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 2119027 times)
  2. What color is each planet? (viewed 891318 times)
  3. At what speed does the earth move around the sun? (viewed 565500 times)
  4. Is the Moon moving away from the Earth? When was this discovered? (viewed 544363 times)
  5. How far is each planet from Earth? (viewed 461122 times)
  6. When will Halley's Comet return? (viewed 413026 times)
  7. How many stars are there in our Galaxy (Milky Way)? (viewed 384201 times)
  8. How long does it take for the Sun's light to reach us? (viewed 382790 times)
  9. Why do the planets orbit the sun? (viewed 369075 times)
  10. What is the universe expanding into? (viewed 364478 times)
  11. How do you measure the distance between Earth and the Sun? (viewed 331938 times)
  12. Which planets have rings? (viewed 319920 times)
  13. Why do stars twinkle? (viewed 313546 times)
  14. Does the Moon rotate? Are there other moons that always keep one face toward their planet? (viewed 297293 times)
  15. How do I build a model rocket? (viewed 286310 times)
  16. What color is Venus? (viewed 270711 times)
  17. What is a white hole? (viewed 263869 times)
  18. Can you hear sounds in space? (viewed 245574 times)
  19. What is the life cycle of a star? (viewed 244057 times)
  20. What are the names of the earth, moon, sun, and solar system? (viewed 235050 times)
  21. What makes the Earth rotate? (viewed 226312 times)
  22. What is that ring (or rainbow) around the moon? (viewed 225629 times)
  23. What are shooting stars? (viewed 224052 times)
  24. What is the largest star? (viewed 221050 times)
  25. What do astronauts eat in space? Can they grow food? (viewed 206114 times)
  26. How do we know the age of the Universe and the Earth? (viewed 200651 times)
  27. Why do planets rotate? (viewed 200481 times)
  28. Can artificial gravity be created in space? (viewed 198590 times)
  29. Is the universe expanding faster than the speed of light? (viewed 195800 times)
  30. How does the location of sunrise and sunset change throughout the year? (viewed 186059 times)
  31. Where did the name 'Earth' come from? (viewed 177869 times)
  32. How can we see the Milky Way if we are inside it? (viewed 175248 times)
  33. What are the different kinds of astronomers? (viewed 174381 times)
  34. What would happen if we did not have a Moon? (viewed 173248 times)
  35. Why isn't the sky bright at night if the universe has so many stars? (viewed 172625 times)
  36. How many Earths fit into the Sun? (viewed 171584 times)
  37. Why is a day divided into 24 hours? (viewed 164812 times)
  38. How does the position of Moonrise and Moonset change? (viewed 159654 times)
  39. Who named the planets and who decides what to name them? (viewed 155083 times)
  40. Why are the Moon and Sun sometimes orange or red? (viewed 151113 times)
  41. When was the last time all 9 planets were aligned? (viewed 150397 times)
  42. Is Pluto a planet? (viewed 149249 times)
  43. Is the distance from the Earth to the Sun changing? (viewed 148185 times)
  44. Why do airplanes take longer to fly West than East? (viewed 146418 times)
  45. What is at the end of the Universe? (viewed 143785 times)
  46. How can I find the star I have "bought"? (viewed 139530 times)
  47. How much money is spent on space exploration? (viewed 139503 times)
  48. Why are there both high and low tides? (viewed 129943 times)
  49. How do astronauts take baths and use restrooms in space? (viewed 128061 times)
  50. What direction do planets rotate? (viewed 127529 times)
  51. What is the largest galaxy? (viewed 126670 times)
  52. Can we feel the Earth spin? (viewed 126476 times)
  53. Is the Sun expanding? Will it ever explode? (viewed 126090 times)
  54. How many known galaxies are there? (viewed 125442 times)
  55. What is a nova? (viewed 121306 times)
  56. Do stars move in the sky? (viewed 121189 times)
  57. Does your weight change between the poles and the equator? (viewed 121077 times)
  58. Can I buy a star? (viewed 115900 times)
  59. What are the advantages and disadvantages of using a telescope in space? (viewed 115618 times)
  60. Will the sun go supernova in six years and destroy Earth (as seen on Yahoo)? (viewed 113235 times)
  61. Why do all the planets orbit in the same plane? (viewed 112017 times)
  62. How are light and heavy elements formed? (viewed 111018 times)
  63. Are there telescopes that can see the flag and lunar rover on the Moon? (viewed 110669 times)
  64. What is the hottest time of day? (viewed 110631 times)
  65. How do stars move in the Galaxy? (viewed 109341 times)
  66. Does the Sun have a scientific name? (viewed 109108 times)
  67. What happens when galaxies collide? (viewed 108796 times)
  68. Why hasn't NASA gone back to the moon? (viewed 108706 times)
  69. Who first measured the speed of light? (viewed 107553 times)
  70. How do rockets work? (viewed 107250 times)
  71. Why do planets have elliptical orbits? (viewed 107091 times)
  72. What is the size of the Solar System? (viewed 106751 times)
  73. Will the magnetic field of the Earth reverse its direction in the future? Will this cause problems? (viewed 106453 times)
  74. What was there before the Big Bang and what is there outside of our universe? (viewed 105803 times)
  75. When is the next comet due to arrive? (viewed 105575 times)
  76. What would happen if an impact caused Earth to stop rotating? (viewed 105316 times)
  77. How much money do astronomers make? (viewed 105166 times)
  78. What is the physical difference between a star and a planet? (viewed 103810 times)
  79. How long does a solar eclipse last? (viewed 103733 times)
  80. Do black holes die? If so how? (viewed 103116 times)
  81. What will happen to life on Earth when the Sun becomes a red giant? (viewed 102966 times)
  82. How many constellations are there? (viewed 102149 times)
  83. How do you calculate the lifetime of the Sun? (viewed 102000 times)
  84. Does evolution contradict the second law of thermodynamics? (viewed 101744 times)
  85. What elements make up the Sun? (viewed 101616 times)
  86. What is the significance of the Tropic of Cancer, Tropic of Capricorn, Arctic Circle and Antarctic Circle? (viewed 100009 times)
  87. What is the observational difference between a star and a planet? (viewed 99708 times)
  88. Does the Sun rotate? (viewed 99624 times)
  89. Does the Sun move around the Milky Way? (viewed 98761 times)
  90. What's the difference between astronomy and astrology? (viewed 98397 times)
  91. What do astronauts do all day in the International Space Station? (viewed 97283 times)
  92. What is apparent magnitude? (viewed 94656 times)
  93. Which planet is most similar to Earth? (viewed 93426 times)
  94. Does gravity vary across the surface of the Earth? (viewed 92761 times)
  95. How many meteorites hit Earth each year? (viewed 92546 times)
  96. What would happen if the gravity on Earth was suddenly turned off? (viewed 91836 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 90436 times)
  98. What are constellations used for? (viewed 90361 times)
  99. How critical is the Earth-Sun distance in maintaining our average temperatures on Earth? (viewed 89714 times)
  100. How do astronomers use math in their jobs? (viewed 89295 times)
  101. Why do different stars appear with seasons? (viewed 88965 times)
  102. Why are stars and planets round? (viewed 88283 times)
  103. Is there a proof that Earth moves? (viewed 87748 times)
  104. Where did the Universe come from? (viewed 87712 times)
  105. Have astronomers discovered Earth's second moon? (viewed 87075 times)
  106. Does the Sun orbit the Earth as well as the Earth orbiting the Sun? (viewed 87010 times)
  107. Why is the Universe flat and not spherical? (viewed 86940 times)
  108. Why is the Moon so bright? (viewed 86828 times)
