galaxy? (viewed 34937 times)
  364. What would happen if two stars collided? (viewed 34825 times)
  365. What was that really big falling star that I saw? (viewed 34804 times)
  366. Is there a simple formula to calculate solar eclipse timings from any position on Earth? (viewed 34569 times)
  367. Is the Earth at the centre of the Universe? (viewed 34558 times)
  368. When we look back to the Big Bang, why don't we see the universe as a tiny speck of matter? (viewed 34458 times)
  369. Why don't astronomers use everyday units to measure distances (what is an AU or a pc)? (viewed 34412 times)
  370. How is it that we see farther out in space (farther back in time) than in the past? (viewed 34405 times)
  371. Is the Local Group expanding along with the entire Universe? (viewed 34358 times)
  372. How do I become both an astronaut and an astronomer? (viewed 34318 times)
  373. Will the Moon be invisible in 500 million years? (viewed 34092 times)
  374. How do sunrise and sunset times change with altitude? (viewed 33694 times)
  375. Why is our solar system so different from all the others we've found? (viewed 33668 times)
  376. Why is Uranus tipped on its side? (viewed 33654 times)
  377. Are Earth and the Moon "twin planets"? (viewed 33647 times)
  378. How dangerous are the asteroids? (viewed 33620 times)
  379. Which American colleges teach astronomy? (viewed 33570 times)
  380. Can we colonize other planets? (viewed 33198 times)
  381. Why do constellations look the same after several years even though all the stars are moving? (viewed 33090 times)
  382. Is it true that the Sun burns off a billion tons of gas every 5 seconds? (viewed 33054 times)
  383. Is the universe really like an expanding balloon? (viewed 32969 times)
  384. Why are there no craters on Earth? Did all the meteorites miss us? (viewed 32943 times)
  385. Is the gravitational force exerted by the Earth on the Moon equal to the centripetal force acting on the Moon? (viewed 32752 times)
  386. Why do astronauts in space need to exercise? (viewed 32642 times)
  387. What are quasars made of? (viewed 32593 times)
  388. How can I calculate distances between stars? (viewed 32529 times)
  389. Can superheavy elements (such as Z=116 or 118) be formed in a supernova? Can we observe them? (viewed 32326 times)
  390. Why doesn't gravity change the speed of light? (viewed 32233 times)
  391. What is dark matter? (viewed 32210 times)
  392. Is it possible to count the stars? (viewed 31902 times)
  393. How big a change in the Earth's orbit would be required to destroy all life? (viewed 31875 times)
  394. Is time travel possible using merging black holes? (viewed 31771 times)
  395. What is happening just around the black hole in the center of the Milky Way? (viewed 31700 times)
  396. Why is the time between two successive full moons different from the lunar synodic month? (viewed 31698 times)
  397. Can we see dead stars with the naked eye? (viewed 31691 times)
  398. Did the speed of light change over the history of the universe? (viewed 31637 times)
  399. How do we measure distances to other stars? (viewed 31623 times)
  400. Does the Milky Way spin counter-clockwise? If so, do all spiral galaxies spin in this direction and why? (viewed 31557 times)
  401. How can we distinguish a star's "real" color from the change in color that we observe due to the star's motion? (viewed 31511 times)
  402. How do I make a scale model of the Solar System? (viewed 31476 times)
  403. What happens when an antimatter black hole collides with a matter blackhole? (viewed 31307 times)
  404. Do we see the same stars from above and below the equator? (viewed 31271 times)
  405. What would happen if a human were exposed to space without wearing a spacesuit? (viewed 31235 times)
  406. How can we tell what the interiors of planets are like? (viewed 31228 times)
  407. Are time machines possible? (viewed 31078 times)
  408. How many moles of stars are in the known universe? (viewed 30944 times)
  409. What happens when you change the mass of a White Dwarf or Neutron Star? (viewed 30912 times)
  410. What do "homogeneity" and "isotropy" mean? (viewed 30911 times)
  411. How are galaxy distances inferred from their recessional velocities? (viewed 30790 times)
  412. What is the farthest in space that we have gone? (viewed 30651 times)
  413. Will the seasons change due to precession? (viewed 30391 times)
