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 2127199 times)
  2. What color is each planet? (viewed 900372 times)
  3. At what speed does the earth move around the sun? (viewed 575540 times)
  4. Is the Moon moving away from the Earth? When was this discovered? (viewed 554495 times)
  5. How far is each planet from Earth? (viewed 464584 times)
  6. When will Halley's Comet return? (viewed 419299 times)
  7. How many stars are there in our Galaxy (Milky Way)? (viewed 386640 times)
  8. How long does it take for the Sun's light to reach us? (viewed 386521 times)
  9. Why do the planets orbit the sun? (viewed 373623 times)
  10. What is the universe expanding into? (viewed 368107 times)
  11. How do you measure the distance between Earth and the Sun? (viewed 337059 times)
  12. Which planets have rings? (viewed 321401 times)
  13. Why do stars twinkle? (viewed 316986 times)
  14. Does the Moon rotate? Are there other moons that always keep one face toward their planet? (viewed 303660 times)
  15. How do I build a model rocket? (viewed 288763 times)
  16. What color is Venus? (viewed 272116 times)
  17. What is a white hole? (viewed 265923 times)
  18. Can you hear sounds in space? (viewed 255308 times)
  19. What is the life cycle of a star? (viewed 245174 times)
  20. What are the names of the earth, moon, sun, and solar system? (viewed 236978 times)
  21. What makes the Earth rotate? (viewed 229849 times)
  22. What is that ring (or rainbow) around the moon? (viewed 229061 times)
  23. What are shooting stars? (viewed 227473 times)
  24. What is the largest star? (viewed 221545 times)
  25. What do astronauts eat in space? Can they grow food? (viewed 208311 times)
  26. How do we know the age of the Universe and the Earth? (viewed 205308 times)
  27. Why do planets rotate? (viewed 204440 times)
  28. Can artificial gravity be created in space? (viewed 204336 times)
  29. What are the different kinds of astronomers? (viewed 202839 times)
  30. Is the universe expanding faster than the speed of light? (viewed 199742 times)
  31. How does the location of sunrise and sunset change throughout the year? (viewed 190654 times)
  32. How can we see the Milky Way if we are inside it? (viewed 179585 times)
  33. Where did the name 'Earth' come from? (viewed 179345 times)
  34. What would happen if we did not have a Moon? (viewed 174676 times)
  35. Why isn't the sky bright at night if the universe has so many stars? (viewed 173688 times)
  36. How many Earths fit into the Sun? (viewed 172166 times)
  37. Why is a day divided into 24 hours? (viewed 168923 times)
  38. How does the position of Moonrise and Moonset change? (viewed 164653 times)
  39. Who named the planets and who decides what to name them? (viewed 157523 times)
  40. Why are the Moon and Sun sometimes orange or red? (viewed 155885 times)
  41. When was the last time all 9 planets were aligned? (viewed 153881 times)
  42. Why do airplanes take longer to fly West than East? (viewed 152391 times)
  43. Is Pluto a planet? (viewed 150141 times)
  44. Is the distance from the Earth to the Sun changing? (viewed 149381 times)
  45. What is at the end of the Universe? (viewed 145982 times)
  46. How can I find the star I have "bought"? (viewed 142660 times)
  47. How much money is spent on space exploration? (viewed 141303 times)
  48. Why are there both high and low tides? (viewed 130589 times)
  49. How do astronauts take baths and use restrooms in space? (viewed 130057 times)
  50. What is a nova? (viewed 128999 times)
  51. Can we feel the Earth spin? (viewed 128993 times)
  52. What direction do planets rotate? (viewed 128981 times)
  53. Is the Sun expanding? Will it ever explode? (viewed 127480 times)
  54. What is the largest galaxy? (viewed 127076 times)
  55. How many known galaxies are there? (viewed 125860 times)
  56. Does your weight change between the poles and the equator? (viewed 125264 times)
  57. Do stars move in the sky? (viewed 122353 times)
  58. What are the advantages and disadvantages of using a telescope in space? (viewed 117349 times)
  59. Can I buy a star? (viewed 116982 times)
  60. Why do all the planets orbit in the same plane? (viewed 115198 times)
  61. Will the sun go supernova in six years and destroy Earth (as seen on Yahoo)? (viewed 114382 times)
  62. How are light and heavy elements formed? (viewed 112761 times)
  63. Are there telescopes that can see the flag and lunar rover on the Moon? (viewed 112164 times)
  64. What is the hottest time of day? (viewed 111295 times)
  65. Does the Sun have a scientific name? (viewed 111014 times)
  66. Why hasn't NASA gone back to the moon? (viewed 110785 times)
  67. How do stars move in the Galaxy? (viewed 110395 times)
  68. What happens when galaxies collide? (viewed 110003 times)
  69. Who first measured the speed of light? (viewed 109620 times)
  70. Why do planets have elliptical orbits? (viewed 109040 times)
  71. How do rockets work? (viewed 108548 times)
  72. What is the size of the Solar System? (viewed 107651 times)
  73. What is the physical difference between a star and a planet? (viewed 107557 times)
  74. Will the magnetic field of the Earth reverse its direction in the future? Will this cause problems? (viewed 106863 times)
  75. What would happen if an impact caused Earth to stop rotating? (viewed 106715 times)
  76. What was there before the Big Bang and what is there outside of our universe? (viewed 106485 times)
  77. How much money do astronomers make? (viewed 106364 times)
  78. When is the next comet due to arrive? (viewed 106142 times)
  79. What will happen to life on Earth when the Sun becomes a red giant? (viewed 104436 times)
  80. Does evolution contradict the second law of thermodynamics? (viewed 104375 times)
  81. How long does a solar eclipse last? (viewed 104356 times)
  82. What is the significance of the Tropic of Cancer, Tropic of Capricorn, Arctic Circle and Antarctic Circle? (viewed 104010 times)
  83. Do black holes die? If so how? (viewed 104009 times)
  84. How do you calculate the lifetime of the Sun? (viewed 103409 times)
  85. How many constellations are there? (viewed 102943 times)
  86. What elements make up the Sun? (viewed 102881 times)
  87. What is the observational difference between a star and a planet? (viewed 101127 times)
  88. Does the Sun rotate? (viewed 100340 times)
  89. What's the difference between astronomy and astrology? (viewed 100016 times)
  90. What do astronauts do all day in the International Space Station? (viewed 99536 times)
  91. Does the Sun move around the Milky Way? (viewed 99246 times)
  92. What is apparent magnitude? (viewed 95573 times)
  93. Does gravity vary across the surface of the Earth? (viewed 95371 times)
  94. What would happen if the gravity on Earth was suddenly turned off? (viewed 94734 times)
  95. Which planet is most similar to Earth? (viewed 94320 times)
  96. How many meteorites hit Earth each year? (viewed 94171 times)
  97. What are constellations used for? (viewed 92269 times)
  98. If Mars is only about 35-60 million miles away at close approach, why does it take 6-8 months to get there? (viewed 91273 times)
  99. Why do different stars appear with seasons? (viewed 90821 times)
  100. How do astronomers use math in their jobs? (viewed 90613 times)
  101. How critical is the Earth-Sun distance in maintaining our average temperatures on Earth? (viewed 90345 times)
  102. What kind of schooling is necessary to become an astronomer? (viewed 89957 times)
  103. Is there a proof that Earth moves? (viewed 89192 times)
  104. Why are stars and planets round? (viewed 89151 times)
  105. Where did the Universe come from? (viewed 89022 times)
  106. Does the Sun orbit the Earth as well as the Earth orbiting the Sun? (viewed 88312 times)
  107. Why is the Moon so bright? (viewed 88303 times)
  108. Why is the Universe flat and not spherical? (viewed 88234 times)
