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 2118031 times)
  2. What color is each planet? (viewed 890173 times)
  3. At what speed does the earth move around the sun? (viewed 564346 times)
  4. Is the Moon moving away from the Earth? When was this discovered? (viewed 543150 times)
  5. How far is each planet from Earth? (viewed 460588 times)
  6. When will Halley's Comet return? (viewed 412055 times)
  7. How many stars are there in our Galaxy (Milky Way)? (viewed 383877 times)
  8. How long does it take for the Sun's light to reach us? (viewed 382224 times)
  9. Why do the planets orbit the sun? (viewed 368501 times)
  10. What is the universe expanding into? (viewed 363949 times)
  11. How do you measure the distance between Earth and the Sun? (viewed 331270 times)
  12. Which planets have rings? (viewed 319682 times)
  13. Why do stars twinkle? (viewed 313072 times)
  14. Does the Moon rotate? Are there other moons that always keep one face toward their planet? (viewed 297042 times)
  15. How do I build a model rocket? (viewed 286058 times)
  16. What color is Venus? (viewed 270547 times)
  17. What is a white hole? (viewed 263453 times)
  18. Can you hear sounds in space? (viewed 244067 times)
  19. What is the life cycle of a star? (viewed 243844 times)
  20. What are the names of the earth, moon, sun, and solar system? (viewed 234736 times)
  21. What makes the Earth rotate? (viewed 225781 times)
  22. What is that ring (or rainbow) around the moon? (viewed 225333 times)
  23. What are shooting stars? (viewed 223513 times)
  24. What is the largest star? (viewed 220975 times)
  25. What do astronauts eat in space? Can they grow food? (viewed 205845 times)
  26. Why do planets rotate? (viewed 200002 times)
  27. How do we know the age of the Universe and the Earth? (viewed 199741 times)
  28. Can artificial gravity be created in space? (viewed 197881 times)
  29. Is the universe expanding faster than the speed of light? (viewed 195171 times)
  30. How does the location of sunrise and sunset change throughout the year? (viewed 185258 times)
  31. Where did the name 'Earth' come from? (viewed 177605 times)
  32. How can we see the Milky Way if we are inside it? (viewed 174626 times)
  33. What would happen if we did not have a Moon? (viewed 173044 times)
  34. Why isn't the sky bright at night if the universe has so many stars? (viewed 172458 times)
  35. What are the different kinds of astronomers? (viewed 172047 times)
  36. How many Earths fit into the Sun? (viewed 171494 times)
  37. Why is a day divided into 24 hours? (viewed 164148 times)
  38. How does the position of Moonrise and Moonset change? (viewed 159025 times)
  39. Who named the planets and who decides what to name them? (viewed 154726 times)
  40. Why are the Moon and Sun sometimes orange or red? (viewed 150447 times)
  41. When was the last time all 9 planets were aligned? (viewed 149958 times)
  42. Is Pluto a planet? (viewed 149134 times)
  43. Is the distance from the Earth to the Sun changing? (viewed 147952 times)
  44. Why do airplanes take longer to fly West than East? (viewed 145382 times)
  45. What is at the end of the Universe? (viewed 143425 times)
  46. How much money is spent on space exploration? (viewed 139278 times)
  47. How can I find the star I have "bought"? (viewed 138959 times)
  48. Why are there both high and low tides? (viewed 129862 times)
  49. How do astronauts take baths and use restrooms in space? (viewed 127749 times)
  50. What direction do planets rotate? (viewed 127337 times)
  51. What is the largest galaxy? (viewed 126608 times)
  52. Can we feel the Earth spin? (viewed 126098 times)
  53. Is the Sun expanding? Will it ever explode? (viewed 125909 times)
  54. How many known galaxies are there? (viewed 125368 times)
  55. Do stars move in the sky? (viewed 121068 times)
  56. What is a nova? (viewed 120707 times)
  57. Does your weight change between the poles and the equator? (viewed 120414 times)
  58. Can I buy a star? (viewed 115717 times)
  59. What are the advantages and disadvantages of using a telescope in space? (viewed 115472 times)
  60. Will the sun go supernova in six years and destroy Earth (as seen on Yahoo)? (viewed 113092 times)
  61. Why do all the planets orbit in the same plane? (viewed 111555 times)
  62. How are light and heavy elements formed? (viewed 110800 times)
  63. What is the hottest time of day? (viewed 110398 times)
  64. Are there telescopes that can see the flag and lunar rover on the Moon? (viewed 110353 times)
  65. How do stars move in the Galaxy? (viewed 109179 times)
  66. Does the Sun have a scientific name? (viewed 108820 times)
  67. What happens when galaxies collide? (viewed 108622 times)
  68. Why hasn't NASA gone back to the moon? (viewed 108236 times)
  69. Who first measured the speed of light? (viewed 107300 times)
  70. How do rockets work? (viewed 107085 times)
  71. Why do planets have elliptical orbits? (viewed 106877 times)
  72. What is the size of the Solar System? (viewed 106630 times)
  73. Will the magnetic field of the Earth reverse its direction in the future? Will this cause problems? (viewed 106379 times)
  74. What was there before the Big Bang and what is there outside of our universe? (viewed 105661 times)
  75. When is the next comet due to arrive? (viewed 105499 times)
  76. What would happen if an impact caused Earth to stop rotating? (viewed 105145 times)
  77. How much money do astronomers make? (viewed 104971 times)
  78. How long does a solar eclipse last? (viewed 103657 times)
  79. What is the physical difference between a star and a planet? (viewed 103193 times)
  80. Do black holes die? If so how? (viewed 102965 times)
  81. What will happen to life on Earth when the Sun becomes a red giant? (viewed 102750 times)
  82. How many constellations are there? (viewed 102039 times)
  83. How do you calculate the lifetime of the Sun? (viewed 101760 times)
  84. What elements make up the Sun? (viewed 101477 times)
  85. Does evolution contradict the second law of thermodynamics? (viewed 101328 times)
  86. What is the significance of the Tropic of Cancer, Tropic of Capricorn, Arctic Circle and Antarctic Circle? (viewed 99677 times)
  87. What is the observational difference between a star and a planet? (viewed 99522 times)
  88. Does the Sun rotate? (viewed 99507 times)
  89. Does the Sun move around the Milky Way? (viewed 98695 times)
  90. What's the difference between astronomy and astrology? (viewed 98142 times)
  91. What do astronauts do all day in the International Space Station? (viewed 97034 times)
  92. What is apparent magnitude? (viewed 94555 times)
  93. Which planet is most similar to Earth? (viewed 93284 times)
  94. Does gravity vary across the surface of the Earth? (viewed 92358 times)
  95. How many meteorites hit Earth each year? (viewed 92303 times)
  96. What would happen if the gravity on Earth was suddenly turned off? (viewed 91411 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 90326 times)
  98. What are constellations used for? (viewed 90192 times)
  99. How critical is the Earth-Sun distance in maintaining our average temperatures on Earth? (viewed 89635 times)
  100. How do astronomers use math in their jobs? (viewed 89083 times)
  101. Why do different stars appear with seasons? (viewed 88797 times)
  102. Why are stars and planets round? (viewed 88151 times)
  103. Is there a proof that Earth moves? (viewed 87605 times)
