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 2118102 times)
  2. What color is each planet? (viewed 890300 times)
  3. At what speed does the earth move around the sun? (viewed 564478 times)
  4. Is the Moon moving away from the Earth? When was this discovered? (viewed 543279 times)
  5. How far is each planet from Earth? (viewed 460648 times)
  6. When will Halley's Comet return? (viewed 412124 times)
  7. How many stars are there in our Galaxy (Milky Way)? (viewed 383917 times)
  8. How long does it take for the Sun's light to reach us? (viewed 382312 times)
  9. Why do the planets orbit the sun? (viewed 368576 times)
  10. What is the universe expanding into? (viewed 363999 times)
  11. How do you measure the distance between Earth and the Sun? (viewed 331358 times)
  12. Which planets have rings? (viewed 319706 times)
  13. Why do stars twinkle? (viewed 313131 times)
  14. Does the Moon rotate? Are there other moons that always keep one face toward their planet? (viewed 297064 times)
  15. How do I build a model rocket? (viewed 286084 times)
  16. What color is Venus? (viewed 270565 times)
  17. What is a white hole? (viewed 263507 times)
  18. Can you hear sounds in space? (viewed 244206 times)
  19. What is the life cycle of a star? (viewed 243859 times)
  20. What are the names of the earth, moon, sun, and solar system? (viewed 234766 times)
  21. What makes the Earth rotate? (viewed 225833 times)
  22. What is that ring (or rainbow) around the moon? (viewed 225360 times)
  23. What are shooting stars? (viewed 223565 times)
  24. What is the largest star? (viewed 220982 times)
  25. What do astronauts eat in space? Can they grow food? (viewed 205877 times)
  26. Why do planets rotate? (viewed 200060 times)
  27. How do we know the age of the Universe and the Earth? (viewed 199842 times)
  28. Can artificial gravity be created in space? (viewed 197944 times)
  29. Is the universe expanding faster than the speed of light? (viewed 195240 times)
  30. How does the location of sunrise and sunset change throughout the year? (viewed 185334 times)
  31. Where did the name 'Earth' come from? (viewed 177625 times)
  32. How can we see the Milky Way if we are inside it? (viewed 174677 times)
  33. What would happen if we did not have a Moon? (viewed 173070 times)
  34. Why isn't the sky bright at night if the universe has so many stars? (viewed 172484 times)
  35. What are the different kinds of astronomers? (viewed 172204 times)
  36. How many Earths fit into the Sun? (viewed 171501 times)
  37. Why is a day divided into 24 hours? (viewed 164207 times)
  38. How does the position of Moonrise and Moonset change? (viewed 159095 times)
  39. Who named the planets and who decides what to name them? (viewed 154773 times)
  40. Why are the Moon and Sun sometimes orange or red? (viewed 150509 times)
  41. When was the last time all 9 planets were aligned? (viewed 150004 times)
  42. Is Pluto a planet? (viewed 149146 times)
  43. Is the distance from the Earth to the Sun changing? (viewed 147975 times)
  44. Why do airplanes take longer to fly West than East? (viewed 145497 times)
  45. What is at the end of the Universe? (viewed 143474 times)
  46. How much money is spent on space exploration? (viewed 139297 times)
  47. How can I find the star I have "bought"? (viewed 139037 times)
  48. Why are there both high and low tides? (viewed 129870 times)
  49. How do astronauts take baths and use restrooms in space? (viewed 127781 times)
  50. What direction do planets rotate? (viewed 127363 times)
  51. What is the largest galaxy? (viewed 126610 times)
  52. Can we feel the Earth spin? (viewed 126136 times)
  53. Is the Sun expanding? Will it ever explode? (viewed 125929 times)
  54. How many known galaxies are there? (viewed 125372 times)
  55. Do stars move in the sky? (viewed 121087 times)
  56. What is a nova? (viewed 120742 times)
  57. Does your weight change between the poles and the equator? (viewed 120481 times)
  58. Can I buy a star? (viewed 115737 times)
  59. What are the advantages and disadvantages of using a telescope in space? (viewed 115491 times)
  60. Will the sun go supernova in six years and destroy Earth (as seen on Yahoo)? (viewed 113110 times)
  61. Why do all the planets orbit in the same plane? (viewed 111603 times)
  62. How are light and heavy elements formed? (viewed 110827 times)
  63. What is the hottest time of day? (viewed 110429 times)
  64. Are there telescopes that can see the flag and lunar rover on the Moon? (viewed 110399 times)
  65. How do stars move in the Galaxy? (viewed 109195 times)
  66. Does the Sun have a scientific name? (viewed 108851 times)
  67. What happens when galaxies collide? (viewed 108643 times)
  68. Why hasn't NASA gone back to the moon? (viewed 108298 times)
  69. Who first measured the speed of light? (viewed 107321 times)
  70. How do rockets work? (viewed 107104 times)
  71. Why do planets have elliptical orbits? (viewed 106905 times)
  72. What is the size of the Solar System? (viewed 106641 times)
  73. Will the magnetic field of the Earth reverse its direction in the future? Will this cause problems? (viewed 106387 times)
  74. What was there before the Big Bang and what is there outside of our universe? (viewed 105683 times)
  75. When is the next comet due to arrive? (viewed 105502 times)
  76. What would happen if an impact caused Earth to stop rotating? (viewed 105158 times)
  77. How much money do astronomers make? (viewed 104999 times)
  78. How long does a solar eclipse last? (viewed 103669 times)
  79. What is the physical difference between a star and a planet? (viewed 103249 times)
  80. Do black holes die? If so how? (viewed 102976 times)
  81. What will happen to life on Earth when the Sun becomes a red giant? (viewed 102774 times)
  82. How many constellations are there? (viewed 102054 times)
  83. How do you calculate the lifetime of the Sun? (viewed 101783 times)
  84. What elements make up the Sun? (viewed 101487 times)
  85. Does evolution contradict the second law of thermodynamics? (viewed 101379 times)
  86. What is the significance of the Tropic of Cancer, Tropic of Capricorn, Arctic Circle and Antarctic Circle? (viewed 99725 times)
  87. What is the observational difference between a star and a planet? (viewed 99546 times)
  88. Does the Sun rotate? (viewed 99517 times)
  89. Does the Sun move around the Milky Way? (viewed 98699 times)
  90. What's the difference between astronomy and astrology? (viewed 98163 times)
  91. What do astronauts do all day in the International Space Station? (viewed 97067 times)
  92. What is apparent magnitude? (viewed 94563 times)
  93. Which planet is most similar to Earth? (viewed 93301 times)
  94. Does gravity vary across the surface of the Earth? (viewed 92406 times)
  95. How many meteorites hit Earth each year? (viewed 92321 times)
  96. What would happen if the gravity on Earth was suddenly turned off? (viewed 91451 times)
  97. If Mars is only about 35-60 million miles away at close approach, why does it take 6-8 months to get there? (viewed 90335 times)
  98. What are constellations used for? (viewed 90214 times)
  99. How critical is the Earth-Sun distance in maintaining our average temperatures on Earth? (viewed 89640 times)
  100. How do astronomers use math in their jobs? (viewed 89106 times)
  101. Why do different stars appear with seasons? (viewed 88815 times)
  102. Why are stars and planets round? (viewed 88162 times)
  103. Is there a proof that Earth moves? (viewed 87624 times)
  104. Where did the Universe come from? (viewed 87529 times)
  105. Have astronomers discovered Earth's second moon? (viewed 87022 times)
  106. Does the Sun orbit the Earth as well as the Earth orbiting the Sun? (viewed 86868 times)
  107. Why is the Universe flat and not spherical? (viewed 86762 times)
  108. Why is the Moon so bright? (viewed 86740 times)
