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 2133878 times)
  2. What color is each planet? (viewed 915878 times)
  3. At what speed does the earth move around the sun? (viewed 587345 times)
  4. Is the Moon moving away from the Earth? When was this discovered? (viewed 566384 times)
  5. How far is each planet from Earth? (viewed 470722 times)
  6. When will Halley's Comet return? (viewed 427348 times)
  7. How long does it take for the Sun's light to reach us? (viewed 391952 times)
  8. How many stars are there in our Galaxy (Milky Way)? (viewed 389055 times)
  9. Why do the planets orbit the sun? (viewed 381217 times)
  10. What is the universe expanding into? (viewed 371699 times)
  11. How do you measure the distance between Earth and the Sun? (viewed 343621 times)
  12. Which planets have rings? (viewed 323167 times)
  13. Why do stars twinkle? (viewed 320449 times)
  14. Does the Moon rotate? Are there other moons that always keep one face toward their planet? (viewed 305337 times)
  15. How do I build a model rocket? (viewed 291087 times)
  16. What color is Venus? (viewed 274321 times)
  17. Can you hear sounds in space? (viewed 268411 times)
  18. What is a white hole? (viewed 267965 times)
  19. What is the life cycle of a star? (viewed 246313 times)
  20. What are the names of the earth, moon, sun, and solar system? (viewed 239566 times)
  21. What makes the Earth rotate? (viewed 233784 times)
  22. What is that ring (or rainbow) around the moon? (viewed 233434 times)
  23. What are shooting stars? (viewed 230199 times)
  24. What are the different kinds of astronomers? (viewed 224835 times)
  25. What is the largest star? (viewed 222034 times)
  26. How do we know the age of the Universe and the Earth? (viewed 212652 times)
  27. What do astronauts eat in space? Can they grow food? (viewed 211391 times)
  28. Can artificial gravity be created in space? (viewed 210734 times)
  29. Why do planets rotate? (viewed 208315 times)
  30. Is the universe expanding faster than the speed of light? (viewed 203833 times)
  31. How does the location of sunrise and sunset change throughout the year? (viewed 196867 times)
  32. How can we see the Milky Way if we are inside it? (viewed 183309 times)
  33. Where did the name 'Earth' come from? (viewed 180742 times)
  34. What would happen if we did not have a Moon? (viewed 176719 times)
  35. Why isn't the sky bright at night if the universe has so many stars? (viewed 174763 times)
  36. Why is a day divided into 24 hours? (viewed 173154 times)
  37. How many Earths fit into the Sun? (viewed 173089 times)
  38. How does the position of Moonrise and Moonset change? (viewed 171633 times)
  39. Who named the planets and who decides what to name them? (viewed 161326 times)
  40. Why are the Moon and Sun sometimes orange or red? (viewed 158671 times)
  41. When was the last time all 9 planets were aligned? (viewed 158281 times)
  42. Why do airplanes take longer to fly West than East? (viewed 157666 times)
  43. Is the distance from the Earth to the Sun changing? (viewed 151045 times)
  44. Is Pluto a planet? (viewed 151020 times)
  45. What is at the end of the Universe? (viewed 148265 times)
  46. How can I find the star I have "bought"? (viewed 145834 times)
  47. How much money is spent on space exploration? (viewed 143633 times)
  48. What is a nova? (viewed 135077 times)
  49. How do astronauts take baths and use restrooms in space? (viewed 132499 times)
  50. Does your weight change between the poles and the equator? (viewed 131668 times)
  51. Can we feel the Earth spin? (viewed 131521 times)
  52. Why are there both high and low tides? (viewed 131321 times)
  53. What direction do planets rotate? (viewed 130680 times)
  54. Is the Sun expanding? Will it ever explode? (viewed 128865 times)
  55. What is the largest galaxy? (viewed 127399 times)
  56. How many known galaxies are there? (viewed 126263 times)
  57. Do stars move in the sky? (viewed 124935 times)
  58. What are the advantages and disadvantages of using a telescope in space? (viewed 120496 times)
  59. Why do all the planets orbit in the same plane? (viewed 118695 times)
  60. Can I buy a star? (viewed 118023 times)
  61. How are light and heavy elements formed? (viewed 115715 times)
  62. Will the sun go supernova in six years and destroy Earth (as seen on Yahoo)? (viewed 115406 times)
  63. Are there telescopes that can see the flag and lunar rover on the Moon? (viewed 113791 times)
  64. Why hasn't NASA gone back to the moon? (viewed 112968 times)
  65. Does the Sun have a scientific name? (viewed 112675 times)
  66. Why do planets have elliptical orbits? (viewed 112447 times)
  67. What is the physical difference between a star and a planet? (viewed 112055 times)
  68. How do stars move in the Galaxy? (viewed 111800 times)
  69. What is the hottest time of day? (viewed 111796 times)
  70. Who first measured the speed of light? (viewed 111738 times)
  71. What happens when galaxies collide? (viewed 111096 times)
  72. How do rockets work? (viewed 110211 times)
  73. What is the size of the Solar System? (viewed 108765 times)
  74. What is the significance of the Tropic of Cancer, Tropic of Capricorn, Arctic Circle and Antarctic Circle? (viewed 108238 times)
  75. What would happen if an impact caused Earth to stop rotating? (viewed 107824 times)
  76. How much money do astronomers make? (viewed 107753 times)
  77. Will the magnetic field of the Earth reverse its direction in the future? Will this cause problems? (viewed 107426 times)
  78. What was there before the Big Bang and what is there outside of our universe? (viewed 107132 times)
  79. When is the next comet due to arrive? (viewed 106783 times)
  80. Does evolution contradict the second law of thermodynamics? (viewed 106741 times)
  81. What will happen to life on Earth when the Sun becomes a red giant? (viewed 106220 times)
  82. How long does a solar eclipse last? (viewed 105647 times)
  83. How do you calculate the lifetime of the Sun? (viewed 105489 times)
  84. What elements make up the Sun? (viewed 104677 times)
  85. Do black holes die? If so how? (viewed 104669 times)
  86. How many constellations are there? (viewed 103812 times)
  87. What do astronauts do all day in the International Space Station? (viewed 102958 times)