  109. What kind of schooling is necessary to become an astronomer? (viewed 86526 times)
  110. What makes the wind? (viewed 86321 times)
  111. What would happen if an asteroid 10 kilometers across hit the Earth? (viewed 85984 times)
  112. What is a singularity? (viewed 85198 times)
  113. How can a star burn with no oxygen? (viewed 83529 times)
  114. Where does the name "Milky Way" come from? (viewed 81736 times)
  115. Why does the Earth tilt back and forward once a year? (viewed 81531 times)
  116. What are RA and DEC? (viewed 81105 times)
  117. What would happen if Earth had more than one moon? (viewed 80378 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 79625 times)
  119. What is the difference between a "star" and a "sun"? (viewed 78275 times)
  120. What kind of rock is the moon made of? (viewed 77602 times)
  121. Since Earth is spinning, why do we land in the same place when we jump or fall? (viewed 77600 times)
  122. What are the requirements for being a planet? (viewed 77342 times)
  123. Why aren't there any green stars? (viewed 76677 times)
  124. How many stars are born and die each day? (viewed 76648 times)
  125. Did astronauts really go to the Moon, or is it a hoax? (viewed 76541 times)
  126. How are galaxies formed? (viewed 76315 times)
  127. How are black holes made? Could one be made close to us? (viewed 74036 times)
  128. Will the Sun become a black hole one day? (viewed 73970 times)
  129. What would happen if a supermassive black hole came close to the Earth? (viewed 73360 times)
  130. What is the density of a black hole? (viewed 73263 times)
  131. Who has landed on the moon? (viewed 73075 times)
  132. What would you see from inside a black hole? (viewed 71317 times)
  133. Why is the moon in a different place every night? (viewed 71114 times)
  134. Do most astronomers believe in God based on the available scientific evidence? (viewed 70501 times)
  135. Can moons have moons? (viewed 70481 times)
  136. What happens to a substance if its speed is more than the speed of light? (viewed 69848 times)
  137. Why can't you see stars during the day? (viewed 69842 times)
  138. How do rockets move in space? (viewed 69659 times)
  139. How do astronomers measure the brightness of stars? (viewed 69604 times)
  140. Can you fire a gun on the Moon? (viewed 69558 times)
  141. How do we weigh objects in space? (viewed 69243 times)
  142. How often does the Sun pass through a spiral arm in the Milky Way? (viewed 69089 times)
  143. How can the Universe expand faster than the speed of light during inflation? (viewed 68979 times)
  144. What are some of the effects of solar flares on Earth? (viewed 68914 times)
  145. What would happen if you took off your helmet in space? (viewed 68688 times)
  146. How is astronomy impacted by trigonometry? (viewed 68139 times)
  147. Does the Mediterranean sea have tides? (viewed 67799 times)
  148. Is it possible to measure the temperature of the Sun? (viewed 67736 times)
  149. How do we know the mass of the Earth and the Moon? (viewed 67689 times)
  150. When the Sun converts mass to energy, do the orbits of the planets change? (viewed 67667 times)
  151. How does the Sun compare to other stars? (viewed 66988 times)
  152. How do you measure a planet's mass? (viewed 66220 times)
  153. Why do stars change colour when they twinkle? (viewed 66166 times)
  154. What are the "dog days of summer"? (viewed 66157 times)
  155. How does the Moon stay "suspended" in the air? (viewed 66001 times)
  156. How are elements heavier than iron formed? (viewed 65469 times)
  157. What is the evidence supporting the nebula theory of Solar System formation? (viewed 65328 times)
  158. What kinds of jobs do astronomers do? (viewed 64868 times)
  159. Why do we not have eclipses every month? (viewed 64844 times)
  160. Does quantum entanglement imply faster than light communication? (viewed 64262 times)
  161. If the universe is infinite does that mean there is an infinite number of "me"s? (viewed 63500 times)
  162. What are black holes made of? (viewed 63345 times)
  163. What causes seasons? (viewed 62993 times)
  164. How did the stars get named? (viewed 62555 times)
  165. When can I see the Moon through the hole in the Pantheon? (viewed 62542 times)
  166. Why doesn't the earliest sunset occur on the shortest day of the year? (viewed 62394 times)
  167. Where does the name "Moon" come from? (viewed 62068 times)
  168. How did asteroids form and what is the difference between an asteroid and a comet? (viewed 61947 times)
  169. How fast is the Universe expanding? (viewed 61793 times)
  170. How do you measure the mass of a star? (viewed 61676 times)
  171. How long would it take the Earth to fall into the Sun? (viewed 61497 times)
  172. Where did the matter in the universe come from? (viewed 61424 times)
  173. Traveling at light speed, how long would it take to get to the nearest galaxy? (viewed 61302 times)
  174. What's the best college for astronomy? (viewed 61222 times)
  175. What are Altitude and Azimuth? (viewed 61102 times)
  176. Why do planets not twinkle? (viewed 61039 times)
  177. Why doesn't the length of each day change much around the solstices? (viewed 60669 times)
  178. How does light pollution affect astronomers? (viewed 60616 times)
  179. Are there stars outside of galaxies? (viewed 60561 times)
  180. What would happen to us if the sun went out for an hour? (viewed 60490 times)
  181. Where, in relation to the entire universe, is the Milky Way located? (viewed 60276 times)
  182. What is the mass of the Universe? (viewed 59719 times)
  183. What's the difference between dark matter and dark energy? (viewed 58616 times)
  184. Does the Moon rotate? (viewed 58240 times)
  185. How can I calculate the position or path of the Sun for a given time and location? (viewed 58200 times)
  186. Could there be life in the galaxies nearest to the Milky Way? (viewed 58095 times)
  187. Why does the Sun's apparent path through the sky change throughout the year? (viewed 57700 times)
  188. Why does the Earth have only one moon? (viewed 57667 times)
  189. Can any galaxies be seen with the naked eye? (viewed 57255 times)
  190. How does the parachute in a model rocket work? (viewed 56543 times)
  191. How does astronomy benefit humankind? (viewed 56448 times)
  192. What is the origin of spiral structure in galaxies? (viewed 56354 times)
  193. What is the shape of the universe? (viewed 56021 times)
  194. How long does the supernova stage of a star last? (viewed 56005 times)
  195. How close was the Moon to the Earth when it formed? (viewed 55965 times)
  196. What makes up most of the Universe? (viewed 55802 times)
  197. What is the largest structure in the universe? (viewed 55519 times)
  198. Where are stars born? (viewed 54867 times)
  199. Why isn't the summer solstice the hottest day of the year? (viewed 54777 times)
  200. Why is looking out into space the same as looking back in time? (viewed 54644 times)
  201. What can we learn from the color of a star? (viewed 54578 times)
  202. What is a star's "spectrum"? (viewed 54445 times)
  203. What is the size of a black hole? (viewed 54341 times)
  204. How do astronauts use math in their jobs? (viewed 54324 times)
  205. Are names given to black holes? (viewed 54311 times)
  206. Can you see satellites? (viewed 53805 times)
  207. Which constellation does our Sun belong to? (viewed 53519 times)
  208. How do you calculate the azimuth and altitude of an object? (viewed 53136 times)
  209. How do we measure the size of the Moon and of the Sun? (viewed 53125 times)
  210. If gravity is a "curvature of space" rather than a force, why do a ball and bullet follow different paths? (viewed 53008 times)
  211. Are aliens or UFOs real? (viewed 52382 times)
  212. How can I find the distance to the Sun on any given day? (viewed 52352 times)