  109. What kind of schooling is necessary to become an astronomer? (viewed 86218 times)
  110. What makes the wind? (viewed 86147 times)
  111. What would happen if an asteroid 10 kilometers across hit the Earth? (viewed 85872 times)
  112. What is a singularity? (viewed 85046 times)
  113. How can a star burn with no oxygen? (viewed 83239 times)
  114. Where does the name "Milky Way" come from? (viewed 81659 times)
  115. Why does the Earth tilt back and forward once a year? (viewed 81421 times)
  116. What are RA and DEC? (viewed 80955 times)
  117. What would happen if Earth had more than one moon? (viewed 80322 times)
  118. Considering the motion of the Earth, the solar system, and the galaxy, how fast am I moving while lying in bed asleep? (viewed 79520 times)
  119. What is the difference between a "star" and a "sun"? (viewed 77868 times)
  120. What kind of rock is the moon made of? (viewed 77569 times)
  121. Since Earth is spinning, why do we land in the same place when we jump or fall? (viewed 77376 times)
  122. What are the requirements for being a planet? (viewed 77183 times)
  123. Why aren't there any green stars? (viewed 76573 times)
  124. Did astronauts really go to the Moon, or is it a hoax? (viewed 76464 times)
  125. How many stars are born and die each day? (viewed 76464 times)
  126. How are galaxies formed? (viewed 76265 times)
  127. How are black holes made? Could one be made close to us? (viewed 73979 times)
  128. Will the Sun become a black hole one day? (viewed 73848 times)
  129. What would happen if a supermassive black hole came close to the Earth? (viewed 73264 times)
  130. What is the density of a black hole? (viewed 73162 times)
  131. Who has landed on the moon? (viewed 73041 times)
  132. What would you see from inside a black hole? (viewed 71241 times)
  133. Why is the moon in a different place every night? (viewed 70902 times)
  134. Can moons have moons? (viewed 70368 times)
  135. Do most astronomers believe in God based on the available scientific evidence? (viewed 70361 times)
  136. What happens to a substance if its speed is more than the speed of light? (viewed 69655 times)
  137. Why can't you see stars during the day? (viewed 69654 times)
  138. How do astronomers measure the brightness of stars? (viewed 69531 times)
  139. How do rockets move in space? (viewed 69514 times)
  140. Can you fire a gun on the Moon? (viewed 69442 times)
  141. How do we weigh objects in space? (viewed 69030 times)
  142. How often does the Sun pass through a spiral arm in the Milky Way? (viewed 68980 times)
  143. How can the Universe expand faster than the speed of light during inflation? (viewed 68861 times)
  144. What are some of the effects of solar flares on Earth? (viewed 68806 times)
  145. What would happen if you took off your helmet in space? (viewed 68406 times)
  146. How is astronomy impacted by trigonometry? (viewed 68019 times)
  147. Is it possible to measure the temperature of the Sun? (viewed 67645 times)
  148. How do we know the mass of the Earth and the Moon? (viewed 67590 times)
  149. When the Sun converts mass to energy, do the orbits of the planets change? (viewed 67502 times)
  150. Does the Mediterranean sea have tides? (viewed 67471 times)
  151. How does the Sun compare to other stars? (viewed 66927 times)
  152. How do you measure a planet's mass? (viewed 66096 times)
  153. What are the "dog days of summer"? (viewed 66072 times)
  154. Why do stars change colour when they twinkle? (viewed 66024 times)
  155. How does the Moon stay "suspended" in the air? (viewed 65889 times)
  156. How are elements heavier than iron formed? (viewed 65342 times)
  157. What is the evidence supporting the nebula theory of Solar System formation? (viewed 65177 times)
  158. What kinds of jobs do astronomers do? (viewed 64807 times)
  159. Why do we not have eclipses every month? (viewed 64709 times)
  160. Does quantum entanglement imply faster than light communication? (viewed 64146 times)
  161. If the universe is infinite does that mean there is an infinite number of "me"s? (viewed 63409 times)
  162. What are black holes made of? (viewed 63290 times)
  163. What causes seasons? (viewed 62947 times)
  164. When can I see the Moon through the hole in the Pantheon? (viewed 62511 times)
  165. How did the stars get named? (viewed 62468 times)
  166. Why doesn't the earliest sunset occur on the shortest day of the year? (viewed 62324 times)
  167. Where does the name "Moon" come from? (viewed 61967 times)
  168. How did asteroids form and what is the difference between an asteroid and a comet? (viewed 61893 times)
  169. How fast is the Universe expanding? (viewed 61721 times)
  170. How do you measure the mass of a star? (viewed 61558 times)
  171. How long would it take the Earth to fall into the Sun? (viewed 61353 times)
  172. Where did the matter in the universe come from? (viewed 61301 times)
  173. Traveling at light speed, how long would it take to get to the nearest galaxy? (viewed 61191 times)
  174. What's the best college for astronomy? (viewed 61153 times)
  175. What are Altitude and Azimuth? (viewed 61021 times)
  176. Why do planets not twinkle? (viewed 60968 times)
  177. Why doesn't the length of each day change much around the solstices? (viewed 60617 times)
  178. How does light pollution affect astronomers? (viewed 60442 times)
  179. What would happen to us if the sun went out for an hour? (viewed 60420 times)
  180. Are there stars outside of galaxies? (viewed 60388 times)
  181. Where, in relation to the entire universe, is the Milky Way located? (viewed 60156 times)
  182. What is the mass of the Universe? (viewed 59665 times)
  183. What's the difference between dark matter and dark energy? (viewed 58477 times)
  184. Does the Moon rotate? (viewed 58193 times)
  185. How can I calculate the position or path of the Sun for a given time and location? (viewed 58107 times)
  186. Could there be life in the galaxies nearest to the Milky Way? (viewed 58041 times)
  187. Why does the Sun's apparent path through the sky change throughout the year? (viewed 57607 times)
  188. Why does the Earth have only one moon? (viewed 57584 times)
  189. Can any galaxies be seen with the naked eye? (viewed 57182 times)
  190. How does the parachute in a model rocket work? (viewed 56447 times)
  191. How does astronomy benefit humankind? (viewed 56296 times)
  192. What is the origin of spiral structure in galaxies? (viewed 56255 times)
  193. What is the shape of the universe? (viewed 55988 times)
  194. How long does the supernova stage of a star last? (viewed 55923 times)
  195. How close was the Moon to the Earth when it formed? (viewed 55858 times)
  196. What makes up most of the Universe? (viewed 55708 times)
  197. What is the largest structure in the universe? (viewed 55489 times)
  198. Where are stars born? (viewed 54842 times)
  199. Why isn't the summer solstice the hottest day of the year? (viewed 54672 times)
  200. What can we learn from the color of a star? (viewed 54446 times)
  201. Why is looking out into space the same as looking back in time? (viewed 54440 times)
  202. What is a star's "spectrum"? (viewed 54409 times)
  203. What is the size of a black hole? (viewed 54289 times)
  204. Are names given to black holes? (viewed 54273 times)
  205. How do astronauts use math in their jobs? (viewed 54265 times)
  206. Can you see satellites? (viewed 53761 times)
  207. Which constellation does our Sun belong to? (viewed 53450 times)
  208. How do you calculate the azimuth and altitude of an object? (viewed 53057 times)
  209. How do we measure the size of the Moon and of the Sun? (viewed 53049 times)
  210. If gravity is a "curvature of space" rather than a force, why do a ball and bullet follow different paths? (viewed 52828 times)
  211. Are aliens or UFOs real? (viewed 52352 times)