  104. Where did the Universe come from? (viewed 87513 times)
  105. Have astronomers discovered Earth's second moon? (viewed 87013 times)
  106. Does the Sun orbit the Earth as well as the Earth orbiting the Sun? (viewed 86853 times)
  107. Why is the Universe flat and not spherical? (viewed 86746 times)
  108. Why is the Moon so bright? (viewed 86730 times)
  109. What kind of schooling is necessary to become an astronomer? (viewed 86183 times)
  110. What makes the wind? (viewed 86127 times)
  111. What would happen if an asteroid 10 kilometers across hit the Earth? (viewed 85853 times)
  112. What is a singularity? (viewed 85028 times)
  113. How can a star burn with no oxygen? (viewed 83203 times)
  114. Where does the name "Milky Way" come from? (viewed 81651 times)
  115. Why does the Earth tilt back and forward once a year? (viewed 81409 times)
  116. What are RA and DEC? (viewed 80934 times)
  117. What would happen if Earth had more than one moon? (viewed 80310 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 79511 times)
  119. What is the difference between a "star" and a "sun"? (viewed 77822 times)
  120. What kind of rock is the moon made of? (viewed 77561 times)
  121. Since Earth is spinning, why do we land in the same place when we jump or fall? (viewed 77345 times)
  122. What are the requirements for being a planet? (viewed 77150 times)
  123. Why aren't there any green stars? (viewed 76557 times)
  124. How many stars are born and die each day? (viewed 76450 times)
  125. Did astronauts really go to the Moon, or is it a hoax? (viewed 76442 times)
  126. How are galaxies formed? (viewed 76257 times)
  127. How are black holes made? Could one be made close to us? (viewed 73972 times)
  128. Will the Sun become a black hole one day? (viewed 73838 times)
  129. What would happen if a supermassive black hole came close to the Earth? (viewed 73250 times)
  130. What is the density of a black hole? (viewed 73146 times)
  131. Who has landed on the moon? (viewed 73039 times)
  132. What would you see from inside a black hole? (viewed 71235 times)
  133. Why is the moon in a different place every night? (viewed 70871 times)
  134. Can moons have moons? (viewed 70349 times)
  135. Do most astronomers believe in God based on the available scientific evidence? (viewed 70340 times)
  136. Why can't you see stars during the day? (viewed 69625 times)
  137. What happens to a substance if its speed is more than the speed of light? (viewed 69610 times)
  138. How do astronomers measure the brightness of stars? (viewed 69520 times)
  139. How do rockets move in space? (viewed 69493 times)
  140. Can you fire a gun on the Moon? (viewed 69436 times)
  141. How do we weigh objects in space? (viewed 69001 times)
  142. How often does the Sun pass through a spiral arm in the Milky Way? (viewed 68972 times)
  143. How can the Universe expand faster than the speed of light during inflation? (viewed 68837 times)
  144. What are some of the effects of solar flares on Earth? (viewed 68791 times)
  145. What would happen if you took off your helmet in space? (viewed 68378 times)
  146. How is astronomy impacted by trigonometry? (viewed 68009 times)
  147. Is it possible to measure the temperature of the Sun? (viewed 67634 times)
  148. How do we know the mass of the Earth and the Moon? (viewed 67581 times)
  149. When the Sun converts mass to energy, do the orbits of the planets change? (viewed 67484 times)
  150. Does the Mediterranean sea have tides? (viewed 67442 times)
  151. How does the Sun compare to other stars? (viewed 66915 times)
  152. How do you measure a planet's mass? (viewed 66083 times)
  153. What are the "dog days of summer"? (viewed 66062 times)
  154. Why do stars change colour when they twinkle? (viewed 66007 times)
  155. How does the Moon stay "suspended" in the air? (viewed 65880 times)
  156. How are elements heavier than iron formed? (viewed 65327 times)
  157. What is the evidence supporting the nebula theory of Solar System formation? (viewed 65167 times)
  158. What kinds of jobs do astronomers do? (viewed 64802 times)
  159. Why do we not have eclipses every month? (viewed 64690 times)
  160. Does quantum entanglement imply faster than light communication? (viewed 64129 times)
  161. If the universe is infinite does that mean there is an infinite number of "me"s? (viewed 63395 times)
  162. What are black holes made of? (viewed 63282 times)
  163. What causes seasons? (viewed 62940 times)
  164. When can I see the Moon through the hole in the Pantheon? (viewed 62505 times)
  165. How did the stars get named? (viewed 62454 times)
  166. Why doesn't the earliest sunset occur on the shortest day of the year? (viewed 62318 times)
  167. Where does the name "Moon" come from? (viewed 61949 times)
  168. How did asteroids form and what is the difference between an asteroid and a comet? (viewed 61889 times)
  169. How fast is the Universe expanding? (viewed 61715 times)
  170. How do you measure the mass of a star? (viewed 61544 times)
  171. How long would it take the Earth to fall into the Sun? (viewed 61333 times)
  172. Where did the matter in the universe come from? (viewed 61284 times)
  173. Traveling at light speed, how long would it take to get to the nearest galaxy? (viewed 61179 times)
  174. What's the best college for astronomy? (viewed 61146 times)
  175. What are Altitude and Azimuth? (viewed 61011 times)
  176. Why do planets not twinkle? (viewed 60955 times)
  177. Why doesn't the length of each day change much around the solstices? (viewed 60610 times)
  178. How does light pollution affect astronomers? (viewed 60431 times)
  179. What would happen to us if the sun went out for an hour? (viewed 60409 times)
  180. Are there stars outside of galaxies? (viewed 60369 times)
  181. Where, in relation to the entire universe, is the Milky Way located? (viewed 60147 times)
  182. What is the mass of the Universe? (viewed 59657 times)
  183. What's the difference between dark matter and dark energy? (viewed 58454 times)
  184. Does the Moon rotate? (viewed 58185 times)
  185. How can I calculate the position or path of the Sun for a given time and location? (viewed 58096 times)
  186. Could there be life in the galaxies nearest to the Milky Way? (viewed 58036 times)
  187. Why does the Sun's apparent path through the sky change throughout the year? (viewed 57594 times)
  188. Why does the Earth have only one moon? (viewed 57575 times)
  189. Can any galaxies be seen with the naked eye? (viewed 57169 times)
  190. How does the parachute in a model rocket work? (viewed 56436 times)
  191. How does astronomy benefit humankind? (viewed 56283 times)
  192. What is the origin of spiral structure in galaxies? (viewed 56252 times)
  193. What is the shape of the universe? (viewed 55984 times)
  194. How long does the supernova stage of a star last? (viewed 55915 times)
  195. How close was the Moon to the Earth when it formed? (viewed 55841 times)
  196. What makes up most of the Universe? (viewed 55700 times)
  197. What is the largest structure in the universe? (viewed 55488 times)
  198. Where are stars born? (viewed 54837 times)
  199. Why isn't the summer solstice the hottest day of the year? (viewed 54657 times)
  200. What can we learn from the color of a star? (viewed 54436 times)
  201. Why is looking out into space the same as looking back in time? (viewed 54422 times)
  202. What is a star's "spectrum"? (viewed 54399 times)
