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 2132602 times)
  2. What color is each planet? (viewed 912978 times)
  3. At what speed does the earth move around the sun? (viewed 585634 times)
  4. Is the Moon moving away from the Earth? When was this discovered? (viewed 564809 times)
  5. How far is each planet from Earth? (viewed 469774 times)
  6. When will Halley's Comet return? (viewed 426628 times)
  7. How long does it take for the Sun's light to reach us? (viewed 390997 times)
  8. How many stars are there in our Galaxy (Milky Way)? (viewed 388667 times)
  9. Why do the planets orbit the sun? (viewed 379990 times)
  10. What is the universe expanding into? (viewed 371134 times)
  11. How do you measure the distance between Earth and the Sun? (viewed 342674 times)
  12. Which planets have rings? (viewed 322865 times)
  13. Why do stars twinkle? (viewed 319852 times)
  14. Does the Moon rotate? Are there other moons that always keep one face toward their planet? (viewed 305123 times)
  15. How do I build a model rocket? (viewed 290750 times)
  16. What color is Venus? (viewed 273923 times)
  17. What is a white hole? (viewed 267670 times)
  18. Can you hear sounds in space? (viewed 264273 times)
  19. What is the life cycle of a star? (viewed 246121 times)
  20. What are the names of the earth, moon, sun, and solar system? (viewed 239087 times)
  21. What is that ring (or rainbow) around the moon? (viewed 233179 times)
  22. What makes the Earth rotate? (viewed 233128 times)
  23. What are shooting stars? (viewed 229685 times)
  24. What is the largest star? (viewed 221953 times)
  25. What are the different kinds of astronomers? (viewed 220657 times)
  26. How do we know the age of the Universe and the Earth? (viewed 211873 times)
  27. What do astronauts eat in space? Can they grow food? (viewed 210971 times)
  28. Can artificial gravity be created in space? (viewed 209849 times)
  29. Why do planets rotate? (viewed 207638 times)
  30. Is the universe expanding faster than the speed of light? (viewed 203193 times)
  31. How does the location of sunrise and sunset change throughout the year? (viewed 195774 times)
  32. How can we see the Milky Way if we are inside it? (viewed 182732 times)
  33. Where did the name 'Earth' come from? (viewed 180499 times)
  34. What would happen if we did not have a Moon? (viewed 176384 times)
  35. Why isn't the sky bright at night if the universe has so many stars? (viewed 174625 times)
  36. How many Earths fit into the Sun? (viewed 172927 times)
  37. Why is a day divided into 24 hours? (viewed 172450 times)
  38. How does the position of Moonrise and Moonset change? (viewed 170739 times)
  39. Who named the planets and who decides what to name them? (viewed 160756 times)
  40. Why are the Moon and Sun sometimes orange or red? (viewed 158398 times)
  41. When was the last time all 9 planets were aligned? (viewed 157533 times)
  42. Why do airplanes take longer to fly West than East? (viewed 156818 times)
  43. Is Pluto a planet? (viewed 150909 times)
  44. Is the distance from the Earth to the Sun changing? (viewed 150790 times)
  45. What is at the end of the Universe? (viewed 147901 times)
  46. How can I find the star I have "bought"? (viewed 145360 times)
  47. How much money is spent on space exploration? (viewed 143211 times)
  48. What is a nova? (viewed 133976 times)
  49. How do astronauts take baths and use restrooms in space? (viewed 132039 times)
  50. Why are there both high and low tides? (viewed 131217 times)
  51. Can we feel the Earth spin? (viewed 131108 times)
  52. Does your weight change between the poles and the equator? (viewed 130618 times)
  53. What direction do planets rotate? (viewed 130408 times)
  54. Is the Sun expanding? Will it ever explode? (viewed 128637 times)
  55. What is the largest galaxy? (viewed 127344 times)
  56. How many known galaxies are there? (viewed 126189 times)
  57. Do stars move in the sky? (viewed 124531 times)
  58. What are the advantages and disadvantages of using a telescope in space? (viewed 120043 times)
  59. Why do all the planets orbit in the same plane? (viewed 118162 times)
  60. Can I buy a star? (viewed 117837 times)
  61. How are light and heavy elements formed? (viewed 115281 times)
  62. Will the sun go supernova in six years and destroy Earth (as seen on Yahoo)? (viewed 115243 times)
  63. Are there telescopes that can see the flag and lunar rover on the Moon? (viewed 113577 times)
  64. Why hasn't NASA gone back to the moon? (viewed 112604 times)
  65. Does the Sun have a scientific name? (viewed 112449 times)
  66. Why do planets have elliptical orbits? (viewed 112003 times)
  67. What is the hottest time of day? (viewed 111715 times)
  68. How do stars move in the Galaxy? (viewed 111548 times)
  69. Who first measured the speed of light? (viewed 111433 times)
  70. What is the physical difference between a star and a planet? (viewed 111259 times)
  71. What happens when galaxies collide? (viewed 110935 times)
  72. How do rockets work? (viewed 109903 times)
  73. What is the size of the Solar System? (viewed 108565 times)
  74. What would happen if an impact caused Earth to stop rotating? (viewed 107648 times)
  75. What is the significance of the Tropic of Cancer, Tropic of Capricorn, Arctic Circle and Antarctic Circle? (viewed 107635 times)
  76. How much money do astronomers make? (viewed 107588 times)
  77. Will the magnetic field of the Earth reverse its direction in the future? Will this cause problems? (viewed 107329 times)
  78. What was there before the Big Bang and what is there outside of our universe? (viewed 107033 times)
  79. When is the next comet due to arrive? (viewed 106704 times)
  80. Does evolution contradict the second law of thermodynamics? (viewed 106366 times)
  81. What will happen to life on Earth when the Sun becomes a red giant? (viewed 105884 times)
  82. How long does a solar eclipse last? (viewed 105479 times)
  83. How do you calculate the lifetime of the Sun? (viewed 105077 times)
  84. Do black holes die? If so how? (viewed 104587 times)
  85. What elements make up the Sun? (viewed 104349 times)
  86. How many constellations are there? (viewed 103656 times)
  87. What is the observational difference between a star and a planet? (viewed 102536 times)
  88. What do astronauts do all day in the International Space Station? (viewed 102367 times)
  89. What's the difference between astronomy and astrology? (viewed 101406 times)
  90. Does the Sun rotate? (viewed 101043 times)
  91. Does the Sun move around the Milky Way? (viewed 99729 times)
  92. Does gravity vary across the surface of the Earth? (viewed 98867 times)
  93. What would happen if the gravity on Earth was suddenly turned off? (viewed 97742 times)
  94. What is apparent magnitude? (viewed 96444 times)
  95. How many meteorites hit Earth each year? (viewed 95756 times)
  96. Which planet is most similar to Earth? (viewed 95449 times)
  97. What are constellations used for? (viewed 94767 times)
  98. Why do different stars appear with seasons? (viewed 93112 times)
  99. What kind of schooling is necessary to become an astronomer? (viewed 92731 times)
  100. If Mars is only about 35-60 million miles away at close approach, why does it take 6-8 months to get there? (viewed 92058 times)
  101. How do astronomers use math in their jobs? (viewed 91815 times)
  102. How critical is the Earth-Sun distance in maintaining our average temperatures on Earth? (viewed 90974 times)
  103. Is there a proof that Earth moves? (viewed 90665 times)
  104. Why are stars and planets round? (viewed 90049 times)
  105. Where did the Universe come from? (viewed 89986 times)
  106. Does the Sun orbit the Earth as well as the Earth orbiting the Sun? (viewed 89542 times)
  107. Why is the Moon so bright? (viewed 89347 times)
  108. Why is the Universe flat and not spherical? (viewed 89218 times)