  212. How can I find the distance to the Sun on any given day? (viewed 52248 times)
  213. What happens to a bullet fired on the moon? (viewed 52202 times)
  214. How do the astronauts communicate in space if sound cannot travel in a vacuum? (viewed 52147 times)
  215. Why do we see stars? (viewed 52139 times)
  216. What other careers involve Astronomy besides Astronomer? (viewed 51962 times)
  217. 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 51896 times)
  218. How can I measure the distance of a star? (viewed 51804 times)
  219. Is the speed of light constant? (viewed 51296 times)
  220. What are some astronomy science fair projects? (viewed 51278 times)
  221. Which hemisphere has the best view of the Milky Way? (viewed 50848 times)
  222. Are there any asteroids on a collision course with Earth? (viewed 50729 times)
  223. How long has there been water on Earth? (viewed 50591 times)
  224. Is time travel possible? (viewed 50111 times)
  225. Why is the sky blue and not blue & purple? (viewed 49925 times)
  226. Who discovered each planet? (viewed 49917 times)
  227. What would happen if the Moon fell out of its orbit around Earth? (viewed 49875 times)
  228. Why does the Moon look big on the horizon? (viewed 49628 times)
  229. Would your weight change as you go underground? (viewed 49558 times)
  230. Are meteorites hot or cold when they hit Earth? (viewed 49530 times)
  231. Can we look back far enough in time to see the Big Bang? (viewed 49439 times)
  232. Why is twilight short near the equator? (viewed 49419 times)
  233. If the Earth's rotation period is less than 24 hours, why don't our clocks fall out of sync with the Sun? (viewed 49369 times)
  234. What do a galaxy's colors mean? Are they its true colors? (viewed 49192 times)
  235. Why is it difficult to understand the expansion of the universe? (viewed 48914 times)
  236. Where did all the water in the universe come from? (viewed 48652 times)
  237. What is a graviton? (viewed 48191 times)
  238. What is the difference between nutation and precession of the Earth? (viewed 48123 times)
  239. If light has no mass, then what draws it into a black hole? (viewed 47932 times)
  240. How is the time of sunrise calculated? (viewed 47835 times)
  241. What skills do astronomers need? (viewed 47783 times)
  242. What's the difference between astronomy and astrophysics? (viewed 47651 times)
  243. Are the planes of solar systems aligned with the plane of the Galaxy? (viewed 47617 times)
  244. How do we know what other planets (and stars, galaxies, etc.) are made of? (viewed 46480 times)
  245. What do I need to do to become an astronomer? (viewed 46374 times)
  246. Do dead stars still shine? (viewed 46012 times)
  247. How do gravitons escape black holes to tell the universe about their gravity? (viewed 45655 times)
  248. Why do the size and brightness of the full moon change? (viewed 45647 times)
  249. What is a wormhole? (viewed 45611 times)
  250. Do supermassive black holes cause galaxy rotation? (viewed 45536 times)
  251. How are black holes discovered? (viewed 45213 times)
  252. Where is the nearest black hole? (viewed 45160 times)
  253. Will we get sucked into the black hole at the center of the Milky Way? (viewed 44982 times)
  254. The Moon slows the Earth's rotation, but how fast was it spinning billions of years ago? (viewed 44604 times)
  255. Why does the Sun appear larger on the horizon than overhead? (viewed 44550 times)
  256. Can we find the place where the Big Bang happened? (viewed 44509 times)
  257. Why can't we see Venus at night when it is an inner planet? (viewed 44458 times)
  258. How do galaxies collide in an expanding universe? (viewed 44437 times)
  259. Can I calculate the size of the Universe by converting light years to kilometres? (viewed 44361 times)
  260. Is the Earth slowly getting larger? (viewed 44294 times)
  261. Why are there stars? (viewed 44233 times)
  262. Why does Barnard 68 appear dark? (viewed 43714 times)
  263. Why are most months 30 or 31 days long? (viewed 43640 times)
  264. Are Kuiper Belt Objects asteroids? Are large Kuiper Belt Objects planets? (viewed 42477 times)
  265. What is the biggest crater recorded on Earth? (viewed 42186 times)
  266. Was the Sun made in a supernova? (viewed 42143 times)
  267. Why don't people walk upside-down on the bottom of the Earth? (viewed 42106 times)
  268. What is the best way to see the Milky Way? (viewed 42067 times)
  269. Could the Universe have expanded faster than the speed of light at the Big Bang? (viewed 41949 times)
  270. Are there eclipses on other planets? (viewed 41858 times)
  271. Is there a "South Star"? (viewed 41814 times)
  272. Why does the location of sunrise change? (viewed 41810 times)
  273. Has there been an experiment that measured speed faster than the speed of light in vacuum? (viewed 41779 times)
  274. How much longer will the Earth last? (viewed 41742 times)
  275. How long could life on Earth survive if the Sun stopped shining? (viewed 41714 times)
  276. Did life originate on Earth, or did it come from somewhere else? (viewed 41611 times)
  277. Why doesn't dark matter fall into a black hole? (viewed 41506 times)
  278. How does Astronomy involve Chemistry? (viewed 41440 times)
  279. What is the difference between the "Doppler" redshift and the "gravitational" or "cosmological" redshift? (viewed 41405 times)
  280. How would the weather on Earth be different if it were a cube? (viewed 41292 times)
  281. Can I buy land on the Moon? (viewed 41272 times)
  282. What happens to spacetime inside a black hole? (viewed 41130 times)
  283. Is the Moon hollow? (viewed 40953 times)
  284. What happens when two black holes get too close? (viewed 40876 times)
  285. Why does the Earth only see one side of the Moon? (viewed 40840 times)
  286. How much can the location of sunset differ from due West? (viewed 40687 times)
  287. What's the biggest meteorite? (viewed 40645 times)
  288. What is time dilation? (viewed 40447 times)
  289. Can the acceleration of the Universe be analogous to apparent acceleration in a airplane? (viewed 40383 times)
  290. What color would Mars be if you were standing on it? (viewed 40349 times)
  291. What is the most distant known galaxy? (viewed 40192 times)
  292. What are the names of the three stars in Orion's belt? (viewed 39970 times)
  293. How can two moons of Saturn share the same orbit? (viewed 39812 times)
  294. What if the Earth rotated twice as fast? (viewed 39556 times)
  295. Could someone travel the universe in his or her own lifetime? (viewed 39337 times)
  296. Can terrestrial planets have rings? (viewed 39313 times)
  297. How long would it take for a mini-black hole to eat the Earth? (viewed 39290 times)
  298. How many Astronauts have been in space? (viewed 39069 times)
  299. Why do people draw stars with five points? (viewed 38907 times)
  300. What are "blue stragglers" in globular clusters? (viewed 38766 times)
  301. Why do pictures of distant galaxies have higher resolution than those of nearby planets? (viewed 38679 times)
  302. Is it possible to see the full Moon and the Sun simultaneously in high northern latitudes when the Sun doesn't set? (viewed 38538 times)
  303. How do we feel heat? (viewed 38525 times)
  304. What is the typical size of a visible shooting star? (viewed 38375 times)
  305. If a white dwarf is a "dead" star, why is it so hot? (viewed 38290 times)
  306. Does Mt. Everest cast a shadow on the moon? (viewed 38101 times)
  307. How do we know that nuclear fusion is still going on in the Sun? (viewed 38089 times)
  308. Is the Great Wall the largest galaxy cluster? (viewed 37989 times)
  309. How fast does the Earth go at perihelion and aphelion? (viewed 37887 times)
  310. How does night and day work? (viewed 37883 times)
  311. Why can we see the sun's image before sunrise and after sunset? (viewed 37854 times)