  213. What happens to a bullet fired on the moon? (viewed 52348 times)
  214. How do the astronauts communicate in space if sound cannot travel in a vacuum? (viewed 52295 times)
  215. Why do we see stars? (viewed 52209 times)
  216. 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 52082 times)
  217. What other careers involve Astronomy besides Astronomer? (viewed 52051 times)
  218. How can I measure the distance of a star? (viewed 51856 times)
  219. Is the speed of light constant? (viewed 51340 times)
  220. What are some astronomy science fair projects? (viewed 51307 times)
  221. Which hemisphere has the best view of the Milky Way? (viewed 51015 times)
  222. Are there any asteroids on a collision course with Earth? (viewed 50821 times)
  223. How long has there been water on Earth? (viewed 50647 times)
  224. Is time travel possible? (viewed 50142 times)
  225. Why is the sky blue and not blue & purple? (viewed 50081 times)
  226. Who discovered each planet? (viewed 49959 times)
  227. What would happen if the Moon fell out of its orbit around Earth? (viewed 49956 times)
  228. Are meteorites hot or cold when they hit Earth? (viewed 49677 times)
  229. Why does the Moon look big on the horizon? (viewed 49672 times)
  230. Would your weight change as you go underground? (viewed 49664 times)
  231. Why is twilight short near the equator? (viewed 49622 times)
  232. Can we look back far enough in time to see the Big Bang? (viewed 49526 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 49413 times)
  234. What do a galaxy's colors mean? Are they its true colors? (viewed 49283 times)
  235. Why is it difficult to understand the expansion of the universe? (viewed 49016 times)
  236. Where did all the water in the universe come from? (viewed 48775 times)
  237. What is a graviton? (viewed 48251 times)
  238. What is the difference between nutation and precession of the Earth? (viewed 48200 times)
  239. If light has no mass, then what draws it into a black hole? (viewed 47996 times)
  240. How is the time of sunrise calculated? (viewed 47977 times)
  241. What skills do astronomers need? (viewed 47850 times)
  242. What's the difference between astronomy and astrophysics? (viewed 47761 times)
  243. Are the planes of solar systems aligned with the plane of the Galaxy? (viewed 47707 times)
  244. How do we know what other planets (and stars, galaxies, etc.) are made of? (viewed 46618 times)
  245. What do I need to do to become an astronomer? (viewed 46419 times)
  246. Do dead stars still shine? (viewed 46079 times)
  247. Why do the size and brightness of the full moon change? (viewed 45711 times)
  248. What is a wormhole? (viewed 45709 times)
  249. How do gravitons escape black holes to tell the universe about their gravity? (viewed 45704 times)
  250. Do supermassive black holes cause galaxy rotation? (viewed 45604 times)
  251. How are black holes discovered? (viewed 45260 times)
  252. Where is the nearest black hole? (viewed 45193 times)
  253. Will we get sucked into the black hole at the center of the Milky Way? (viewed 45013 times)
  254. The Moon slows the Earth's rotation, but how fast was it spinning billions of years ago? (viewed 44699 times)
  255. Why does the Sun appear larger on the horizon than overhead? (viewed 44667 times)
  256. Can we find the place where the Big Bang happened? (viewed 44633 times)
  257. Why can't we see Venus at night when it is an inner planet? (viewed 44503 times)
  258. How do galaxies collide in an expanding universe? (viewed 44483 times)
  259. Can I calculate the size of the Universe by converting light years to kilometres? (viewed 44415 times)
  260. Is the Earth slowly getting larger? (viewed 44354 times)
  261. Why are there stars? (viewed 44323 times)
  262. Why are most months 30 or 31 days long? (viewed 43882 times)
  263. Why does Barnard 68 appear dark? (viewed 43772 times)
  264. Are Kuiper Belt Objects asteroids? Are large Kuiper Belt Objects planets? (viewed 42576 times)
  265. Why don't people walk upside-down on the bottom of the Earth? (viewed 42314 times)
  266. Was the Sun made in a supernova? (viewed 42218 times)
  267. What is the biggest crater recorded on Earth? (viewed 42207 times)
  268. What is the best way to see the Milky Way? (viewed 42157 times)
  269. Could the Universe have expanded faster than the speed of light at the Big Bang? (viewed 42027 times)
  270. Are there eclipses on other planets? (viewed 41927 times)
  271. Is there a "South Star"? (viewed 41891 times)
  272. Why does the location of sunrise change? (viewed 41886 times)
  273. Has there been an experiment that measured speed faster than the speed of light in vacuum? (viewed 41836 times)
  274. How long could life on Earth survive if the Sun stopped shining? (viewed 41789 times)
  275. How much longer will the Earth last? (viewed 41773 times)
  276. Did life originate on Earth, or did it come from somewhere else? (viewed 41714 times)
  277. Why doesn't dark matter fall into a black hole? (viewed 41562 times)
  278. How does Astronomy involve Chemistry? (viewed 41523 times)
  279. What is the difference between the "Doppler" redshift and the "gravitational" or "cosmological" redshift? (viewed 41462 times)
  280. How would the weather on Earth be different if it were a cube? (viewed 41346 times)
  281. Can I buy land on the Moon? (viewed 41289 times)
  282. What happens to spacetime inside a black hole? (viewed 41185 times)
  283. Is the Moon hollow? (viewed 40987 times)
  284. What happens when two black holes get too close? (viewed 40908 times)
  285. Why does the Earth only see one side of the Moon? (viewed 40890 times)
  286. How much can the location of sunset differ from due West? (viewed 40831 times)
  287. What's the biggest meteorite? (viewed 40661 times)
  288. Can the acceleration of the Universe be analogous to apparent acceleration in a airplane? (viewed 40525 times)
  289. What is time dilation? (viewed 40475 times)
  290. What color would Mars be if you were standing on it? (viewed 40387 times)
  291. What is the most distant known galaxy? (viewed 40236 times)
  292. What are the names of the three stars in Orion's belt? (viewed 40029 times)
  293. How can two moons of Saturn share the same orbit? (viewed 39850 times)
  294. What if the Earth rotated twice as fast? (viewed 39616 times)
  295. Could someone travel the universe in his or her own lifetime? (viewed 39402 times)
  296. Can terrestrial planets have rings? (viewed 39359 times)
  297. How long would it take for a mini-black hole to eat the Earth? (viewed 39325 times)
  298. How many Astronauts have been in space? (viewed 39103 times)
  299. Why do people draw stars with five points? (viewed 38979 times)
  300. What are "blue stragglers" in globular clusters? (viewed 38802 times)
  301. Why do pictures of distant galaxies have higher resolution than those of nearby planets? (viewed 38718 times)
  302. How do we feel heat? (viewed 38633 times)
  303. Is it possible to see the full Moon and the Sun simultaneously in high northern latitudes when the Sun doesn't set? (viewed 38614 times)
  304. What is the typical size of a visible shooting star? (viewed 38421 times)
  305. If a white dwarf is a "dead" star, why is it so hot? (viewed 38327 times)
  306. How do we know that nuclear fusion is still going on in the Sun? (viewed 38168 times)
  307. Does Mt. Everest cast a shadow on the moon? (viewed 38147 times)
  308. Is the Great Wall the largest galaxy cluster? (viewed 38031 times)
  309. Why can we see the sun's image before sunrise and after sunset? (viewed 37990 times)
  310. How fast does the Earth go at perihelion and aphelion? (viewed 37960 times)
  311. How does night and day work? (viewed 37932 times)
  312. Can a person go into a black hole and come out alive? (viewed 37714 times)