  203. What is the size of a black hole? (viewed 54284 times)
  204. Are names given to black holes? (viewed 54266 times)
  205. How do astronauts use math in their jobs? (viewed 54253 times)
  206. Can you see satellites? (viewed 53758 times)
  207. Which constellation does our Sun belong to? (viewed 53443 times)
  208. How do you calculate the azimuth and altitude of an object? (viewed 53045 times)
  209. How do we measure the size of the Moon and of the Sun? (viewed 53037 times)
  210. If gravity is a "curvature of space" rather than a force, why do a ball and bullet follow different paths? (viewed 52812 times)
  211. Are aliens or UFOs real? (viewed 52349 times)
  212. How can I find the distance to the Sun on any given day? (viewed 52236 times)
  213. What happens to a bullet fired on the moon? (viewed 52183 times)
  214. How do the astronauts communicate in space if sound cannot travel in a vacuum? (viewed 52132 times)
  215. Why do we see stars? (viewed 52128 times)
  216. What other careers involve Astronomy besides Astronomer? (viewed 51952 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 51882 times)
  218. How can I measure the distance of a star? (viewed 51794 times)
  219. Is the speed of light constant? (viewed 51281 times)
  220. What are some astronomy science fair projects? (viewed 51273 times)
  221. Which hemisphere has the best view of the Milky Way? (viewed 50834 times)
  222. Are there any asteroids on a collision course with Earth? (viewed 50716 times)
  223. How long has there been water on Earth? (viewed 50586 times)
  224. Is time travel possible? (viewed 50106 times)
  225. Who discovered each planet? (viewed 49911 times)
  226. Why is the sky blue and not blue & purple? (viewed 49868 times)
  227. What would happen if the Moon fell out of its orbit around Earth? (viewed 49865 times)
  228. Why does the Moon look big on the horizon? (viewed 49624 times)
  229. Would your weight change as you go underground? (viewed 49547 times)
  230. Are meteorites hot or cold when they hit Earth? (viewed 49518 times)
  231. Can we look back far enough in time to see the Big Bang? (viewed 49429 times)
  232. Why is twilight short near the equator? (viewed 49390 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 49365 times)
  234. What do a galaxy's colors mean? Are they its true colors? (viewed 49182 times)
  235. Why is it difficult to understand the expansion of the universe? (viewed 48904 times)
  236. Where did all the water in the universe come from? (viewed 48644 times)
  237. What is a graviton? (viewed 48189 times)
  238. What is the difference between nutation and precession of the Earth? (viewed 48117 times)
  239. If light has no mass, then what draws it into a black hole? (viewed 47926 times)
  240. How is the time of sunrise calculated? (viewed 47821 times)
  241. What skills do astronomers need? (viewed 47769 times)
  242. What's the difference between astronomy and astrophysics? (viewed 47644 times)
  243. Are the planes of solar systems aligned with the plane of the Galaxy? (viewed 47604 times)
  244. How do we know what other planets (and stars, galaxies, etc.) are made of? (viewed 46458 times)
  245. What do I need to do to become an astronomer? (viewed 46368 times)
  246. Do dead stars still shine? (viewed 46006 times)
  247. How do gravitons escape black holes to tell the universe about their gravity? (viewed 45649 times)
  248. Why do the size and brightness of the full moon change? (viewed 45638 times)
  249. What is a wormhole? (viewed 45596 times)
  250. Do supermassive black holes cause galaxy rotation? (viewed 45533 times)
  251. How are black holes discovered? (viewed 45208 times)
  252. Where is the nearest black hole? (viewed 45155 times)
  253. Will we get sucked into the black hole at the center of the Milky Way? (viewed 44979 times)
  254. The Moon slows the Earth's rotation, but how fast was it spinning billions of years ago? (viewed 44599 times)
  255. Why does the Sun appear larger on the horizon than overhead? (viewed 44535 times)
  256. Can we find the place where the Big Bang happened? (viewed 44489 times)
  257. Why can't we see Venus at night when it is an inner planet? (viewed 44448 times)
  258. How do galaxies collide in an expanding universe? (viewed 44432 times)
  259. Can I calculate the size of the Universe by converting light years to kilometres? (viewed 44352 times)
  260. Is the Earth slowly getting larger? (viewed 44286 times)
  261. Why are there stars? (viewed 44221 times)
  262. Why does Barnard 68 appear dark? (viewed 43708 times)
  263. Why are most months 30 or 31 days long? (viewed 43618 times)
  264. Are Kuiper Belt Objects asteroids? Are large Kuiper Belt Objects planets? (viewed 42469 times)
  265. What is the biggest crater recorded on Earth? (viewed 42182 times)
  266. Was the Sun made in a supernova? (viewed 42139 times)
  267. Why don't people walk upside-down on the bottom of the Earth? (viewed 42077 times)
  268. What is the best way to see the Milky Way? (viewed 42053 times)
  269. Could the Universe have expanded faster than the speed of light at the Big Bang? (viewed 41941 times)
  270. Are there eclipses on other planets? (viewed 41852 times)
  271. Why does the location of sunrise change? (viewed 41804 times)
  272. Is there a "South Star"? (viewed 41804 times)
  273. Has there been an experiment that measured speed faster than the speed of light in vacuum? (viewed 41772 times)
  274. How much longer will the Earth last? (viewed 41736 times)
  275. How long could life on Earth survive if the Sun stopped shining? (viewed 41702 times)
  276. Did life originate on Earth, or did it come from somewhere else? (viewed 41596 times)
  277. Why doesn't dark matter fall into a black hole? (viewed 41496 times)
  278. How does Astronomy involve Chemistry? (viewed 41430 times)
  279. What is the difference between the "Doppler" redshift and the "gravitational" or "cosmological" redshift? (viewed 41393 times)
  280. How would the weather on Earth be different if it were a cube? (viewed 41286 times)
  281. Can I buy land on the Moon? (viewed 41267 times)
  282. What happens to spacetime inside a black hole? (viewed 41122 times)
  283. Is the Moon hollow? (viewed 40952 times)
  284. What happens when two black holes get too close? (viewed 40874 times)
  285. Why does the Earth only see one side of the Moon? (viewed 40836 times)
  286. How much can the location of sunset differ from due West? (viewed 40666 times)
  287. What's the biggest meteorite? (viewed 40645 times)
  288. What is time dilation? (viewed 40443 times)
  289. Can the acceleration of the Universe be analogous to apparent acceleration in a airplane? (viewed 40371 times)
  290. What color would Mars be if you were standing on it? (viewed 40345 times)
  291. What is the most distant known galaxy? (viewed 40184 times)
  292. What are the names of the three stars in Orion's belt? (viewed 39963 times)
  293. How can two moons of Saturn share the same orbit? (viewed 39809 times)
  294. What if the Earth rotated twice as fast? (viewed 39553 times)
  295. Could someone travel the universe in his or her own lifetime? (viewed 39329 times)
  296. Can terrestrial planets have rings? (viewed 39306 times)
  297. How long would it take for a mini-black hole to eat the Earth? (viewed 39286 times)
  298. How many Astronauts have been in space? (viewed 39062 times)