  312. Can a person go into a black hole and come out alive? (viewed 37663 times)
  313. What is a dimension? (viewed 37551 times)
  314. Does the Sun have an iron surface? (viewed 37513 times)
  315. What is the speed of gravity? (viewed 37469 times)
  316. Can you see the future as you fall into a black hole? (viewed 37422 times)
  317. Why are Saturn's rings flat? (viewed 37381 times)
  318. Can I communicate faster than light? (viewed 37359 times)
  319. Where do planetary rings come from, and what are they made of? (viewed 37358 times)
  320. On which days can I see the Moon in the evening / morning and why is this so? (viewed 37289 times)
  321. What can I use for fuel in my homemade rocket? (viewed 37211 times)
  322. What is Earthrise over the Moon? (viewed 37203 times)
  323. How big is the universe? (viewed 37174 times)
  324. Where is the supernova remnant that led to our solar system? (viewed 37103 times)
  325. Do you think it's possible to maintain life on other planets? (viewed 37094 times)
  326. Is the Sun always up for exactly 12 hours at the equator? (viewed 36982 times)
  327. What is the approximate GPA needed in High School in Math and Science to be an astronomer? (viewed 36903 times)
  328. Who (and when) discovered that the earth's axis is on a 23 degree tilt? (viewed 36828 times)
  329. Are all stars the same? (viewed 36776 times)
  330. How do we determine the age of the universe? (viewed 36610 times)
  331. Is there really a 10th planet? (viewed 36609 times)
  332. Why do clocks turn in the opposite direction from the Earth and Moon? (viewed 36545 times)
  333. What companies or businesses can astronomers work for? (viewed 36492 times)
  334. Why is sea water salty, and not lake water? (viewed 36423 times)
  335. What would happen to the Earth if an asteroid hit the Moon? (viewed 36234 times)
  336. How many stars can I see? (viewed 36161 times)
  337. How do I tell which planet is which? (viewed 36083 times)
  338. Does the Coriolis force determine which way my toilet drains? Does it affect black holes? (viewed 36075 times)
  339. Is there a beginning and an end to a galaxy's life? (viewed 35902 times)
  340. If the universe is 15 billion years old, how can it be larger than 15 billion light years across? (viewed 35820 times)
  341. Do the Sun's or Earth's magnetic field reverse? (viewed 35627 times)
  342. How do we know the Milky Way is a spiral galaxy? (viewed 35586 times)
  343. How can the universe be "flat"? We're 3D! (viewed 35412 times)
  344. How do we define distance in an expanding universe? (viewed 35340 times)
  345. How are photons created and destroyed? (viewed 35296 times)
  346. How can I find my age on another planet? (viewed 35187 times)
  347. Is Andromeda part of the Milky Way? Where can I find them in the sky? (viewed 34900 times)
  348. Why have star signs shifted by one constellation? (viewed 34687 times)
  349. What was that really big falling star that I saw? (viewed 34416 times)
  350. How does the brightness of a star depend on its distance from us? (viewed 34380 times)
  351. Why do humans want to go in space? (viewed 34367 times)
  352. Why are there blue shifted galaxies? (viewed 34295 times)
  353. What is the pattern to the distances between each planet and the sun? (viewed 34187 times)
  354. How are planets detected around other stars? (viewed 34178 times)
  355. What would happen if two stars collided? (viewed 34088 times)
  356. Can a lunar and a solar eclipse happen in the same month? When will this happen next? (viewed 34079 times)
  357. Who came up with the name "black hole"? (viewed 34078 times)
  358. What is the significance of the second focus of elliptical orbits of planets in our Solar System? (viewed 33961 times)
  359. How do astronauts communicate with their families from space? (viewed 33942 times)
  360. When we look back to the Big Bang, why don't we see the universe as a tiny speck of matter? (viewed 33929 times)
  361. Is the Earth at the centre of the Universe? (viewed 33922 times)
  362. How can we estimate the number of Earth-like planets in the Galaxy? (viewed 33912 times)
  363. Is there a simple formula to calculate solar eclipse timings from any position on Earth? (viewed 33814 times)
  364. What kind of eyepieces do I need to look at planets? (viewed 33786 times)
  365. Will we ever stop having solar eclipses because of the moon's motion away from the Earth? (viewed 33737 times)
  366. Why don't astronomers use everyday units to measure distances (what is an AU or a pc)? (viewed 33719 times)
  367. How is it that we see farther out in space (farther back in time) than in the past? (viewed 33462 times)
  368. Will the Moon be invisible in 500 million years? (viewed 33402 times)
  369. Are Earth and the Moon "twin planets"? (viewed 33229 times)
  370. Which American colleges teach astronomy? (viewed 33111 times)
  371. How dangerous are the asteroids? (viewed 33094 times)
  372. Why is our solar system so different from all the others we've found? (viewed 33026 times)
  373. How do I become both an astronaut and an astronomer? (viewed 32904 times)
  374. Why is Uranus tipped on its side? (viewed 32896 times)
  375. Can we colonize other planets? (viewed 32794 times)
  376. How hot is each one of the layers of the sun? (viewed 32594 times)
  377. How do sunrise and sunset times change with altitude? (viewed 32179 times)
  378. What are quasars made of? (viewed 32063 times)
  379. How can I calculate distances between stars? (viewed 32061 times)
  380. Why do constellations look the same after several years even though all the stars are moving? (viewed 31919 times)
  381. Why do astronauts in space need to exercise? (viewed 31867 times)
  382. Why are there no craters on Earth? Did all the meteorites miss us? (viewed 31854 times)
  383. Why doesn't gravity change the speed of light? (viewed 31810 times)
  384. Can you describe a day on the job as an astronomer? (viewed 31614 times)
  385. Is the universe really like an expanding balloon? (viewed 31577 times)
  386. Is it possible to count the stars? (viewed 31523 times)
  387. Is it true that the Sun burns off a billion tons of gas every 5 seconds? (viewed 31482 times)
  388. What is dark matter? (viewed 31455 times)
  389. Is the gravitational force exerted by the Earth on the Moon equal to the centripetal force acting on the Moon? (viewed 31446 times)
  390. Is time travel possible using merging black holes? (viewed 31443 times)
  391. Why can't a plane fly slowly and let the Earth pass underneath? (viewed 31342 times)
  392. What is happening just around the black hole in the center of the Milky Way? (viewed 31300 times)
  393. Can superheavy elements (such as Z=116 or 118) be formed in a supernova? Can we observe them? (viewed 31214 times)
  394. Did the speed of light change over the history of the universe? (viewed 31127 times)
  395. Can we see dead stars with the naked eye? (viewed 31063 times)
  396. How big a change in the Earth's orbit would be required to destroy all life? (viewed 31063 times)
  397. How can we distinguish a star's "real" color from the change in color that we observe due to the star's motion? (viewed 31012 times)
  398. How do we measure distances to other stars? (viewed 30928 times)
  399. Is the Local Group expanding along with the entire Universe? (viewed 30893 times)
  400. What happens when an antimatter black hole collides with a matter blackhole? (viewed 30783 times)
  401. How do I make a scale model of the Solar System? (viewed 30775 times)
  402. Are time machines possible? (viewed 30734 times)
  403. How many moles of stars are in the known universe? (viewed 30312 times)
  404. How are galaxy distances inferred from their recessional velocities? (viewed 30081 times)
  405. Is there any limitation to what a black hole can "suck" in? (viewed 29921 times)