  313. Does the Sun have an iron surface? (viewed 37624 times)
  314. What is a dimension? (viewed 37605 times)
  315. Why are Saturn's rings flat? (viewed 37523 times)
  316. What is the speed of gravity? (viewed 37501 times)
  317. Can you see the future as you fall into a black hole? (viewed 37496 times)
  318. Can I communicate faster than light? (viewed 37406 times)
  319. Where do planetary rings come from, and what are they made of? (viewed 37405 times)
  320. On which days can I see the Moon in the evening / morning and why is this so? (viewed 37355 times)
  321. What is Earthrise over the Moon? (viewed 37237 times)
  322. What can I use for fuel in my homemade rocket? (viewed 37232 times)
  323. How big is the universe? (viewed 37195 times)
  324. Do you think it's possible to maintain life on other planets? (viewed 37184 times)
  325. Where is the supernova remnant that led to our solar system? (viewed 37133 times)
  326. Is the Sun always up for exactly 12 hours at the equator? (viewed 37107 times)
  327. What is the approximate GPA needed in High School in Math and Science to be an astronomer? (viewed 36952 times)
  328. Who (and when) discovered that the earth's axis is on a 23 degree tilt? (viewed 36909 times)
  329. Are all stars the same? (viewed 36823 times)
  330. Why do clocks turn in the opposite direction from the Earth and Moon? (viewed 36698 times)
  331. How do we determine the age of the universe? (viewed 36664 times)
  332. Is there really a 10th planet? (viewed 36635 times)
  333. What companies or businesses can astronomers work for? (viewed 36554 times)
  334. Why is sea water salty, and not lake water? (viewed 36472 times)
  335. What would happen to the Earth if an asteroid hit the Moon? (viewed 36260 times)
  336. How many stars can I see? (viewed 36184 times)
  337. Does the Coriolis force determine which way my toilet drains? Does it affect black holes? (viewed 36111 times)
  338. How do I tell which planet is which? (viewed 36099 times)
  339. Is there a beginning and an end to a galaxy's life? (viewed 35967 times)
  340. If the universe is 15 billion years old, how can it be larger than 15 billion light years across? (viewed 35950 times)
  341. Do the Sun's or Earth's magnetic field reverse? (viewed 35650 times)
  342. How do we know the Milky Way is a spiral galaxy? (viewed 35626 times)
  343. How can the universe be "flat"? We're 3D! (viewed 35506 times)
  344. How do we define distance in an expanding universe? (viewed 35414 times)
  345. How are photons created and destroyed? (viewed 35394 times)
  346. How can I find my age on another planet? (viewed 35211 times)
  347. Is Andromeda part of the Milky Way? Where can I find them in the sky? (viewed 34934 times)
  348. Why have star signs shifted by one constellation? (viewed 34731 times)
  349. Why are there blue shifted galaxies? (viewed 34454 times)
  350. What was that really big falling star that I saw? (viewed 34440 times)
  351. How does the brightness of a star depend on its distance from us? (viewed 34419 times)
  352. Why do humans want to go in space? (viewed 34416 times)
  353. What is the pattern to the distances between each planet and the sun? (viewed 34243 times)
  354. How are planets detected around other stars? (viewed 34235 times)
  355. Can a lunar and a solar eclipse happen in the same month? When will this happen next? (viewed 34173 times)
  356. What would happen if two stars collided? (viewed 34141 times)
  357. Who came up with the name "black hole"? (viewed 34124 times)
  358. What is the significance of the second focus of elliptical orbits of planets in our Solar System? (viewed 34004 times)
  359. How do astronauts communicate with their families from space? (viewed 33977 times)
  360. Is the Earth at the centre of the Universe? (viewed 33976 times)
  361. When we look back to the Big Bang, why don't we see the universe as a tiny speck of matter? (viewed 33956 times)
  362. How can we estimate the number of Earth-like planets in the Galaxy? (viewed 33950 times)
  363. Is there a simple formula to calculate solar eclipse timings from any position on Earth? (viewed 33862 times)
  364. What kind of eyepieces do I need to look at planets? (viewed 33860 times)
  365. Will we ever stop having solar eclipses because of the moon's motion away from the Earth? (viewed 33813 times)
  366. Why don't astronomers use everyday units to measure distances (what is an AU or a pc)? (viewed 33745 times)
  367. How is it that we see farther out in space (farther back in time) than in the past? (viewed 33505 times)
  368. Will the Moon be invisible in 500 million years? (viewed 33434 times)
  369. Are Earth and the Moon "twin planets"? (viewed 33250 times)
  370. Which American colleges teach astronomy? (viewed 33128 times)
  371. How dangerous are the asteroids? (viewed 33120 times)
  372. Why is our solar system so different from all the others we've found? (viewed 33058 times)
  373. How do I become both an astronaut and an astronomer? (viewed 32958 times)
  374. Why is Uranus tipped on its side? (viewed 32924 times)
  375. Can we colonize other planets? (viewed 32817 times)
  376. How hot is each one of the layers of the sun? (viewed 32653 times)
  377. How do sunrise and sunset times change with altitude? (viewed 32264 times)
  378. What are quasars made of? (viewed 32092 times)
  379. How can I calculate distances between stars? (viewed 32078 times)
  380. Why do constellations look the same after several years even though all the stars are moving? (viewed 31970 times)
  381. Why do astronauts in space need to exercise? (viewed 31894 times)
  382. Why are there no craters on Earth? Did all the meteorites miss us? (viewed 31879 times)
  383. Why doesn't gravity change the speed of light? (viewed 31830 times)
  384. Can you describe a day on the job as an astronomer? (viewed 31716 times)
  385. Why can't a plane fly slowly and let the Earth pass underneath? (viewed 31682 times)
  386. Is the universe really like an expanding balloon? (viewed 31635 times)
  387. Is it true that the Sun burns off a billion tons of gas every 5 seconds? (viewed 31557 times)
  388. Is it possible to count the stars? (viewed 31549 times)
  389. What is dark matter? (viewed 31493 times)
  390. Is the gravitational force exerted by the Earth on the Moon equal to the centripetal force acting on the Moon? (viewed 31489 times)
  391. Is time travel possible using merging black holes? (viewed 31457 times)
  392. What is happening just around the black hole in the center of the Milky Way? (viewed 31327 times)
  393. Can superheavy elements (such as Z=116 or 118) be formed in a supernova? Can we observe them? (viewed 31257 times)
  394. Did the speed of light change over the history of the universe? (viewed 31157 times)
  395. How big a change in the Earth's orbit would be required to destroy all life? (viewed 31095 times)
  396. Can we see dead stars with the naked eye? (viewed 31085 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 31040 times)
  398. Is the Local Group expanding along with the entire Universe? (viewed 31024 times)
  399. How do we measure distances to other stars? (viewed 30956 times)
  400. How do I make a scale model of the Solar System? (viewed 30811 times)
  401. What happens when an antimatter black hole collides with a matter blackhole? (viewed 30809 times)
  402. Are time machines possible? (viewed 30755 times)
  403. How many moles of stars are in the known universe? (viewed 30343 times)
  404. How are galaxy distances inferred from their recessional velocities? (viewed 30118 times)
  405. How can we tell what the interiors of planets are like? (viewed 29941 times)
  406. Is there any limitation to what a black hole can "suck" in? (viewed 29934 times)
  407. What happens when you change the mass of a White Dwarf or Neutron Star? (viewed 29854 times)