  109. What makes the wind? (viewed 88634 times)
  110. What would happen if an asteroid 10 kilometers across hit the Earth? (viewed 88051 times)
  111. Have astronomers discovered Earth's second moon? (viewed 87875 times)
  112. How can a star burn with no oxygen? (viewed 87489 times)
  113. What is a singularity? (viewed 87085 times)
  114. What is the difference between a "star" and a "sun"? (viewed 86334 times)
  115. Why does the Earth tilt back and forward once a year? (viewed 83379 times)
  116. What are RA and DEC? (viewed 83290 times)
  117. Where does the name "Milky Way" come from? (viewed 83022 times)
  118. What are the requirements for being a planet? (viewed 82960 times)
  119. What would happen if Earth had more than one moon? (viewed 81435 times)
  120. Considering the motion of the Earth, the solar system, and the galaxy, how fast am I moving while lying in bed asleep? (viewed 81287 times)
  121. Since Earth is spinning, why do we land in the same place when we jump or fall? (viewed 81039 times)
  122. How many stars are born and die each day? (viewed 79578 times)
  123. Why aren't there any green stars? (viewed 78442 times)
  124. What kind of rock is the moon made of? (viewed 78313 times)
  125. Did astronauts really go to the Moon, or is it a hoax? (viewed 77564 times)
  126. How are galaxies formed? (viewed 77368 times)
  127. Why is the moon in a different place every night? (viewed 76121 times)
  128. Will the Sun become a black hole one day? (viewed 75436 times)
  129. How are black holes made? Could one be made close to us? (viewed 75119 times)
  130. What is the density of a black hole? (viewed 74994 times)
  131. What would happen if a supermassive black hole came close to the Earth? (viewed 74657 times)
  132. How do we weigh objects in space? (viewed 73788 times)
  133. Who has landed on the moon? (viewed 73629 times)
  134. Do most astronomers believe in God based on the available scientific evidence? (viewed 72406 times)
  135. Can moons have moons? (viewed 72337 times)
  136. What would you see from inside a black hole? (viewed 72293 times)
  137. What happens to a substance if its speed is more than the speed of light? (viewed 72056 times)
  138. Why can't you see stars during the day? (viewed 72033 times)
  139. How do rockets move in space? (viewed 72031 times)
  140. Does the Mediterranean sea have tides? (viewed 71607 times)
  141. How often does the Sun pass through a spiral arm in the Milky Way? (viewed 71466 times)
  142. How do astronomers measure the brightness of stars? (viewed 71222 times)
  143. Can you fire a gun on the Moon? (viewed 71079 times)
  144. What would happen if you took off your helmet in space? (viewed 71001 times)
  145. What are some of the effects of solar flares on Earth? (viewed 70881 times)
  146. How can the Universe expand faster than the speed of light during inflation? (viewed 70860 times)
  147. When the Sun converts mass to energy, do the orbits of the planets change? (viewed 70681 times)
  148. How do we know the mass of the Earth and the Moon? (viewed 69941 times)
  149. How is astronomy impacted by trigonometry? (viewed 69735 times)
  150. What is the evidence supporting the nebula theory of Solar System formation? (viewed 69627 times)
  151. Is it possible to measure the temperature of the Sun? (viewed 69336 times)
  152. Why do we not have eclipses every month? (viewed 68888 times)
  153. How do you measure a planet's mass? (viewed 68550 times)
  154. Why do stars change colour when they twinkle? (viewed 68376 times)
  155. How does the Sun compare to other stars? (viewed 68258 times)
  156. How does the Moon stay "suspended" in the air? (viewed 68031 times)
  157. How are elements heavier than iron formed? (viewed 67510 times)
  158. What are the "dog days of summer"? (viewed 67134 times)
  159. What kinds of jobs do astronomers do? (viewed 65933 times)
  160. Does quantum entanglement imply faster than light communication? (viewed 65770 times)
  161. If the universe is infinite does that mean there is an infinite number of "me"s? (viewed 64834 times)
  162. What are black holes made of? (viewed 64085 times)
  163. How did the stars get named? (viewed 63962 times)
  164. Where does the name "Moon" come from? (viewed 63793 times)
  165. What causes seasons? (viewed 63689 times)
  166. How long would it take the Earth to fall into the Sun? (viewed 63636 times)
  167. Why doesn't the earliest sunset occur on the shortest day of the year? (viewed 63471 times)
  168. Where did the matter in the universe come from? (viewed 63312 times)
  169. How does light pollution affect astronomers? (viewed 63290 times)
  170. How do you measure the mass of a star? (viewed 63282 times)
  171. What are Altitude and Azimuth? (viewed 63211 times)
  172. How did asteroids form and what is the difference between an asteroid and a comet? (viewed 63077 times)
  173. When can I see the Moon through the hole in the Pantheon? (viewed 62961 times)
  174. Traveling at light speed, how long would it take to get to the nearest galaxy? (viewed 62872 times)
  175. How fast is the Universe expanding? (viewed 62782 times)
  176. Are there stars outside of galaxies? (viewed 62775 times)
  177. Why do planets not twinkle? (viewed 62028 times)
  178. What's the best college for astronomy? (viewed 62009 times)
  179. Where, in relation to the entire universe, is the Milky Way located? (viewed 61715 times)
  180. Why doesn't the length of each day change much around the solstices? (viewed 61395 times)
  181. What would happen to us if the sun went out for an hour? (viewed 61348 times)
  182. What's the difference between dark matter and dark energy? (viewed 60740 times)
  183. What is the mass of the Universe? (viewed 60476 times)
  184. Why does the Sun's apparent path through the sky change throughout the year? (viewed 59502 times)
  185. How can I calculate the position or path of the Sun for a given time and location? (viewed 59397 times)
  186. How does astronomy benefit humankind? (viewed 59097 times)
  187. Does the Moon rotate? (viewed 59007 times)
  188. Why does the Earth have only one moon? (viewed 58869 times)
  189. Could there be life in the galaxies nearest to the Milky Way? (viewed 58842 times)
  190. How does the parachute in a model rocket work? (viewed 58520 times)
  191. Can any galaxies be seen with the naked eye? (viewed 58430 times)
  192. What is the origin of spiral structure in galaxies? (viewed 58253 times)
  193. Why is looking out into space the same as looking back in time? (viewed 58164 times)
  194. How close was the Moon to the Earth when it formed? (viewed 58022 times)
  195. How long does the supernova stage of a star last? (viewed 57444 times)
  196. What makes up most of the Universe? (viewed 57355 times)
  197. What can we learn from the color of a star? (viewed 57220 times)
  198. What is the shape of the universe? (viewed 56609 times)
  199. Why isn't the summer solstice the hottest day of the year? (viewed 55953 times)
  200. What is the largest structure in the universe? (viewed 55808 times)
  201. How do astronauts use math in their jobs? (viewed 55719 times)
  202. What is a star's "spectrum"? (viewed 55506 times)
  203. Where are stars born? (viewed 55259 times)
  204. If gravity is a "curvature of space" rather than a force, why do a ball and bullet follow different paths? (viewed 55138 times)
  205. What is the size of a black hole? (viewed 55078 times)
  206. How do the astronauts communicate in space if sound cannot travel in a vacuum? (viewed 55008 times)
  207. Are names given to black holes? (viewed 54734 times)
  208. How do you calculate the azimuth and altitude of an object? (viewed 54643 times)
  209. How do we measure the size of the Moon and of the Sun? (viewed 54576 times)
  210. Which constellation does our Sun belong to? (viewed 54528 times)