  414. Can astronauts produce water in space? (viewed 30288 times)
  415. How can we know that there are other galaxies if we cannot leave ours? (viewed 30237 times)
  416. Is there any limitation to what a black hole can "suck" in? (viewed 30221 times)
  417. How was the starting point for the Julian Date system chosen? (viewed 30207 times)
  418. How do we know if the universe will keep expanding forever? (viewed 30128 times)
  419. Aren't jobs in astronomy scarce? (viewed 30055 times)
  420. What are the closest and/or brightest stars? (viewed 30055 times)
  421. Does the Moon look different in the northern and southern hemispheres? (viewed 29953 times)
  422. How can I tell if the rock I found is a meteorite? (viewed 29941 times)
  423. Why does the SETI project search for radio signals? (viewed 29892 times)
  424. What's that dark spot on the Sun? (viewed 29875 times)
  425. How long does it take the Big Dipper to move in the sky? (viewed 29833 times)
  426. Why do we study black holes? (viewed 29811 times)
  427. Do astronomers believe in astrology? (viewed 29786 times)
  428. Did I see the Aurora Borealis as a child? (viewed 29614 times)
  429. When are there 5 Sundays in February? (viewed 29540 times)
  430. Why do most moons orbit their planets at the equator? (viewed 29475 times)
  431. Do you believe in UFOs? (viewed 29421 times)
  432. What are the facts about the Star of Bethlehem? (viewed 29420 times)
  433. Wouldn't the Big Bang theory be considered a hypothesis and not a theory? (viewed 29418 times)
  434. Don't tachyons travel faster than light? (viewed 29337 times)
  435. What are the atmospheres of Mars and Pluto like? (viewed 29315 times)
  436. Can you use an infinite line of reflectors to send light to the edge of the Universe? (viewed 29294 times)
  437. Could an astronaut or satellite fall into a black hole that we didn't know about? (viewed 29206 times)
  438. Could you tell me about the life cycle of galaxies? (viewed 29058 times)
  439. What does the term "visible universe" mean? (viewed 29050 times)
  440. What colors are visible through an amateur telescope? (viewed 28923 times)
  441. Was I hit by a meteorite? (viewed 28767 times)
  442. How can geometry be different in space? (viewed 28750 times)
  443. How are galaxies named? (viewed 28749 times)
  444. Has anyone made a map of the Milky Way? (viewed 28744 times)
  445. Why do so many of the world's UFO sightings happen in America? (viewed 28731 times)
  446. Why are the compositions of comets and asteroids different? (viewed 28695 times)
  447. What's the best thing about being an astronomer? (viewed 28469 times)
  448. Can two lunar eclipses occur in the same month? (viewed 28439 times)
  449. How do astronomers measure the radius of a star? (viewed 28357 times)
  450. What is the origin of the stellar classification system "OBAFGKM"? (viewed 28314 times)
  451. How do asteroids, meteors and comets disappear? (viewed 28257 times)
  452. How much time do astronomers spend looking through telescopes? (viewed 28008 times)
  453. How do I explain to my children why the Moon has phases? (viewed 27905 times)
  454. Will winter and summer constellations change due to abnormal warmth or cold on Earth? (viewed 27895 times)
  455. How can we see galaxies if their stars are so faint? (viewed 27847 times)
  456. Have there been other Big Bangs before? (viewed 27711 times)
  457. How will the two black holes that are going to collide affect Earth? (viewed 27683 times)
  458. How are galaxies and solar systems similar? (viewed 27670 times)
  459. Do asteroids hit the sun? (viewed 27483 times)
  460. Is there a project I can do on black holes? (viewed 27466 times)
  461. Do the magnitudes and colors of stars ever change? (viewed 27450 times)
  462. How close do you have to come to the Earth to be influenced by its gravity? (viewed 27417 times)
  463. Can life exist on the recently discovered extrasolar planets? (viewed 27365 times)
  464. How can we measure distances to more stars? (viewed 27311 times)
  465. Is the Milky Way a collision of two galaxies? (viewed 27283 times)
  466. Could you escape from a black hole if you were able to go faster than the speed of light? (viewed 27211 times)
  467. How do scientists slow light down? (viewed 27140 times)
  468. Can a human give birth in space? (viewed 27126 times)
  469. What supernova created the Crab nebula? (viewed 27005 times)