  109. What makes the wind? (viewed 87642 times)
  110. Have astronomers discovered Earth's second moon? (viewed 87514 times)
  111. What would happen if an asteroid 10 kilometers across hit the Earth? (viewed 86830 times)
  112. What is a singularity? (viewed 86295 times)
  113. How can a star burn with no oxygen? (viewed 85692 times)
  114. What is the difference between a "star" and a "sun"? (viewed 84041 times)
  115. Where does the name "Milky Way" come from? (viewed 82441 times)
  116. Why does the Earth tilt back and forward once a year? (viewed 82372 times)
  117. What are RA and DEC? (viewed 82200 times)
  118. What would happen if Earth had more than one moon? (viewed 80919 times)
  119. Considering the motion of the Earth, the solar system, and the galaxy, how fast am I moving while lying in bed asleep? (viewed 80602 times)
  120. Since Earth is spinning, why do we land in the same place when we jump or fall? (viewed 79345 times)
  121. What are the requirements for being a planet? (viewed 79138 times)
  122. How many stars are born and die each day? (viewed 78113 times)
  123. What kind of rock is the moon made of? (viewed 77983 times)
  124. Why aren't there any green stars? (viewed 77568 times)
  125. Did astronauts really go to the Moon, or is it a hoax? (viewed 77117 times)
  126. How are galaxies formed? (viewed 76762 times)
  127. Will the Sun become a black hole one day? (viewed 74776 times)
  128. How are black holes made? Could one be made close to us? (viewed 74611 times)
  129. What is the density of a black hole? (viewed 74202 times)
  130. What would happen if a supermassive black hole came close to the Earth? (viewed 74037 times)
  131. Why is the moon in a different place every night? (viewed 73640 times)
  132. Who has landed on the moon? (viewed 73374 times)
  133. What would you see from inside a black hole? (viewed 71880 times)
  134. Do most astronomers believe in God based on the available scientific evidence? (viewed 71582 times)
  135. Can moons have moons? (viewed 71461 times)
  136. How do we weigh objects in space? (viewed 71087 times)
  137. Why can't you see stars during the day? (viewed 71015 times)
  138. What happens to a substance if its speed is more than the speed of light? (viewed 71011 times)
  139. How do rockets move in space? (viewed 70729 times)
  140. How often does the Sun pass through a spiral arm in the Milky Way? (viewed 70493 times)
  141. Can you fire a gun on the Moon? (viewed 70482 times)
  142. How do astronomers measure the brightness of stars? (viewed 70203 times)
  143. How can the Universe expand faster than the speed of light during inflation? (viewed 70123 times)
  144. Does the Mediterranean sea have tides? (viewed 70072 times)
  145. What would happen if you took off your helmet in space? (viewed 69941 times)
  146. What are some of the effects of solar flares on Earth? (viewed 69799 times)
  147. When the Sun converts mass to energy, do the orbits of the planets change? (viewed 69297 times)
  148. How is astronomy impacted by trigonometry? (viewed 68763 times)
  149. How do we know the mass of the Earth and the Moon? (viewed 68728 times)
  150. Is it possible to measure the temperature of the Sun? (viewed 68503 times)
  151. How does the Sun compare to other stars? (viewed 67421 times)
  152. Why do stars change colour when they twinkle? (viewed 67331 times)
  153. How do you measure a planet's mass? (viewed 67221 times)
  154. How does the Moon stay "suspended" in the air? (viewed 66892 times)
  155. What are the "dog days of summer"? (viewed 66720 times)
  156. What is the evidence supporting the nebula theory of Solar System formation? (viewed 66633 times)
  157. How are elements heavier than iron formed? (viewed 66390 times)
  158. Why do we not have eclipses every month? (viewed 66323 times)
  159. What kinds of jobs do astronomers do? (viewed 65587 times)
  160. Does quantum entanglement imply faster than light communication? (viewed 65095 times)
  161. If the universe is infinite does that mean there is an infinite number of "me"s? (viewed 64205 times)
  162. What are black holes made of? (viewed 63738 times)
  163. What causes seasons? (viewed 63330 times)
  164. How did the stars get named? (viewed 63202 times)
  165. Why doesn't the earliest sunset occur on the shortest day of the year? (viewed 62974 times)
  166. Where does the name "Moon" come from? (viewed 62852 times)
  167. When can I see the Moon through the hole in the Pantheon? (viewed 62756 times)
  168. How long would it take the Earth to fall into the Sun? (viewed 62592 times)
  169. Where did the matter in the universe come from? (viewed 62425 times)
  170. How did asteroids form and what is the difference between an asteroid and a comet? (viewed 62408 times)
  171. How fast is the Universe expanding? (viewed 62366 times)
  172. How do you measure the mass of a star? (viewed 62246 times)
  173. Traveling at light speed, how long would it take to get to the nearest galaxy? (viewed 62150 times)
  174. What are Altitude and Azimuth? (viewed 62132 times)
  175. How does light pollution affect astronomers? (viewed 62032 times)
  176. Are there stars outside of galaxies? (viewed 61819 times)
  177. What's the best college for astronomy? (viewed 61691 times)
  178. Why do planets not twinkle? (viewed 61608 times)
  179. Where, in relation to the entire universe, is the Milky Way located? (viewed 61099 times)
  180. Why doesn't the length of each day change much around the solstices? (viewed 61049 times)
  181. What would happen to us if the sun went out for an hour? (viewed 60922 times)
  182. What is the mass of the Universe? (viewed 60155 times)
  183. What's the difference between dark matter and dark energy? (viewed 59637 times)
  184. How can I calculate the position or path of the Sun for a given time and location? (viewed 58787 times)
  185. Does the Moon rotate? (viewed 58666 times)
  186. Could there be life in the galaxies nearest to the Milky Way? (viewed 58518 times)
  187. Why does the Sun's apparent path through the sky change throughout the year? (viewed 58451 times)
  188. Why does the Earth have only one moon? (viewed 58208 times)
  189. Can any galaxies be seen with the naked eye? (viewed 57861 times)
  190. How does astronomy benefit humankind? (viewed 57832 times)
  191. How does the parachute in a model rocket work? (viewed 57480 times)
  192. What is the origin of spiral structure in galaxies? (viewed 57410 times)
  193. How close was the Moon to the Earth when it formed? (viewed 57206 times)
  194. How long does the supernova stage of a star last? (viewed 56739 times)
  195. What makes up most of the Universe? (viewed 56478 times)
  196. What is the shape of the universe? (viewed 56341 times)
  197. Why is looking out into space the same as looking back in time? (viewed 56291 times)
  198. What is the largest structure in the universe? (viewed 55687 times)
  199. What can we learn from the color of a star? (viewed 55685 times)
  200. Why isn't the summer solstice the hottest day of the year? (viewed 55426 times)
  201. Where are stars born? (viewed 55081 times)
  202. How do astronauts use math in their jobs? (viewed 55056 times)
  203. What is a star's "spectrum"? (viewed 54860 times)
  204. What is the size of a black hole? (viewed 54731 times)
  205. Are names given to black holes? (viewed 54529 times)
  206. If gravity is a "curvature of space" rather than a force, why do a ball and bullet follow different paths? (viewed 54215 times)
  207. Can you see satellites? (viewed 54109 times)
  208. Which constellation does our Sun belong to? (viewed 54072 times)
  209. How do we measure the size of the Moon and of the Sun? (viewed 53852 times)
  210. How do you calculate the azimuth and altitude of an object? (viewed 53825 times)
  211. How do the astronauts communicate in space if sound cannot travel in a vacuum? (viewed 53621 times)