  211. What happens to a bullet fired on the moon? (viewed 54345 times)
  212. Can you see satellites? (viewed 54325 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 54052 times)
  214. How can I find the distance to the Sun on any given day? (viewed 53503 times)
  215. What other careers involve Astronomy besides Astronomer? (viewed 53269 times)
  216. Why do we see stars? (viewed 53114 times)
  217. Are aliens or UFOs real? (viewed 52997 times)
  218. Which hemisphere has the best view of the Milky Way? (viewed 52786 times)
  219. How can I measure the distance of a star? (viewed 52745 times)
  220. Is the speed of light constant? (viewed 52270 times)
  221. Are there any asteroids on a collision course with Earth? (viewed 51900 times)
  222. Why is twilight short near the equator? (viewed 51839 times)
  223. Where did all the water in the universe come from? (viewed 51822 times)
  224. What are some astronomy science fair projects? (viewed 51743 times)
  225. Why is the sky blue and not blue & purple? (viewed 51692 times)
  226. How long has there been water on Earth? (viewed 51689 times)
  227. Are meteorites hot or cold when they hit Earth? (viewed 51513 times)
  228. What would happen if the Moon fell out of its orbit around Earth? (viewed 51285 times)
  229. What do a galaxy's colors mean? Are they its true colors? (viewed 51125 times)
  230. Would your weight change as you go underground? (viewed 51048 times)
  231. Is time travel possible? (viewed 50743 times)
  232. Can we look back far enough in time to see the Big Bang? (viewed 50612 times)
  233. Who discovered each planet? (viewed 50505 times)
  234. Why does the Moon look big on the horizon? (viewed 50475 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 50198 times)
  236. What skills do astronomers need? (viewed 49833 times)
  237. How is the time of sunrise calculated? (viewed 49667 times)
  238. Why is it difficult to understand the expansion of the universe? (viewed 49643 times)
  239. What is the difference between nutation and precession of the Earth? (viewed 49592 times)
  240. Are the planes of solar systems aligned with the plane of the Galaxy? (viewed 49539 times)
  241. What is a graviton? (viewed 49127 times)
  242. What's the difference between astronomy and astrophysics? (viewed 49107 times)
  243. How do we know what other planets (and stars, galaxies, etc.) are made of? (viewed 48924 times)
  244. If light has no mass, then what draws it into a black hole? (viewed 48656 times)
  245. Why do the size and brightness of the full moon change? (viewed 47121 times)
  246. What do I need to do to become an astronomer? (viewed 47106 times)
  247. Do supermassive black holes cause galaxy rotation? (viewed 46883 times)
  248. How do gravitons escape black holes to tell the universe about their gravity? (viewed 46764 times)
  249. Do dead stars still shine? (viewed 46702 times)
  250. Why are most months 30 or 31 days long? (viewed 46484 times)
  251. What is a wormhole? (viewed 46448 times)
  252. Why does the Sun appear larger on the horizon than overhead? (viewed 46382 times)
  253. How are black holes discovered? (viewed 46371 times)
  254. Can we find the place where the Big Bang happened? (viewed 46104 times)
  255. The Moon slows the Earth's rotation, but how fast was it spinning billions of years ago? (viewed 45901 times)
  256. Will we get sucked into the black hole at the center of the Milky Way? (viewed 45555 times)
  257. Where is the nearest black hole? (viewed 45532 times)
  258. Why are there stars? (viewed 45473 times)
  259. Is the Earth slowly getting larger? (viewed 45455 times)
  260. Why can't we see Venus at night when it is an inner planet? (viewed 45408 times)
  261. How do galaxies collide in an expanding universe? (viewed 45180 times)
  262. Can I calculate the size of the Universe by converting light years to kilometres? (viewed 44910 times)
  263. Can the acceleration of the Universe be analogous to apparent acceleration in a airplane? (viewed 44896 times)
  264. Why does Barnard 68 appear dark? (viewed 44471 times)
  265. Why don't people walk upside-down on the bottom of the Earth? (viewed 44437 times)
  266. Are Kuiper Belt Objects asteroids? Are large Kuiper Belt Objects planets? (viewed 44116 times)
  267. Did life originate on Earth, or did it come from somewhere else? (viewed 43966 times)
  268. Are there eclipses on other planets? (viewed 43474 times)
  269. What is the best way to see the Milky Way? (viewed 43164 times)
  270. Could the Universe have expanded faster than the speed of light at the Big Bang? (viewed 43049 times)
  271. Is there a "South Star"? (viewed 43048 times)
  272. How does Astronomy involve Chemistry? (viewed 43046 times)
  273. Why does the location of sunrise change? (viewed 42915 times)
  274. Has there been an experiment that measured speed faster than the speed of light in vacuum? (viewed 42862 times)
  275. What is the difference between the "Doppler" redshift and the "gravitational" or "cosmological" redshift? (viewed 42734 times)
  276. How long could life on Earth survive if the Sun stopped shining? (viewed 42704 times)
  277. Was the Sun made in a supernova? (viewed 42661 times)
  278. What is the biggest crater recorded on Earth? (viewed 42580 times)
  279. How much can the location of sunset differ from due West? (viewed 42469 times)
  280. How would the weather on Earth be different if it were a cube? (viewed 42420 times)
  281. Why doesn't dark matter fall into a black hole? (viewed 42281 times)
  282. How much longer will the Earth last? (viewed 42227 times)
  283. What happens to spacetime inside a black hole? (viewed 41914 times)
  284. Can I buy land on the Moon? (viewed 41602 times)
  285. Why does the Earth only see one side of the Moon? (viewed 41503 times)
  286. Is the Moon hollow? (viewed 41364 times)
  287. What happens when two black holes get too close? (viewed 41309 times)
  288. What are the names of the three stars in Orion's belt? (viewed 41231 times)
  289. What's the biggest meteorite? (viewed 40904 times)
  290. What color would Mars be if you were standing on it? (viewed 40855 times)
  291. What is time dilation? (viewed 40847 times)
  292. What if the Earth rotated twice as fast? (viewed 40756 times)
  293. What is the most distant known galaxy? (viewed 40601 times)
  294. How can two moons of Saturn share the same orbit? (viewed 40437 times)
  295. Why do people draw stars with five points? (viewed 40241 times)
  296. Could someone travel the universe in his or her own lifetime? (viewed 40184 times)
  297. How do we feel heat? (viewed 40163 times)
  298. Can terrestrial planets have rings? (viewed 39984 times)
  299. Is it possible to see the full Moon and the Sun simultaneously in high northern latitudes when the Sun doesn't set? (viewed 39979 times)
  300. Why can we see the sun's image before sunrise and after sunset? (viewed 39784 times)
  301. How long would it take for a mini-black hole to eat the Earth? (viewed 39709 times)
  302. What are "blue stragglers" in globular clusters? (viewed 39609 times)
  303. How many Astronauts have been in space? (viewed 39593 times)
  304. How fast does the Earth go at perihelion and aphelion? (viewed 39252 times)
  305. Why do pictures of distant galaxies have higher resolution than those of nearby planets? (viewed 39157 times)
  306. How do we know that nuclear fusion is still going on in the Sun? (viewed 39156 times)
  307. What is the typical size of a visible shooting star? (viewed 38923 times)
  308. If a white dwarf is a "dead" star, why is it so hot? (viewed 38899 times)
  309. Is the Sun always up for exactly 12 hours at the equator? (viewed 38875 times)
  310. Does the Sun have an iron surface? (viewed 38815 times)
  311. Do you think it's possible to maintain life on other planets? (viewed 38769 times)