  406. How can we tell what the interiors of planets are like? (viewed 29906 times)
  407. What happens when you change the mass of a White Dwarf or Neutron Star? (viewed 29799 times)
  408. Why is the time between two successive full moons different from the lunar synodic month? (viewed 29742 times)
  409. What is the farthest in space that we have gone? (viewed 29721 times)
  410. What do "homogeneity" and "isotropy" mean? (viewed 29574 times)
  411. What's that dark spot on the Sun? (viewed 29508 times)
  412. How can we know that there are other galaxies if we cannot leave ours? (viewed 29485 times)
  413. What are the closest and/or brightest stars? (viewed 29415 times)
  414. How can I tell if the rock I found is a meteorite? (viewed 29384 times)
  415. Can astronauts produce water in space? (viewed 29368 times)
  416. Will the seasons change due to precession? (viewed 29341 times)
  417. Does the Milky Way spin counter-clockwise? If so, do all spiral galaxies spin in this direction and why? (viewed 29325 times)
  418. How was the starting point for the Julian Date system chosen? (viewed 29194 times)
  419. Aren't jobs in astronomy scarce? (viewed 29186 times)
  420. Do astronomers believe in astrology? (viewed 29063 times)
  421. How do we know if the universe will keep expanding forever? (viewed 29027 times)
  422. Did I see the Aurora Borealis as a child? (viewed 29025 times)
  423. Why does the SETI project search for radio signals? (viewed 28995 times)
  424. How long does it take the Big Dipper to move in the sky? (viewed 28970 times)
  425. What are the facts about the Star of Bethlehem? (viewed 28968 times)
  426. Don't tachyons travel faster than light? (viewed 28949 times)
  427. Could an astronaut or satellite fall into a black hole that we didn't know about? (viewed 28921 times)
  428. Why do most moons orbit their planets at the equator? (viewed 28918 times)
  429. Why do we study black holes? (viewed 28846 times)
  430. What are the atmospheres of Mars and Pluto like? (viewed 28772 times)
  431. When are there 5 Sundays in February? (viewed 28734 times)
  432. Wouldn't the Big Bang theory be considered a hypothesis and not a theory? (viewed 28676 times)
  433. Do we see the same stars from above and below the equator? (viewed 28455 times)
  434. Has anyone made a map of the Milky Way? (viewed 28434 times)
  435. Was I hit by a meteorite? (viewed 28419 times)
  436. How are galaxies named? (viewed 28296 times)
  437. Can you use an infinite line of reflectors to send light to the edge of the Universe? (viewed 28294 times)
  438. What does the term "visible universe" mean? (viewed 28291 times)
  439. What colors are visible through an amateur telescope? (viewed 28290 times)
  440. Could you tell me about the life cycle of galaxies? (viewed 28265 times)
  441. Do you believe in UFOs? (viewed 28229 times)
  442. How can geometry be different in space? (viewed 28194 times)
  443. Why are the compositions of comets and asteroids different? (viewed 27909 times)
  444. How do asteroids, meteors and comets disappear? (viewed 27635 times)
  445. What's the best thing about being an astronomer? (viewed 27629 times)
  446. How much time do astronomers spend looking through telescopes? (viewed 27558 times)
  447. Will winter and summer constellations change due to abnormal warmth or cold on Earth? (viewed 27537 times)
  448. How do astronomers measure the radius of a star? (viewed 27418 times)
  449. Why do so many of the world's UFO sightings happen in America? (viewed 27417 times)
  450. How will the two black holes that are going to collide affect Earth? (viewed 27372 times)
  451. Have there been other Big Bangs before? (viewed 27344 times)
  452. Can two lunar eclipses occur in the same month? (viewed 27342 times)
  453. How can we see galaxies if their stars are so faint? (viewed 27330 times)
  454. How do I explain to my children why the Moon has phases? (viewed 27119 times)
  455. Can life exist on the recently discovered extrasolar planets? (viewed 27117 times)
  456. How are galaxies and solar systems similar? (viewed 27030 times)
  457. How close do you have to come to the Earth to be influenced by its gravity? (viewed 27024 times)
  458. Is the Milky Way a collision of two galaxies? (viewed 26945 times)
  459. Is there a project I can do on black holes? (viewed 26893 times)
  460. How can we measure distances to more stars? (viewed 26826 times)
  461. What is the origin of the stellar classification system "OBAFGKM"? (viewed 26780 times)
  462. Could you escape from a black hole if you were able to go faster than the speed of light? (viewed 26759 times)
  463. How do scientists slow light down? (viewed 26695 times)
  464. Do the magnitudes and colors of stars ever change? (viewed 26642 times)
  465. Is infinite temperature possible? (viewed 26540 times)
  466. Do we know everything about the Sun? (viewed 26511 times)
  467. How close does a supernova need to be to damage the Earth's environment? (viewed 26502 times)
  468. Can "tired light theory" explain the observed redshifts of galaxies? (viewed 26385 times)
  469. What supernova created the Crab nebula? (viewed 26362 times)
  470. Can one star orbit another? (viewed 26346 times)
  471. Do asteroids hit the sun? (viewed 26338 times)
  472. Is it worthwhile to continue the search for extraterrestrial life? (viewed 26325 times)
  473. How far does a galaxy extend? (viewed 26164 times)
  474. What causes gamma ray bursts? (viewed 26158 times)
  475. Can double stars have planets? (viewed 26151 times)
  476. How do I polar align my telescope? (viewed 26022 times)
  477. Is there such a thing as hyperspace? (viewed 25936 times)
  478. What will happen to the Milky Way in the future? (viewed 25933 times)
  479. What type of energy does a black hole have? (viewed 25895 times)
  480. Can astronauts play musical instruments in space? (viewed 25884 times)
  481. What happens to the material that has been sucked into a black hole? (viewed 25878 times)
  482. What is the farthest Northern Latitude in which the Magellanic Clouds can be seen? (viewed 25817 times)
  483. Which way does the sun travel in the southern hemisphere? (viewed 25817 times)
  484. What is sidereal time? (viewed 25802 times)
  485. Why do the explosions of Type Ia supernovae have a more predictable spectrum than those of regular Type II supernovae? (viewed 25750 times)
  486. Is there oxygen in the atmospheres of other planets? (viewed 25682 times)
  487. What is a Cepheid variable? (viewed 25626 times)
  488. What is "nothing", from a scientific point of view? (viewed 25606 times)
  489. How will a change in the speed of light affect the evolution of the Universe? (viewed 25600 times)
  490. What's the object I saw that moved across the sky and then got very bright? (viewed 25551 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 25536 times)
  492. Which part of the sky did the famous 'wow' signal originate from? (viewed 25506 times)
  493. How different would the night sky have looked in 40,000 B.C.? (viewed 25441 times)
  494. Is there sound coming from the Sun? (viewed 25393 times)
  495. How do we know what parameters to use when simulating the collision of the Milky Way and Andromeda? (viewed 25362 times)
  496. Why do we assume that the universe is homogeneous? (viewed 25311 times)
  497. How do we know that sunspots are associated with the Sun's magnetic field? (viewed 25268 times)
  498. Can a human give birth in space? (viewed 25249 times)
  499. When did people discover that the Sun is a star? (viewed 25199 times)
  500. Why is the shadow on the Moon the shape it is? (viewed 25183 times)
  501. Are there any dark stars or dark galaxies made of dark matter? (viewed 25151 times)
  502. When unmanned spacecraft accelerate in space, what causes them to slow down? (viewed 25121 times)