  212. What happens to a bullet fired on the moon? (viewed 53338 times)
  213. Is the Moon seen as a crescent (and not a "boat") all over the world? Is the same phase of the moon visible from the Northern and Southern hemispheres? (viewed 53105 times)
  214. How can I find the distance to the Sun on any given day? (viewed 52907 times)
  215. What other careers involve Astronomy besides Astronomer? (viewed 52771 times)
  216. Are aliens or UFOs real? (viewed 52713 times)
  217. Why do we see stars? (viewed 52678 times)
  218. How can I measure the distance of a star? (viewed 52364 times)
  219. Which hemisphere has the best view of the Milky Way? (viewed 51983 times)
  220. Is the speed of light constant? (viewed 51791 times)
  221. What are some astronomy science fair projects? (viewed 51550 times)
  222. Are there any asteroids on a collision course with Earth? (viewed 51416 times)
  223. How long has there been water on Earth? (viewed 51167 times)
  224. Why is the sky blue and not blue & purple? (viewed 51004 times)
  225. Why is twilight short near the equator? (viewed 50795 times)
  226. Are meteorites hot or cold when they hit Earth? (viewed 50677 times)
  227. What would happen if the Moon fell out of its orbit around Earth? (viewed 50646 times)
  228. Where did all the water in the universe come from? (viewed 50632 times)
  229. Is time travel possible? (viewed 50469 times)
  230. Would your weight change as you go underground? (viewed 50431 times)
  231. Who discovered each planet? (viewed 50243 times)
  232. Can we look back far enough in time to see the Big Bang? (viewed 50127 times)
  233. Why does the Moon look big on the horizon? (viewed 50114 times)
  234. What do a galaxy's colors mean? Are they its true colors? (viewed 50088 times)
  235. If the Earth's rotation period is less than 24 hours, why don't our clocks fall out of sync with the Sun? (viewed 49824 times)
  236. Why is it difficult to understand the expansion of the universe? (viewed 49376 times)
  237. What skills do astronomers need? (viewed 48965 times)
  238. What is the difference between nutation and precession of the Earth? (viewed 48907 times)
  239. How is the time of sunrise calculated? (viewed 48796 times)
  240. What is a graviton? (viewed 48733 times)
  241. Are the planes of solar systems aligned with the plane of the Galaxy? (viewed 48640 times)
  242. What's the difference between astronomy and astrophysics? (viewed 48527 times)
  243. If light has no mass, then what draws it into a black hole? (viewed 48359 times)
  244. How do we know what other planets (and stars, galaxies, etc.) are made of? (viewed 47721 times)
  245. What do I need to do to become an astronomer? (viewed 46776 times)
  246. Why do the size and brightness of the full moon change? (viewed 46456 times)
  247. Do dead stars still shine? (viewed 46412 times)
  248. Do supermassive black holes cause galaxy rotation? (viewed 46343 times)
  249. How do gravitons escape black holes to tell the universe about their gravity? (viewed 46323 times)
  250. What is a wormhole? (viewed 46190 times)
  251. How are black holes discovered? (viewed 45872 times)
  252. Why does the Sun appear larger on the horizon than overhead? (viewed 45657 times)
  253. Can we find the place where the Big Bang happened? (viewed 45403 times)
  254. Where is the nearest black hole? (viewed 45366 times)
  255. The Moon slows the Earth's rotation, but how fast was it spinning billions of years ago? (viewed 45304 times)
  256. Will we get sucked into the black hole at the center of the Milky Way? (viewed 45276 times)
  257. Why are most months 30 or 31 days long? (viewed 45257 times)
  258. Why can't we see Venus at night when it is an inner planet? (viewed 45006 times)
  259. Is the Earth slowly getting larger? (viewed 44934 times)
  260. Why are there stars? (viewed 44927 times)
  261. How do galaxies collide in an expanding universe? (viewed 44882 times)
  262. Can I calculate the size of the Universe by converting light years to kilometres? (viewed 44705 times)
  263. Why does Barnard 68 appear dark? (viewed 44218 times)
  264. Why don't people walk upside-down on the bottom of the Earth? (viewed 43462 times)
  265. Are Kuiper Belt Objects asteroids? Are large Kuiper Belt Objects planets? (viewed 43414 times)
  266. Can the acceleration of the Universe be analogous to apparent acceleration in a airplane? (viewed 43053 times)
  267. Did life originate on Earth, or did it come from somewhere else? (viewed 42792 times)
  268. What is the best way to see the Milky Way? (viewed 42732 times)
  269. Are there eclipses on other planets? (viewed 42675 times)
  270. Could the Universe have expanded faster than the speed of light at the Big Bang? (viewed 42642 times)
  271. Is there a "South Star"? (viewed 42491 times)
  272. Was the Sun made in a supernova? (viewed 42452 times)
  273. How does Astronomy involve Chemistry? (viewed 42438 times)
  274. Why does the location of sunrise change? (viewed 42405 times)
  275. What is the biggest crater recorded on Earth? (viewed 42397 times)
  276. Has there been an experiment that measured speed faster than the speed of light in vacuum? (viewed 42330 times)
  277. How long could life on Earth survive if the Sun stopped shining? (viewed 42221 times)
  278. What is the difference between the "Doppler" redshift and the "gravitational" or "cosmological" redshift? (viewed 42174 times)
  279. How much longer will the Earth last? (viewed 42007 times)
  280. How would the weather on Earth be different if it were a cube? (viewed 41997 times)
  281. Why doesn't dark matter fall into a black hole? (viewed 41991 times)
  282. How much can the location of sunset differ from due West? (viewed 41776 times)
  283. What happens to spacetime inside a black hole? (viewed 41622 times)
  284. Can I buy land on the Moon? (viewed 41460 times)
  285. Is the Moon hollow? (viewed 41206 times)
  286. Why does the Earth only see one side of the Moon? (viewed 41200 times)
  287. What happens when two black holes get too close? (viewed 41126 times)
  288. What's the biggest meteorite? (viewed 40799 times)
  289. What are the names of the three stars in Orion's belt? (viewed 40750 times)
  290. What is time dilation? (viewed 40665 times)
  291. What color would Mars be if you were standing on it? (viewed 40629 times)
  292. What is the most distant known galaxy? (viewed 40449 times)
  293. What if the Earth rotated twice as fast? (viewed 40206 times)
  294. How can two moons of Saturn share the same orbit? (viewed 40174 times)
  295. Could someone travel the universe in his or her own lifetime? (viewed 39857 times)
  296. Can terrestrial planets have rings? (viewed 39700 times)
  297. Why do people draw stars with five points? (viewed 39697 times)
  298. How long would it take for a mini-black hole to eat the Earth? (viewed 39531 times)
  299. How do we feel heat? (viewed 39430 times)
  300. How many Astronauts have been in space? (viewed 39369 times)
  301. Is it possible to see the full Moon and the Sun simultaneously in high northern latitudes when the Sun doesn't set? (viewed 39367 times)
  302. What are "blue stragglers" in globular clusters? (viewed 39277 times)
  303. Why do pictures of distant galaxies have higher resolution than those of nearby planets? (viewed 38957 times)
  304. Why can we see the sun's image before sunrise and after sunset? (viewed 38943 times)
  305. What is the typical size of a visible shooting star? (viewed 38732 times)
  306. If a white dwarf is a "dead" star, why is it so hot? (viewed 38625 times)
  307. How do we know that nuclear fusion is still going on in the Sun? (viewed 38560 times)
  308. How fast does the Earth go at perihelion and aphelion? (viewed 38500 times)
  309. Does Mt. Everest cast a shadow on the moon? (viewed 38404 times)
  310. Is the Great Wall the largest galaxy cluster? (viewed 38403 times)