  312. Why are Saturn's rings flat? (viewed 38666 times)
  313. Is the Great Wall the largest galaxy cluster? (viewed 38644 times)
  314. Does Mt. Everest cast a shadow on the moon? (viewed 38620 times)
  315. Why do clocks turn in the opposite direction from the Earth and Moon? (viewed 38552 times)
  316. On which days can I see the Moon in the evening / morning and why is this so? (viewed 38424 times)
  317. How does night and day work? (viewed 38422 times)
  318. What is a dimension? (viewed 38408 times)
  319. Can you see the future as you fall into a black hole? (viewed 38370 times)
  320. Who (and when) discovered that the earth's axis is on a 23 degree tilt? (viewed 38306 times)
  321. Can a person go into a black hole and come out alive? (viewed 38215 times)
  322. Where do planetary rings come from, and what are they made of? (viewed 38055 times)
  323. Can I communicate faster than light? (viewed 38034 times)
  324. What is the speed of gravity? (viewed 37855 times)
  325. Are all stars the same? (viewed 37752 times)
  326. What is Earthrise over the Moon? (viewed 37726 times)
  327. What companies or businesses can astronomers work for? (viewed 37636 times)
  328. How do we define distance in an expanding universe? (viewed 37529 times)
  329. How do we determine the age of the universe? (viewed 37526 times)
  330. What is the approximate GPA needed in High School in Math and Science to be an astronomer? (viewed 37512 times)
  331. Where is the supernova remnant that led to our solar system? (viewed 37508 times)
  332. What can I use for fuel in my homemade rocket? (viewed 37465 times)
  333. How big is the universe? (viewed 37436 times)
  334. Is there really a 10th planet? (viewed 37130 times)
  335. Why is sea water salty, and not lake water? (viewed 37127 times)
  336. Is there a beginning and an end to a galaxy's life? (viewed 36907 times)
  337. How can the universe be "flat"? We're 3D! (viewed 36839 times)
  338. Does the Coriolis force determine which way my toilet drains? Does it affect black holes? (viewed 36763 times)
  339. If the universe is 15 billion years old, how can it be larger than 15 billion light years across? (viewed 36751 times)
  340. What would happen to the Earth if an asteroid hit the Moon? (viewed 36606 times)
  341. How do we know the Milky Way is a spiral galaxy? (viewed 36564 times)
  342. How many stars can I see? (viewed 36549 times)
  343. How are photons created and destroyed? (viewed 36491 times)
  344. How do I tell which planet is which? (viewed 36396 times)
  345. Why are there blue shifted galaxies? (viewed 35954 times)
  346. Do the Sun's or Earth's magnetic field reverse? (viewed 35951 times)
  347. How can I find my age on another planet? (viewed 35736 times)
  348. Can a lunar and a solar eclipse happen in the same month? When will this happen next? (viewed 35516 times)
  349. Is Andromeda part of the Milky Way? Where can I find them in the sky? (viewed 35357 times)
  350. Why have star signs shifted by one constellation? (viewed 35332 times)
  351. How are planets detected around other stars? (viewed 35294 times)
  352. How does the brightness of a star depend on its distance from us? (viewed 35230 times)
  353. Why do humans want to go in space? (viewed 35228 times)
  354. What is the pattern to the distances between each planet and the sun? (viewed 35202 times)
  355. What kind of eyepieces do I need to look at planets? (viewed 35181 times)
  356. Will we ever stop having solar eclipses because of the moon's motion away from the Earth? (viewed 35054 times)
  357. Why can't a plane fly slowly and let the Earth pass underneath? (viewed 34981 times)
  358. What is the significance of the second focus of elliptical orbits of planets in our Solar System? (viewed 34956 times)
  359. Who came up with the name "black hole"? (viewed 34707 times)
  360. What was that really big falling star that I saw? (viewed 34691 times)
  361. What would happen if two stars collided? (viewed 34639 times)
  362. How can we estimate the number of Earth-like planets in the Galaxy? (viewed 34638 times)
  363. How do astronauts communicate with their families from space? (viewed 34609 times)
  364. Is there a simple formula to calculate solar eclipse timings from any position on Earth? (viewed 34383 times)
  365. Is the Earth at the centre of the Universe? (viewed 34352 times)
  366. When we look back to the Big Bang, why don't we see the universe as a tiny speck of matter? (viewed 34279 times)
  367. How hot is each one of the layers of the sun? (viewed 34194 times)
  368. How is it that we see farther out in space (farther back in time) than in the past? (viewed 34161 times)
  369. Why don't astronomers use everyday units to measure distances (what is an AU or a pc)? (viewed 34149 times)
  370. Can you describe a day on the job as an astronomer? (viewed 34039 times)
  371. Will the Moon be invisible in 500 million years? (viewed 33894 times)
  372. How do I become both an astronaut and an astronomer? (viewed 33828 times)
  373. Are Earth and the Moon "twin planets"? (viewed 33524 times)
  374. Why is our solar system so different from all the others we've found? (viewed 33467 times)
  375. How dangerous are the asteroids? (viewed 33462 times)
  376. Which American colleges teach astronomy? (viewed 33417 times)
  377. Is the Local Group expanding along with the entire Universe? (viewed 33356 times)
  378. Why is Uranus tipped on its side? (viewed 33351 times)
  379. How do sunrise and sunset times change with altitude? (viewed 33205 times)
  380. Can we colonize other planets? (viewed 33075 times)
  381. Why do constellations look the same after several years even though all the stars are moving? (viewed 32774 times)
  382. Is it true that the Sun burns off a billion tons of gas every 5 seconds? (viewed 32564 times)
  383. Is the universe really like an expanding balloon? (viewed 32535 times)
  384. Why are there no craters on Earth? Did all the meteorites miss us? (viewed 32519 times)
  385. What are quasars made of? (viewed 32400 times)
  386. Why do astronauts in space need to exercise? (viewed 32398 times)
  387. How can I calculate distances between stars? (viewed 32378 times)
  388. Is the gravitational force exerted by the Earth on the Moon equal to the centripetal force acting on the Moon? (viewed 32334 times)
  389. Can superheavy elements (such as Z=116 or 118) be formed in a supernova? Can we observe them? (viewed 32115 times)
  390. Why doesn't gravity change the speed of light? (viewed 32108 times)
  391. What is dark matter? (viewed 31986 times)
  392. Is it possible to count the stars? (viewed 31812 times)
  393. Is time travel possible using merging black holes? (viewed 31664 times)
  394. How big a change in the Earth's orbit would be required to destroy all life? (viewed 31617 times)
  395. What is happening just around the black hole in the center of the Milky Way? (viewed 31574 times)
  396. Did the speed of light change over the history of the universe? (viewed 31482 times)
  397. Can we see dead stars with the naked eye? (viewed 31480 times)
  398. How do we measure distances to other stars? (viewed 31388 times)
  399. How can we distinguish a star's "real" color from the change in color that we observe due to the star's motion? (viewed 31368 times)
  400. How do I make a scale model of the Solar System? (viewed 31278 times)
  401. Why is the time between two successive full moons different from the lunar synodic month? (viewed 31233 times)
  402. What happens when an antimatter black hole collides with a matter blackhole? (viewed 31147 times)
  403. Are time machines possible? (viewed 30977 times)
  404. How many moles of stars are in the known universe? (viewed 30768 times)
  405. How can we tell what the interiors of planets are like? (viewed 30700 times)
  406. Does the Milky Way spin counter-clockwise? If so, do all spiral galaxies spin in this direction and why? (viewed 30594 times)