  503. Are planetary nebulae the result of supernovae? (viewed 25116 times)
  504. What calculations go into predicting eclipses? (viewed 25101 times)
  505. Does the Moon look different in the northern and southern hemispheres? (viewed 25077 times)
  506. If we invented special suits could we ever go to the sun? (viewed 25055 times)
  507. Was Stonehenge built to mark solar phenomena? (viewed 25050 times)
  508. Is there a list of the sizes of different kinds of stars? (viewed 25010 times)
  509. What is the difference between homogeneity and isotropy? (viewed 24995 times)
  510. What is our galaxy's halo made of, and how was it formed? (viewed 24975 times)
  511. What process would bring about a quark star? (viewed 24943 times)
  512. What's so exciting about the new planet around 55 Cancri? (viewed 24881 times)
  513. Can I see a quasar? (viewed 24869 times)
  514. What is a Dyson Sphere? (viewed 24835 times)
  515. Did a giant impact cause the Dark Ages? (viewed 24818 times)
  516. How many sunspots can the Sun have at once? (viewed 24812 times)
  517. How are asteroid compositions and classifications determined? (viewed 24771 times)
  518. Have gravitational waves been proven to exist? (viewed 24764 times)
  519. Can I see details on Venus? (viewed 24711 times)
  520. Can any comparison be made between spiral galaxies and hurricanes? (viewed 24654 times)
  521. Why are there active volcanos on Io? (viewed 24492 times)
  522. Why are there more maria on the near side of the Moon? (viewed 24487 times)
  523. What equipment do I need for astrophotography? (viewed 24455 times)
  524. Does Cerenkov radiation travel faster than light? (viewed 24442 times)
  525. How is it proved that the Universe is expanding? (viewed 24417 times)
  526. Is there any possibility that the Solar System or the Universe is in a black hole? (viewed 24380 times)
  527. What happened to all the black holes that were around in the early universe? (viewed 24374 times)
  528. Why are telescopes kept in cold conditions? (viewed 24230 times)
  529. What happened to the girl who named Pluto? (viewed 24190 times)
  530. Would the biggest airplanes cause tsunamis if they crashed? (viewed 24182 times)
  531. If clocks run slow in a gravitational field, how can we know the true age of the Solar System and Universe? (viewed 24166 times)
  532. How big was the Sun when it first "fired up"? (viewed 24156 times)
  533. How can we compare dark matter and dark energy? (viewed 24125 times)
  534. If the Universe was infinitely dense at the Big Bang, why didn't time stand still? (viewed 24032 times)
  535. What caused Shoemaker-Levy 9 to split up? (viewed 24019 times)
  536. Could we send a space mission to a comet? (viewed 24002 times)
  537. Why do photos of space taken from space never show any stars? (viewed 23997 times)
  538. How long do supernova remnants last? (viewed 23952 times)
  539. Could we be seeing dead stars? (viewed 23875 times)
  540. How do solar flares affect airline pilots? (viewed 23861 times)
  541. Why doesn't light from distant galaxies reach us instantaneously? (viewed 23850 times)
  542. How are sunspots formed? (viewed 23842 times)
  543. How big is the Hubble Ultra Deep Field image? (viewed 23697 times)
  544. Could a different theory of gravity explain the dark matter mystery? (viewed 23677 times)
  545. How does the Earth compare in size to the entire universe at the present epoch? (viewed 23657 times)
  546. Can you give me advice on buying a telescope? (viewed 23652 times)
  547. As the universe expands, why don't galaxies get stretched out? (viewed 23633 times)
  548. How many comets are currently orbiting our sun? (viewed 23590 times)
  549. Why doesn't NASA build rotating spacecraft to simulate gravity? (viewed 23588 times)
  550. Why is the Hubble Space Telescope in space? (viewed 23524 times)
  551. Can you tell time by the Big Dipper? (viewed 23490 times)
  552. What would happen if a human were exposed to space without wearing a spacesuit? (viewed 23486 times)
  553. Where does the kinetic energy of infalling bodies come from? (viewed 23450 times)
  554. Can I build an instrument to measure the size of the Sun and of the Moon? (viewed 23447 times)
  555. How do we know that superclusters are the largest structures in the universe? (viewed 23419 times)
  556. How powerful are quasars? (viewed 23345 times)
  557. Would extraterrestrial civilizations know that there is life on Earth? (viewed 23281 times)
  558. Did I really hear a meteor? (viewed 23252 times)
  559. Why is it important to study meteorites? (viewed 23210 times)
  560. How is the Cepheid yardstick validated? (viewed 23202 times)
  561. Why are telescopes located in remote places? (viewed 23060 times)
  562. Can supernovae hinder the formation of life in galaxies? (viewed 23055 times)
  563. What would happen if there was a collision between two white dwarfs? (viewed 23054 times)
  564. Do unmanned spacecraft like Voyager travel in straight lines? (viewed 23051 times)
  565. Did time go slower just after the Big Bang? (viewed 23033 times)
  566. Are there any new craters on the moon? (viewed 23020 times)
  567. Why are stars of different masses? (viewed 23000 times)
  568. Do galaxies orbit around anything? (viewed 22960 times)
  569. How can I contribute to science as an amateur astronomer? (viewed 22940 times)
  570. How do planets capture satellites? (viewed 22918 times)
  571. Do similar laws of physics throughout the Universe imply that all life must be like life on Earth? (viewed 22915 times)
  572. Do the Earth's magnetic poles ever change places? (viewed 22915 times)
  573. Are the asteroids the remains of a planet which broke apart? (viewed 22902 times)
  574. How do I become an astronomical artist? (viewed 22887 times)
  575. What kind of instruments are used to detect extrasolar planets? (viewed 22867 times)
  576. How could galaxies have gotten so far away in only 15 billion years? (viewed 22729 times)
  577. Could there have been multiple Big Bangs at different places in the universe? (viewed 22721 times)
  578. How are astronomy and poetry linked? (viewed 22682 times)
  579. How do unmanned space probes avoid running into things? (viewed 22653 times)
  580. What kind of telescope should I use for astrophotography? (viewed 22603 times)
  581. Why can't relative velocities add up to more than the speed of light? (viewed 22582 times)
  582. Could dark energy come from matter anti-matter pairs forming spontaneously and then annihilating? (viewed 22521 times)
  583. Why is NASA shutting down the Hubble Space Telescope? (viewed 22516 times)
  584. Can I listen to the SETI@home radio signal? (viewed 22501 times)
  585. How can you tell if a crescent moon is preceding or following a new-moon phase? (viewed 22474 times)
  586. Are the properties of extrasolar planets known? (viewed 22449 times)
  587. Does the Sun have any heavy elements? (viewed 22407 times)
  588. Will we discover an 11th planet? What would it be called? (viewed 22265 times)
  589. What class of spiral galaxy is the Milky Way? (viewed 22231 times)
  590. Can the theory of formation of the solar system explain all the observables? (viewed 22228 times)
  591. What month was it when Odysseus saw Orion in 1000BC? (viewed 22207 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 22197 times)
  593. How do astronomers observe the Sun's interior? (viewed 21942 times)
  594. Why does one side of Mars look more catastrophic than the other? (viewed 21927 times)
  595. What makes a satellite geosyncronise itself with Earth's orbit? (viewed 21920 times)
  596. Why does the apparent density of galaxies drop off at larger distances? (viewed 21882 times)
  597. Would a planet near the galactic center have a brighter night sky? (viewed 21835 times)
  598. Is it possible for amateurs to do optical interferometry? (viewed 21735 times)
  599. What is the solar cycle? (viewed 21688 times)