  470. How close does a supernova need to be to damage the Earth's environment? (viewed 26969 times)
  471. Is it worthwhile to continue the search for extraterrestrial life? (viewed 26962 times)
  472. Is infinite temperature possible? (viewed 26958 times)
  473. Can "tired light theory" explain the observed redshifts of galaxies? (viewed 26929 times)
  474. What causes gamma ray bursts? (viewed 26928 times)
  475. Can double stars have planets? (viewed 26895 times)
  476. Do we know everything about the Sun? (viewed 26845 times)
  477. Is there oxygen in the atmospheres of other planets? (viewed 26775 times)
  478. Can one star orbit another? (viewed 26684 times)
  479. Which part of the sky did the famous 'wow' signal originate from? (viewed 26660 times)
  480. How far does a galaxy extend? (viewed 26548 times)
  481. Why did the Pioneer and Voyager take only 2 years to reach Jupiter, while Galileo and Cassini took more than 5 years? (viewed 26486 times)
  482. Can astronauts play musical instruments in space? (viewed 26481 times)
  483. What will happen to the Milky Way in the future? (viewed 26469 times)
  484. What is sidereal time? (viewed 26397 times)
  485. How do I polar align my telescope? (viewed 26363 times)
  486. Which way does the sun travel in the southern hemisphere? (viewed 26346 times)
  487. What type of energy does a black hole have? (viewed 26283 times)
  488. What is the farthest Northern Latitude in which the Magellanic Clouds can be seen? (viewed 26235 times)
  489. Is there such a thing as hyperspace? (viewed 26222 times)
  490. Is there sound coming from the Sun? (viewed 26215 times)
  491. What is a Cepheid variable? (viewed 26210 times)
  492. What is "nothing", from a scientific point of view? (viewed 26175 times)
  493. What happens to the material that has been sucked into a black hole? (viewed 26171 times)
  494. When did people discover that the Sun is a star? (viewed 26159 times)
  495. How different would the night sky have looked in 40,000 B.C.? (viewed 26153 times)
  496. What's the object I saw that moved across the sky and then got very bright? (viewed 26151 times)
  497. Why do the explosions of Type Ia supernovae have a more predictable spectrum than those of regular Type II supernovae? (viewed 26096 times)
  498. Are planetary nebulae the result of supernovae? (viewed 26076 times)
  499. How will a change in the speed of light affect the evolution of the Universe? (viewed 25971 times)
  500. Why is the shadow on the Moon the shape it is? (viewed 25924 times)
  501. Why do we assume that the universe is homogeneous? (viewed 25811 times)
  502. If we invented special suits could we ever go to the sun? (viewed 25744 times)
  503. How do we know that sunspots are associated with the Sun's magnetic field? (viewed 25738 times)
  504. When unmanned spacecraft accelerate in space, what causes them to slow down? (viewed 25732 times)
  505. How do we know what parameters to use when simulating the collision of the Milky Way and Andromeda? (viewed 25709 times)
  506. What is our galaxy's halo made of, and how was it formed? (viewed 25667 times)
  507. What is the difference between homogeneity and isotropy? (viewed 25634 times)
  508. What calculations go into predicting eclipses? (viewed 25558 times)
  509. Are there any dark stars or dark galaxies made of dark matter? (viewed 25517 times)
  510. Can I see a quasar? (viewed 25410 times)
  511. How many sunspots can the Sun have at once? (viewed 25390 times)
  512. How are asteroid compositions and classifications determined? (viewed 25379 times)
  513. Was Stonehenge built to mark solar phenomena? (viewed 25354 times)
  514. Is there a list of the sizes of different kinds of stars? (viewed 25345 times)
  515. What process would bring about a quark star? (viewed 25292 times)
  516. Why are there more maria on the near side of the Moon? (viewed 25251 times)
  517. Can any comparison be made between spiral galaxies and hurricanes? (viewed 25237 times)
  518. Can I see details on Venus? (viewed 25234 times)
  519. What happened to the girl who named Pluto? (viewed 25201 times)
  520. Did a giant impact cause the Dark Ages? (viewed 25175 times)
  521. What's so exciting about the new planet around 55 Cancri? (viewed 25167 times)
  522. How big is the Hubble Ultra Deep Field image? (viewed 25154 times)
  523. Have gravitational waves been proven to exist? (viewed 25066 times)