  299. Why do people draw stars with five points? (viewed 38896 times)
  300. What are "blue stragglers" in globular clusters? (viewed 38761 times)
  301. Why do pictures of distant galaxies have higher resolution than those of nearby planets? (viewed 38676 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 38524 times)
  303. How do we feel heat? (viewed 38516 times)
  304. What is the typical size of a visible shooting star? (viewed 38373 times)
  305. If a white dwarf is a "dead" star, why is it so hot? (viewed 38284 times)
  306. Does Mt. Everest cast a shadow on the moon? (viewed 38095 times)
  307. How do we know that nuclear fusion is still going on in the Sun? (viewed 38077 times)
  308. Is the Great Wall the largest galaxy cluster? (viewed 37987 times)
  309. How fast does the Earth go at perihelion and aphelion? (viewed 37882 times)
  310. How does night and day work? (viewed 37879 times)
  311. Why can we see the sun's image before sunrise and after sunset? (viewed 37839 times)
  312. Can a person go into a black hole and come out alive? (viewed 37660 times)
  313. What is a dimension? (viewed 37546 times)
  314. Does the Sun have an iron surface? (viewed 37505 times)
  315. What is the speed of gravity? (viewed 37457 times)
  316. Can you see the future as you fall into a black hole? (viewed 37415 times)
  317. Can I communicate faster than light? (viewed 37353 times)
  318. Where do planetary rings come from, and what are they made of? (viewed 37352 times)
  319. On which days can I see the Moon in the evening / morning and why is this so? (viewed 37277 times)
  320. Why are Saturn's rings flat? (viewed 37255 times)
  321. What can I use for fuel in my homemade rocket? (viewed 37209 times)
  322. What is Earthrise over the Moon? (viewed 37195 times)
  323. How big is the universe? (viewed 37168 times)
  324. Where is the supernova remnant that led to our solar system? (viewed 37096 times)
  325. Do you think it's possible to maintain life on other planets? (viewed 37090 times)
  326. Is the Sun always up for exactly 12 hours at the equator? (viewed 36966 times)
  327. What is the approximate GPA needed in High School in Math and Science to be an astronomer? (viewed 36894 times)
  328. Who (and when) discovered that the earth's axis is on a 23 degree tilt? (viewed 36815 times)
  329. Are all stars the same? (viewed 36772 times)
  330. Is there really a 10th planet? (viewed 36608 times)
  331. How do we determine the age of the universe? (viewed 36597 times)
  332. Why do clocks turn in the opposite direction from the Earth and Moon? (viewed 36533 times)
  333. What companies or businesses can astronomers work for? (viewed 36484 times)
  334. Why is sea water salty, and not lake water? (viewed 36416 times)
  335. What would happen to the Earth if an asteroid hit the Moon? (viewed 36229 times)
  336. How many stars can I see? (viewed 36157 times)
  337. How do I tell which planet is which? (viewed 36079 times)
  338. Does the Coriolis force determine which way my toilet drains? Does it affect black holes? (viewed 36071 times)
  339. Is there a beginning and an end to a galaxy's life? (viewed 35898 times)
  340. If the universe is 15 billion years old, how can it be larger than 15 billion light years across? (viewed 35784 times)
  341. Do the Sun's or Earth's magnetic field reverse? (viewed 35626 times)
  342. How do we know the Milky Way is a spiral galaxy? (viewed 35576 times)
  343. How can the universe be "flat"? We're 3D! (viewed 35406 times)
  344. How do we define distance in an expanding universe? (viewed 35329 times)
  345. How are photons created and destroyed? (viewed 35292 times)
  346. How can I find my age on another planet? (viewed 35183 times)
  347. Is Andromeda part of the Milky Way? Where can I find them in the sky? (viewed 34893 times)
  348. Why have star signs shifted by one constellation? (viewed 34681 times)
  349. What was that really big falling star that I saw? (viewed 34414 times)
  350. How does the brightness of a star depend on its distance from us? (viewed 34375 times)
  351. Why do humans want to go in space? (viewed 34361 times)
  352. Why are there blue shifted galaxies? (viewed 34284 times)
  353. What is the pattern to the distances between each planet and the sun? (viewed 34182 times)
  354. How are planets detected around other stars? (viewed 34174 times)
  355. What would happen if two stars collided? (viewed 34083 times)
  356. Can a lunar and a solar eclipse happen in the same month? When will this happen next? (viewed 34075 times)
  357. Who came up with the name "black hole"? (viewed 34074 times)
  358. What is the significance of the second focus of elliptical orbits of planets in our Solar System? (viewed 33957 times)
  359. How do astronauts communicate with their families from space? (viewed 33938 times)
  360. When we look back to the Big Bang, why don't we see the universe as a tiny speck of matter? (viewed 33924 times)
  361. Is the Earth at the centre of the Universe? (viewed 33912 times)
  362. How can we estimate the number of Earth-like planets in the Galaxy? (viewed 33907 times)
  363. Is there a simple formula to calculate solar eclipse timings from any position on Earth? (viewed 33804 times)
  364. What kind of eyepieces do I need to look at planets? (viewed 33773 times)
  365. Will we ever stop having solar eclipses because of the moon's motion away from the Earth? (viewed 33731 times)
  366. Why don't astronomers use everyday units to measure distances (what is an AU or a pc)? (viewed 33716 times)
  367. How is it that we see farther out in space (farther back in time) than in the past? (viewed 33458 times)
  368. Will the Moon be invisible in 500 million years? (viewed 33402 times)
  369. Are Earth and the Moon "twin planets"? (viewed 33226 times)
  370. Which American colleges teach astronomy? (viewed 33106 times)
  371. How dangerous are the asteroids? (viewed 33093 times)
  372. Why is our solar system so different from all the others we've found? (viewed 33025 times)
  373. How do I become both an astronaut and an astronomer? (viewed 32892 times)
  374. Why is Uranus tipped on its side? (viewed 32890 times)
  375. Can we colonize other planets? (viewed 32791 times)
  376. How hot is each one of the layers of the sun? (viewed 32583 times)
  377. How do sunrise and sunset times change with altitude? (viewed 32167 times)
  378. What are quasars made of? (viewed 32061 times)
  379. How can I calculate distances between stars? (viewed 32059 times)
  380. Why do constellations look the same after several years even though all the stars are moving? (viewed 31911 times)
  381. Why do astronauts in space need to exercise? (viewed 31864 times)
  382. Why are there no craters on Earth? Did all the meteorites miss us? (viewed 31847 times)
  383. Why doesn't gravity change the speed of light? (viewed 31804 times)
  384. Can you describe a day on the job as an astronomer? (viewed 31602 times)
  385. Is the universe really like an expanding balloon? (viewed 31573 times)
  386. Is it possible to count the stars? (viewed 31521 times)
  387. Is it true that the Sun burns off a billion tons of gas every 5 seconds? (viewed 31473 times)
  388. What is dark matter? (viewed 31452 times)
  389. Is the gravitational force exerted by the Earth on the Moon equal to the centripetal force acting on the Moon? (viewed 31445 times)
  390. Is time travel possible using merging black holes? (viewed 31442 times)