  407. How are galaxy distances inferred from their recessional velocities? (viewed 30583 times)
  408. What would happen if a human were exposed to space without wearing a spacesuit? (viewed 30524 times)
  409. What happens when you change the mass of a White Dwarf or Neutron Star? (viewed 30508 times)
  410. What do "homogeneity" and "isotropy" mean? (viewed 30456 times)
  411. Do we see the same stars from above and below the equator? (viewed 30424 times)
  412. What is the farthest in space that we have gone? (viewed 30252 times)
  413. Is there any limitation to what a black hole can "suck" in? (viewed 30116 times)
  414. Will the seasons change due to precession? (viewed 30089 times)
  415. Can astronauts produce water in space? (viewed 29977 times)
  416. How can we know that there are other galaxies if we cannot leave ours? (viewed 29970 times)
  417. How was the starting point for the Julian Date system chosen? (viewed 29913 times)
  418. What are the closest and/or brightest stars? (viewed 29896 times)
  419. Aren't jobs in astronomy scarce? (viewed 29805 times)
  420. How can I tell if the rock I found is a meteorite? (viewed 29776 times)
  421. What's that dark spot on the Sun? (viewed 29762 times)
  422. How do we know if the universe will keep expanding forever? (viewed 29733 times)
  423. Why does the SETI project search for radio signals? (viewed 29591 times)
  424. Do astronomers believe in astrology? (viewed 29570 times)
  425. How long does it take the Big Dipper to move in the sky? (viewed 29564 times)
  426. Did I see the Aurora Borealis as a child? (viewed 29467 times)
  427. Why do we study black holes? (viewed 29437 times)
  428. Why do most moons orbit their planets at the equator? (viewed 29320 times)
  429. When are there 5 Sundays in February? (viewed 29285 times)
  430. What are the facts about the Star of Bethlehem? (viewed 29269 times)
  431. Don't tachyons travel faster than light? (viewed 29202 times)
  432. Wouldn't the Big Bang theory be considered a hypothesis and not a theory? (viewed 29156 times)
  433. What are the atmospheres of Mars and Pluto like? (viewed 29142 times)
  434. Could an astronaut or satellite fall into a black hole that we didn't know about? (viewed 29103 times)
  435. Do you believe in UFOs? (viewed 29036 times)
  436. Can you use an infinite line of reflectors to send light to the edge of the Universe? (viewed 28966 times)
  437. What does the term "visible universe" mean? (viewed 28828 times)
  438. Could you tell me about the life cycle of galaxies? (viewed 28785 times)
  439. What colors are visible through an amateur telescope? (viewed 28727 times)
  440. Has anyone made a map of the Milky Way? (viewed 28646 times)
  441. Was I hit by a meteorite? (viewed 28640 times)
  442. How are galaxies named? (viewed 28622 times)
  443. How can geometry be different in space? (viewed 28581 times)
  444. Does the Moon look different in the northern and southern hemispheres? (viewed 28552 times)
  445. Why are the compositions of comets and asteroids different? (viewed 28388 times)
  446. Why do so many of the world's UFO sightings happen in America? (viewed 28330 times)
  447. What's the best thing about being an astronomer? (viewed 28221 times)
  448. Can two lunar eclipses occur in the same month? (viewed 28135 times)
  449. How do asteroids, meteors and comets disappear? (viewed 28051 times)
  450. How do astronomers measure the radius of a star? (viewed 28025 times)
  451. How much time do astronomers spend looking through telescopes? (viewed 27862 times)
  452. What is the origin of the stellar classification system "OBAFGKM"? (viewed 27780 times)
  453. Will winter and summer constellations change due to abnormal warmth or cold on Earth? (viewed 27742 times)
  454. How can we see galaxies if their stars are so faint? (viewed 27674 times)
  455. How do I explain to my children why the Moon has phases? (viewed 27643 times)
  456. How will the two black holes that are going to collide affect Earth? (viewed 27575 times)
  457. Have there been other Big Bangs before? (viewed 27567 times)
  458. How are galaxies and solar systems similar? (viewed 27529 times)
  459. Is there a project I can do on black holes? (viewed 27304 times)
  460. How close do you have to come to the Earth to be influenced by its gravity? (viewed 27297 times)
  461. Can life exist on the recently discovered extrasolar planets? (viewed 27293 times)
  462. Do the magnitudes and colors of stars ever change? (viewed 27229 times)
  463. Is the Milky Way a collision of two galaxies? (viewed 27192 times)
  464. How can we measure distances to more stars? (viewed 27128 times)
  465. Do asteroids hit the sun? (viewed 27106 times)
  466. Could you escape from a black hole if you were able to go faster than the speed of light? (viewed 27054 times)
  467. How do scientists slow light down? (viewed 27032 times)
  468. Is infinite temperature possible? (viewed 26843 times)
  469. How close does a supernova need to be to damage the Earth's environment? (viewed 26829 times)
  470. Is it worthwhile to continue the search for extraterrestrial life? (viewed 26775 times)
  471. What supernova created the Crab nebula? (viewed 26772 times)
  472. Do we know everything about the Sun? (viewed 26756 times)
  473. Can "tired light theory" explain the observed redshifts of galaxies? (viewed 26753 times)
  474. Can double stars have planets? (viewed 26694 times)
  475. What causes gamma ray bursts? (viewed 26625 times)
  476. Can one star orbit another? (viewed 26585 times)
  477. Can a human give birth in space? (viewed 26537 times)
  478. How far does a galaxy extend? (viewed 26443 times)
  479. Is there oxygen in the atmospheres of other planets? (viewed 26406 times)
  480. Which part of the sky did the famous 'wow' signal originate from? (viewed 26346 times)
  481. What will happen to the Milky Way in the future? (viewed 26304 times)
  482. Can astronauts play musical instruments in space? (viewed 26276 times)
  483. How do I polar align my telescope? (viewed 26269 times)
  484. What is sidereal time? (viewed 26206 times)
  485. Which way does the sun travel in the southern hemisphere? (viewed 26183 times)
  486. What type of energy does a black hole have? (viewed 26155 times)
  487. What is the farthest Northern Latitude in which the Magellanic Clouds can be seen? (viewed 26124 times)
  488. Is there such a thing as hyperspace? (viewed 26123 times)
  489. Why did the Pioneer and Voyager take only 2 years to reach Jupiter, while Galileo and Cassini took more than 5 years? (viewed 26101 times)
  490. What happens to the material that has been sucked into a black hole? (viewed 26064 times)
  491. What is a Cepheid variable? (viewed 26039 times)
  492. What is "nothing", from a scientific point of view? (viewed 26014 times)
  493. Is there sound coming from the Sun? (viewed 26007 times)
  494. Why do the explosions of Type Ia supernovae have a more predictable spectrum than those of regular Type II supernovae? (viewed 25990 times)
  495. What's the object I saw that moved across the sky and then got very bright? (viewed 25969 times)
  496. How different would the night sky have looked in 40,000 B.C.? (viewed 25957 times)
  497. When did people discover that the Sun is a star? (viewed 25886 times)
  498. How will a change in the speed of light affect the evolution of the Universe? (viewed 25860 times)
  499. Are planetary nebulae the result of supernovae? (viewed 25706 times)
  500. Why is the shadow on the Moon the shape it is? (viewed 25692 times)
  501. Why do we assume that the universe is homogeneous? (viewed 25665 times)
  502. How do we know what parameters to use when simulating the collision of the Milky Way and Andromeda? (viewed 25593 times)