  524. What is a Dyson Sphere? (viewed 25066 times)
  525. Would the biggest airplanes cause tsunamis if they crashed? (viewed 25051 times)
  526. What happened to all the black holes that were around in the early universe? (viewed 25044 times)
  527. Why are telescopes kept in cold conditions? (viewed 24994 times)
  528. What equipment do I need for astrophotography? (viewed 24973 times)
  529. How is it proved that the Universe is expanding? (viewed 24927 times)
  530. If clocks run slow in a gravitational field, how can we know the true age of the Solar System and Universe? (viewed 24869 times)
  531. Does Cerenkov radiation travel faster than light? (viewed 24861 times)
  532. Why are there active volcanos on Io? (viewed 24830 times)
  533. Is there any possibility that the Solar System or the Universe is in a black hole? (viewed 24720 times)
  534. If the Universe was infinitely dense at the Big Bang, why didn't time stand still? (viewed 24686 times)
  535. How long do supernova remnants last? (viewed 24515 times)
  536. How can we compare dark matter and dark energy? (viewed 24506 times)
  537. How big was the Sun when it first "fired up"? (viewed 24484 times)
  538. What caused Shoemaker-Levy 9 to split up? (viewed 24370 times)
  539. How do solar flares affect airline pilots? (viewed 24355 times)
  540. Why do photos of space taken from space never show any stars? (viewed 24352 times)
  541. Could we send a space mission to a comet? (viewed 24343 times)
  542. Can you give me advice on buying a telescope? (viewed 24320 times)
  543. Why doesn't light from distant galaxies reach us instantaneously? (viewed 24258 times)
  544. How are sunspots formed? (viewed 24211 times)
  545. How can I contribute to science as an amateur astronomer? (viewed 24190 times)
  546. How does the Earth compare in size to the entire universe at the present epoch? (viewed 24168 times)
  547. Why is it important to study meteorites? (viewed 24165 times)
  548. Why doesn't NASA build rotating spacecraft to simulate gravity? (viewed 24149 times)
  549. Can I build an instrument to measure the size of the Sun and of the Moon? (viewed 24148 times)
  550. How do unmanned space probes avoid running into things? (viewed 24115 times)
  551. Why are telescopes located in remote places? (viewed 24099 times)
  552. Could a different theory of gravity explain the dark matter mystery? (viewed 24094 times)
  553. Could we be seeing dead stars? (viewed 24090 times)
  554. Where does the kinetic energy of infalling bodies come from? (viewed 24071 times)
  555. As the universe expands, why don't galaxies get stretched out? (viewed 23991 times)
  556. Are the asteroids the remains of a planet which broke apart? (viewed 23942 times)
  557. How many comets are currently orbiting our sun? (viewed 23917 times)
  558. Did I really hear a meteor? (viewed 23894 times)
  559. Can you tell time by the Big Dipper? (viewed 23838 times)
  560. Why is the Hubble Space Telescope in space? (viewed 23776 times)
  561. Would extraterrestrial civilizations know that there is life on Earth? (viewed 23672 times)
  562. How do we know that superclusters are the largest structures in the universe? (viewed 23663 times)
  563. How powerful are quasars? (viewed 23616 times)
  564. How is the Cepheid yardstick validated? (viewed 23612 times)
  565. Do the Earth's magnetic poles ever change places? (viewed 23600 times)
  566. Do unmanned spacecraft like Voyager travel in straight lines? (viewed 23566 times)
  567. Do galaxies orbit around anything? (viewed 23495 times)
  568. Why can't relative velocities add up to more than the speed of light? (viewed 23493 times)
  569. Did time go slower just after the Big Bang? (viewed 23482 times)
  570. Why are stars of different masses? (viewed 23451 times)
  571. How could galaxies have gotten so far away in only 15 billion years? (viewed 23423 times)
  572. Can supernovae hinder the formation of life in galaxies? (viewed 23399 times)
  573. Are there any new craters on the moon? (viewed 23381 times)
  574. What kind of instruments are used to detect extrasolar planets? (viewed 23377 times)
  575. What would happen if there was a collision between two white dwarfs? (viewed 23343 times)
  576. How do I become an astronomical artist? (viewed 23322 times)
  577. Do similar laws of physics throughout the Universe imply that all life must be like life on Earth? (viewed 23298 times)