  391. Why can't a plane fly slowly and let the Earth pass underneath? (viewed 31309 times)
  392. What is happening just around the black hole in the center of the Milky Way? (viewed 31295 times)
  393. Can superheavy elements (such as Z=116 or 118) be formed in a supernova? Can we observe them? (viewed 31207 times)
  394. Did the speed of light change over the history of the universe? (viewed 31123 times)
  395. How big a change in the Earth's orbit would be required to destroy all life? (viewed 31060 times)
  396. Can we see dead stars with the naked eye? (viewed 31059 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 31010 times)
  398. How do we measure distances to other stars? (viewed 30923 times)
  399. Is the Local Group expanding along with the entire Universe? (viewed 30879 times)
  400. What happens when an antimatter black hole collides with a matter blackhole? (viewed 30780 times)
  401. How do I make a scale model of the Solar System? (viewed 30771 times)
  402. Are time machines possible? (viewed 30731 times)
  403. How many moles of stars are in the known universe? (viewed 30303 times)
  404. How are galaxy distances inferred from their recessional velocities? (viewed 30076 times)
  405. Is there any limitation to what a black hole can "suck" in? (viewed 29920 times)
  406. How can we tell what the interiors of planets are like? (viewed 29902 times)
  407. What happens when you change the mass of a White Dwarf or Neutron Star? (viewed 29789 times)
  408. Why is the time between two successive full moons different from the lunar synodic month? (viewed 29731 times)
  409. What is the farthest in space that we have gone? (viewed 29719 times)
  410. What do "homogeneity" and "isotropy" mean? (viewed 29569 times)
  411. What's that dark spot on the Sun? (viewed 29506 times)
  412. How can we know that there are other galaxies if we cannot leave ours? (viewed 29484 times)
  413. What are the closest and/or brightest stars? (viewed 29411 times)
  414. How can I tell if the rock I found is a meteorite? (viewed 29382 times)
  415. Can astronauts produce water in space? (viewed 29366 times)
  416. Will the seasons change due to precession? (viewed 29336 times)
  417. Does the Milky Way spin counter-clockwise? If so, do all spiral galaxies spin in this direction and why? (viewed 29314 times)
  418. How was the starting point for the Julian Date system chosen? (viewed 29189 times)
  419. Aren't jobs in astronomy scarce? (viewed 29182 times)
  420. Do astronomers believe in astrology? (viewed 29062 times)
  421. Did I see the Aurora Borealis as a child? (viewed 29023 times)
  422. How do we know if the universe will keep expanding forever? (viewed 29022 times)
  423. Why does the SETI project search for radio signals? (viewed 28991 times)
  424. What are the facts about the Star of Bethlehem? (viewed 28964 times)
  425. How long does it take the Big Dipper to move in the sky? (viewed 28964 times)
  426. Don't tachyons travel faster than light? (viewed 28946 times)
  427. Could an astronaut or satellite fall into a black hole that we didn't know about? (viewed 28920 times)
  428. Why do most moons orbit their planets at the equator? (viewed 28914 times)
  429. Why do we study black holes? (viewed 28840 times)
  430. What are the atmospheres of Mars and Pluto like? (viewed 28771 times)
  431. When are there 5 Sundays in February? (viewed 28728 times)
  432. Wouldn't the Big Bang theory be considered a hypothesis and not a theory? (viewed 28673 times)
  433. Do we see the same stars from above and below the equator? (viewed 28444 times)
  434. Has anyone made a map of the Milky Way? (viewed 28432 times)
  435. Was I hit by a meteorite? (viewed 28418 times)
  436. How are galaxies named? (viewed 28293 times)
  437. Can you use an infinite line of reflectors to send light to the edge of the Universe? (viewed 28289 times)
  438. What does the term "visible universe" mean? (viewed 28287 times)
  439. What colors are visible through an amateur telescope? (viewed 28282 times)
  440. Could you tell me about the life cycle of galaxies? (viewed 28262 times)
  441. Do you believe in UFOs? (viewed 28225 times)
  442. How can geometry be different in space? (viewed 28191 times)
  443. Why are the compositions of comets and asteroids different? (viewed 27907 times)
  444. How do asteroids, meteors and comets disappear? (viewed 27630 times)
  445. What's the best thing about being an astronomer? (viewed 27624 times)
  446. How much time do astronomers spend looking through telescopes? (viewed 27556 times)
  447. Will winter and summer constellations change due to abnormal warmth or cold on Earth? (viewed 27535 times)
  448. How do astronomers measure the radius of a star? (viewed 27411 times)
  449. Why do so many of the world's UFO sightings happen in America? (viewed 27408 times)
  450. How will the two black holes that are going to collide affect Earth? (viewed 27370 times)
  451. Have there been other Big Bangs before? (viewed 27344 times)
  452. Can two lunar eclipses occur in the same month? (viewed 27335 times)
  453. How can we see galaxies if their stars are so faint? (viewed 27328 times)
  454. Can life exist on the recently discovered extrasolar planets? (viewed 27116 times)
  455. How do I explain to my children why the Moon has phases? (viewed 27116 times)
  456. How are galaxies and solar systems similar? (viewed 27028 times)
  457. How close do you have to come to the Earth to be influenced by its gravity? (viewed 27020 times)
  458. Is the Milky Way a collision of two galaxies? (viewed 26941 times)
  459. Is there a project I can do on black holes? (viewed 26891 times)
  460. How can we measure distances to more stars? (viewed 26823 times)
  461. What is the origin of the stellar classification system "OBAFGKM"? (viewed 26773 times)
  462. Could you escape from a black hole if you were able to go faster than the speed of light? (viewed 26753 times)
  463. How do scientists slow light down? (viewed 26687 times)
  464. Do the magnitudes and colors of stars ever change? (viewed 26639 times)
  465. Is infinite temperature possible? (viewed 26540 times)
  466. Do we know everything about the Sun? (viewed 26510 times)
  467. How close does a supernova need to be to damage the Earth's environment? (viewed 26500 times)
  468. Can "tired light theory" explain the observed redshifts of galaxies? (viewed 26382 times)
  469. What supernova created the Crab nebula? (viewed 26360 times)
  470. Can one star orbit another? (viewed 26341 times)
  471. Do asteroids hit the sun? (viewed 26335 times)
  472. Is it worthwhile to continue the search for extraterrestrial life? (viewed 26322 times)
  473. How far does a galaxy extend? (viewed 26158 times)
  474. What causes gamma ray bursts? (viewed 26156 times)
  475. Can double stars have planets? (viewed 26148 times)
  476. How do I polar align my telescope? (viewed 26020 times)
  477. Is there such a thing as hyperspace? (viewed 25934 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 25893 times)
  480. Can astronauts play musical instruments in space? (viewed 25882 times)
  481. What happens to the material that has been sucked into a black hole? (viewed 25876 times)
  482. Which way does the sun travel in the southern hemisphere? (viewed 25815 times)
  483. What is the farthest Northern Latitude in which the Magellanic Clouds can be seen? (viewed 25814 times)