  88. What is the observational difference between a star and a planet? (viewed 102867 times)
  89. What's the difference between astronomy and astrology? (viewed 101645 times)
  90. Does the Sun rotate? (viewed 101207 times)
  91. Does the Sun move around the Milky Way? (viewed 99809 times)
  92. Does gravity vary across the surface of the Earth? (viewed 99488 times)
  93. What would happen if the gravity on Earth was suddenly turned off? (viewed 98380 times)
  94. What is apparent magnitude? (viewed 96639 times)
  95. How many meteorites hit Earth each year? (viewed 96031 times)
  96. Which planet is most similar to Earth? (viewed 95765 times)
  97. What are constellations used for? (viewed 95311 times)
  98. Why do different stars appear with seasons? (viewed 93588 times)
  99. What kind of schooling is necessary to become an astronomer? (viewed 93178 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 92208 times)
  101. How do astronomers use math in their jobs? (viewed 92046 times)
  102. How critical is the Earth-Sun distance in maintaining our average temperatures on Earth? (viewed 91089 times)
  103. Is there a proof that Earth moves? (viewed 91014 times)
  104. Where did the Universe come from? (viewed 90201 times)
  105. Why are stars and planets round? (viewed 90167 times)
  106. Does the Sun orbit the Earth as well as the Earth orbiting the Sun? (viewed 89797 times)
  107. Why is the Moon so bright? (viewed 89454 times)
  108. Why is the Universe flat and not spherical? (viewed 89406 times)
  109. What makes the wind? (viewed 88829 times)
  110. What would happen if an asteroid 10 kilometers across hit the Earth? (viewed 88199 times)
  111. Have astronomers discovered Earth's second moon? (viewed 87936 times)
  112. How can a star burn with no oxygen? (viewed 87828 times)
  113. What is a singularity? (viewed 87243 times)
  114. What is the difference between a "star" and a "sun"? (viewed 86840 times)
  115. What are the requirements for being a planet? (viewed 83622 times)
  116. Why does the Earth tilt back and forward once a year? (viewed 83563 times)
  117. What are RA and DEC? (viewed 83448 times)
  118. Where does the name "Milky Way" come from? (viewed 83151 times)
  119. What would happen if Earth had more than one moon? (viewed 81540 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 81452 times)
  121. Since Earth is spinning, why do we land in the same place when we jump or fall? (viewed 81330 times)
  122. How many stars are born and die each day? (viewed 79883 times)
  123. Why aren't there any green stars? (viewed 78628 times)
  124. What kind of rock is the moon made of? (viewed 78371 times)
  125. Did astronauts really go to the Moon, or is it a hoax? (viewed 77670 times)
  126. How are galaxies formed? (viewed 77495 times)
  127. Why is the moon in a different place every night? (viewed 76495 times)
  128. Will the Sun become a black hole one day? (viewed 75544 times)
  129. How are black holes made? Could one be made close to us? (viewed 75225 times)
  130. What is the density of a black hole? (viewed 75107 times)
  131. What would happen if a supermassive black hole came close to the Earth? (viewed 74770 times)
  132. How do we weigh objects in space? (viewed 74269 times)
  133. Who has landed on the moon? (viewed 73678 times)
  134. Do most astronomers believe in God based on the available scientific evidence? (viewed 72545 times)
  135. Can moons have moons? (viewed 72493 times)
  136. What would you see from inside a black hole? (viewed 72393 times)
  137. What happens to a substance if its speed is more than the speed of light? (viewed 72254 times)
  138. How do rockets move in space? (viewed 72230 times)
  139. Why can't you see stars during the day? (viewed 72202 times)
  140. Does the Mediterranean sea have tides? (viewed 71876 times)
  141. How often does the Sun pass through a spiral arm in the Milky Way? (viewed 71693 times)
  142. How do astronomers measure the brightness of stars? (viewed 71474 times)
  143. What would happen if you took off your helmet in space? (viewed 71309 times)
  144. Can you fire a gun on the Moon? (viewed 71182 times)
  145. What are some of the effects of solar flares on Earth? (viewed 71063 times)
  146. How can the Universe expand faster than the speed of light during inflation? (viewed 71028 times)
  147. When the Sun converts mass to energy, do the orbits of the planets change? (viewed 70947 times)
  148. How do we know the mass of the Earth and the Moon? (viewed 70171 times)
  149. What is the evidence supporting the nebula theory of Solar System formation? (viewed 70055 times)
  150. How is astronomy impacted by trigonometry? (viewed 69894 times)
  151. Is it possible to measure the temperature of the Sun? (viewed 69501 times)
  152. Why do we not have eclipses every month? (viewed 69320 times)
  153. How do you measure a planet's mass? (viewed 68810 times)
  154. Why do stars change colour when they twinkle? (viewed 68614 times)
  155. How does the Sun compare to other stars? (viewed 68445 times)
  156. How does the Moon stay "suspended" in the air? (viewed 68279 times)
  157. How are elements heavier than iron formed? (viewed 67716 times)
  158. What are the "dog days of summer"? (viewed 67196 times)
  159. What kinds of jobs do astronomers do? (viewed 66023 times)
  160. Does quantum entanglement imply faster than light communication? (viewed 65880 times)
  161. If the universe is infinite does that mean there is an infinite number of "me"s? (viewed 64957 times)
  162. What are black holes made of? (viewed 64138 times)
  163. How did the stars get named? (viewed 64103 times)
  164. Where does the name "Moon" come from? (viewed 63971 times)
  165. How long would it take the Earth to fall into the Sun? (viewed 63809 times)
  166. What causes seasons? (viewed 63752 times)
  167. How do you measure the mass of a star? (viewed 63601 times)
  168. How does light pollution affect astronomers? (viewed 63573 times)
  169. Why doesn't the earliest sunset occur on the shortest day of the year? (viewed 63565 times)
  170. Where did the matter in the universe come from? (viewed 63472 times)
  171. What are Altitude and Azimuth? (viewed 63346 times)