  578. How do planets capture satellites? (viewed 23273 times)
  579. How are astronomy and poetry linked? (viewed 23216 times)
  580. What kind of telescope should I use for astrophotography? (viewed 23215 times)
  581. Could there have been multiple Big Bangs at different places in the universe? (viewed 23206 times)
  582. Could dark energy come from matter anti-matter pairs forming spontaneously and then annihilating? (viewed 23054 times)
  583. How do astronomers observe the Sun's interior? (viewed 23035 times)
  584. Can I listen to the SETI@home radio signal? (viewed 22946 times)
  585. Why is NASA shutting down the Hubble Space Telescope? (viewed 22929 times)
  586. How can you tell if a crescent moon is preceding or following a new-moon phase? (viewed 22899 times)
  587. Does the Sun have any heavy elements? (viewed 22840 times)
  588. 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 22767 times)
  589. Can the theory of formation of the solar system explain all the observables? (viewed 22735 times)
  590. What class of spiral galaxy is the Milky Way? (viewed 22708 times)
  591. Are the properties of extrasolar planets known? (viewed 22703 times)
  592. Will we discover an 11th planet? What would it be called? (viewed 22640 times)
  593. What month was it when Odysseus saw Orion in 1000BC? (viewed 22508 times)
  594. Where was the water in the big bang? (viewed 22463 times)
  595. Could we send a manned mission to the outer planets? (viewed 22411 times)
  596. Is it possible for amateurs to do optical interferometry? (viewed 22325 times)
  597. What makes a satellite geosyncronise itself with Earth's orbit? (viewed 22306 times)
  598. How can water be chemically trapped in rocks? (viewed 22281 times)
  599. Why do spacecraft need heat shields coming back to Earth but not leaving? (viewed 22263 times)
  600. Why does the apparent density of galaxies drop off at larger distances? (viewed 22245 times)
  601. Why does one side of Mars look more catastrophic than the other? (viewed 22203 times)
  602. Would a planet near the galactic center have a brighter night sky? (viewed 22139 times)
  603. Do stars' orbits in galaxies obey Kepler's Laws? (viewed 22042 times)
  604. Why are accretion disks flat? (viewed 21934 times)
  605. Can other terrestrial moons be (or have been) stable? (viewed 21851 times)
  606. Why was the Platonic year named after Plato? (viewed 21843 times)
  607. What is the solar cycle? (viewed 21831 times)
  608. What would the Big Crunch look like to an observer on Earth? (viewed 21756 times)
  609. How are supernovae discovered? (viewed 21718 times)
  610. How can the Sun have such a strong gravitational field if it's made of gasses? (viewed 21692 times)
  611. What is meant by "stopping down a telescope"? (viewed 21628 times)
  612. Can a black hole come back to the visual universe through a "little bang"? (viewed 21613 times)
  613. Does inflation allow for an infinite number of universes? (viewed 21587 times)
  614. Why doesn't the hydrogen on Jupiter explode? (viewed 21559 times)
  615. Could our position in the universe affect our perceptions of the expansion? (viewed 21508 times)
  616. Did I find a rock that came from the Moon? (viewed 21318 times)
  617. Have astronomers observed any phenomena that could be produced by extraterrestrial civilizations? (viewed 21307 times)
  618. What is the SU(3) quark model? (viewed 21266 times)
  619. Can gravitational lensing from intervening galaxies cause the observed ripples in the Cosmic Microwave Background? (viewed 21214 times)
  620. Will I be able to see the shadow of the Moon streaking towards me in a total solar eclipse? (viewed 21156 times)
  621. Does a photon observe other photons moving past it at the speed of light? (viewed 21134 times)
  622. What's new with the Big Bang? (viewed 20943 times)
  623. How can we find galaxies behind the Milky Way? (viewed 20943 times)
  624. Could photons be dark matter? (viewed 20938 times)
  625. How fast do particles travel in space? (viewed 20896 times)
  626. Why is the WMAP picture of the CMB an ellipse? (viewed 20854 times)
  627. Can planets collide with one another? (viewed 20853 times)
  628. Why search for only Earth-like life on other planets? (viewed 20829 times)
  629. Why can we have solar eclipses? (viewed 20819 times)
  630. Is it possible to build a cheap device to measure declination? (viewed 20792 times)