  311. How does night and day work? (viewed 38232 times)
  312. Does the Sun have an iron surface? (viewed 38231 times)
  313. Why are Saturn's rings flat? (viewed 38169 times)
  314. Do you think it's possible to maintain life on other planets? (viewed 38113 times)
  315. Is the Sun always up for exactly 12 hours at the equator? (viewed 38096 times)
  316. What is a dimension? (viewed 38087 times)
  317. Can you see the future as you fall into a black hole? (viewed 37986 times)
  318. Can a person go into a black hole and come out alive? (viewed 37984 times)
  319. On which days can I see the Moon in the evening / morning and why is this so? (viewed 37853 times)
  320. Can I communicate faster than light? (viewed 37766 times)
  321. Where do planetary rings come from, and what are they made of? (viewed 37717 times)
  322. What is the speed of gravity? (viewed 37706 times)
  323. Why do clocks turn in the opposite direction from the Earth and Moon? (viewed 37693 times)
  324. Who (and when) discovered that the earth's axis is on a 23 degree tilt? (viewed 37657 times)
  325. What is Earthrise over the Moon? (viewed 37502 times)
  326. What can I use for fuel in my homemade rocket? (viewed 37358 times)
  327. How big is the universe? (viewed 37319 times)
  328. Where is the supernova remnant that led to our solar system? (viewed 37317 times)
  329. What is the approximate GPA needed in High School in Math and Science to be an astronomer? (viewed 37266 times)
  330. Are all stars the same? (viewed 37259 times)
  331. What companies or businesses can astronomers work for? (viewed 37184 times)
  332. How do we determine the age of the universe? (viewed 37095 times)
  333. Is there really a 10th planet? (viewed 36937 times)
  334. Why is sea water salty, and not lake water? (viewed 36805 times)
  335. Does the Coriolis force determine which way my toilet drains? Does it affect black holes? (viewed 36490 times)
  336. Is there a beginning and an end to a galaxy's life? (viewed 36480 times)
  337. What would happen to the Earth if an asteroid hit the Moon? (viewed 36439 times)
  338. If the universe is 15 billion years old, how can it be larger than 15 billion light years across? (viewed 36405 times)
  339. How many stars can I see? (viewed 36378 times)
  340. How can the universe be "flat"? We're 3D! (viewed 36281 times)
  341. How do I tell which planet is which? (viewed 36270 times)
  342. How do we know the Milky Way is a spiral galaxy? (viewed 36101 times)
  343. How do we define distance in an expanding universe? (viewed 35988 times)
  344. How are photons created and destroyed? (viewed 35978 times)
  345. Do the Sun's or Earth's magnetic field reverse? (viewed 35826 times)
  346. How can I find my age on another planet? (viewed 35453 times)
  347. Why are there blue shifted galaxies? (viewed 35334 times)
  348. Is Andromeda part of the Milky Way? Where can I find them in the sky? (viewed 35170 times)
  349. Why have star signs shifted by one constellation? (viewed 35067 times)
  350. Why do humans want to go in space? (viewed 34858 times)
  351. How does the brightness of a star depend on its distance from us? (viewed 34782 times)
  352. Can a lunar and a solar eclipse happen in the same month? When will this happen next? (viewed 34696 times)
  353. What is the pattern to the distances between each planet and the sun? (viewed 34668 times)
  354. How are planets detected around other stars? (viewed 34629 times)
  355. What was that really big falling star that I saw? (viewed 34579 times)
  356. What kind of eyepieces do I need to look at planets? (viewed 34545 times)
  357. What is the significance of the second focus of elliptical orbits of planets in our Solar System? (viewed 34466 times)
  358. Who came up with the name "black hole"? (viewed 34457 times)
  359. What would happen if two stars collided? (viewed 34446 times)
  360. Will we ever stop having solar eclipses because of the moon's motion away from the Earth? (viewed 34407 times)
  361. How can we estimate the number of Earth-like planets in the Galaxy? (viewed 34324 times)
  362. How do astronauts communicate with their families from space? (viewed 34310 times)
  363. Is the Earth at the centre of the Universe? (viewed 34194 times)
  364. Is there a simple formula to calculate solar eclipse timings from any position on Earth? (viewed 34150 times)
  365. When we look back to the Big Bang, why don't we see the universe as a tiny speck of matter? (viewed 34134 times)
  366. Why don't astronomers use everyday units to measure distances (what is an AU or a pc)? (viewed 33923 times)
  367. How is it that we see farther out in space (farther back in time) than in the past? (viewed 33850 times)
  368. Will the Moon be invisible in 500 million years? (viewed 33690 times)
  369. Why can't a plane fly slowly and let the Earth pass underneath? (viewed 33455 times)
  370. How do I become both an astronaut and an astronomer? (viewed 33434 times)
  371. Are Earth and the Moon "twin planets"? (viewed 33387 times)
  372. How dangerous are the asteroids? (viewed 33331 times)
  373. Which American colleges teach astronomy? (viewed 33294 times)
  374. Why is our solar system so different from all the others we've found? (viewed 33243 times)
  375. How hot is each one of the layers of the sun? (viewed 33210 times)
  376. Why is Uranus tipped on its side? (viewed 33138 times)
  377. Can you describe a day on the job as an astronomer? (viewed 33003 times)
  378. Can we colonize other planets? (viewed 32960 times)
  379. How do sunrise and sunset times change with altitude? (viewed 32757 times)
  380. Is the Local Group expanding along with the entire Universe? (viewed 32493 times)
  381. Why do constellations look the same after several years even though all the stars are moving? (viewed 32382 times)
  382. What are quasars made of? (viewed 32274 times)
  383. How can I calculate distances between stars? (viewed 32230 times)
  384. Is it true that the Sun burns off a billion tons of gas every 5 seconds? (viewed 32198 times)
  385. Is the universe really like an expanding balloon? (viewed 32158 times)
  386. Why do astronauts in space need to exercise? (viewed 32154 times)
  387. Why are there no craters on Earth? Did all the meteorites miss us? (viewed 32112 times)
  388. Why doesn't gravity change the speed of light? (viewed 31990 times)
  389. Is the gravitational force exerted by the Earth on the Moon equal to the centripetal force acting on the Moon? (viewed 31805 times)
  390. What is dark matter? (viewed 31770 times)
  391. Is it possible to count the stars? (viewed 31700 times)
  392. Can superheavy elements (such as Z=116 or 118) be formed in a supernova? Can we observe them? (viewed 31653 times)
  393. Is time travel possible using merging black holes? (viewed 31572 times)
  394. What is happening just around the black hole in the center of the Milky Way? (viewed 31461 times)
  395. Did the speed of light change over the history of the universe? (viewed 31340 times)
  396. Can we see dead stars with the naked eye? (viewed 31319 times)
  397. How big a change in the Earth's orbit would be required to destroy all life? (viewed 31296 times)
  398. How can we distinguish a star's "real" color from the change in color that we observe due to the star's motion? (viewed 31200 times)
  399. How do we measure distances to other stars? (viewed 31194 times)
  400. How do I make a scale model of the Solar System? (viewed 31045 times)
  401. What happens when an antimatter black hole collides with a matter blackhole? (viewed 30991 times)
  402. Are time machines possible? (viewed 30874 times)
  403. How many moles of stars are in the known universe? (viewed 30578 times)
  404. How are galaxy distances inferred from their recessional velocities? (viewed 30362 times)
  405. Why is the time between two successive full moons different from the lunar synodic month? (viewed 30335 times)