  408. Why is the time between two successive full moons different from the lunar synodic month? (viewed 29806 times)
  409. What is the farthest in space that we have gone? (viewed 29747 times)
  410. What do "homogeneity" and "isotropy" mean? (viewed 29660 times)
  411. What's that dark spot on the Sun? (viewed 29522 times)
  412. How can we know that there are other galaxies if we cannot leave ours? (viewed 29515 times)
  413. What are the closest and/or brightest stars? (viewed 29441 times)
  414. Does the Milky Way spin counter-clockwise? If so, do all spiral galaxies spin in this direction and why? (viewed 29413 times)
  415. How can I tell if the rock I found is a meteorite? (viewed 29406 times)
  416. Can astronauts produce water in space? (viewed 29404 times)
  417. Will the seasons change due to precession? (viewed 29374 times)
  418. How was the starting point for the Julian Date system chosen? (viewed 29246 times)
  419. Aren't jobs in astronomy scarce? (viewed 29212 times)
  420. Do astronomers believe in astrology? (viewed 29091 times)
  421. How do we know if the universe will keep expanding forever? (viewed 29064 times)
  422. Did I see the Aurora Borealis as a child? (viewed 29051 times)
  423. Why does the SETI project search for radio signals? (viewed 29048 times)
  424. How long does it take the Big Dipper to move in the sky? (viewed 29015 times)
  425. What are the facts about the Star of Bethlehem? (viewed 28984 times)
  426. Don't tachyons travel faster than light? (viewed 28978 times)
  427. Could an astronaut or satellite fall into a black hole that we didn't know about? (viewed 28938 times)
  428. Why do most moons orbit their planets at the equator? (viewed 28935 times)
  429. Why do we study black holes? (viewed 28878 times)
  430. What are the atmospheres of Mars and Pluto like? (viewed 28793 times)
  431. When are there 5 Sundays in February? (viewed 28770 times)
  432. Wouldn't the Big Bang theory be considered a hypothesis and not a theory? (viewed 28707 times)
  433. Do we see the same stars from above and below the equator? (viewed 28570 times)
  434. Has anyone made a map of the Milky Way? (viewed 28446 times)
  435. Was I hit by a meteorite? (viewed 28437 times)
  436. Can you use an infinite line of reflectors to send light to the edge of the Universe? (viewed 28336 times)
  437. What does the term "visible universe" mean? (viewed 28319 times)
  438. How are galaxies named? (viewed 28313 times)
  439. What colors are visible through an amateur telescope? (viewed 28312 times)
  440. Could you tell me about the life cycle of galaxies? (viewed 28302 times)
  441. Do you believe in UFOs? (viewed 28268 times)
  442. How can geometry be different in space? (viewed 28216 times)
  443. Why are the compositions of comets and asteroids different? (viewed 27938 times)
  444. What's the best thing about being an astronomer? (viewed 27665 times)
  445. How do asteroids, meteors and comets disappear? (viewed 27657 times)
  446. How much time do astronomers spend looking through telescopes? (viewed 27570 times)
  447. Will winter and summer constellations change due to abnormal warmth or cold on Earth? (viewed 27554 times)
  448. Why do so many of the world's UFO sightings happen in America? (viewed 27478 times)
  449. How do astronomers measure the radius of a star? (viewed 27458 times)
  450. How will the two black holes that are going to collide affect Earth? (viewed 27389 times)
  451. Can two lunar eclipses occur in the same month? (viewed 27388 times)
  452. Have there been other Big Bangs before? (viewed 27356 times)
  453. How can we see galaxies if their stars are so faint? (viewed 27349 times)
  454. How do I explain to my children why the Moon has phases? (viewed 27157 times)
  455. Can life exist on the recently discovered extrasolar planets? (viewed 27123 times)
  456. How are galaxies and solar systems similar? (viewed 27064 times)
  457. How close do you have to come to the Earth to be influenced by its gravity? (viewed 27045 times)
  458. Is the Milky Way a collision of two galaxies? (viewed 26957 times)
  459. Is there a project I can do on black holes? (viewed 26918 times)
  460. How can we measure distances to more stars? (viewed 26846 times)
  461. What is the origin of the stellar classification system "OBAFGKM"? (viewed 26821 times)
  462. Could you escape from a black hole if you were able to go faster than the speed of light? (viewed 26790 times)
  463. How do scientists slow light down? (viewed 26731 times)
  464. Do the magnitudes and colors of stars ever change? (viewed 26683 times)
  465. Is infinite temperature possible? (viewed 26556 times)
  466. Do we know everything about the Sun? (viewed 26527 times)
  467. How close does a supernova need to be to damage the Earth's environment? (viewed 26517 times)
  468. Can "tired light theory" explain the observed redshifts of galaxies? (viewed 26418 times)
  469. Do asteroids hit the sun? (viewed 26387 times)
  470. What supernova created the Crab nebula? (viewed 26385 times)
  471. Can one star orbit another? (viewed 26361 times)
  472. Is it worthwhile to continue the search for extraterrestrial life? (viewed 26350 times)
  473. Can double stars have planets? (viewed 26201 times)
  474. What causes gamma ray bursts? (viewed 26199 times)
  475. How far does a galaxy extend? (viewed 26189 times)
  476. How do I polar align my telescope? (viewed 26034 times)
  477. What will happen to the Milky Way in the future? (viewed 25953 times)
  478. Is there such a thing as hyperspace? (viewed 25948 times)
  479. Can astronauts play musical instruments in space? (viewed 25911 times)
  480. What type of energy does a black hole have? (viewed 25906 times)
  481. What happens to the material that has been sucked into a black hole? (viewed 25893 times)
  482. Which way does the sun travel in the southern hemisphere? (viewed 25847 times)
  483. What is the farthest Northern Latitude in which the Magellanic Clouds can be seen? (viewed 25846 times)
  484. What is sidereal time? (viewed 25829 times)
  485. Why do the explosions of Type Ia supernovae have a more predictable spectrum than those of regular Type II supernovae? (viewed 25770 times)
  486. Is there oxygen in the atmospheres of other planets? (viewed 25714 times)
  487. What is a Cepheid variable? (viewed 25667 times)
  488. What is "nothing", from a scientific point of view? (viewed 25642 times)
  489. How will a change in the speed of light affect the evolution of the Universe? (viewed 25627 times)
  490. What's the object I saw that moved across the sky and then got very bright? (viewed 25572 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 25562 times)
  492. Which part of the sky did the famous 'wow' signal originate from? (viewed 25554 times)
  493. How different would the night sky have looked in 40,000 B.C.? (viewed 25465 times)
  494. Is there sound coming from the Sun? (viewed 25444 times)
  495. How do we know what parameters to use when simulating the collision of the Milky Way and Andromeda? (viewed 25379 times)
  496. Can a human give birth in space? (viewed 25359 times)
  497. Why do we assume that the universe is homogeneous? (viewed 25342 times)
  498. How do we know that sunspots are associated with the Sun's magnetic field? (viewed 25288 times)
  499. Does the Moon look different in the northern and southern hemispheres? (viewed 25239 times)
  500. When did people discover that the Sun is a star? (viewed 25236 times)
  501. Why is the shadow on the Moon the shape it is? (viewed 25203 times)
  502. Are there any dark stars or dark galaxies made of dark matter? (viewed 25168 times)
  503. Are planetary nebulae the result of supernovae? (viewed 25159 times)
  504. When unmanned spacecraft accelerate in space, what causes them to slow down? (viewed 25146 times)