  600. Where was the water in the big bang? (viewed 21622 times)
  601. Could we send a manned mission to the outer planets? (viewed 21613 times)
  602. Do stars' orbits in galaxies obey Kepler's Laws? (viewed 21574 times)
  603. Can other terrestrial moons be (or have been) stable? (viewed 21545 times)
  604. Why was the Platonic year named after Plato? (viewed 21484 times)
  605. How are supernovae discovered? (viewed 21470 times)
  606. Can a black hole come back to the visual universe through a "little bang"? (viewed 21415 times)
  607. What would the Big Crunch look like to an observer on Earth? (viewed 21396 times)
  608. Does inflation allow for an infinite number of universes? (viewed 21334 times)
  609. Why are accretion disks flat? (viewed 21284 times)
  610. Could our position in the universe affect our perceptions of the expansion? (viewed 21280 times)
  611. What is meant by "stopping down a telescope"? (viewed 21265 times)
  612. How can water be chemically trapped in rocks? (viewed 21256 times)
  613. Why do spacecraft need heat shields coming back to Earth but not leaving? (viewed 21210 times)
  614. Why doesn't the hydrogen on Jupiter explode? (viewed 21188 times)
  615. Did I find a rock that came from the Moon? (viewed 20974 times)
  616. Have astronomers observed any phenomena that could be produced by extraterrestrial civilizations? (viewed 20960 times)
  617. Does a photon observe other photons moving past it at the speed of light? (viewed 20938 times)
  618. What is the SU(3) quark model? (viewed 20926 times)
  619. How can the Sun have such a strong gravitational field if it's made of gasses? (viewed 20925 times)
  620. Can gravitational lensing from intervening galaxies cause the observed ripples in the Cosmic Microwave Background? (viewed 20904 times)
  621. What's new with the Big Bang? (viewed 20648 times)
  622. Will I be able to see the shadow of the Moon streaking towards me in a total solar eclipse? (viewed 20607 times)
  623. Could photons be dark matter? (viewed 20539 times)
  624. Is it possible to build a cheap device to measure declination? (viewed 20518 times)
  625. Why can we have solar eclipses? (viewed 20503 times)
  626. If comets are boiling away, why are there any left? (viewed 20475 times)
  627. How can we find galaxies behind the Milky Way? (viewed 20466 times)
  628. How fast do particles travel in space? (viewed 20427 times)
  629. Why do some eclipses take longer than others? (viewed 20412 times)
  630. Why search for only Earth-like life on other planets? (viewed 20376 times)
  631. Where can I find information on the moons of other planets? (viewed 20350 times)
  632. How much power is contained in a beam of light? (viewed 20270 times)
  633. Why is the WMAP picture of the CMB an ellipse? (viewed 20208 times)
  634. Why is pressure broadening greater in low mass stars than in high mass stars? (viewed 20182 times)
  635. What would an "open geometry" for the universe look like? (viewed 20088 times)
  636. What are the boundaries of the constellations? (viewed 20050 times)
  637. Did the Sumerians measure precession? (viewed 19997 times)
  638. What kinds of star clusters are there? (viewed 19976 times)
  639. Why is the Cosmic Microwave Background not absorbed by interstellar hydrogen? (viewed 19955 times)
  640. How do astronomers come up with their facts? (viewed 19943 times)
  641. Why aren't discoveries of extrasolar planets reported on the news? (viewed 19920 times)
  642. How do bars form in spiral galaxies? (viewed 19865 times)
  643. Why don't astronauts sublimate in space? (viewed 19840 times)
  644. How do photons from distant objects maintain enough energy to reach us? (viewed 19802 times)
  645. Can HST see the Oort cloud? (viewed 19774 times)
  646. Do electrons age? (viewed 19716 times)
  647. Can planets collide with one another? (viewed 19684 times)
  648. Do constellations looks the same from space? (viewed 19660 times)
  649. Can the Space Shuttle abort and return to Earth before reaching orbit? (viewed 19617 times)
  650. Can we make a movie of the Milky Way galaxy's rotation? (viewed 19606 times)
  651. How did Mars get so dusty? (viewed 19538 times)
  652. How long is twilight on the Moon? (viewed 19490 times)
  653. Does the shuttle worry about space junk? (viewed 19431 times)
  654. What are collections of galaxies called? (viewed 19399 times)
  655. How does melting a material reset its radioactive clock? (viewed 19393 times)
  656. Why do supernova remnants look like rings rather than spheres? (viewed 19347 times)
  657. How do you classify galaxies? (viewed 19303 times)
  658. Will astronauts ever be able to go ice-skating on Europa? (viewed 19286 times)
  659. Where can I see Newton's original reflecting telescope? (viewed 19271 times)
  660. Why don't all neutron stars become pulsars? (viewed 19213 times)
  661. What is the best time of the year to see eclipses? (viewed 19164 times)
  662. Why doesn't SETI concentrate its observations to the nearby stars and the solar systems that we are discovering? (viewed 19148 times)
  663. How can we understand the meaning of large numbers like "a million million?" (viewed 19122 times)
  664. Will the next generation telescope OWL be able to detect an Earth like extrasolar planet? (viewed 19072 times)
  665. What causes a particle to decay? (viewed 19044 times)
  666. How can I nominate myself for a Nobel Prize in Physics? (viewed 18964 times)
  667. How long has humanity known that we live in a galaxy similar to others in the Universe? (viewed 18936 times)
  668. Will the Leonid meteor shower go away? (viewed 18926 times)
  669. What are "curled" dimensions? (viewed 18803 times)
  670. Is light of different colors affected differently by gravity? (viewed 18784 times)
  671. What was that eclipse I saw in the sky? (viewed 18688 times)
  672. How does interferometry work? (viewed 18643 times)
  673. How do distant galaxies differ from those nearby? (viewed 18557 times)
  674. Does the temperature of matter increase as it is accelerated to relativistic speeds? (viewed 18532 times)
  675. Do asteroids ever do anything good in the Solar System? (viewed 18522 times)
  676. How do we find out about the star formation histories of galaxies? (viewed 18517 times)
  677. Why is it called astronomy when all the other sciences end in -ology? (viewed 18506 times)
  678. How does the color index of a star relate to its actual color? (viewed 18465 times)
  679. Can astronomers observe anything when the moon is full? (viewed 18446 times)
  680. Wouldn't the vast distances of space distort SETI signals into unintelligeble forms? (viewed 18398 times)
  681. If nothing can escape a black hole, why do some black holes have jets? (viewed 18383 times)
  682. What kind of interference must astronomers contend with when observing? (viewed 18337 times)
  683. Are black holes spherical? (viewed 18317 times)
  684. What would happen if you went back in time and killed your grandmother? (viewed 18310 times)
  685. Why will fusion wait until hydrogen is gone before starting to fuse heavier atoms? (viewed 18250 times)
  686. Do we really observe the edges of galaxies at different epochs? (viewed 18248 times)
  687. What do stellar classifications mean? (viewed 18237 times)
  688. Can you tell me the characteristics of W, R, N and S type stars? (viewed 18229 times)
  689. How are astronauts trained for weightlessness? (viewed 18149 times)
  690. How can I watch the Perseid meteor shower? (viewed 18142 times)
  691. What is the three-body problem? (viewed 18061 times)
  692. If photons have zero mass, why do they feel the effects of gravity? (viewed 17987 times)
  693. Why aren't accretion disks around giant stars as hot as accretion disks around black holes? (viewed 17965 times)
  694. If the universe is "bounded" today, could it one day become "unbounded"? (viewed 17895 times)