  484. What is sidereal time? (viewed 25800 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 25680 times)
  487. What is a Cepheid variable? (viewed 25619 times)
  488. What is "nothing", from a scientific point of view? (viewed 25600 times)
  489. How will a change in the speed of light affect the evolution of the Universe? (viewed 25599 times)
  490. What's the object I saw that moved across the sky and then got very bright? (viewed 25544 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 25531 times)
  492. Which part of the sky did the famous 'wow' signal originate from? (viewed 25502 times)
  493. How different would the night sky have looked in 40,000 B.C.? (viewed 25437 times)
  494. Is there sound coming from the Sun? (viewed 25389 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 25307 times)
  497. How do we know that sunspots are associated with the Sun's magnetic field? (viewed 25267 times)
  498. Can a human give birth in space? (viewed 25231 times)
  499. When did people discover that the Sun is a star? (viewed 25191 times)
  500. Why is the shadow on the Moon the shape it is? (viewed 25175 times)
  501. Are there any dark stars or dark galaxies made of dark matter? (viewed 25149 times)
  502. When unmanned spacecraft accelerate in space, what causes them to slow down? (viewed 25114 times)
  503. Are planetary nebulae the result of supernovae? (viewed 25113 times)
  504. What calculations go into predicting eclipses? (viewed 25098 times)
  505. Does the Moon look different in the northern and southern hemispheres? (viewed 25054 times)
  506. Was Stonehenge built to mark solar phenomena? (viewed 25050 times)
  507. If we invented special suits could we ever go to the sun? (viewed 25050 times)
  508. Is there a list of the sizes of different kinds of stars? (viewed 25006 times)
  509. What is the difference between homogeneity and isotropy? (viewed 24992 times)
  510. What is our galaxy's halo made of, and how was it formed? (viewed 24973 times)
  511. What process would bring about a quark star? (viewed 24940 times)
  512. What's so exciting about the new planet around 55 Cancri? (viewed 24879 times)
  513. Can I see a quasar? (viewed 24865 times)
  514. What is a Dyson Sphere? (viewed 24833 times)
  515. Did a giant impact cause the Dark Ages? (viewed 24818 times)
  516. How many sunspots can the Sun have at once? (viewed 24807 times)
  517. How are asteroid compositions and classifications determined? (viewed 24769 times)
  518. Have gravitational waves been proven to exist? (viewed 24761 times)
  519. Can I see details on Venus? (viewed 24703 times)
  520. Can any comparison be made between spiral galaxies and hurricanes? (viewed 24654 times)
  521. Why are there active volcanos on Io? (viewed 24491 times)
  522. Why are there more maria on the near side of the Moon? (viewed 24478 times)
  523. What equipment do I need for astrophotography? (viewed 24454 times)
  524. Does Cerenkov radiation travel faster than light? (viewed 24438 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 24378 times)
  527. What happened to all the black holes that were around in the early universe? (viewed 24372 times)
  528. Why are telescopes kept in cold conditions? (viewed 24228 times)
  529. What happened to the girl who named Pluto? (viewed 24184 times)
  530. Would the biggest airplanes cause tsunamis if they crashed? (viewed 24178 times)
  531. If clocks run slow in a gravitational field, how can we know the true age of the Solar System and Universe? (viewed 24163 times)
  532. How big was the Sun when it first "fired up"? (viewed 24153 times)
  533. How can we compare dark matter and dark energy? (viewed 24121 times)
  534. If the Universe was infinitely dense at the Big Bang, why didn't time stand still? (viewed 24027 times)
  535. What caused Shoemaker-Levy 9 to split up? (viewed 24016 times)
  536. Could we send a space mission to a comet? (viewed 24000 times)
  537. Why do photos of space taken from space never show any stars? (viewed 23994 times)
  538. How long do supernova remnants last? (viewed 23948 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 23846 times)
  542. How are sunspots formed? (viewed 23841 times)
  543. How big is the Hubble Ultra Deep Field image? (viewed 23693 times)
  544. Could a different theory of gravity explain the dark matter mystery? (viewed 23674 times)
  545. How does the Earth compare in size to the entire universe at the present epoch? (viewed 23653 times)
  546. Can you give me advice on buying a telescope? (viewed 23647 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 23587 times)
  550. Why is the Hubble Space Telescope in space? (viewed 23524 times)
  551. Can you tell time by the Big Dipper? (viewed 23487 times)
  552. What would happen if a human were exposed to space without wearing a spacesuit? (viewed 23470 times)
  553. Where does the kinetic energy of infalling bodies come from? (viewed 23449 times)
  554. Can I build an instrument to measure the size of the Sun and of the Moon? (viewed 23446 times)
  555. How do we know that superclusters are the largest structures in the universe? (viewed 23419 times)
  556. How powerful are quasars? (viewed 23343 times)
  557. Would extraterrestrial civilizations know that there is life on Earth? (viewed 23278 times)
  558. Did I really hear a meteor? (viewed 23248 times)
  559. Why is it important to study meteorites? (viewed 23206 times)
  560. How is the Cepheid yardstick validated? (viewed 23194 times)
  561. Why are telescopes located in remote places? (viewed 23059 times)
  562. Can supernovae hinder the formation of life in galaxies? (viewed 23053 times)
  563. What would happen if there was a collision between two white dwarfs? (viewed 23052 times)
  564. Do unmanned spacecraft like Voyager travel in straight lines? (viewed 23048 times)
  565. Did time go slower just after the Big Bang? (viewed 23025 times)
  566. Are there any new craters on the moon? (viewed 23018 times)
  567. Why are stars of different masses? (viewed 22998 times)
  568. Do galaxies orbit around anything? (viewed 22959 times)
  569. How can I contribute to science as an amateur astronomer? (viewed 22935 times)
  570. How do planets capture satellites? (viewed 22917 times)
  571. Do similar laws of physics throughout the Universe imply that all life must be like life on Earth? (viewed 22914 times)
  572. Do the Earth's magnetic poles ever change places? (viewed 22911 times)
  573. Are the asteroids the remains of a planet which broke apart? (viewed 22897 times)
  574. How do I become an astronomical artist? (viewed 22883 times)
  575. What kind of instruments are used to detect extrasolar planets? (viewed 22862 times)
  576. How could galaxies have gotten so far away in only 15 billion years? (viewed 22728 times)
  577. Could there have been multiple Big Bangs at different places in the universe? (viewed 22720 times)
  578. How are astronomy and poetry linked? (viewed 22681 times)
  579. How do unmanned space probes avoid running into things? (viewed 22646 times)
  580. What kind of telescope should I use for astrophotography? (viewed 22601 times)
  581. Why can't relative velocities add up to more than the speed of light? (viewed 22574 times)
  582. Could dark energy come from matter anti-matter pairs forming spontaneously and then annihilating? (viewed 22519 times)
  583. Why is NASA shutting down the Hubble Space Telescope? (viewed 22510 times)
  584. Can I listen to the SETI@home radio signal? (viewed 22497 times)