  505. What calculations go into predicting eclipses? (viewed 25116 times)
  506. If we invented special suits could we ever go to the sun? (viewed 25098 times)
  507. Was Stonehenge built to mark solar phenomena? (viewed 25058 times)
  508. What is the difference between homogeneity and isotropy? (viewed 25034 times)
  509. Is there a list of the sizes of different kinds of stars? (viewed 25026 times)
  510. What is our galaxy's halo made of, and how was it formed? (viewed 25001 times)
  511. What process would bring about a quark star? (viewed 24956 times)
  512. Can I see a quasar? (viewed 24896 times)
  513. What's so exciting about the new planet around 55 Cancri? (viewed 24893 times)
  514. What is a Dyson Sphere? (viewed 24845 times)
  515. How many sunspots can the Sun have at once? (viewed 24838 times)
  516. Did a giant impact cause the Dark Ages? (viewed 24835 times)
  517. How are asteroid compositions and classifications determined? (viewed 24796 times)
  518. Have gravitational waves been proven to exist? (viewed 24776 times)
  519. Can I see details on Venus? (viewed 24735 times)
  520. Can any comparison be made between spiral galaxies and hurricanes? (viewed 24673 times)
  521. Why are there more maria on the near side of the Moon? (viewed 24526 times)
  522. Why are there active volcanos on Io? (viewed 24504 times)
  523. What equipment do I need for astrophotography? (viewed 24488 times)
  524. Does Cerenkov radiation travel faster than light? (viewed 24461 times)
  525. How is it proved that the Universe is expanding? (viewed 24443 times)
  526. What happened to all the black holes that were around in the early universe? (viewed 24399 times)
  527. Is there any possibility that the Solar System or the Universe is in a black hole? (viewed 24393 times)
  528. Why are telescopes kept in cold conditions? (viewed 24262 times)
  529. What happened to the girl who named Pluto? (viewed 24230 times)
  530. Would the biggest airplanes cause tsunamis if they crashed? (viewed 24218 times)
  531. If clocks run slow in a gravitational field, how can we know the true age of the Solar System and Universe? (viewed 24187 times)
  532. How big was the Sun when it first "fired up"? (viewed 24174 times)
  533. How can we compare dark matter and dark energy? (viewed 24143 times)
  534. If the Universe was infinitely dense at the Big Bang, why didn't time stand still? (viewed 24059 times)
  535. What caused Shoemaker-Levy 9 to split up? (viewed 24035 times)
  536. Could we send a space mission to a comet? (viewed 24020 times)
  537. Why do photos of space taken from space never show any stars? (viewed 24017 times)
  538. How long do supernova remnants last? (viewed 23981 times)
  539. How do solar flares affect airline pilots? (viewed 23892 times)
  540. Could we be seeing dead stars? (viewed 23890 times)
  541. Why doesn't light from distant galaxies reach us instantaneously? (viewed 23869 times)
  542. How are sunspots formed? (viewed 23860 times)
  543. How big is the Hubble Ultra Deep Field image? (viewed 23745 times)
  544. Could a different theory of gravity explain the dark matter mystery? (viewed 23700 times)
  545. Can you give me advice on buying a telescope? (viewed 23690 times)
  546. How does the Earth compare in size to the entire universe at the present epoch? (viewed 23686 times)
  547. As the universe expands, why don't galaxies get stretched out? (viewed 23644 times)
  548. Why doesn't NASA build rotating spacecraft to simulate gravity? (viewed 23605 times)
  549. How many comets are currently orbiting our sun? (viewed 23604 times)
  550. What would happen if a human were exposed to space without wearing a spacesuit? (viewed 23585 times)
  551. Why is the Hubble Space Telescope in space? (viewed 23542 times)
  552. Can you tell time by the Big Dipper? (viewed 23515 times)
  553. Where does the kinetic energy of infalling bodies come from? (viewed 23484 times)
  554. Can I build an instrument to measure the size of the Sun and of the Moon? (viewed 23473 times)
  555. How do we know that superclusters are the largest structures in the universe? (viewed 23431 times)
  556. How powerful are quasars? (viewed 23359 times)
  557. Would extraterrestrial civilizations know that there is life on Earth? (viewed 23291 times)
  558. Did I really hear a meteor? (viewed 23276 times)
  559. Why is it important to study meteorites? (viewed 23237 times)
  560. How is the Cepheid yardstick validated? (viewed 23219 times)
  561. Why are telescopes located in remote places? (viewed 23090 times)
  562. What would happen if there was a collision between two white dwarfs? (viewed 23077 times)
  563. Do unmanned spacecraft like Voyager travel in straight lines? (viewed 23076 times)
  564. Can supernovae hinder the formation of life in galaxies? (viewed 23067 times)
  565. Did time go slower just after the Big Bang? (viewed 23055 times)
  566. Are there any new craters on the moon? (viewed 23036 times)
  567. Why are stars of different masses? (viewed 23018 times)
  568. How can I contribute to science as an amateur astronomer? (viewed 22982 times)
  569. Do galaxies orbit around anything? (viewed 22975 times)
  570. Do the Earth's magnetic poles ever change places? (viewed 22955 times)
  571. How do planets capture satellites? (viewed 22938 times)
  572. Do similar laws of physics throughout the Universe imply that all life must be like life on Earth? (viewed 22938 times)
  573. Are the asteroids the remains of a planet which broke apart? (viewed 22931 times)
  574. How do I become an astronomical artist? (viewed 22912 times)
  575. What kind of instruments are used to detect extrasolar planets? (viewed 22888 times)
  576. How could galaxies have gotten so far away in only 15 billion years? (viewed 22758 times)
  577. Could there have been multiple Big Bangs at different places in the universe? (viewed 22748 times)
  578. How do unmanned space probes avoid running into things? (viewed 22712 times)
  579. How are astronomy and poetry linked? (viewed 22706 times)
  580. Why can't relative velocities add up to more than the speed of light? (viewed 22627 times)
  581. What kind of telescope should I use for astrophotography? (viewed 22623 times)
  582. Could dark energy come from matter anti-matter pairs forming spontaneously and then annihilating? (viewed 22548 times)
  583. Why is NASA shutting down the Hubble Space Telescope? (viewed 22539 times)
  584. Can I listen to the SETI@home radio signal? (viewed 22522 times)
  585. How can you tell if a crescent moon is preceding or following a new-moon phase? (viewed 22504 times)
  586. Are the properties of extrasolar planets known? (viewed 22462 times)
  587. Does the Sun have any heavy elements? (viewed 22431 times)
  588. Will we discover an 11th planet? What would it be called? (viewed 22283 times)
  589. What class of spiral galaxy is the Milky Way? (viewed 22252 times)
  590. Can the theory of formation of the solar system explain all the observables? (viewed 22249 times)
  591. 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 22229 times)
  592. What month was it when Odysseus saw Orion in 1000BC? (viewed 22226 times)
  593. How do astronomers observe the Sun's interior? (viewed 21979 times)
  594. Why does one side of Mars look more catastrophic than the other? (viewed 21944 times)
  595. What makes a satellite geosyncronise itself with Earth's orbit? (viewed 21932 times)
  596. Why does the apparent density of galaxies drop off at larger distances? (viewed 21897 times)
  597. Would a planet near the galactic center have a brighter night sky? (viewed 21847 times)
  598. Is it possible for amateurs to do optical interferometry? (viewed 21748 times)
  599. What is the solar cycle? (viewed 21695 times)
  600. Where was the water in the big bang? (viewed 21658 times)