  503. How do we know that sunspots are associated with the Sun's magnetic field? (viewed 25556 times)
  504. When unmanned spacecraft accelerate in space, what causes them to slow down? (viewed 25550 times)
  505. If we invented special suits could we ever go to the sun? (viewed 25550 times)
  506. What is the difference between homogeneity and isotropy? (viewed 25432 times)
  507. What calculations go into predicting eclipses? (viewed 25421 times)
  508. Are there any dark stars or dark galaxies made of dark matter? (viewed 25409 times)
  509. What is our galaxy's halo made of, and how was it formed? (viewed 25406 times)
  510. Was Stonehenge built to mark solar phenomena? (viewed 25278 times)
  511. Can I see a quasar? (viewed 25256 times)
  512. Is there a list of the sizes of different kinds of stars? (viewed 25219 times)
  513. How many sunspots can the Sun have at once? (viewed 25194 times)
  514. What process would bring about a quark star? (viewed 25181 times)
  515. How are asteroid compositions and classifications determined? (viewed 25171 times)
  516. What's so exciting about the new planet around 55 Cancri? (viewed 25088 times)
  517. Can any comparison be made between spiral galaxies and hurricanes? (viewed 25080 times)
  518. Can I see details on Venus? (viewed 25067 times)
  519. Did a giant impact cause the Dark Ages? (viewed 25067 times)
  520. What is a Dyson Sphere? (viewed 25003 times)
  521. Why are there more maria on the near side of the Moon? (viewed 24985 times)
  522. Have gravitational waves been proven to exist? (viewed 24981 times)
  523. What happened to the girl who named Pluto? (viewed 24941 times)
  524. What happened to all the black holes that were around in the early universe? (viewed 24845 times)
  525. Would the biggest airplanes cause tsunamis if they crashed? (viewed 24842 times)
  526. What equipment do I need for astrophotography? (viewed 24833 times)
  527. How is it proved that the Universe is expanding? (viewed 24785 times)
  528. Why are telescopes kept in cold conditions? (viewed 24772 times)
  529. Does Cerenkov radiation travel faster than light? (viewed 24724 times)
  530. How big is the Hubble Ultra Deep Field image? (viewed 24719 times)
  531. Why are there active volcanos on Io? (viewed 24706 times)
  532. Is there any possibility that the Solar System or the Universe is in a black hole? (viewed 24621 times)
  533. If clocks run slow in a gravitational field, how can we know the true age of the Solar System and Universe? (viewed 24481 times)
  534. If the Universe was infinitely dense at the Big Bang, why didn't time stand still? (viewed 24417 times)
  535. How can we compare dark matter and dark energy? (viewed 24408 times)
  536. How big was the Sun when it first "fired up"? (viewed 24386 times)
  537. How long do supernova remnants last? (viewed 24332 times)
  538. What caused Shoemaker-Levy 9 to split up? (viewed 24265 times)
  539. Why do photos of space taken from space never show any stars? (viewed 24230 times)
  540. Could we send a space mission to a comet? (viewed 24230 times)
  541. How do solar flares affect airline pilots? (viewed 24218 times)
  542. Can you give me advice on buying a telescope? (viewed 24155 times)
  543. Why doesn't light from distant galaxies reach us instantaneously? (viewed 24136 times)
  544. How are sunspots formed? (viewed 24082 times)
  545. Could we be seeing dead stars? (viewed 24018 times)
  546. How does the Earth compare in size to the entire universe at the present epoch? (viewed 23996 times)
  547. Could a different theory of gravity explain the dark matter mystery? (viewed 23976 times)
  548. Can I build an instrument to measure the size of the Sun and of the Moon? (viewed 23919 times)
  549. Why doesn't NASA build rotating spacecraft to simulate gravity? (viewed 23917 times)
  550. Where does the kinetic energy of infalling bodies come from? (viewed 23904 times)
  551. Why is it important to study meteorites? (viewed 23894 times)
  552. How can I contribute to science as an amateur astronomer? (viewed 23893 times)
  553. As the universe expands, why don't galaxies get stretched out? (viewed 23879 times)
  554. How many comets are currently orbiting our sun? (viewed 23813 times)
  555. Can you tell time by the Big Dipper? (viewed 23728 times)
  556. Why are telescopes located in remote places? (viewed 23727 times)
  557. Did I really hear a meteor? (viewed 23713 times)
  558. Why is the Hubble Space Telescope in space? (viewed 23700 times)
  559. Are the asteroids the remains of a planet which broke apart? (viewed 23645 times)
  560. How do unmanned space probes avoid running into things? (viewed 23611 times)
  561. How do we know that superclusters are the largest structures in the universe? (viewed 23584 times)
  562. How powerful are quasars? (viewed 23543 times)
  563. Would extraterrestrial civilizations know that there is life on Earth? (viewed 23533 times)
  564. How is the Cepheid yardstick validated? (viewed 23474 times)
  565. Do the Earth's magnetic poles ever change places? (viewed 23414 times)
  566. Do unmanned spacecraft like Voyager travel in straight lines? (viewed 23392 times)
  567. Did time go slower just after the Big Bang? (viewed 23351 times)
  568. Can supernovae hinder the formation of life in galaxies? (viewed 23307 times)
  569. Why are stars of different masses? (viewed 23286 times)
  570. Are there any new craters on the moon? (viewed 23282 times)
  571. Do galaxies orbit around anything? (viewed 23273 times)
  572. What would happen if there was a collision between two white dwarfs? (viewed 23242 times)
  573. What kind of instruments are used to detect extrasolar planets? (viewed 23228 times)
  574. How could galaxies have gotten so far away in only 15 billion years? (viewed 23212 times)
  575. Why can't relative velocities add up to more than the speed of light? (viewed 23208 times)
  576. How do I become an astronomical artist? (viewed 23187 times)
  577. Do similar laws of physics throughout the Universe imply that all life must be like life on Earth? (viewed 23173 times)
  578. How do planets capture satellites? (viewed 23157 times)
  579. Could there have been multiple Big Bangs at different places in the universe? (viewed 23060 times)
  580. How are astronomy and poetry linked? (viewed 23056 times)
  581. What kind of telescope should I use for astrophotography? (viewed 23013 times)
  582. Could dark energy come from matter anti-matter pairs forming spontaneously and then annihilating? (viewed 22914 times)
  583. Why is NASA shutting down the Hubble Space Telescope? (viewed 22830 times)
  584. Can I listen to the SETI@home radio signal? (viewed 22809 times)
  585. How can you tell if a crescent moon is preceding or following a new-moon phase? (viewed 22764 times)
  586. Does the Sun have any heavy elements? (viewed 22707 times)
  587. Are the properties of extrasolar planets known? (viewed 22616 times)
  588. What class of spiral galaxy is the Milky Way? (viewed 22577 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 22567 times)
  590. Can the theory of formation of the solar system explain all the observables? (viewed 22553 times)
  591. Will we discover an 11th planet? What would it be called? (viewed 22531 times)
  592. How do astronomers observe the Sun's interior? (viewed 22516 times)
  593. What month was it when Odysseus saw Orion in 1000BC? (viewed 22412 times)
  594. Where was the water in the big bang? (viewed 22201 times)
  595. What makes a satellite geosyncronise itself with Earth's orbit? (viewed 22177 times)
  596. Is it possible for amateurs to do optical interferometry? (viewed 22148 times)
  597. Why does the apparent density of galaxies drop off at larger distances? (viewed 22130 times)
  598. Why does one side of Mars look more catastrophic than the other? (viewed 22123 times)
  599. Could we send a manned mission to the outer planets? (viewed 22103 times)