  631. If comets are boiling away, why are there any left? (viewed 20762 times)
  632. Do constellations looks the same from space? (viewed 20746 times)
  633. Where can I find information on the moons of other planets? (viewed 20741 times)
  634. How much power is contained in a beam of light? (viewed 20706 times)
  635. Why do some eclipses take longer than others? (viewed 20664 times)
  636. Why is pressure broadening greater in low mass stars than in high mass stars? (viewed 20545 times)
  637. Did the Sumerians measure precession? (viewed 20417 times)
  638. What are the boundaries of the constellations? (viewed 20416 times)
  639. What would an "open geometry" for the universe look like? (viewed 20399 times)
  640. What kinds of star clusters are there? (viewed 20327 times)
  641. What are collections of galaxies called? (viewed 20234 times)
  642. How did Mars get so dusty? (viewed 20186 times)
  643. How do photons from distant objects maintain enough energy to reach us? (viewed 20180 times)
  644. Why aren't discoveries of extrasolar planets reported on the news? (viewed 20164 times)
  645. Why don't astronauts sublimate in space? (viewed 20162 times)
  646. How do astronomers come up with their facts? (viewed 20149 times)
  647. Why is the Cosmic Microwave Background not absorbed by interstellar hydrogen? (viewed 20147 times)
  648. How do bars form in spiral galaxies? (viewed 20140 times)
  649. If photons have zero mass, why do they feel the effects of gravity? (viewed 20029 times)
  650. Do electrons age? (viewed 19976 times)
  651. Can HST see the Oort cloud? (viewed 19974 times)
  652. Can we make a movie of the Milky Way galaxy's rotation? (viewed 19895 times)
  653. How long is twilight on the Moon? (viewed 19831 times)
  654. Can the Space Shuttle abort and return to Earth before reaching orbit? (viewed 19827 times)
  655. Will astronauts ever be able to go ice-skating on Europa? (viewed 19786 times)
  656. How does melting a material reset its radioactive clock? (viewed 19767 times)
  657. Why don't all neutron stars become pulsars? (viewed 19738 times)
  658. Does the shuttle worry about space junk? (viewed 19693 times)
  659. Where can I see Newton's original reflecting telescope? (viewed 19648 times)
  660. Why do supernova remnants look like rings rather than spheres? (viewed 19634 times)
  661. How do you classify galaxies? (viewed 19633 times)
  662. How can we understand the meaning of large numbers like "a million million?" (viewed 19556 times)
  663. Why doesn't SETI concentrate its observations to the nearby stars and the solar systems that we are discovering? (viewed 19463 times)
  664. What is the best time of the year to see eclipses? (viewed 19462 times)
  665. Why is it called astronomy when all the other sciences end in -ology? (viewed 19440 times)
  666. How does the color index of a star relate to its actual color? (viewed 19440 times)
  667. What causes a particle to decay? (viewed 19428 times)
  668. Will the next generation telescope OWL be able to detect an Earth like extrasolar planet? (viewed 19397 times)
  669. How can I nominate myself for a Nobel Prize in Physics? (viewed 19276 times)
  670. How long has humanity known that we live in a galaxy similar to others in the Universe? (viewed 19243 times)
  671. If nothing can escape a black hole, why do some black holes have jets? (viewed 19198 times)
  672. Will the Leonid meteor shower go away? (viewed 19193 times)
  673. Are black holes spherical? (viewed 19191 times)
  674. What are "curled" dimensions? (viewed 19098 times)
  675. Is light of different colors affected differently by gravity? (viewed 19000 times)
  676. Do asteroids ever do anything good in the Solar System? (viewed 18963 times)
  677. How does interferometry work? (viewed 18951 times)
  678. What would happen if you went back in time and killed your grandmother? (viewed 18884 times)
  679. How do distant galaxies differ from those nearby? (viewed 18882 times)
  680. What kind of interference must astronomers contend with when observing? (viewed 18876 times)
  681. What was that eclipse I saw in the sky? (viewed 18872 times)
  682. Does the temperature of matter increase as it is accelerated to relativistic speeds? (viewed 18855 times)
  683. Wouldn't the vast distances of space distort SETI signals into unintelligeble forms? (viewed 18777 times)