  585. How can you tell if a crescent moon is preceding or following a new-moon phase? (viewed 22470 times)
  586. Are the properties of extrasolar planets known? (viewed 22448 times)
  587. Does the Sun have any heavy elements? (viewed 22406 times)
  588. Will we discover an 11th planet? What would it be called? (viewed 22261 times)
  589. What class of spiral galaxy is the Milky Way? (viewed 22230 times)
  590. Can the theory of formation of the solar system explain all the observables? (viewed 22227 times)
  591. What month was it when Odysseus saw Orion in 1000BC? (viewed 22205 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 22189 times)
  593. How do astronomers observe the Sun's interior? (viewed 21936 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 21918 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 21729 times)
  599. What is the solar cycle? (viewed 21687 times)
  600. Where was the water in the big bang? (viewed 21618 times)
  601. Could we send a manned mission to the outer planets? (viewed 21610 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 21543 times)
  604. Why was the Platonic year named after Plato? (viewed 21482 times)
  605. How are supernovae discovered? (viewed 21468 times)
  606. Can a black hole come back to the visual universe through a "little bang"? (viewed 21413 times)
  607. What would the Big Crunch look like to an observer on Earth? (viewed 21395 times)
  608. Does inflation allow for an infinite number of universes? (viewed 21333 times)
  609. Why are accretion disks flat? (viewed 21280 times)
  610. Could our position in the universe affect our perceptions of the expansion? (viewed 21278 times)
  611. What is meant by "stopping down a telescope"? (viewed 21260 times)
  612. How can water be chemically trapped in rocks? (viewed 21245 times)
  613. Why do spacecraft need heat shields coming back to Earth but not leaving? (viewed 21206 times)
  614. Why doesn't the hydrogen on Jupiter explode? (viewed 21186 times)
  615. Did I find a rock that came from the Moon? (viewed 20972 times)
  616. Have astronomers observed any phenomena that could be produced by extraterrestrial civilizations? (viewed 20957 times)
  617. Does a photon observe other photons moving past it at the speed of light? (viewed 20937 times)
  618. How can the Sun have such a strong gravitational field if it's made of gasses? (viewed 20925 times)
  619. What is the SU(3) quark model? (viewed 20924 times)
  620. Can gravitational lensing from intervening galaxies cause the observed ripples in the Cosmic Microwave Background? (viewed 20902 times)
  621. What's new with the Big Bang? (viewed 20645 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 20512 times)
  625. Why can we have solar eclipses? (viewed 20500 times)
  626. If comets are boiling away, why are there any left? (viewed 20472 times)
  627. How can we find galaxies behind the Milky Way? (viewed 20462 times)
  628. How fast do particles travel in space? (viewed 20424 times)
  629. Why do some eclipses take longer than others? (viewed 20411 times)
  630. Why search for only Earth-like life on other planets? (viewed 20373 times)
  631. Where can I find information on the moons of other planets? (viewed 20349 times)
  632. How much power is contained in a beam of light? (viewed 20266 times)
  633. Why is the WMAP picture of the CMB an ellipse? (viewed 20202 times)
  634. Why is pressure broadening greater in low mass stars than in high mass stars? (viewed 20179 times)
  635. What would an "open geometry" for the universe look like? (viewed 20086 times)
  636. What are the boundaries of the constellations? (viewed 20048 times)
  637. Did the Sumerians measure precession? (viewed 19995 times)
  638. What kinds of star clusters are there? (viewed 19974 times)
  639. Why is the Cosmic Microwave Background not absorbed by interstellar hydrogen? (viewed 19953 times)
  640. How do astronomers come up with their facts? (viewed 19941 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 19838 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 19773 times)
  646. Do electrons age? (viewed 19712 times)
  647. Can planets collide with one another? (viewed 19677 times)
  648. Do constellations looks the same from space? (viewed 19627 times)
  649. Can the Space Shuttle abort and return to Earth before reaching orbit? (viewed 19614 times)
  650. Can we make a movie of the Milky Way galaxy's rotation? (viewed 19605 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 19429 times)
  654. What are collections of galaxies called? (viewed 19395 times)
  655. How does melting a material reset its radioactive clock? (viewed 19392 times)
  656. Why do supernova remnants look like rings rather than spheres? (viewed 19345 times)
  657. How do you classify galaxies? (viewed 19297 times)
  658. Will astronauts ever be able to go ice-skating on Europa? (viewed 19281 times)
  659. Where can I see Newton's original reflecting telescope? (viewed 19269 times)
  660. Why don't all neutron stars become pulsars? (viewed 19206 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 19147 times)
  663. How can we understand the meaning of large numbers like "a million million?" (viewed 19119 times)
  664. Will the next generation telescope OWL be able to detect an Earth like extrasolar planet? (viewed 19070 times)
  665. What causes a particle to decay? (viewed 19043 times)
  666. How can I nominate myself for a Nobel Prize in Physics? (viewed 18962 times)
  667. How long has humanity known that we live in a galaxy similar to others in the Universe? (viewed 18931 times)
  668. Will the Leonid meteor shower go away? (viewed 18925 times)
  669. What are "curled" dimensions? (viewed 18803 times)
  670. Is light of different colors affected differently by gravity? (viewed 18783 times)
  671. What was that eclipse I saw in the sky? (viewed 18686 times)
  672. How does interferometry work? (viewed 18636 times)
  673. How do distant galaxies differ from those nearby? (viewed 18554 times)
  674. Does the temperature of matter increase as it is accelerated to relativistic speeds? (viewed 18529 times)
  675. Do asteroids ever do anything good in the Solar System? (viewed 18520 times)
  676. How do we find out about the star formation histories of galaxies? (viewed 18516 times)
  677. Why is it called astronomy when all the other sciences end in -ology? (viewed 18502 times)
  678. How does the color index of a star relate to its actual color? (viewed 18460 times)
  679. Can astronomers observe anything when the moon is full? (viewed 18443 times)
  680. Wouldn't the vast distances of space distort SETI signals into unintelligeble forms? (viewed 18393 times)
  681. If nothing can escape a black hole, why do some black holes have jets? (viewed 18382 times)
  682. What kind of interference must astronomers contend with when observing? (viewed 18336 times)
  683. Are black holes spherical? (viewed 18314 times)
  684. What would happen if you went back in time and killed your grandmother? (viewed 18301 times)
  685. Why will fusion wait until hydrogen is gone before starting to fuse heavier atoms? (viewed 18249 times)
  686. Do we really observe the edges of galaxies at different epochs? (viewed 18246 times)
  687. What do stellar classifications mean? (viewed 18234 times)
  688. Can you tell me the characteristics of W, R, N and S type stars? (viewed 18227 times)