  172. How did asteroids form and what is the difference between an asteroid and a comet? (viewed 63237 times)
  173. Traveling at light speed, how long would it take to get to the nearest galaxy? (viewed 63048 times)
  174. When can I see the Moon through the hole in the Pantheon? (viewed 63010 times)
  175. Are there stars outside of galaxies? (viewed 62954 times)
  176. How fast is the Universe expanding? (viewed 62863 times)
  177. Why do planets not twinkle? (viewed 62120 times)
  178. What's the best college for astronomy? (viewed 62073 times)
  179. Where, in relation to the entire universe, is the Milky Way located? (viewed 61831 times)
  180. What would happen to us if the sun went out for an hour? (viewed 61488 times)
  181. Why doesn't the length of each day change much around the solstices? (viewed 61456 times)
  182. What's the difference between dark matter and dark energy? (viewed 60907 times)
  183. What is the mass of the Universe? (viewed 60560 times)
  184. Why does the Sun's apparent path through the sky change throughout the year? (viewed 59777 times)
  185. How can I calculate the position or path of the Sun for a given time and location? (viewed 59524 times)
  186. How does astronomy benefit humankind? (viewed 59346 times)
  187. Does the Moon rotate? (viewed 59056 times)
  188. Why does the Earth have only one moon? (viewed 58960 times)
  189. Could there be life in the galaxies nearest to the Milky Way? (viewed 58916 times)
  190. How does the parachute in a model rocket work? (viewed 58681 times)
  191. Can any galaxies be seen with the naked eye? (viewed 58528 times)
  192. Why is looking out into space the same as looking back in time? (viewed 58478 times)
  193. What is the origin of spiral structure in galaxies? (viewed 58408 times)
  194. How close was the Moon to the Earth when it formed? (viewed 58153 times)
  195. What can we learn from the color of a star? (viewed 57622 times)
  196. How long does the supernova stage of a star last? (viewed 57583 times)
  197. What makes up most of the Universe? (viewed 57493 times)
  198. What is the shape of the universe? (viewed 56645 times)
  199. Why isn't the summer solstice the hottest day of the year? (viewed 56035 times)
  200. How do astronauts use math in their jobs? (viewed 55829 times)
  201. What is the largest structure in the universe? (viewed 55827 times)
  202. What is a star's "spectrum"? (viewed 55642 times)
  203. If gravity is a "curvature of space" rather than a force, why do a ball and bullet follow different paths? (viewed 55347 times)
  204. How do the astronauts communicate in space if sound cannot travel in a vacuum? (viewed 55345 times)
  205. Where are stars born? (viewed 55296 times)
  206. What is the size of a black hole? (viewed 55130 times)
  207. Are names given to black holes? (viewed 54769 times)
  208. How do you calculate the azimuth and altitude of an object? (viewed 54749 times)
  209. How do we measure the size of the Moon and of the Sun? (viewed 54706 times)
  210. Which constellation does our Sun belong to? (viewed 54596 times)
  211. What happens to a bullet fired on the moon? (viewed 54484 times)
  212. Can you see satellites? (viewed 54375 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 54280 times)
  214. How can I find the distance to the Sun on any given day? (viewed 53603 times)
  215. What other careers involve Astronomy besides Astronomer? (viewed 53372 times)
  216. Why do we see stars? (viewed 53186 times)
  217. Are aliens or UFOs real? (viewed 53038 times)
  218. Which hemisphere has the best view of the Milky Way? (viewed 52925 times)
  219. How can I measure the distance of a star? (viewed 52822 times)
  220. Is the speed of light constant? (viewed 52385 times)
  221. Where did all the water in the universe come from? (viewed 52148 times)
  222. Why is twilight short near the equator? (viewed 52005 times)
  223. Are there any asteroids on a collision course with Earth? (viewed 51990 times)
  224. Why is the sky blue and not blue & purple? (viewed 51847 times)
  225. How long has there been water on Earth? (viewed 51797 times)
  226. What are some astronomy science fair projects? (viewed 51778 times)
  227. Are meteorites hot or cold when they hit Earth? (viewed 51692 times)
  228. What would happen if the Moon fell out of its orbit around Earth? (viewed 51405 times)
  229. What do a galaxy's colors mean? Are they its true colors? (viewed 51308 times)
  230. Would your weight change as you go underground? (viewed 51177 times)
  231. Is time travel possible? (viewed 50782 times)
  232. Can we look back far enough in time to see the Big Bang? (viewed 50702 times)
  233. Who discovered each planet? (viewed 50564 times)
  234. Why does the Moon look big on the horizon? (viewed 50542 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 50310 times)
  236. What skills do astronomers need? (viewed 49984 times)
  237. How is the time of sunrise calculated? (viewed 49858 times)
  238. Are the planes of solar systems aligned with the plane of the Galaxy? (viewed 49716 times)
  239. Why is it difficult to understand the expansion of the universe? (viewed 49676 times)
  240. What is the difference between nutation and precession of the Earth? (viewed 49674 times)
  241. What's the difference between astronomy and astrophysics? (viewed 49218 times)
  242. How do we know what other planets (and stars, galaxies, etc.) are made of? (viewed 49215 times)
  243. What is a graviton? (viewed 49196 times)
  244. If light has no mass, then what draws it into a black hole? (viewed 48709 times)
  245. Why do the size and brightness of the full moon change? (viewed 47244 times)
  246. What do I need to do to become an astronomer? (viewed 47168 times)
  247. Do supermassive black holes cause galaxy rotation? (viewed 47014 times)
  248. How do gravitons escape black holes to tell the universe about their gravity? (viewed 46851 times)
  249. Do dead stars still shine? (viewed 46761 times)
  250. Why are most months 30 or 31 days long? (viewed 46700 times)
  251. Why does the Sun appear larger on the horizon than overhead? (viewed 46519 times)
  252. What is a wormhole? (viewed 46502 times)
  253. How are black holes discovered? (viewed 46480 times)
  254. Can we find the place where the Big Bang happened? (viewed 46272 times)