  600. Would a planet near the galactic center have a brighter night sky? (viewed 22046 times)
  601. How can water be chemically trapped in rocks? (viewed 21923 times)
  602. Do stars' orbits in galaxies obey Kepler's Laws? (viewed 21898 times)
  603. Why do spacecraft need heat shields coming back to Earth but not leaving? (viewed 21833 times)
  604. What is the solar cycle? (viewed 21788 times)
  605. Can other terrestrial moons be (or have been) stable? (viewed 21752 times)
  606. Why was the Platonic year named after Plato? (viewed 21746 times)
  607. Why are accretion disks flat? (viewed 21681 times)
  608. How are supernovae discovered? (viewed 21649 times)
  609. What would the Big Crunch look like to an observer on Earth? (viewed 21644 times)
  610. Can a black hole come back to the visual universe through a "little bang"? (viewed 21543 times)
  611. What is meant by "stopping down a telescope"? (viewed 21537 times)
  612. Does inflation allow for an infinite number of universes? (viewed 21504 times)
  613. Could our position in the universe affect our perceptions of the expansion? (viewed 21442 times)
  614. Why doesn't the hydrogen on Jupiter explode? (viewed 21442 times)
  615. How can the Sun have such a strong gravitational field if it's made of gasses? (viewed 21415 times)
  616. Did I find a rock that came from the Moon? (viewed 21209 times)
  617. Have astronomers observed any phenomena that could be produced by extraterrestrial civilizations? (viewed 21201 times)
  618. What is the SU(3) quark model? (viewed 21169 times)
  619. Can gravitational lensing from intervening galaxies cause the observed ripples in the Cosmic Microwave Background? (viewed 21135 times)
  620. Does a photon observe other photons moving past it at the speed of light? (viewed 21060 times)
  621. Will I be able to see the shadow of the Moon streaking towards me in a total solar eclipse? (viewed 21013 times)
  622. What's new with the Big Bang? (viewed 20847 times)
  623. Could photons be dark matter? (viewed 20813 times)
  624. How can we find galaxies behind the Milky Way? (viewed 20810 times)
  625. How fast do particles travel in space? (viewed 20754 times)
  626. Is it possible to build a cheap device to measure declination? (viewed 20723 times)
  627. Why can we have solar eclipses? (viewed 20721 times)
  628. Why search for only Earth-like life on other planets? (viewed 20702 times)
  629. Why is the WMAP picture of the CMB an ellipse? (viewed 20702 times)
  630. If comets are boiling away, why are there any left? (viewed 20660 times)
  631. Where can I find information on the moons of other planets? (viewed 20635 times)
  632. Why do some eclipses take longer than others? (viewed 20593 times)
  633. How much power is contained in a beam of light? (viewed 20572 times)
  634. Can planets collide with one another? (viewed 20465 times)
  635. Why is pressure broadening greater in low mass stars than in high mass stars? (viewed 20441 times)
  636. Do constellations looks the same from space? (viewed 20424 times)
  637. What are the boundaries of the constellations? (viewed 20337 times)
  638. What would an "open geometry" for the universe look like? (viewed 20311 times)
  639. Did the Sumerians measure precession? (viewed 20296 times)
  640. What kinds of star clusters are there? (viewed 20201 times)
  641. Why is the Cosmic Microwave Background not absorbed by interstellar hydrogen? (viewed 20096 times)
  642. Why aren't discoveries of extrasolar planets reported on the news? (viewed 20085 times)
  643. How do astronomers come up with their facts? (viewed 20084 times)
  644. Why don't astronauts sublimate in space? (viewed 20068 times)
  645. How do photons from distant objects maintain enough energy to reach us? (viewed 20068 times)
  646. How do bars form in spiral galaxies? (viewed 20056 times)
  647. How did Mars get so dusty? (viewed 20001 times)
  648. What are collections of galaxies called? (viewed 19970 times)
  649. Can HST see the Oort cloud? (viewed 19912 times)
  650. Do electrons age? (viewed 19899 times)
  651. Can we make a movie of the Milky Way galaxy's rotation? (viewed 19804 times)
  652. Can the Space Shuttle abort and return to Earth before reaching orbit? (viewed 19761 times)
  653. How long is twilight on the Moon? (viewed 19754 times)
  654. Will astronauts ever be able to go ice-skating on Europa? (viewed 19664 times)
  655. How does melting a material reset its radioactive clock? (viewed 19640 times)
  656. Does the shuttle worry about space junk? (viewed 19614 times)
  657. Why do supernova remnants look like rings rather than spheres? (viewed 19547 times)
  658. Where can I see Newton's original reflecting telescope? (viewed 19546 times)
  659. Why don't all neutron stars become pulsars? (viewed 19539 times)
  660. How do you classify galaxies? (viewed 19522 times)
  661. How can we understand the meaning of large numbers like "a million million?" (viewed 19439 times)
  662. What is the best time of the year to see eclipses? (viewed 19392 times)
  663. If photons have zero mass, why do they feel the effects of gravity? (viewed 19379 times)
  664. Why doesn't SETI concentrate its observations to the nearby stars and the solar systems that we are discovering? (viewed 19374 times)
  665. What causes a particle to decay? (viewed 19321 times)
  666. Will the next generation telescope OWL be able to detect an Earth like extrasolar planet? (viewed 19289 times)
  667. Why is it called astronomy when all the other sciences end in -ology? (viewed 19223 times)
  668. How can I nominate myself for a Nobel Prize in Physics? (viewed 19180 times)
  669. How does the color index of a star relate to its actual color? (viewed 19151 times)
  670. How long has humanity known that we live in a galaxy similar to others in the Universe? (viewed 19143 times)
  671. Will the Leonid meteor shower go away? (viewed 19110 times)
  672. What are "curled" dimensions? (viewed 19006 times)
  673. Is light of different colors affected differently by gravity? (viewed 18922 times)
  674. If nothing can escape a black hole, why do some black holes have jets? (viewed 18886 times)
  675. How does interferometry work? (viewed 18848 times)
  676. What was that eclipse I saw in the sky? (viewed 18819 times)
  677. Do asteroids ever do anything good in the Solar System? (viewed 18809 times)
  678. How do distant galaxies differ from those nearby? (viewed 18772 times)
  679. Does the temperature of matter increase as it is accelerated to relativistic speeds? (viewed 18764 times)
  680. What would happen if you went back in time and killed your grandmother? (viewed 18738 times)
  681. Are black holes spherical? (viewed 18736 times)
  682. What kind of interference must astronomers contend with when observing? (viewed 18726 times)
  683. How do we find out about the star formation histories of galaxies? (viewed 18687 times)
  684. Wouldn't the vast distances of space distort SETI signals into unintelligeble forms? (viewed 18683 times)
  685. Why will fusion wait until hydrogen is gone before starting to fuse heavier atoms? (viewed 18587 times)
  686. Can astronomers observe anything when the moon is full? (viewed 18584 times)
  687. How can I watch the Perseid meteor shower? (viewed 18546 times)
  688. What do stellar classifications mean? (viewed 18488 times)
  689. Do we really observe the edges of galaxies at different epochs? (viewed 18467 times)
  690. Can you tell me the characteristics of W, R, N and S type stars? (viewed 18424 times)
  691. How are astronauts trained for weightlessness? (viewed 18367 times)
  692. What is the three-body problem? (viewed 18344 times)
  693. Why aren't accretion disks around giant stars as hot as accretion disks around black holes? (viewed 18318 times)
  694. If the universe is "bounded" today, could it one day become "unbounded"? (viewed 18121 times)