  684. How do we find out about the star formation histories of galaxies? (viewed 18759 times)
  685. Why will fusion wait until hydrogen is gone before starting to fuse heavier atoms? (viewed 18713 times)
  686. How can I watch the Perseid meteor shower? (viewed 18638 times)
  687. Can astronomers observe anything when the moon is full? (viewed 18638 times)
  688. What do stellar classifications mean? (viewed 18620 times)
  689. Do we really observe the edges of galaxies at different epochs? (viewed 18559 times)
  690. Why aren't accretion disks around giant stars as hot as accretion disks around black holes? (viewed 18515 times)
  691. Can you tell me the characteristics of W, R, N and S type stars? (viewed 18500 times)
  692. How are astronauts trained for weightlessness? (viewed 18499 times)
  693. What is the three-body problem? (viewed 18432 times)
  694. If the universe is "bounded" today, could it one day become "unbounded"? (viewed 18211 times)
  695. What happens to the helium formed in the sun? (viewed 18171 times)
  696. Will the diameter of a cluster of galaxies change with redshift? (viewed 18166 times)
  697. Is cosmic expansion happening on microscopic scales? (viewed 18032 times)
  698. When measuring the expansion of the universe, do astronomers consider that they're seeing how galaxies moved long ago, not today? (viewed 18003 times)
  699. How do supernovae show us that the Universe's expansion is accelerating? (viewed 17848 times)
  700. How can I find out if the new moon has been sighted? (viewed 17804 times)
  701. Could neutrinos be dark matter? (viewed 17729 times)
  702. Do we have to worry about relativity when studying galactic objects? (viewed 17654 times)
  703. Does lunar gardening really work? (viewed 17647 times)
  704. What kinds of cancer research have been done in space? (viewed 17491 times)
  705. How does a star take mass from another star? (viewed 17361 times)
  706. Could the Universe's dark matter be made up of black holes? (viewed 17304 times)
  707. How can you tell the difference between single and multiple extrasolar planets? (viewed 17141 times)
  708. What is Hot Dark Matter theory? (viewed 17107 times)
  709. Is it a coincidence that we can have total solar eclipses? Are there other planets which also have them? (viewed 16930 times)
  710. How do we know the density of some extrasolar planets? (viewed 16879 times)
  711. What is the photoelectric effect? Why can't multiple low-frequency photons free an electron? (viewed 16796 times)
  712. Is the green flash real? (viewed 16779 times)
  713. What time is sunrise/sunset or moonrise/moonset at my location? (viewed 16652 times)
  714. How does libration allow us to see more than 50% of the Moon? (viewed 16587 times)
  715. How can observations of the distant universe prove that the expansion is accelerating *now*? (viewed 16553 times)
  716. Is light blueshifted when it is gravitationally lensed? (viewed 16434 times)
  717. Do binary or triple star systems form together? (viewed 16432 times)
  718. No matter how fast the universe is expanding, shouldn't gravity eventually make it recollapse? (viewed 16342 times)
  719. What do meteorites tell us about life on other planets? (viewed 16235 times)
  720. Why is it easier to see a star if you look slightly to the side? (viewed 16176 times)
  721. Can we prove that the Moon isn't hollow? (viewed 16136 times)
  722. What percent of the time can astronomers observe without interference from the Moon? (viewed 16090 times)
  723. 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 16070 times)
  724. If the sun went out and our atmosphere froze solid, what color would it be? (viewed 16063 times)
  725. How has light from 13 billion years ago not passed us by? (viewed 16004 times)
  726. Could matter-anti-matter repulsion power the expansion of the universe? (viewed 15854 times)
  727. Why doesn't the ammonia and methane in Jupiter's atmosphere sink into the core? (viewed 15724 times)
  728. How do we detect incoming meteorites? (viewed 15606 times)
  729. What was different on Mars in the past to allow liquid water to be present? (viewed 15592 times)
  730. When will Hale-Bopp return? (viewed 15511 times)
  731. Why don't skydivers burn up like meteors? (viewed 15491 times)
  732. Are there any 'lonely galaxies'? (viewed 15470 times)
  733. Has anyone ever seen a star "turn on"? (viewed 15289 times)