  255. The Moon slows the Earth's rotation, but how fast was it spinning billions of years ago? (viewed 46016 times)
  256. Will we get sucked into the black hole at the center of the Milky Way? (viewed 45611 times)
  257. Why are there stars? (viewed 45573 times)
  258. Where is the nearest black hole? (viewed 45566 times)
  259. Is the Earth slowly getting larger? (viewed 45553 times)
  260. Why can't we see Venus at night when it is an inner planet? (viewed 45506 times)
  261. Can the acceleration of the Universe be analogous to apparent acceleration in a airplane? (viewed 45259 times)
  262. How do galaxies collide in an expanding universe? (viewed 45236 times)
  263. Can I calculate the size of the Universe by converting light years to kilometres? (viewed 44951 times)
  264. Why don't people walk upside-down on the bottom of the Earth? (viewed 44627 times)
  265. Why does Barnard 68 appear dark? (viewed 44526 times)
  266. Are Kuiper Belt Objects asteroids? Are large Kuiper Belt Objects planets? (viewed 44237 times)
  267. Did life originate on Earth, or did it come from somewhere else? (viewed 44137 times)
  268. Are there eclipses on other planets? (viewed 43614 times)
  269. What is the best way to see the Milky Way? (viewed 43237 times)
  270. How does Astronomy involve Chemistry? (viewed 43171 times)
  271. Could the Universe have expanded faster than the speed of light at the Big Bang? (viewed 43146 times)
  272. Is there a "South Star"? (viewed 43135 times)
  273. Why does the location of sunrise change? (viewed 43014 times)
  274. Has there been an experiment that measured speed faster than the speed of light in vacuum? (viewed 42942 times)
  275. How long could life on Earth survive if the Sun stopped shining? (viewed 42871 times)
  276. What is the difference between the "Doppler" redshift and the "gravitational" or "cosmological" redshift? (viewed 42848 times)
  277. Was the Sun made in a supernova? (viewed 42700 times)
  278. How much can the location of sunset differ from due West? (viewed 42620 times)
  279. What is the biggest crater recorded on Earth? (viewed 42608 times)
  280. How would the weather on Earth be different if it were a cube? (viewed 42514 times)
  281. Why doesn't dark matter fall into a black hole? (viewed 42351 times)
  282. How much longer will the Earth last? (viewed 42272 times)
  283. What happens to spacetime inside a black hole? (viewed 41985 times)
  284. Can I buy land on the Moon? (viewed 41632 times)
  285. Why does the Earth only see one side of the Moon? (viewed 41560 times)
  286. Is the Moon hollow? (viewed 41396 times)
  287. What are the names of the three stars in Orion's belt? (viewed 41349 times)
  288. What happens when two black holes get too close? (viewed 41346 times)
  289. What's the biggest meteorite? (viewed 40927 times)
  290. What color would Mars be if you were standing on it? (viewed 40891 times)
  291. What is time dilation? (viewed 40884 times)
  292. What if the Earth rotated twice as fast? (viewed 40830 times)
  293. What is the most distant known galaxy? (viewed 40619 times)
  294. How can two moons of Saturn share the same orbit? (viewed 40493 times)
  295. Why do people draw stars with five points? (viewed 40351 times)
  296. How do we feel heat? (viewed 40274 times)
  297. Could someone travel the universe in his or her own lifetime? (viewed 40270 times)
  298. Is it possible to see the full Moon and the Sun simultaneously in high northern latitudes when the Sun doesn't set? (viewed 40060 times)
  299. Can terrestrial planets have rings? (viewed 40039 times)
  300. Why can we see the sun's image before sunrise and after sunset? (viewed 39941 times)
  301. How long would it take for a mini-black hole to eat the Earth? (viewed 39743 times)
  302. What are "blue stragglers" in globular clusters? (viewed 39699 times)
  303. How many Astronauts have been in space? (viewed 39619 times)
  304. How fast does the Earth go at perihelion and aphelion? (viewed 39373 times)
  305. How do we know that nuclear fusion is still going on in the Sun? (viewed 39327 times)
  306. Why do pictures of distant galaxies have higher resolution than those of nearby planets? (viewed 39180 times)
  307. Is the Sun always up for exactly 12 hours at the equator? (viewed 39063 times)
  308. If a white dwarf is a "dead" star, why is it so hot? (viewed 38964 times)
  309. What is the typical size of a visible shooting star? (viewed 38963 times)
  310. Does the Sun have an iron surface? (viewed 38933 times)
  311. Do you think it's possible to maintain life on other planets? (viewed 38903 times)
  312. Why are Saturn's rings flat? (viewed 38785 times)
  313. Why do clocks turn in the opposite direction from the Earth and Moon? (viewed 38750 times)
  314. Is the Great Wall the largest galaxy cluster? (viewed 38700 times)
  315. Does Mt. Everest cast a shadow on the moon? (viewed 38661 times)
  316. On which days can I see the Moon in the evening / morning and why is this so? (viewed 38503 times)
  317. What is a dimension? (viewed 38481 times)
  318. How does night and day work? (viewed 38477 times)
  319. Can you see the future as you fall into a black hole? (viewed 38445 times)
  320. Who (and when) discovered that the earth's axis is on a 23 degree tilt? (viewed 38416 times)
  321. Can a person go into a black hole and come out alive? (viewed 38274 times)
  322. Where do planetary rings come from, and what are they made of? (viewed 38133 times)
  323. Can I communicate faster than light? (viewed 38084 times)
  324. What is the speed of gravity? (viewed 37894 times)
  325. Are all stars the same? (viewed 37867 times)
  326. What is Earthrise over the Moon? (viewed 37781 times)
  327. What companies or businesses can astronomers work for? (viewed 37703 times)
  328. How do we define distance in an expanding universe? (viewed 37683 times)
  329. How do we determine the age of the universe? (viewed 37616 times)
  330. What is the approximate GPA needed in High School in Math and Science to be an astronomer? (viewed 37559 times)
  331. Where is the supernova remnant that led to our solar system? (viewed 37541 times)
  332. What can I use for fuel in my homemade rocket? (viewed 37481 times)
  333. How big is the universe? (viewed 37451 times)