  601. Could we send a manned mission to the outer planets? (viewed 21641 times)
  602. Do stars' orbits in galaxies obey Kepler's Laws? (viewed 21599 times)
  603. Can other terrestrial moons be (or have been) stable? (viewed 21567 times)
  604. Why was the Platonic year named after Plato? (viewed 21503 times)
  605. How are supernovae discovered? (viewed 21482 times)
  606. Can a black hole come back to the visual universe through a "little bang"? (viewed 21422 times)
  607. What would the Big Crunch look like to an observer on Earth? (viewed 21412 times)
  608. Does inflation allow for an infinite number of universes? (viewed 21346 times)
  609. Why are accretion disks flat? (viewed 21309 times)
  610. How can water be chemically trapped in rocks? (viewed 21297 times)
  611. Could our position in the universe affect our perceptions of the expansion? (viewed 21294 times)
  612. What is meant by "stopping down a telescope"? (viewed 21288 times)
  613. Why do spacecraft need heat shields coming back to Earth but not leaving? (viewed 21254 times)
  614. Why doesn't the hydrogen on Jupiter explode? (viewed 21204 times)
  615. Did I find a rock that came from the Moon? (viewed 20990 times)
  616. Have astronomers observed any phenomena that could be produced by extraterrestrial civilizations? (viewed 20982 times)
  617. How can the Sun have such a strong gravitational field if it's made of gasses? (viewed 20952 times)
  618. Does a photon observe other photons moving past it at the speed of light? (viewed 20946 times)
  619. What is the SU(3) quark model? (viewed 20946 times)
  620. Can gravitational lensing from intervening galaxies cause the observed ripples in the Cosmic Microwave Background? (viewed 20921 times)
  621. What's new with the Big Bang? (viewed 20663 times)
  622. Will I be able to see the shadow of the Moon streaking towards me in a total solar eclipse? (viewed 20623 times)
  623. Could photons be dark matter? (viewed 20564 times)
  624. Is it possible to build a cheap device to measure declination? (viewed 20534 times)
  625. Why can we have solar eclipses? (viewed 20518 times)
  626. How can we find galaxies behind the Milky Way? (viewed 20488 times)
  627. If comets are boiling away, why are there any left? (viewed 20486 times)
  628. How fast do particles travel in space? (viewed 20440 times)
  629. Why do some eclipses take longer than others? (viewed 20422 times)
  630. Why search for only Earth-like life on other planets? (viewed 20402 times)
  631. Where can I find information on the moons of other planets? (viewed 20367 times)
  632. How much power is contained in a beam of light? (viewed 20292 times)
  633. Why is the WMAP picture of the CMB an ellipse? (viewed 20257 times)
  634. Why is pressure broadening greater in low mass stars than in high mass stars? (viewed 20204 times)
  635. What would an "open geometry" for the universe look like? (viewed 20103 times)
  636. What are the boundaries of the constellations? (viewed 20071 times)
  637. Did the Sumerians measure precession? (viewed 20023 times)
  638. What kinds of star clusters are there? (viewed 19990 times)
  639. Why is the Cosmic Microwave Background not absorbed by interstellar hydrogen? (viewed 19963 times)
  640. How do astronomers come up with their facts? (viewed 19958 times)
  641. Why aren't discoveries of extrasolar planets reported on the news? (viewed 19930 times)
  642. How do bars form in spiral galaxies? (viewed 19885 times)
  643. Why don't astronauts sublimate in space? (viewed 19856 times)
  644. How do photons from distant objects maintain enough energy to reach us? (viewed 19818 times)
  645. Can HST see the Oort cloud? (viewed 19787 times)
  646. Can planets collide with one another? (viewed 19731 times)
  647. Do electrons age? (viewed 19727 times)
  648. Do constellations looks the same from space? (viewed 19700 times)
  649. Can the Space Shuttle abort and return to Earth before reaching orbit? (viewed 19626 times)
  650. Can we make a movie of the Milky Way galaxy's rotation? (viewed 19616 times)
  651. How did Mars get so dusty? (viewed 19569 times)
  652. How long is twilight on the Moon? (viewed 19509 times)
  653. Does the shuttle worry about space junk? (viewed 19441 times)
  654. What are collections of galaxies called? (viewed 19431 times)
  655. How does melting a material reset its radioactive clock? (viewed 19407 times)
  656. Why do supernova remnants look like rings rather than spheres? (viewed 19361 times)
  657. Will astronauts ever be able to go ice-skating on Europa? (viewed 19320 times)
  658. How do you classify galaxies? (viewed 19311 times)
  659. Where can I see Newton's original reflecting telescope? (viewed 19290 times)
  660. Why don't all neutron stars become pulsars? (viewed 19245 times)
  661. What is the best time of the year to see eclipses? (viewed 19178 times)
  662. Why doesn't SETI concentrate its observations to the nearby stars and the solar systems that we are discovering? (viewed 19177 times)
  663. How can we understand the meaning of large numbers like "a million million?" (viewed 19144 times)
  664. Will the next generation telescope OWL be able to detect an Earth like extrasolar planet? (viewed 19085 times)
  665. What causes a particle to decay? (viewed 19062 times)
  666. How can I nominate myself for a Nobel Prize in Physics? (viewed 18980 times)
  667. How long has humanity known that we live in a galaxy similar to others in the Universe? (viewed 18949 times)
  668. Will the Leonid meteor shower go away? (viewed 18938 times)
  669. What are "curled" dimensions? (viewed 18816 times)
  670. Is light of different colors affected differently by gravity? (viewed 18796 times)
  671. What was that eclipse I saw in the sky? (viewed 18698 times)
  672. How does interferometry work? (viewed 18653 times)
  673. How do distant galaxies differ from those nearby? (viewed 18571 times)
  674. How does the color index of a star relate to its actual color? (viewed 18548 times)
  675. Does the temperature of matter increase as it is accelerated to relativistic speeds? (viewed 18547 times)
  676. Why is it called astronomy when all the other sciences end in -ology? (viewed 18543 times)
  677. Do asteroids ever do anything good in the Solar System? (viewed 18534 times)
  678. How do we find out about the star formation histories of galaxies? (viewed 18527 times)
  679. Can astronomers observe anything when the moon is full? (viewed 18460 times)
  680. Wouldn't the vast distances of space distort SETI signals into unintelligeble forms? (viewed 18421 times)
  681. If nothing can escape a black hole, why do some black holes have jets? (viewed 18409 times)
  682. What kind of interference must astronomers contend with when observing? (viewed 18356 times)
  683. Are black holes spherical? (viewed 18345 times)
  684. What would happen if you went back in time and killed your grandmother? (viewed 18344 times)
  685. Why will fusion wait until hydrogen is gone before starting to fuse heavier atoms? (viewed 18269 times)
  686. Do we really observe the edges of galaxies at different epochs? (viewed 18263 times)
  687. What do stellar classifications mean? (viewed 18257 times)
  688. Can you tell me the characteristics of W, R, N and S type stars? (viewed 18247 times)
  689. How are astronauts trained for weightlessness? (viewed 18167 times)
  690. How can I watch the Perseid meteor shower? (viewed 18163 times)
  691. If photons have zero mass, why do they feel the effects of gravity? (viewed 18090 times)
  692. What is the three-body problem? (viewed 18076 times)
  693. Why aren't accretion disks around giant stars as hot as accretion disks around black holes? (viewed 17991 times)
  694. If the universe is "bounded" today, could it one day become "unbounded"? (viewed 17909 times)