  734. Why are craters round? (viewed 14964 times)
  735. During close approaches, can Mars appear in our sky as large as the Moon? (viewed 14701 times)
  736. How are planets affected by the Hot Ionised Medium? (viewed 14525 times)
  737. Can the sun rise from the west on Mars? (viewed 14448 times)
  738. What are the largest radio wavelengths observed from radio sources in the sky? (viewed 14122 times)
  739. Why was Mir burnt up in the atmosphere? (viewed 14079 times)
  740. How can we discern different galaxies/clusters along the same line of sight? (viewed 13956 times)
  741. What is the relationship between the width of a star trail on a photo and the star's intensity? (viewed 13529 times)
  742. Can we harvest H & O from space to make water? (viewed 13462 times)
  743. Why does Titan, in spite of being smaller than Mars, have an atmosphere more dense than Earth's? (viewed 13365 times)
  744. What is between the Oort cloud and the closest star? (viewed 12888 times)
  745. What happens to the Earth as the moon gets farther away and will it ever go away entirely? (viewed 12180 times)
  746. Could a planetary system survive if its star merged with another, or if its star went supernova? (viewed 12051 times)
  747. Are there solar tides? (viewed 11936 times)
  748. Does weightlessness affect hunger? (viewed 11698 times)
  749. Is Earth-moon tidal friction causing global warming? (viewed 11585 times)
  750. Is the moon spherical? (viewed 11379 times)
  751. Do planets radiate noise? (viewed 11366 times)
  752. Why is the Moon higher in the sky in winter and lower in the summer? (viewed 11265 times)
  753. Is dark energy affected by black holes? (viewed 11064 times)
  754. Where are the protons and electrons in a Neutron Star? (viewed 10826 times)
  755. What would happen if a nuclear-powered shuttle exploded? (viewed 10709 times)
  756. Is the Moon always visible during winter on the North Pole? (viewed 10640 times)
  757. Wait, I'm still confused why information can't travel faster than the speed of light. (viewed 10227 times)
  758. Will the Pioneer and Voyager probes ever leave the Milky Way? (viewed 9795 times)
  759. Do more meteorites fall at low latitudes? (viewed 9777 times)
  760. Will Comet Elenin (C/2010 X1) affect the Earth on its close approach in Fall 2011? (viewed 9739 times)
  761. Did the Moon or planets form in a manner similar to that of Earth? (viewed 9718 times)
  762. What are the possible ends of the universe? (viewed 9684 times)
  763. If there are infinity universes, will every thing that is possible happen? (viewed 9496 times)
  764. Is it sensible to consider terraforming Mars? (viewed 9418 times)
  765. What color are meteors? (viewed 9194 times)
  766. Where is everybody? (viewed 8683 times)
  767. Why does Mars have a dusty atmosphere? (viewed 8363 times)
  768. Does the singularity in a black hole create a new Universe? (viewed 8213 times)
  769. The naming of Mars (viewed 8197 times)
  770. If I were traveling through space, could I see distant galaxies with my own eyes? (viewed 8158 times)
  771. Is the reddish dust of Mars biogenic? (viewed 8020 times)
  772. Where is the Spitzer Space Telescope? (viewed 7463 times)
  773. Why do astronomers use telescopes? (viewed 7395 times)
  774. When will humans travel to Mars and revisit the Moon? (viewed 7180 times)
  775. How likely is it for a planet to transit its star? (viewed 6738 times)
  776. What causes the aurora? (viewed 6616 times)
  777. Does the particles involved in a star's final core collapse travel faster than the speed of light? (viewed 6515 times)
  778. When is the best time to observe zodiacal light? (viewed 6362 times)
  779. How did a transit of Venus provide astronomers with the first measurement of the Earth-Sun distance? (viewed 5423 times)
  780. Can the Sun be closer to the Earth than any planet is to Earth? (viewed 4866 times)
  781. Cosmologists say the expansion of the universe is accelerating, what is driving this? (viewed 4197 times)
  782. Can we hear sound on Titan? (viewed 3951 times)
  783. Does the direction of the moon's crescent change through the night? (viewed 3803 times)
  784. What do all the angles in a table for a planet's orbit mean? (viewed 3642 times)
  785. How do I maximize my chances of seeing shooting stars? (viewed 3100 times)
  786. Are exoplanets real? (viewed 2619 times)
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