  334. Why is sea water salty, and not lake water? (viewed 37169 times)
  335. Is there really a 10th planet? (viewed 37165 times)
  336. Is there a beginning and an end to a galaxy's life? (viewed 36977 times)
  337. How can the universe be "flat"? We're 3D! (viewed 36950 times)
  338. If the universe is 15 billion years old, how can it be larger than 15 billion light years across? (viewed 36828 times)
  339. Does the Coriolis force determine which way my toilet drains? Does it affect black holes? (viewed 36825 times)
  340. How do we know the Milky Way is a spiral galaxy? (viewed 36662 times)
  341. What would happen to the Earth if an asteroid hit the Moon? (viewed 36633 times)
  342. How many stars can I see? (viewed 36573 times)
  343. How are photons created and destroyed? (viewed 36562 times)
  344. How do I tell which planet is which? (viewed 36422 times)
  345. Why are there blue shifted galaxies? (viewed 36079 times)
  346. Do the Sun's or Earth's magnetic field reverse? (viewed 35980 times)
  347. How can I find my age on another planet? (viewed 35789 times)
  348. Can a lunar and a solar eclipse happen in the same month? When will this happen next? (viewed 35604 times)
  349. How are planets detected around other stars? (viewed 35440 times)
  350. Is Andromeda part of the Milky Way? Where can I find them in the sky? (viewed 35391 times)
  351. Why have star signs shifted by one constellation? (viewed 35381 times)
  352. How does the brightness of a star depend on its distance from us? (viewed 35368 times)
  353. Why can't a plane fly slowly and let the Earth pass underneath? (viewed 35335 times)
  354. What is the pattern to the distances between each planet and the sun? (viewed 35320 times)
  355. Why do humans want to go in space? (viewed 35313 times)
  356. What kind of eyepieces do I need to look at planets? (viewed 35293 times)
  357. Will we ever stop having solar eclipses because of the moon's motion away from the Earth? (viewed 35163 times)
  358. What is the significance of the second focus of elliptical orbits of planets in our Solar System? (viewed 35027 times)
  359. Who came up with the name "black hole"? (viewed 34752 times)
  360. What was that really big falling star that I saw? (viewed 34710 times)
  361. How can we estimate the number of Earth-like planets in the Galaxy? (viewed 34689 times)
  362. How do astronauts communicate with their families from space? (viewed 34681 times)
  363. What would happen if two stars collided? (viewed 34672 times)
  364. Is there a simple formula to calculate solar eclipse timings from any position on Earth? (viewed 34421 times)
  365. Is the Earth at the centre of the Universe? (viewed 34396 times)
  366. How hot is each one of the layers of the sun? (viewed 34348 times)
  367. When we look back to the Big Bang, why don't we see the universe as a tiny speck of matter? (viewed 34312 times)
  368. How is it that we see farther out in space (farther back in time) than in the past? (viewed 34207 times)
  369. Can you describe a day on the job as an astronomer? (viewed 34207 times)
  370. Why don't astronomers use everyday units to measure distances (what is an AU or a pc)? (viewed 34203 times)
  371. Will the Moon be invisible in 500 million years? (viewed 33931 times)
  372. How do I become both an astronaut and an astronomer? (viewed 33905 times)
  373. Are Earth and the Moon "twin planets"? (viewed 33547 times)
  374. Is the Local Group expanding along with the entire Universe? (viewed 33547 times)
  375. Why is our solar system so different from all the others we've found? (viewed 33504 times)
  376. How dangerous are the asteroids? (viewed 33496 times)
  377. Which American colleges teach astronomy? (viewed 33440 times)
  378. Why is Uranus tipped on its side? (viewed 33401 times)
  379. How do sunrise and sunset times change with altitude? (viewed 33301 times)
  380. Can we colonize other planets? (viewed 33098 times)
  381. Why do constellations look the same after several years even though all the stars are moving? (viewed 32838 times)
  382. Is it true that the Sun burns off a billion tons of gas every 5 seconds? (viewed 32644 times)
  383. Why are there no craters on Earth? Did all the meteorites miss us? (viewed 32629 times)
  384. Is the universe really like an expanding balloon? (viewed 32605 times)
  385. Why do astronauts in space need to exercise? (viewed 32440 times)
  386. What are quasars made of? (viewed 32428 times)
  387. How can I calculate distances between stars? (viewed 32408 times)
  388. Is the gravitational force exerted by the Earth on the Moon equal to the centripetal force acting on the Moon? (viewed 32406 times)
  389. Can superheavy elements (such as Z=116 or 118) be formed in a supernova? Can we observe them? (viewed 32152 times)
  390. Why doesn't gravity change the speed of light? (viewed 32121 times)
  391. What is dark matter? (viewed 32023 times)
  392. Is it possible to count the stars? (viewed 31833 times)
  393. Is time travel possible using merging black holes? (viewed 31681 times)
  394. How big a change in the Earth's orbit would be required to destroy all life? (viewed 31672 times)
  395. What is happening just around the black hole in the center of the Milky Way? (viewed 31594 times)
  396. Can we see dead stars with the naked eye? (viewed 31516 times)
  397. Did the speed of light change over the history of the universe? (viewed 31510 times)
  398. How do we measure distances to other stars? (viewed 31422 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 31389 times)
  400. Why is the time between two successive full moons different from the lunar synodic month? (viewed 31332 times)
  401. How do I make a scale model of the Solar System? (viewed 31320 times)
  402. What happens when an antimatter black hole collides with a matter blackhole? (viewed 31163 times)
  403. Are time machines possible? (viewed 30992 times)
  404. How many moles of stars are in the known universe? (viewed 30807 times)
  405. How can we tell what the interiors of planets are like? (viewed 30786 times)
  406. Does the Milky Way spin counter-clockwise? If so, do all spiral galaxies spin in this direction and why? (viewed 30698 times)
  407. What would happen if a human were exposed to space without wearing a spacesuit? (viewed 30659 times)