  689. How are astronauts trained for weightlessness? (viewed 18143 times)
  690. How can I watch the Perseid meteor shower? (viewed 18138 times)
  691. What is the three-body problem? (viewed 18060 times)
  692. If photons have zero mass, why do they feel the effects of gravity? (viewed 17981 times)
  693. Why aren't accretion disks around giant stars as hot as accretion disks around black holes? (viewed 17963 times)
  694. If the universe is "bounded" today, could it one day become "unbounded"? (viewed 17890 times)
  695. Will the diameter of a cluster of galaxies change with redshift? (viewed 17844 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 17564 times)
  698. Do we have to worry about relativity when studying galactic objects? (viewed 17380 times)
  699. Could neutrinos be dark matter? (viewed 17299 times)
  700. What kinds of cancer research have been done in space? (viewed 17198 times)
  701. How does a star take mass from another star? (viewed 17114 times)
  702. How can you tell the difference between single and multiple extrasolar planets? (viewed 16910 times)
  703. Could the Universe's dark matter be made up of black holes? (viewed 16903 times)
  704. Does lunar gardening really work? (viewed 16865 times)
  705. What is Hot Dark Matter theory? (viewed 16821 times)
  706. When measuring the expansion of the universe, do astronomers consider that they're seeing how galaxies moved long ago, not today? (viewed 16813 times)
  707. How do supernovae show us that the Universe's expansion is accelerating? (viewed 16653 times)
  708. Is it a coincidence that we can have total solar eclipses? Are there other planets which also have them? (viewed 16388 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 16289 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 16214 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 16154 times)
  715. Do binary or triple star systems form together? (viewed 16135 times)
  716. No matter how fast the universe is expanding, shouldn't gravity eventually make it recollapse? (viewed 16097 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 15813 times)
  719. Why is it easier to see a star if you look slightly to the side? (viewed 15692 times)
  720. What happens to the helium formed in the sun? (viewed 15609 times)
  721. Could matter-anti-matter repulsion power the expansion of the universe? (viewed 15602 times)
  722. If the sun went out and our atmosphere froze solid, what color would it be? (viewed 15430 times)
  723. Can we prove that the Moon isn't hollow? (viewed 15380 times)
  724. Why doesn't the ammonia and methane in Jupiter's atmosphere sink into the core? (viewed 15327 times)
  725. Are there any 'lonely galaxies'? (viewed 15217 times)
  726. How do we detect incoming meteorites? (viewed 15083 times)
  727. What was different on Mars in the past to allow liquid water to be present? (viewed 14968 times)
  728. When will Hale-Bopp return? (viewed 14816 times)
  729. Why don't skydivers burn up like meteors? (viewed 14726 times)
  730. Has anyone ever seen a star "turn on"? (viewed 14532 times)
  731. During close approaches, can Mars appear in our sky as large as the Moon? (viewed 14530 times)
  732. How are planets affected by the Hot Ionised Medium? (viewed 14295 times)
  733. How has light from 13 billion years ago not passed us by? (viewed 14151 times)
  734. Why are craters round? (viewed 14060 times)
  735. Can the sun rise from the west on Mars? (viewed 13844 times)
  736. Why was Mir burnt up in the atmosphere? (viewed 13836 times)
  737. What are the largest radio wavelengths observed from radio sources in the sky? (viewed 13818 times)
  738. How can we discern different galaxies/clusters along the same line of sight? (viewed 13726 times)
  739. What is the relationship between the width of a star trail on a photo and the star's intensity? (viewed 13296 times)
  740. Can we harvest H & O from space to make water? (viewed 12813 times)
  741. What is between the Oort cloud and the closest star? (viewed 12493 times)
  742. Why does Titan, in spite of being smaller than Mars, have an atmosphere more dense than Earth's? (viewed 12361 times)
  743. What time is sunrise/sunset or moonrise/moonset at my location? (viewed 12169 times)
  744. Could a planetary system survive if its star merged with another, or if its star went supernova? (viewed 11617 times)
  745. Are there solar tides? (viewed 11583 times)
  746. Does weightlessness affect hunger? (viewed 11493 times)
  747. Is Earth-moon tidal friction causing global warming? (viewed 10951 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 10828 times)
  749. Do planets radiate noise? (viewed 10779 times)
  750. Is the moon spherical? (viewed 10604 times)
  751. What happens to the Earth as the moon gets farther away and will it ever go away entirely? (viewed 10512 times)
  752. What would happen if a nuclear-powered shuttle exploded? (viewed 10387 times)
  753. Is dark energy affected by black holes? (viewed 10371 times)
  754. Why is the Moon higher in the sky in winter and lower in the summer? (viewed 9779 times)
  755. Where are the protons and electrons in a Neutron Star? (viewed 9654 times)
  756. Did the Moon or planets form in a manner similar to that of Earth? (viewed 9454 times)
  757. Do more meteorites fall at low latitudes? (viewed 9439 times)
  758. What are the possible ends of the universe? (viewed 9284 times)
  759. Will Comet Elenin (C/2010 X1) affect the Earth on its close approach in Fall 2011? (viewed 9274 times)
  760. Wait, I'm still confused why information can't travel faster than the speed of light. (viewed 9269 times)
  761. Is it sensible to consider terraforming Mars? (viewed 9198 times)
  762. If there are infinity universes, will every thing that is possible happen? (viewed 9167 times)
  763. Will the Pioneer and Voyager probes ever leave the Milky Way? (viewed 9158 times)
  764. Is the Moon always visible during winter on the North Pole? (viewed 9107 times)
  765. What color are meteors? (viewed 8745 times)
  766. Where is everybody? (viewed 8444 times)
  767. Why does Mars have a dusty atmosphere? (viewed 7926 times)
  768. The naming of Mars (viewed 7840 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 7737 times)
  771. Is the reddish dust of Mars biogenic? (viewed 7582 times)
  772. Where is the Spitzer Space Telescope? (viewed 7069 times)
  773. When will humans travel to Mars and revisit the Moon? (viewed 6980 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 6076 times)
  776. How likely is it for a planet to transit its star? (viewed 5958 times)
  777. What causes the aurora? (viewed 5827 times)
  778. Why do astronomers use telescopes? (viewed 5716 times)
  779. How did a transit of Venus provide astronomers with the first measurement of the Earth-Sun distance? (viewed 4815 times)
  780. Can the Sun be closer to the Earth than any planet is to Earth? (viewed 4128 times)
  781. Cosmologists say the expansion of the universe is accelerating, what is driving this? (viewed 3671 times)
  782. Can we hear sound on Titan? (viewed 3625 times)
  783. Does the direction of the moon's crescent change through the night? (viewed 3415 times)
  784. What do all the angles in a table for a planet's orbit mean? (viewed 3184 times)
  785. How do I maximize my chances of seeing shooting stars? (viewed 2483 times)
  786. Are exoplanets real? (viewed 2222 times)
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