  406. How can we tell what the interiors of planets are like? (viewed 30271 times)
  407. What happens when you change the mass of a White Dwarf or Neutron Star? (viewed 30212 times)
  408. What do "homogeneity" and "isotropy" mean? (viewed 30060 times)
  409. Does the Milky Way spin counter-clockwise? If so, do all spiral galaxies spin in this direction and why? (viewed 30057 times)
  410. Is there any limitation to what a black hole can "suck" in? (viewed 30041 times)
  411. What is the farthest in space that we have gone? (viewed 30001 times)
  412. What would happen if a human were exposed to space without wearing a spacesuit? (viewed 29991 times)
  413. Will the seasons change due to precession? (viewed 29776 times)
  414. How can we know that there are other galaxies if we cannot leave ours? (viewed 29743 times)
  415. Can astronauts produce water in space? (viewed 29705 times)
  416. What are the closest and/or brightest stars? (viewed 29685 times)
  417. How was the starting point for the Julian Date system chosen? (viewed 29627 times)
  418. What's that dark spot on the Sun? (viewed 29621 times)
  419. How can I tell if the rock I found is a meteorite? (viewed 29613 times)
  420. Do we see the same stars from above and below the equator? (viewed 29597 times)
  421. Aren't jobs in astronomy scarce? (viewed 29592 times)
  422. How do we know if the universe will keep expanding forever? (viewed 29413 times)
  423. Do astronomers believe in astrology? (viewed 29352 times)
  424. Did I see the Aurora Borealis as a child? (viewed 29311 times)
  425. Why does the SETI project search for radio signals? (viewed 29308 times)
  426. How long does it take the Big Dipper to move in the sky? (viewed 29288 times)
  427. What are the facts about the Star of Bethlehem? (viewed 29142 times)
  428. Why do most moons orbit their planets at the equator? (viewed 29105 times)
  429. Don't tachyons travel faster than light? (viewed 29102 times)
  430. Why do we study black holes? (viewed 29090 times)
  431. When are there 5 Sundays in February? (viewed 29072 times)
  432. Could an astronaut or satellite fall into a black hole that we didn't know about? (viewed 29022 times)
  433. What are the atmospheres of Mars and Pluto like? (viewed 28977 times)
  434. Wouldn't the Big Bang theory be considered a hypothesis and not a theory? (viewed 28949 times)
  435. Do you believe in UFOs? (viewed 28774 times)
  436. Can you use an infinite line of reflectors to send light to the edge of the Universe? (viewed 28699 times)
  437. What does the term "visible universe" mean? (viewed 28642 times)
  438. Could you tell me about the life cycle of galaxies? (viewed 28563 times)
  439. Has anyone made a map of the Milky Way? (viewed 28549 times)
  440. Was I hit by a meteorite? (viewed 28544 times)
  441. What colors are visible through an amateur telescope? (viewed 28526 times)
  442. How are galaxies named? (viewed 28488 times)
  443. How can geometry be different in space? (viewed 28427 times)
  444. Why are the compositions of comets and asteroids different? (viewed 28140 times)
  445. Why do so many of the world's UFO sightings happen in America? (viewed 28009 times)
  446. What's the best thing about being an astronomer? (viewed 28004 times)
  447. How do asteroids, meteors and comets disappear? (viewed 27854 times)
  448. Can two lunar eclipses occur in the same month? (viewed 27748 times)
  449. How much time do astronomers spend looking through telescopes? (viewed 27739 times)
  450. How do astronomers measure the radius of a star? (viewed 27684 times)
  451. Will winter and summer constellations change due to abnormal warmth or cold on Earth? (viewed 27656 times)
  452. How can we see galaxies if their stars are so faint? (viewed 27514 times)
  453. How will the two black holes that are going to collide affect Earth? (viewed 27488 times)
  454. Have there been other Big Bangs before? (viewed 27472 times)
  455. How do I explain to my children why the Moon has phases? (viewed 27415 times)
  456. What is the origin of the stellar classification system "OBAFGKM"? (viewed 27347 times)
  457. How are galaxies and solar systems similar? (viewed 27282 times)
  458. Can life exist on the recently discovered extrasolar planets? (viewed 27222 times)
  459. How close do you have to come to the Earth to be influenced by its gravity? (viewed 27177 times)
  460. Is there a project I can do on black holes? (viewed 27125 times)
  461. Is the Milky Way a collision of two galaxies? (viewed 27095 times)
  462. Does the Moon look different in the northern and southern hemispheres? (viewed 27072 times)
  463. Do the magnitudes and colors of stars ever change? (viewed 27006 times)
  464. How can we measure distances to more stars? (viewed 26991 times)
  465. Could you escape from a black hole if you were able to go faster than the speed of light? (viewed 26941 times)
  466. How do scientists slow light down? (viewed 26894 times)
  467. Do asteroids hit the sun? (viewed 26740 times)
  468. Is infinite temperature possible? (viewed 26701 times)
  469. How close does a supernova need to be to damage the Earth's environment? (viewed 26685 times)
  470. Do we know everything about the Sun? (viewed 26667 times)
  471. Can "tired light theory" explain the observed redshifts of galaxies? (viewed 26612 times)
  472. What supernova created the Crab nebula? (viewed 26600 times)
  473. Is it worthwhile to continue the search for extraterrestrial life? (viewed 26579 times)
  474. Can double stars have planets? (viewed 26485 times)
  475. Can one star orbit another? (viewed 26479 times)
  476. What causes gamma ray bursts? (viewed 26416 times)
  477. How far does a galaxy extend? (viewed 26345 times)
  478. How do I polar align my telescope? (viewed 26165 times)
  479. What will happen to the Milky Way in the future? (viewed 26143 times)
  480. Can astronauts play musical instruments in space? (viewed 26120 times)
  481. Is there such a thing as hyperspace? (viewed 26050 times)
  482. Which part of the sky did the famous 'wow' signal originate from? (viewed 26042 times)
  483. What type of energy does a black hole have? (viewed 26041 times)
  484. Which way does the sun travel in the southern hemisphere? (viewed 26037 times)
  485. What is sidereal time? (viewed 26035 times)
  486. Is there oxygen in the atmospheres of other planets? (viewed 26033 times)
  487. What is the farthest Northern Latitude in which the Magellanic Clouds can be seen? (viewed 26008 times)
  488. Can a human give birth in space? (viewed 25986 times)
  489. What happens to the material that has been sucked into a black hole? (viewed 25980 times)
  490. Why do the explosions of Type Ia supernovae have a more predictable spectrum than those of regular Type II supernovae? (viewed 25901 times)
  491. What is a Cepheid variable? (viewed 25880 times)
  492. What is "nothing", from a scientific point of view? (viewed 25860 times)
  493. Why did the Pioneer and Voyager take only 2 years to reach Jupiter, while Galileo and Cassini took more than 5 years? (viewed 25818 times)
  494. What's the object I saw that moved across the sky and then got very bright? (viewed 25790 times)
  495. Is there sound coming from the Sun? (viewed 25783 times)
  496. How will a change in the speed of light affect the evolution of the Universe? (viewed 25763 times)
  497. How different would the night sky have looked in 40,000 B.C.? (viewed 25744 times)
  498. When did people discover that the Sun is a star? (viewed 25560 times)
  499. Why do we assume that the universe is homogeneous? (viewed 25525 times)
  500. How do we know what parameters to use when simulating the collision of the Milky Way and Andromeda? (viewed 25508 times)
  501. Why is the shadow on the Moon the shape it is? (viewed 25484 times)
  502. How do we know that sunspots are associated with the Sun's magnetic field? (viewed 25424 times)