  408. How are galaxy distances inferred from their recessional velocities? (viewed 30620 times)
  409. Do we see the same stars from above and below the equator? (viewed 30597 times)
  410. What happens when you change the mass of a White Dwarf or Neutron Star? (viewed 30577 times)
  411. What do "homogeneity" and "isotropy" mean? (viewed 30523 times)
  412. What is the farthest in space that we have gone? (viewed 30299 times)
  413. Will the seasons change due to precession? (viewed 30151 times)
  414. Is there any limitation to what a black hole can "suck" in? (viewed 30140 times)
  415. Can astronauts produce water in space? (viewed 30043 times)
  416. How can we know that there are other galaxies if we cannot leave ours? (viewed 30007 times)
  417. How was the starting point for the Julian Date system chosen? (viewed 29975 times)
  418. What are the closest and/or brightest stars? (viewed 29933 times)
  419. Aren't jobs in astronomy scarce? (viewed 29855 times)
  420. How can I tell if the rock I found is a meteorite? (viewed 29814 times)
  421. How do we know if the universe will keep expanding forever? (viewed 29794 times)
  422. What's that dark spot on the Sun? (viewed 29787 times)
  423. Why does the SETI project search for radio signals? (viewed 29649 times)
  424. How long does it take the Big Dipper to move in the sky? (viewed 29621 times)
  425. Do astronomers believe in astrology? (viewed 29605 times)
  426. Did I see the Aurora Borealis as a child? (viewed 29502 times)
  427. Why do we study black holes? (viewed 29490 times)
  428. Why do most moons orbit their planets at the equator? (viewed 29350 times)
  429. When are there 5 Sundays in February? (viewed 29328 times)
  430. What are the facts about the Star of Bethlehem? (viewed 29306 times)
  431. Don't tachyons travel faster than light? (viewed 29225 times)
  432. Wouldn't the Big Bang theory be considered a hypothesis and not a theory? (viewed 29197 times)
  433. What are the atmospheres of Mars and Pluto like? (viewed 29177 times)
  434. Could an astronaut or satellite fall into a black hole that we didn't know about? (viewed 29124 times)
  435. Do you believe in UFOs? (viewed 29117 times)
  436. Can you use an infinite line of reflectors to send light to the edge of the Universe? (viewed 29020 times)
  437. What does the term "visible universe" mean? (viewed 28860 times)
  438. Could you tell me about the life cycle of galaxies? (viewed 28851 times)
  439. Does the Moon look different in the northern and southern hemispheres? (viewed 28830 times)
  440. What colors are visible through an amateur telescope? (viewed 28760 times)
  441. Has anyone made a map of the Milky Way? (viewed 28669 times)
  442. Was I hit by a meteorite? (viewed 28656 times)
  443. How are galaxies named? (viewed 28643 times)
  444. How can geometry be different in space? (viewed 28608 times)
  445. Why are the compositions of comets and asteroids different? (viewed 28455 times)
  446. Why do so many of the world's UFO sightings happen in America? (viewed 28421 times)
  447. What's the best thing about being an astronomer? (viewed 28261 times)
  448. Can two lunar eclipses occur in the same month? (viewed 28215 times)
  449. How do asteroids, meteors and comets disappear? (viewed 28086 times)
  450. How do astronomers measure the radius of a star? (viewed 28084 times)
  451. What is the origin of the stellar classification system "OBAFGKM"? (viewed 27885 times)
  452. How much time do astronomers spend looking through telescopes? (viewed 27880 times)
  453. Will winter and summer constellations change due to abnormal warmth or cold on Earth? (viewed 27765 times)
  454. How can we see galaxies if their stars are so faint? (viewed 27707 times)
  455. How do I explain to my children why the Moon has phases? (viewed 27684 times)
  456. How will the two black holes that are going to collide affect Earth? (viewed 27598 times)
  457. Have there been other Big Bangs before? (viewed 27594 times)
  458. How are galaxies and solar systems similar? (viewed 27567 times)
  459. Is there a project I can do on black holes? (viewed 27326 times)
  460. How close do you have to come to the Earth to be influenced by its gravity? (viewed 27317 times)
  461. Can life exist on the recently discovered extrasolar planets? (viewed 27308 times)
  462. Do the magnitudes and colors of stars ever change? (viewed 27281 times)
  463. Is the Milky Way a collision of two galaxies? (viewed 27208 times)
  464. Do asteroids hit the sun? (viewed 27162 times)
  465. How can we measure distances to more stars? (viewed 27158 times)
  466. Could you escape from a black hole if you were able to go faster than the speed of light? (viewed 27074 times)
  467. How do scientists slow light down? (viewed 27051 times)
  468. How close does a supernova need to be to damage the Earth's environment? (viewed 26863 times)
  469. Is infinite temperature possible? (viewed 26860 times)
  470. What supernova created the Crab nebula? (viewed 26824 times)
  471. Is it worthwhile to continue the search for extraterrestrial life? (viewed 26822 times)
  472. Can "tired light theory" explain the observed redshifts of galaxies? (viewed 26781 times)
  473. Do we know everything about the Sun? (viewed 26778 times)
  474. Can double stars have planets? (viewed 26726 times)
  475. What causes gamma ray bursts? (viewed 26674 times)
  476. Can a human give birth in space? (viewed 26655 times)
  477. Can one star orbit another? (viewed 26603 times)
  478. Is there oxygen in the atmospheres of other planets? (viewed 26465 times)
  479. How far does a galaxy extend? (viewed 26458 times)
  480. Which part of the sky did the famous 'wow' signal originate from? (viewed 26425 times)
  481. What will happen to the Milky Way in the future? (viewed 26342 times)
  482. Can astronauts play musical instruments in space? (viewed 26306 times)
  483. How do I polar align my telescope? (viewed 26287 times)
  484. What is sidereal time? (viewed 26240 times)
  485. Which way does the sun travel in the southern hemisphere? (viewed 26218 times)
  486. What type of energy does a black hole have? (viewed 26175 times)
  487. Why did the Pioneer and Voyager take only 2 years to reach Jupiter, while Galileo and Cassini took more than 5 years? (viewed 26153 times)