  695. Will the diameter of a cluster of galaxies change with redshift? (viewed 17847 times)
  696. Is cosmic expansion happening on microscopic scales? (viewed 17700 times)
  697. How can I find out if the new moon has been sighted? (viewed 17565 times)
  698. Do we have to worry about relativity when studying galactic objects? (viewed 17380 times)
  699. Could neutrinos be dark matter? (viewed 17303 times)
  700. What kinds of cancer research have been done in space? (viewed 17200 times)
  701. How does a star take mass from another star? (viewed 17115 times)
  702. How can you tell the difference between single and multiple extrasolar planets? (viewed 16911 times)
  703. Could the Universe's dark matter be made up of black holes? (viewed 16903 times)
  704. Does lunar gardening really work? (viewed 16866 times)
  705. What is Hot Dark Matter theory? (viewed 16824 times)
  706. When measuring the expansion of the universe, do astronomers consider that they're seeing how galaxies moved long ago, not today? (viewed 16818 times)
  707. How do supernovae show us that the Universe's expansion is accelerating? (viewed 16658 times)
  708. Is it a coincidence that we can have total solar eclipses? Are there other planets which also have them? (viewed 16390 times)
  709. How does libration allow us to see more than 50% of the Moon? (viewed 16342 times)
  710. Is the green flash real? (viewed 16295 times)
  711. How can observations of the distant universe prove that the expansion is accelerating *now*? (viewed 16287 times)
  712. How do we know the density of some extrasolar planets? (viewed 16217 times)
  713. Is light blueshifted when it is gravitationally lensed? (viewed 16178 times)
  714. What is the photoelectric effect? Why can't multiple low-frequency photons free an electron? (viewed 16156 times)
  715. Do binary or triple star systems form together? (viewed 16136 times)
  716. No matter how fast the universe is expanding, shouldn't gravity eventually make it recollapse? (viewed 16099 times)
  717. What percent of the time can astronomers observe without interference from the Moon? (viewed 15889 times)
  718. What do meteorites tell us about life on other planets? (viewed 15829 times)
  719. Why is it easier to see a star if you look slightly to the side? (viewed 15697 times)
  720. What happens to the helium formed in the sun? (viewed 15627 times)
  721. Could matter-anti-matter repulsion power the expansion of the universe? (viewed 15603 times)
  722. If the sun went out and our atmosphere froze solid, what color would it be? (viewed 15435 times)
  723. Can we prove that the Moon isn't hollow? (viewed 15386 times)
  724. Why doesn't the ammonia and methane in Jupiter's atmosphere sink into the core? (viewed 15329 times)
  725. Are there any 'lonely galaxies'? (viewed 15220 times)
  726. How do we detect incoming meteorites? (viewed 15087 times)
  727. What was different on Mars in the past to allow liquid water to be present? (viewed 14970 times)
  728. When will Hale-Bopp return? (viewed 14822 times)
  729. Why don't skydivers burn up like meteors? (viewed 14728 times)
  730. Has anyone ever seen a star "turn on"? (viewed 14534 times)
  731. During close approaches, can Mars appear in our sky as large as the Moon? (viewed 14531 times)
  732. How are planets affected by the Hot Ionised Medium? (viewed 14296 times)
  733. How has light from 13 billion years ago not passed us by? (viewed 14161 times)
  734. Why are craters round? (viewed 14066 times)
  735. Can the sun rise from the west on Mars? (viewed 13847 times)
  736. Why was Mir burnt up in the atmosphere? (viewed 13840 times)
  737. What are the largest radio wavelengths observed from radio sources in the sky? (viewed 13822 times)
  738. How can we discern different galaxies/clusters along the same line of sight? (viewed 13727 times)
  739. What is the relationship between the width of a star trail on a photo and the star's intensity? (viewed 13297 times)
  740. Can we harvest H & O from space to make water? (viewed 12815 times)
  741. What is between the Oort cloud and the closest star? (viewed 12498 times)
  742. Why does Titan, in spite of being smaller than Mars, have an atmosphere more dense than Earth's? (viewed 12364 times)
  743. What time is sunrise/sunset or moonrise/moonset at my location? (viewed 12181 times)
  744. Could a planetary system survive if its star merged with another, or if its star went supernova? (viewed 11620 times)
  745. Are there solar tides? (viewed 11587 times)
  746. Does weightlessness affect hunger? (viewed 11494 times)
  747. Is Earth-moon tidal friction causing global warming? (viewed 10957 times)
  748. 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 10844 times)
  749. Do planets radiate noise? (viewed 10781 times)
  750. Is the moon spherical? (viewed 10611 times)
  751. What happens to the Earth as the moon gets farther away and will it ever go away entirely? (viewed 10517 times)
  752. What would happen if a nuclear-powered shuttle exploded? (viewed 10391 times)
  753. Is dark energy affected by black holes? (viewed 10374 times)
  754. Why is the Moon higher in the sky in winter and lower in the summer? (viewed 9791 times)
  755. Where are the protons and electrons in a Neutron Star? (viewed 9664 times)
  756. Did the Moon or planets form in a manner similar to that of Earth? (viewed 9455 times)
  757. Do more meteorites fall at low latitudes? (viewed 9443 times)
  758. What are the possible ends of the universe? (viewed 9286 times)
  759. Will Comet Elenin (C/2010 X1) affect the Earth on its close approach in Fall 2011? (viewed 9275 times)
  760. Wait, I'm still confused why information can't travel faster than the speed of light. (viewed 9274 times)
  761. Is it sensible to consider terraforming Mars? (viewed 9203 times)
  762. If there are infinity universes, will every thing that is possible happen? (viewed 9168 times)
  763. Will the Pioneer and Voyager probes ever leave the Milky Way? (viewed 9164 times)
  764. Is the Moon always visible during winter on the North Pole? (viewed 9116 times)
  765. What color are meteors? (viewed 8749 times)
  766. Where is everybody? (viewed 8445 times)
  767. Why does Mars have a dusty atmosphere? (viewed 7927 times)
  768. The naming of Mars (viewed 7843 times)
  769. If I were traveling through space, could I see distant galaxies with my own eyes? (viewed 7817 times)
  770. Does the singularity in a black hole create a new Universe? (viewed 7739 times)
  771. Is the reddish dust of Mars biogenic? (viewed 7583 times)
  772. Where is the Spitzer Space Telescope? (viewed 7069 times)
  773. When will humans travel to Mars and revisit the Moon? (viewed 6981 times)
  774. Does the particles involved in a star's final core collapse travel faster than the speed of light? (viewed 6332 times)
  775. When is the best time to observe zodiacal light? (viewed 6081 times)
  776. How likely is it for a planet to transit its star? (viewed 5963 times)
  777. What causes the aurora? (viewed 5838 times)
  778. Why do astronomers use telescopes? (viewed 5724 times)
  779. How did a transit of Venus provide astronomers with the first measurement of the Earth-Sun distance? (viewed 4824 times)
  780. Can the Sun be closer to the Earth than any planet is to Earth? (viewed 4133 times)
  781. Cosmologists say the expansion of the universe is accelerating, what is driving this? (viewed 3674 times)
  782. Can we hear sound on Titan? (viewed 3627 times)
  783. Does the direction of the moon's crescent change through the night? (viewed 3416 times)
  784. What do all the angles in a table for a planet's orbit mean? (viewed 3188 times)
  785. How do I maximize my chances of seeing shooting stars? (viewed 2484 times)
  786. Are exoplanets real? (viewed 2224 times)
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