  503. Are planetary nebulae the result of supernovae? (viewed 25396 times)
  504. If we invented special suits could we ever go to the sun? (viewed 25393 times)
  505. When unmanned spacecraft accelerate in space, what causes them to slow down? (viewed 25370 times)
  506. Are there any dark stars or dark galaxies made of dark matter? (viewed 25297 times)
  507. What calculations go into predicting eclipses? (viewed 25257 times)
  508. What is the difference between homogeneity and isotropy? (viewed 25243 times)
  509. Was Stonehenge built to mark solar phenomena? (viewed 25196 times)
  510. What is our galaxy's halo made of, and how was it formed? (viewed 25195 times)
  511. Is there a list of the sizes of different kinds of stars? (viewed 25129 times)
  512. Can I see a quasar? (viewed 25105 times)
  513. What process would bring about a quark star? (viewed 25090 times)
  514. How many sunspots can the Sun have at once? (viewed 25021 times)
  515. What's so exciting about the new planet around 55 Cancri? (viewed 24990 times)
  516. How are asteroid compositions and classifications determined? (viewed 24976 times)
  517. Did a giant impact cause the Dark Ages? (viewed 24967 times)
  518. What is a Dyson Sphere? (viewed 24921 times)
  519. Can I see details on Venus? (viewed 24913 times)
  520. Can any comparison be made between spiral galaxies and hurricanes? (viewed 24909 times)
  521. Have gravitational waves been proven to exist? (viewed 24908 times)
  522. Why are there more maria on the near side of the Moon? (viewed 24755 times)
  523. What equipment do I need for astrophotography? (viewed 24699 times)
  524. What happened to all the black holes that were around in the early universe? (viewed 24681 times)
  525. What happened to the girl who named Pluto? (viewed 24672 times)
  526. How is it proved that the Universe is expanding? (viewed 24625 times)
  527. Why are there active volcanos on Io? (viewed 24614 times)
  528. Would the biggest airplanes cause tsunamis if they crashed? (viewed 24596 times)
  529. Does Cerenkov radiation travel faster than light? (viewed 24594 times)
  530. Why are telescopes kept in cold conditions? (viewed 24565 times)
  531. Is there any possibility that the Solar System or the Universe is in a black hole? (viewed 24502 times)
  532. If clocks run slow in a gravitational field, how can we know the true age of the Solar System and Universe? (viewed 24332 times)
  533. How big is the Hubble Ultra Deep Field image? (viewed 24316 times)
  534. How big was the Sun when it first "fired up"? (viewed 24288 times)
  535. How can we compare dark matter and dark energy? (viewed 24284 times)
  536. If the Universe was infinitely dense at the Big Bang, why didn't time stand still? (viewed 24249 times)
  537. How long do supernova remnants last? (viewed 24177 times)
  538. What caused Shoemaker-Levy 9 to split up? (viewed 24156 times)
  539. Why do photos of space taken from space never show any stars? (viewed 24141 times)
  540. Could we send a space mission to a comet? (viewed 24127 times)
  541. How do solar flares affect airline pilots? (viewed 24084 times)
  542. Why doesn't light from distant galaxies reach us instantaneously? (viewed 24034 times)
  543. How are sunspots formed? (viewed 23963 times)
  544. Could we be seeing dead stars? (viewed 23959 times)
  545. Can you give me advice on buying a telescope? (viewed 23954 times)
  546. How does the Earth compare in size to the entire universe at the present epoch? (viewed 23855 times)
  547. Could a different theory of gravity explain the dark matter mystery? (viewed 23840 times)
  548. As the universe expands, why don't galaxies get stretched out? (viewed 23773 times)
  549. Why doesn't NASA build rotating spacecraft to simulate gravity? (viewed 23759 times)
  550. Where does the kinetic energy of infalling bodies come from? (viewed 23754 times)
  551. Can I build an instrument to measure the size of the Sun and of the Moon? (viewed 23732 times)
  552. How many comets are currently orbiting our sun? (viewed 23703 times)
  553. Can you tell time by the Big Dipper? (viewed 23636 times)
  554. Why is the Hubble Space Telescope in space? (viewed 23631 times)
  555. Did I really hear a meteor? (viewed 23530 times)
  556. Why is it important to study meteorites? (viewed 23528 times)
  557. How do we know that superclusters are the largest structures in the universe? (viewed 23516 times)
  558. How can I contribute to science as an amateur astronomer? (viewed 23466 times)
  559. How powerful are quasars? (viewed 23462 times)
  560. Would extraterrestrial civilizations know that there is life on Earth? (viewed 23453 times)
  561. Why are telescopes located in remote places? (viewed 23417 times)
  562. How is the Cepheid yardstick validated? (viewed 23353 times)
  563. Are the asteroids the remains of a planet which broke apart? (viewed 23329 times)
  564. Do unmanned spacecraft like Voyager travel in straight lines? (viewed 23264 times)
  565. Did time go slower just after the Big Bang? (viewed 23230 times)
  566. Do the Earth's magnetic poles ever change places? (viewed 23197 times)
  567. Are there any new craters on the moon? (viewed 23179 times)
  568. What would happen if there was a collision between two white dwarfs? (viewed 23173 times)
  569. Can supernovae hinder the formation of life in galaxies? (viewed 23173 times)
  570. Do galaxies orbit around anything? (viewed 23163 times)
  571. Why are stars of different masses? (viewed 23157 times)
  572. How do unmanned space probes avoid running into things? (viewed 23157 times)
  573. Do similar laws of physics throughout the Universe imply that all life must be like life on Earth? (viewed 23070 times)
  574. How do planets capture satellites? (viewed 23059 times)
  575. What kind of instruments are used to detect extrasolar planets? (viewed 23054 times)
  576. How do I become an astronomical artist? (viewed 23053 times)
  577. How could galaxies have gotten so far away in only 15 billion years? (viewed 23033 times)
  578. Why can't relative velocities add up to more than the speed of light? (viewed 22988 times)
  579. Could there have been multiple Big Bangs at different places in the universe? (viewed 22910 times)
  580. What kind of telescope should I use for astrophotography? (viewed 22879 times)
  581. How are astronomy and poetry linked? (viewed 22873 times)
  582. Could dark energy come from matter anti-matter pairs forming spontaneously and then annihilating? (viewed 22782 times)
  583. Why is NASA shutting down the Hubble Space Telescope? (viewed 22701 times)
  584. Can I listen to the SETI@home radio signal? (viewed 22692 times)
  585. How can you tell if a crescent moon is preceding or following a new-moon phase? (viewed 22640 times)
  586. Does the Sun have any heavy elements? (viewed 22583 times)
  587. Are the properties of extrasolar planets known? (viewed 22536 times)
  588. What class of spiral galaxy is the Milky Way? (viewed 22447 times)
  589. 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 22436 times)
  590. Will we discover an 11th planet? What would it be called? (viewed 22404 times)
  591. Can the theory of formation of the solar system explain all the observables? (viewed 22391 times)
  592. What month was it when Odysseus saw Orion in 1000BC? (viewed 22329 times)
  593. How do astronomers observe the Sun's interior? (viewed 22208 times)
  594. What makes a satellite geosyncronise itself with Earth's orbit? (viewed 22054 times)
  595. Why does one side of Mars look more catastrophic than the other? (viewed 22049 times)
  596. Why does the apparent density of galaxies drop off at larger distances? (viewed 22022 times)
  597. Where was the water in the big bang? (viewed 22000 times)
  598. Is it possible for amateurs to do optical interferometry? (viewed 21973 times)