  488. What is the farthest Northern Latitude in which the Magellanic Clouds can be seen? (viewed 26144 times)
  489. Is there such a thing as hyperspace? (viewed 26144 times)
  490. What happens to the material that has been sucked into a black hole? (viewed 26085 times)
  491. What is a Cepheid variable? (viewed 26074 times)
  492. What is "nothing", from a scientific point of view? (viewed 26044 times)
  493. Is there sound coming from the Sun? (viewed 26044 times)
  494. What's the object I saw that moved across the sky and then got very bright? (viewed 26028 times)
  495. Why do the explosions of Type Ia supernovae have a more predictable spectrum than those of regular Type II supernovae? (viewed 26018 times)
  496. How different would the night sky have looked in 40,000 B.C.? (viewed 25996 times)
  497. When did people discover that the Sun is a star? (viewed 25937 times)
  498. How will a change in the speed of light affect the evolution of the Universe? (viewed 25875 times)
  499. Are planetary nebulae the result of supernovae? (viewed 25771 times)
  500. Why is the shadow on the Moon the shape it is? (viewed 25737 times)
  501. Why do we assume that the universe is homogeneous? (viewed 25687 times)
  502. How do we know what parameters to use when simulating the collision of the Milky Way and Andromeda? (viewed 25613 times)
  503. If we invented special suits could we ever go to the sun? (viewed 25596 times)
  504. How do we know that sunspots are associated with the Sun's magnetic field? (viewed 25589 times)
  505. When unmanned spacecraft accelerate in space, what causes them to slow down? (viewed 25582 times)
  506. What is the difference between homogeneity and isotropy? (viewed 25471 times)
  507. What calculations go into predicting eclipses? (viewed 25444 times)
  508. What is our galaxy's halo made of, and how was it formed? (viewed 25444 times)
  509. Are there any dark stars or dark galaxies made of dark matter? (viewed 25434 times)
  510. Was Stonehenge built to mark solar phenomena? (viewed 25292 times)
  511. Can I see a quasar? (viewed 25281 times)
  512. How many sunspots can the Sun have at once? (viewed 25254 times)
  513. Is there a list of the sizes of different kinds of stars? (viewed 25235 times)
  514. How are asteroid compositions and classifications determined? (viewed 25213 times)
  515. What process would bring about a quark star? (viewed 25203 times)
  516. What's so exciting about the new planet around 55 Cancri? (viewed 25110 times)
  517. Can any comparison be made between spiral galaxies and hurricanes? (viewed 25108 times)
  518. Can I see details on Venus? (viewed 25103 times)
  519. Did a giant impact cause the Dark Ages? (viewed 25089 times)
  520. Why are there more maria on the near side of the Moon? (viewed 25035 times)
  521. What is a Dyson Sphere? (viewed 25019 times)
  522. What happened to the girl who named Pluto? (viewed 24994 times)
  523. Have gravitational waves been proven to exist? (viewed 24993 times)
  524. Would the biggest airplanes cause tsunamis if they crashed? (viewed 24895 times)
  525. What happened to all the black holes that were around in the early universe? (viewed 24888 times)
  526. What equipment do I need for astrophotography? (viewed 24855 times)
  527. Why are telescopes kept in cold conditions? (viewed 24822 times)
  528. How is it proved that the Universe is expanding? (viewed 24820 times)
  529. How big is the Hubble Ultra Deep Field image? (viewed 24802 times)
  530. Does Cerenkov radiation travel faster than light? (viewed 24747 times)
  531. Why are there active volcanos on Io? (viewed 24724 times)
  532. Is there any possibility that the Solar System or the Universe is in a black hole? (viewed 24638 times)
  533. If clocks run slow in a gravitational field, how can we know the true age of the Solar System and Universe? (viewed 24519 times)
  534. If the Universe was infinitely dense at the Big Bang, why didn't time stand still? (viewed 24460 times)
  535. How can we compare dark matter and dark energy? (viewed 24425 times)
  536. How big was the Sun when it first "fired up"? (viewed 24404 times)
  537. How long do supernova remnants last? (viewed 24364 times)
  538. What caused Shoemaker-Levy 9 to split up? (viewed 24283 times)
  539. Why do photos of space taken from space never show any stars? (viewed 24249 times)
  540. How do solar flares affect airline pilots? (viewed 24247 times)
  541. Could we send a space mission to a comet? (viewed 24246 times)
  542. Can you give me advice on buying a telescope? (viewed 24197 times)
  543. Why doesn't light from distant galaxies reach us instantaneously? (viewed 24157 times)
  544. How are sunspots formed? (viewed 24109 times)
  545. Could we be seeing dead stars? (viewed 24030 times)
  546. How does the Earth compare in size to the entire universe at the present epoch? (viewed 24021 times)
  547. Could a different theory of gravity explain the dark matter mystery? (viewed 23998 times)
  548. Can I build an instrument to measure the size of the Sun and of the Moon? (viewed 23973 times)
  549. How can I contribute to science as an amateur astronomer? (viewed 23961 times)
  550. Why is it important to study meteorites? (viewed 23945 times)
  551. Where does the kinetic energy of infalling bodies come from? (viewed 23944 times)
  552. Why doesn't NASA build rotating spacecraft to simulate gravity? (viewed 23943 times)
  553. As the universe expands, why don't galaxies get stretched out? (viewed 23901 times)
  554. How many comets are currently orbiting our sun? (viewed 23839 times)
  555. Why are telescopes located in remote places? (viewed 23821 times)
  556. Can you tell time by the Big Dipper? (viewed 23749 times)
  557. Did I really hear a meteor? (viewed 23743 times)
  558. Why is the Hubble Space Telescope in space? (viewed 23712 times)
  559. Are the asteroids the remains of a planet which broke apart? (viewed 23707 times)
  560. How do unmanned space probes avoid running into things? (viewed 23668 times)
  561. How do we know that superclusters are the largest structures in the universe? (viewed 23603 times)
  562. How powerful are quasars? (viewed 23559 times)