  695. Will the diameter of a cluster of galaxies change with redshift? (viewed 18070 times)
  696. Is cosmic expansion happening on microscopic scales? (viewed 17936 times)
  697. How can I find out if the new moon has been sighted? (viewed 17745 times)
  698. When measuring the expansion of the universe, do astronomers consider that they're seeing how galaxies moved long ago, not today? (viewed 17637 times)
  699. Could neutrinos be dark matter? (viewed 17603 times)
  700. Do we have to worry about relativity when studying galactic objects? (viewed 17579 times)
  701. How do supernovae show us that the Universe's expansion is accelerating? (viewed 17436 times)
  702. Does lunar gardening really work? (viewed 17413 times)
  703. What kinds of cancer research have been done in space? (viewed 17412 times)
  704. How does a star take mass from another star? (viewed 17277 times)
  705. What happens to the helium formed in the sun? (viewed 17232 times)
  706. Could the Universe's dark matter be made up of black holes? (viewed 17178 times)
  707. How can you tell the difference between single and multiple extrasolar planets? (viewed 17070 times)
  708. What is Hot Dark Matter theory? (viewed 17026 times)
  709. Is it a coincidence that we can have total solar eclipses? Are there other planets which also have them? (viewed 16788 times)
  710. How do we know the density of some extrasolar planets? (viewed 16697 times)
  711. Is the green flash real? (viewed 16660 times)
  712. What is the photoelectric effect? Why can't multiple low-frequency photons free an electron? (viewed 16623 times)
  713. How does libration allow us to see more than 50% of the Moon? (viewed 16497 times)
  714. How can observations of the distant universe prove that the expansion is accelerating *now*? (viewed 16481 times)
  715. Is light blueshifted when it is gravitationally lensed? (viewed 16351 times)
  716. Do binary or triple star systems form together? (viewed 16303 times)
  717. No matter how fast the universe is expanding, shouldn't gravity eventually make it recollapse? (viewed 16268 times)
  718. What do meteorites tell us about life on other planets? (viewed 16064 times)
  719. What percent of the time can astronomers observe without interference from the Moon? (viewed 16033 times)
  720. Why is it easier to see a star if you look slightly to the side? (viewed 16020 times)
  721. Can we prove that the Moon isn't hollow? (viewed 15947 times)
  722. If the sun went out and our atmosphere froze solid, what color would it be? (viewed 15868 times)
  723. Could matter-anti-matter repulsion power the expansion of the universe? (viewed 15784 times)
  724. How has light from 13 billion years ago not passed us by? (viewed 15592 times)
  725. Why doesn't the ammonia and methane in Jupiter's atmosphere sink into the core? (viewed 15588 times)
  726. What time is sunrise/sunset or moonrise/moonset at my location? (viewed 15533 times)
  727. How do we detect incoming meteorites? (viewed 15508 times)
  728. Are there any 'lonely galaxies'? (viewed 15395 times)
  729. What was different on Mars in the past to allow liquid water to be present? (viewed 15376 times)
  730. When will Hale-Bopp return? (viewed 15334 times)
  731. Why don't skydivers burn up like meteors? (viewed 15258 times)
  732. Has anyone ever seen a star "turn on"? (viewed 15063 times)
  733. Why are craters round? (viewed 14689 times)
  734. During close approaches, can Mars appear in our sky as large as the Moon? (viewed 14650 times)
  735. 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 14628 times)
  736. How are planets affected by the Hot Ionised Medium? (viewed 14457 times)
  737. Can the sun rise from the west on Mars? (viewed 14238 times)
  738. What are the largest radio wavelengths observed from radio sources in the sky? (viewed 14036 times)
  739. Why was Mir burnt up in the atmosphere? (viewed 13996 times)
  740. How can we discern different galaxies/clusters along the same line of sight? (viewed 13899 times)
  741. What is the relationship between the width of a star trail on a photo and the star's intensity? (viewed 13467 times)
  742. Can we harvest H & O from space to make water? (viewed 13276 times)
  743. Why does Titan, in spite of being smaller than Mars, have an atmosphere more dense than Earth's? (viewed 12919 times)
  744. What is between the Oort cloud and the closest star? (viewed 12753 times)
  745. Could a planetary system survive if its star merged with another, or if its star went supernova? (viewed 11921 times)
  746. Are there solar tides? (viewed 11839 times)
  747. What happens to the Earth as the moon gets farther away and will it ever go away entirely? (viewed 11683 times)
  748. Does weightlessness affect hunger? (viewed 11632 times)
  749. Is Earth-moon tidal friction causing global warming? (viewed 11427 times)
  750. Do planets radiate noise? (viewed 11204 times)
  751. Is the moon spherical? (viewed 11138 times)
  752. Is dark energy affected by black holes? (viewed 10897 times)
  753. Why is the Moon higher in the sky in winter and lower in the summer? (viewed 10817 times)
  754. What would happen if a nuclear-powered shuttle exploded? (viewed 10630 times)
  755. Where are the protons and electrons in a Neutron Star? (viewed 10468 times)
  756. Is the Moon always visible during winter on the North Pole? (viewed 10143 times)
  757. Wait, I'm still confused why information can't travel faster than the speed of light. (viewed 9917 times)
  758. Do more meteorites fall at low latitudes? (viewed 9682 times)
  759. Did the Moon or planets form in a manner similar to that of Earth? (viewed 9643 times)
  760. Will the Pioneer and Voyager probes ever leave the Milky Way? (viewed 9580 times)
  761. Will Comet Elenin (C/2010 X1) affect the Earth on its close approach in Fall 2011? (viewed 9580 times)
  762. What are the possible ends of the universe? (viewed 9562 times)
  763. If there are infinity universes, will every thing that is possible happen? (viewed 9406 times)
  764. Is it sensible to consider terraforming Mars? (viewed 9357 times)
  765. What color are meteors? (viewed 9018 times)
  766. Where is everybody? (viewed 8613 times)
  767. Why does Mars have a dusty atmosphere? (viewed 8240 times)
  768. Does the singularity in a black hole create a new Universe? (viewed 8107 times)
  769. The naming of Mars (viewed 8101 times)
  770. If I were traveling through space, could I see distant galaxies with my own eyes? (viewed 8050 times)
  771. Is the reddish dust of Mars biogenic? (viewed 7899 times)
  772. Where is the Spitzer Space Telescope? (viewed 7324 times)
  773. When will humans travel to Mars and revisit the Moon? (viewed 7112 times)
  774. Why do astronomers use telescopes? (viewed 6759 times)
  775. How likely is it for a planet to transit its star? (viewed 6530 times)
  776. Does the particles involved in a star's final core collapse travel faster than the speed of light? (viewed 6459 times)
  777. What causes the aurora? (viewed 6383 times)
  778. When is the best time to observe zodiacal light? (viewed 6279 times)
  779. How did a transit of Venus provide astronomers with the first measurement of the Earth-Sun distance? (viewed 5241 times)
  780. Can the Sun be closer to the Earth than any planet is to Earth? (viewed 4637 times)
  781. Cosmologists say the expansion of the universe is accelerating, what is driving this? (viewed 4063 times)
  782. Can we hear sound on Titan? (viewed 3834 times)
  783. Does the direction of the moon's crescent change through the night? (viewed 3671 times)
  784. What do all the angles in a table for a planet's orbit mean? (viewed 3526 times)
  785. How do I maximize my chances of seeing shooting stars? (viewed 2890 times)
  786. Are exoplanets real? (viewed 2513 times)
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