  599. Would a planet near the galactic center have a brighter night sky? (viewed 21957 times)
  600. Could we send a manned mission to the outer planets? (viewed 21889 times)
  601. Do stars' orbits in galaxies obey Kepler's Laws? (viewed 21753 times)
  602. What is the solar cycle? (viewed 21743 times)
  603. Can other terrestrial moons be (or have been) stable? (viewed 21665 times)
  604. How can water be chemically trapped in rocks? (viewed 21646 times)
  605. Why was the Platonic year named after Plato? (viewed 21635 times)
  606. How are supernovae discovered? (viewed 21569 times)
  607. Why do spacecraft need heat shields coming back to Earth but not leaving? (viewed 21551 times)
  608. What would the Big Crunch look like to an observer on Earth? (viewed 21543 times)
  609. Why are accretion disks flat? (viewed 21504 times)
  610. Can a black hole come back to the visual universe through a "little bang"? (viewed 21496 times)
  611. What is meant by "stopping down a telescope"? (viewed 21436 times)
  612. Does inflation allow for an infinite number of universes? (viewed 21434 times)
  613. Could our position in the universe affect our perceptions of the expansion? (viewed 21381 times)
  614. Why doesn't the hydrogen on Jupiter explode? (viewed 21319 times)
  615. How can the Sun have such a strong gravitational field if it's made of gasses? (viewed 21197 times)
  616. Have astronomers observed any phenomena that could be produced by extraterrestrial civilizations? (viewed 21111 times)
  617. Did I find a rock that came from the Moon? (viewed 21109 times)
  618. What is the SU(3) quark model? (viewed 21068 times)
  619. Can gravitational lensing from intervening galaxies cause the observed ripples in the Cosmic Microwave Background? (viewed 21045 times)
  620. Does a photon observe other photons moving past it at the speed of light? (viewed 21014 times)
  621. Will I be able to see the shadow of the Moon streaking towards me in a total solar eclipse? (viewed 20858 times)
  622. What's new with the Big Bang? (viewed 20776 times)
  623. Could photons be dark matter? (viewed 20707 times)
  624. How can we find galaxies behind the Milky Way? (viewed 20668 times)
  625. Is it possible to build a cheap device to measure declination? (viewed 20648 times)
  626. Why search for only Earth-like life on other planets? (viewed 20624 times)
  627. Why can we have solar eclipses? (viewed 20615 times)
  628. How fast do particles travel in space? (viewed 20590 times)
  629. If comets are boiling away, why are there any left? (viewed 20587 times)
  630. Why is the WMAP picture of the CMB an ellipse? (viewed 20538 times)
  631. Where can I find information on the moons of other planets? (viewed 20509 times)
  632. Why do some eclipses take longer than others? (viewed 20507 times)
  633. How much power is contained in a beam of light? (viewed 20451 times)
  634. Why is pressure broadening greater in low mass stars than in high mass stars? (viewed 20302 times)
  635. What would an "open geometry" for the universe look like? (viewed 20220 times)
  636. What are the boundaries of the constellations? (viewed 20217 times)
  637. Did the Sumerians measure precession? (viewed 20170 times)
  638. Can planets collide with one another? (viewed 20130 times)
  639. What kinds of star clusters are there? (viewed 20089 times)
  640. Do constellations looks the same from space? (viewed 20062 times)
  641. Why is the Cosmic Microwave Background not absorbed by interstellar hydrogen? (viewed 20039 times)
  642. How do astronomers come up with their facts? (viewed 20028 times)
  643. Why aren't discoveries of extrasolar planets reported on the news? (viewed 20017 times)
  644. How do bars form in spiral galaxies? (viewed 19978 times)
  645. Why don't astronauts sublimate in space? (viewed 19976 times)
  646. How do photons from distant objects maintain enough energy to reach us? (viewed 19953 times)
  647. Can HST see the Oort cloud? (viewed 19853 times)
  648. Do electrons age? (viewed 19829 times)
  649. How did Mars get so dusty? (viewed 19827 times)
  650. Can we make a movie of the Milky Way galaxy's rotation? (viewed 19715 times)
  651. Can the Space Shuttle abort and return to Earth before reaching orbit? (viewed 19711 times)
  652. What are collections of galaxies called? (viewed 19706 times)
  653. How long is twilight on the Moon? (viewed 19636 times)
  654. Does the shuttle worry about space junk? (viewed 19544 times)
  655. Will astronauts ever be able to go ice-skating on Europa? (viewed 19519 times)
  656. How does melting a material reset its radioactive clock? (viewed 19516 times)
  657. Why do supernova remnants look like rings rather than spheres? (viewed 19476 times)
  658. Where can I see Newton's original reflecting telescope? (viewed 19438 times)
  659. How do you classify galaxies? (viewed 19430 times)
  660. Why don't all neutron stars become pulsars? (viewed 19402 times)
  661. How can we understand the meaning of large numbers like "a million million?" (viewed 19320 times)
  662. Why doesn't SETI concentrate its observations to the nearby stars and the solar systems that we are discovering? (viewed 19293 times)
  663. What is the best time of the year to see eclipses? (viewed 19274 times)
  664. Will the next generation telescope OWL be able to detect an Earth like extrasolar planet? (viewed 19193 times)
  665. What causes a particle to decay? (viewed 19181 times)
  666. How can I nominate myself for a Nobel Prize in Physics? (viewed 19098 times)
  667. How long has humanity known that we live in a galaxy similar to others in the Universe? (viewed 19053 times)
  668. Will the Leonid meteor shower go away? (viewed 19022 times)
  669. Why is it called astronomy when all the other sciences end in -ology? (viewed 18988 times)
  670. What are "curled" dimensions? (viewed 18922 times)
  671. How does the color index of a star relate to its actual color? (viewed 18876 times)
  672. Is light of different colors affected differently by gravity? (viewed 18856 times)
  673. What was that eclipse I saw in the sky? (viewed 18761 times)
  674. How does interferometry work? (viewed 18752 times)
  675. If photons have zero mass, why do they feel the effects of gravity? (viewed 18731 times)
  676. How do distant galaxies differ from those nearby? (viewed 18676 times)
  677. If nothing can escape a black hole, why do some black holes have jets? (viewed 18673 times)
  678. Do asteroids ever do anything good in the Solar System? (viewed 18650 times)
  679. Does the temperature of matter increase as it is accelerated to relativistic speeds? (viewed 18636 times)
  680. What kind of interference must astronomers contend with when observing? (viewed 18612 times)
  681. How do we find out about the star formation histories of galaxies? (viewed 18607 times)
  682. What would happen if you went back in time and killed your grandmother? (viewed 18585 times)
  683. Wouldn't the vast distances of space distort SETI signals into unintelligeble forms? (viewed 18571 times)
  684. Are black holes spherical? (viewed 18569 times)
  685. Can astronomers observe anything when the moon is full? (viewed 18535 times)
  686. Why will fusion wait until hydrogen is gone before starting to fuse heavier atoms? (viewed 18434 times)
  687. How can I watch the Perseid meteor shower? (viewed 18426 times)
  688. Do we really observe the edges of galaxies at different epochs? (viewed 18367 times)
  689. What do stellar classifications mean? (viewed 18350 times)
  690. Can you tell me the characteristics of W, R, N and S type stars? (viewed 18339 times)
  691. How are astronauts trained for weightlessness? (viewed 18266 times)
  692. What is the three-body problem? (viewed 18226 times)
  693. Why aren't accretion disks around giant stars as hot as accretion disks around black holes? (viewed 18169 times)
  694. If the universe is "bounded" today, could it one day become "unbounded"? (viewed 18004 times)