  695. Will the diameter of a cluster of galaxies change with redshift? (viewed 17858 times)
  696. Is cosmic expansion happening on microscopic scales? (viewed 17717 times)
  697. How can I find out if the new moon has been sighted? (viewed 17596 times)
  698. Do we have to worry about relativity when studying galactic objects? (viewed 17398 times)
  699. Could neutrinos be dark matter? (viewed 17328 times)
  700. What kinds of cancer research have been done in space? (viewed 17219 times)
  701. How does a star take mass from another star? (viewed 17129 times)
  702. How can you tell the difference between single and multiple extrasolar planets? (viewed 16927 times)
  703. Could the Universe's dark matter be made up of black holes? (viewed 16926 times)
  704. Does lunar gardening really work? (viewed 16895 times)
  705. When measuring the expansion of the universe, do astronomers consider that they're seeing how galaxies moved long ago, not today? (viewed 16854 times)
  706. What is Hot Dark Matter theory? (viewed 16850 times)
  707. How do supernovae show us that the Universe's expansion is accelerating? (viewed 16706 times)
  708. Is it a coincidence that we can have total solar eclipses? Are there other planets which also have them? (viewed 16414 times)
  709. How does libration allow us to see more than 50% of the Moon? (viewed 16352 times)
  710. Is the green flash real? (viewed 16329 times)
  711. How can observations of the distant universe prove that the expansion is accelerating *now*? (viewed 16304 times)
  712. How do we know the density of some extrasolar planets? (viewed 16238 times)
  713. Is light blueshifted when it is gravitationally lensed? (viewed 16190 times)
  714. What is the photoelectric effect? Why can't multiple low-frequency photons free an electron? (viewed 16181 times)
  715. Do binary or triple star systems form together? (viewed 16152 times)
  716. No matter how fast the universe is expanding, shouldn't gravity eventually make it recollapse? (viewed 16112 times)
  717. What percent of the time can astronomers observe without interference from the Moon? (viewed 15902 times)
  718. What do meteorites tell us about life on other planets? (viewed 15843 times)
  719. Why is it easier to see a star if you look slightly to the side? (viewed 15720 times)
  720. What happens to the helium formed in the sun? (viewed 15712 times)
  721. Could matter-anti-matter repulsion power the expansion of the universe? (viewed 15617 times)
  722. If the sun went out and our atmosphere froze solid, what color would it be? (viewed 15466 times)
  723. Can we prove that the Moon isn't hollow? (viewed 15432 times)
  724. Why doesn't the ammonia and methane in Jupiter's atmosphere sink into the core? (viewed 15350 times)
  725. Are there any 'lonely galaxies'? (viewed 15229 times)
  726. How do we detect incoming meteorites? (viewed 15110 times)
  727. What was different on Mars in the past to allow liquid water to be present? (viewed 14987 times)
  728. When will Hale-Bopp return? (viewed 14846 times)
  729. Why don't skydivers burn up like meteors? (viewed 14756 times)
  730. Has anyone ever seen a star "turn on"? (viewed 14575 times)
  731. During close approaches, can Mars appear in our sky as large as the Moon? (viewed 14543 times)
  732. How are planets affected by the Hot Ionised Medium? (viewed 14311 times)
  733. How has light from 13 billion years ago not passed us by? (viewed 14214 times)
  734. Why are craters round? (viewed 14127 times)
  735. Can the sun rise from the west on Mars? (viewed 13875 times)
  736. Why was Mir burnt up in the atmosphere? (viewed 13852 times)
  737. What are the largest radio wavelengths observed from radio sources in the sky? (viewed 13830 times)
  738. How can we discern different galaxies/clusters along the same line of sight? (viewed 13736 times)
  739. What is the relationship between the width of a star trail on a photo and the star's intensity? (viewed 13307 times)
  740. Can we harvest H & O from space to make water? (viewed 12858 times)
  741. What is between the Oort cloud and the closest star? (viewed 12515 times)
  742. Why does Titan, in spite of being smaller than Mars, have an atmosphere more dense than Earth's? (viewed 12410 times)
  743. What time is sunrise/sunset or moonrise/moonset at my location? (viewed 12320 times)
  744. Could a planetary system survive if its star merged with another, or if its star went supernova? (viewed 11645 times)
  745. Are there solar tides? (viewed 11602 times)
  746. Does weightlessness affect hunger? (viewed 11507 times)
  747. Is Earth-moon tidal friction causing global warming? (viewed 11037 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 11008 times)
  749. Do planets radiate noise? (viewed 10805 times)
  750. Is the moon spherical? (viewed 10645 times)
  751. What happens to the Earth as the moon gets farther away and will it ever go away entirely? (viewed 10589 times)
  752. What would happen if a nuclear-powered shuttle exploded? (viewed 10410 times)
  753. Is dark energy affected by black holes? (viewed 10404 times)
  754. Why is the Moon higher in the sky in winter and lower in the summer? (viewed 9835 times)
  755. Where are the protons and electrons in a Neutron Star? (viewed 9722 times)
  756. Did the Moon or planets form in a manner similar to that of Earth? (viewed 9467 times)
  757. Do more meteorites fall at low latitudes? (viewed 9463 times)
  758. Wait, I'm still confused why information can't travel faster than the speed of light. (viewed 9321 times)
  759. What are the possible ends of the universe? (viewed 9306 times)
  760. Will Comet Elenin (C/2010 X1) affect the Earth on its close approach in Fall 2011? (viewed 9300 times)
  761. Is it sensible to consider terraforming Mars? (viewed 9214 times)
  762. Is the Moon always visible during winter on the North Pole? (viewed 9200 times)
  763. Will the Pioneer and Voyager probes ever leave the Milky Way? (viewed 9194 times)
  764. If there are infinity universes, will every thing that is possible happen? (viewed 9182 times)
  765. What color are meteors? (viewed 8761 times)
  766. Where is everybody? (viewed 8455 times)
  767. Why does Mars have a dusty atmosphere? (viewed 7950 times)
  768. The naming of Mars (viewed 7862 times)
  769. If I were traveling through space, could I see distant galaxies with my own eyes? (viewed 7836 times)
  770. Does the singularity in a black hole create a new Universe? (viewed 7755 times)
  771. Is the reddish dust of Mars biogenic? (viewed 7599 times)
  772. Where is the Spitzer Space Telescope? (viewed 7086 times)
  773. When will humans travel to Mars and revisit the Moon? (viewed 6993 times)
  774. Does the particles involved in a star's final core collapse travel faster than the speed of light? (viewed 6341 times)
  775. When is the best time to observe zodiacal light? (viewed 6101 times)
  776. How likely is it for a planet to transit its star? (viewed 6009 times)
  777. What causes the aurora? (viewed 5885 times)
  778. Why do astronomers use telescopes? (viewed 5801 times)
  779. How did a transit of Venus provide astronomers with the first measurement of the Earth-Sun distance? (viewed 4852 times)
  780. Can the Sun be closer to the Earth than any planet is to Earth? (viewed 4178 times)
  781. Cosmologists say the expansion of the universe is accelerating, what is driving this? (viewed 3695 times)
  782. Can we hear sound on Titan? (viewed 3641 times)
  783. Does the direction of the moon's crescent change through the night? (viewed 3441 times)
  784. What do all the angles in a table for a planet's orbit mean? (viewed 3204 times)
  785. How do I maximize my chances of seeing shooting stars? (viewed 2509 times)
  786. Are exoplanets real? (viewed 2242 times)
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