  695. Will the diameter of a cluster of galaxies change with redshift? (viewed 17979 times)
  696. Is cosmic expansion happening on microscopic scales? (viewed 17809 times)
  697. How can I find out if the new moon has been sighted? (viewed 17678 times)
  698. Could neutrinos be dark matter? (viewed 17509 times)
  699. Do we have to worry about relativity when studying galactic objects? (viewed 17478 times)
  700. What kinds of cancer research have been done in space? (viewed 17329 times)
  701. When measuring the expansion of the universe, do astronomers consider that they're seeing how galaxies moved long ago, not today? (viewed 17293 times)
  702. Does lunar gardening really work? (viewed 17214 times)
  703. How does a star take mass from another star? (viewed 17209 times)
  704. How do supernovae show us that the Universe's expansion is accelerating? (viewed 17108 times)
  705. Could the Universe's dark matter be made up of black holes? (viewed 17061 times)
  706. How can you tell the difference between single and multiple extrasolar planets? (viewed 17011 times)
  707. What is Hot Dark Matter theory? (viewed 16936 times)
  708. Is it a coincidence that we can have total solar eclipses? Are there other planets which also have them? (viewed 16604 times)
  709. Is the green flash real? (viewed 16537 times)
  710. How does libration allow us to see more than 50% of the Moon? (viewed 16441 times)
  711. What is the photoelectric effect? Why can't multiple low-frequency photons free an electron? (viewed 16428 times)
  712. How can observations of the distant universe prove that the expansion is accelerating *now*? (viewed 16416 times)
  713. What happens to the helium formed in the sun? (viewed 16416 times)
  714. How do we know the density of some extrasolar planets? (viewed 16408 times)
  715. Is light blueshifted when it is gravitationally lensed? (viewed 16277 times)
  716. Do binary or triple star systems form together? (viewed 16229 times)
  717. No matter how fast the universe is expanding, shouldn't gravity eventually make it recollapse? (viewed 16199 times)
  718. What percent of the time can astronomers observe without interference from the Moon? (viewed 15975 times)
  719. What do meteorites tell us about life on other planets? (viewed 15950 times)
  720. Why is it easier to see a star if you look slightly to the side? (viewed 15871 times)
  721. Could matter-anti-matter repulsion power the expansion of the universe? (viewed 15707 times)
  722. Can we prove that the Moon isn't hollow? (viewed 15694 times)
  723. If the sun went out and our atmosphere froze solid, what color would it be? (viewed 15679 times)
  724. Why doesn't the ammonia and methane in Jupiter's atmosphere sink into the core? (viewed 15498 times)
  725. Are there any 'lonely galaxies'? (viewed 15326 times)
  726. How do we detect incoming meteorites? (viewed 15289 times)
  727. What was different on Mars in the past to allow liquid water to be present? (viewed 15204 times)
  728. When will Hale-Bopp return? (viewed 15071 times)
  729. Why don't skydivers burn up like meteors? (viewed 15062 times)
  730. Has anyone ever seen a star "turn on"? (viewed 14817 times)
  731. How has light from 13 billion years ago not passed us by? (viewed 14646 times)
  732. During close approaches, can Mars appear in our sky as large as the Moon? (viewed 14601 times)
  733. Why are craters round? (viewed 14410 times)
  734. How are planets affected by the Hot Ionised Medium? (viewed 14397 times)
  735. Can the sun rise from the west on Mars? (viewed 14037 times)
  736. What are the largest radio wavelengths observed from radio sources in the sky? (viewed 13943 times)
  737. Why was Mir burnt up in the atmosphere? (viewed 13934 times)
  738. How can we discern different galaxies/clusters along the same line of sight? (viewed 13832 times)
  739. What time is sunrise/sunset or moonrise/moonset at my location? (viewed 13736 times)
  740. What is the relationship between the width of a star trail on a photo and the star's intensity? (viewed 13405 times)
  741. Can we harvest H & O from space to make water? (viewed 13127 times)
  742. 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 12775 times)
  743. Why does Titan, in spite of being smaller than Mars, have an atmosphere more dense than Earth's? (viewed 12651 times)
  744. What is between the Oort cloud and the closest star? (viewed 12630 times)
  745. Could a planetary system survive if its star merged with another, or if its star went supernova? (viewed 11768 times)
  746. Are there solar tides? (viewed 11732 times)
  747. Does weightlessness affect hunger? (viewed 11577 times)
  748. Is Earth-moon tidal friction causing global warming? (viewed 11252 times)
  749. What happens to the Earth as the moon gets farther away and will it ever go away entirely? (viewed 11130 times)
  750. Do planets radiate noise? (viewed 10996 times)
  751. Is the moon spherical? (viewed 10913 times)
  752. Is dark energy affected by black holes? (viewed 10732 times)
  753. What would happen if a nuclear-powered shuttle exploded? (viewed 10543 times)
  754. Why is the Moon higher in the sky in winter and lower in the summer? (viewed 10318 times)
  755. Where are the protons and electrons in a Neutron Star? (viewed 10073 times)
  756. Wait, I'm still confused why information can't travel faster than the speed of light. (viewed 9668 times)
  757. Is the Moon always visible during winter on the North Pole? (viewed 9637 times)
  758. Do more meteorites fall at low latitudes? (viewed 9586 times)
  759. Did the Moon or planets form in a manner similar to that of Earth? (viewed 9565 times)
  760. What are the possible ends of the universe? (viewed 9453 times)
  761. Will Comet Elenin (C/2010 X1) affect the Earth on its close approach in Fall 2011? (viewed 9441 times)
  762. Will the Pioneer and Voyager probes ever leave the Milky Way? (viewed 9419 times)
  763. If there are infinity universes, will every thing that is possible happen? (viewed 9313 times)
  764. Is it sensible to consider terraforming Mars? (viewed 9291 times)
  765. What color are meteors? (viewed 8913 times)
  766. Where is everybody? (viewed 8542 times)
  767. Why does Mars have a dusty atmosphere? (viewed 8114 times)
  768. The naming of Mars (viewed 7996 times)
  769. Does the singularity in a black hole create a new Universe? (viewed 7952 times)
  770. If I were traveling through space, could I see distant galaxies with my own eyes? (viewed 7942 times)
  771. Is the reddish dust of Mars biogenic? (viewed 7797 times)
  772. Where is the Spitzer Space Telescope? (viewed 7185 times)
  773. When will humans travel to Mars and revisit the Moon? (viewed 7062 times)
  774. Does the particles involved in a star's final core collapse travel faster than the speed of light? (viewed 6405 times)
  775. How likely is it for a planet to transit its star? (viewed 6338 times)
  776. When is the best time to observe zodiacal light? (viewed 6199 times)
  777. Why do astronomers use telescopes? (viewed 6195 times)
  778. What causes the aurora? (viewed 6093 times)
  779. How did a transit of Venus provide astronomers with the first measurement of the Earth-Sun distance? (viewed 5069 times)
  780. Can the Sun be closer to the Earth than any planet is to Earth? (viewed 4414 times)
  781. Cosmologists say the expansion of the universe is accelerating, what is driving this? (viewed 3890 times)
  782. Can we hear sound on Titan? (viewed 3737 times)
  783. Does the direction of the moon's crescent change through the night? (viewed 3554 times)
  784. What do all the angles in a table for a planet's orbit mean? (viewed 3405 times)
  785. How do I maximize my chances of seeing shooting stars? (viewed 2717 times)
  786. Are exoplanets real? (viewed 2387 times)
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