  563. Would extraterrestrial civilizations know that there is life on Earth? (viewed 23557 times)
  564. How is the Cepheid yardstick validated? (viewed 23497 times)
  565. Do the Earth's magnetic poles ever change places? (viewed 23454 times)
  566. Do unmanned spacecraft like Voyager travel in straight lines? (viewed 23426 times)
  567. Did time go slower just after the Big Bang? (viewed 23375 times)
  568. Do galaxies orbit around anything? (viewed 23326 times)
  569. Can supernovae hinder the formation of life in galaxies? (viewed 23321 times)
  570. Why are stars of different masses? (viewed 23310 times)
  571. Are there any new craters on the moon? (viewed 23305 times)
  572. Why can't relative velocities add up to more than the speed of light? (viewed 23268 times)
  573. How could galaxies have gotten so far away in only 15 billion years? (viewed 23264 times)
  574. What would happen if there was a collision between two white dwarfs? (viewed 23257 times)
  575. What kind of instruments are used to detect extrasolar planets? (viewed 23248 times)
  576. Do similar laws of physics throughout the Universe imply that all life must be like life on Earth? (viewed 23209 times)
  577. How do I become an astronomical artist? (viewed 23203 times)
  578. How do planets capture satellites? (viewed 23177 times)
  579. How are astronomy and poetry linked? (viewed 23094 times)
  580. Could there have been multiple Big Bangs at different places in the universe? (viewed 23084 times)
  581. What kind of telescope should I use for astrophotography? (viewed 23052 times)
  582. Could dark energy come from matter anti-matter pairs forming spontaneously and then annihilating? (viewed 22940 times)
  583. Why is NASA shutting down the Hubble Space Telescope? (viewed 22842 times)
  584. Can I listen to the SETI@home radio signal? (viewed 22838 times)
  585. How can you tell if a crescent moon is preceding or following a new-moon phase? (viewed 22801 times)
  586. Does the Sun have any heavy elements? (viewed 22730 times)
  587. Are the properties of extrasolar planets known? (viewed 22626 times)
  588. How do astronomers observe the Sun's interior? (viewed 22610 times)
  589. What class of spiral galaxy is the Milky Way? (viewed 22604 times)
  590. 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 22596 times)
  591. Can the theory of formation of the solar system explain all the observables? (viewed 22585 times)
  592. Will we discover an 11th planet? What would it be called? (viewed 22547 times)
  593. What month was it when Odysseus saw Orion in 1000BC? (viewed 22436 times)
  594. Where was the water in the big bang? (viewed 22254 times)
  595. What makes a satellite geosyncronise itself with Earth's orbit? (viewed 22200 times)
  596. Is it possible for amateurs to do optical interferometry? (viewed 22176 times)
  597. Could we send a manned mission to the outer planets? (viewed 22145 times)
  598. Why does the apparent density of galaxies drop off at larger distances? (viewed 22144 times)
  599. Why does one side of Mars look more catastrophic than the other? (viewed 22138 times)
  600. Would a planet near the galactic center have a brighter night sky? (viewed 22063 times)
  601. How can water be chemically trapped in rocks? (viewed 21991 times)
  602. Do stars' orbits in galaxies obey Kepler's Laws? (viewed 21928 times)
  603. Why do spacecraft need heat shields coming back to Earth but not leaving? (viewed 21906 times)
  604. What is the solar cycle? (viewed 21795 times)
  605. Can other terrestrial moons be (or have been) stable? (viewed 21772 times)
  606. Why was the Platonic year named after Plato? (viewed 21762 times)
  607. Why are accretion disks flat? (viewed 21714 times)
  608. What would the Big Crunch look like to an observer on Earth? (viewed 21667 times)
  609. How are supernovae discovered? (viewed 21658 times)
  610. What is meant by "stopping down a telescope"? (viewed 21558 times)
  611. Can a black hole come back to the visual universe through a "little bang"? (viewed 21553 times)
  612. Does inflation allow for an infinite number of universes? (viewed 21523 times)
  613. Why doesn't the hydrogen on Jupiter explode? (viewed 21462 times)
  614. Could our position in the universe affect our perceptions of the expansion? (viewed 21455 times)
  615. How can the Sun have such a strong gravitational field if it's made of gasses? (viewed 21455 times)
  616. Did I find a rock that came from the Moon? (viewed 21230 times)
  617. Have astronomers observed any phenomena that could be produced by extraterrestrial civilizations? (viewed 21220 times)
  618. What is the SU(3) quark model? (viewed 21186 times)
  619. Can gravitational lensing from intervening galaxies cause the observed ripples in the Cosmic Microwave Background? (viewed 21149 times)
  620. Does a photon observe other photons moving past it at the speed of light? (viewed 21075 times)
  621. Will I be able to see the shadow of the Moon streaking towards me in a total solar eclipse? (viewed 21050 times)
  622. What's new with the Big Bang? (viewed 20865 times)
  623. Could photons be dark matter? (viewed 20831 times)
  624. How can we find galaxies behind the Milky Way? (viewed 20831 times)
  625. How fast do particles travel in space? (viewed 20779 times)
  626. Why can we have solar eclipses? (viewed 20742 times)
  627. Why is the WMAP picture of the CMB an ellipse? (viewed 20735 times)
  628. Is it possible to build a cheap device to measure declination? (viewed 20733 times)
  629. Why search for only Earth-like life on other planets? (viewed 20724 times)
  630. If comets are boiling away, why are there any left? (viewed 20677 times)
  631. Where can I find information on the moons of other planets? (viewed 20657 times)
  632. Why do some eclipses take longer than others? (viewed 20612 times)
  633. How much power is contained in a beam of light? (viewed 20593 times)
  634. Can planets collide with one another? (viewed 20521 times)
  635. Do constellations looks the same from space? (viewed 20509 times)
  636. Why is pressure broadening greater in low mass stars than in high mass stars? (viewed 20461 times)
  637. What are the boundaries of the constellations? (viewed 20347 times)
  638. Did the Sumerians measure precession? (viewed 20323 times)
  639. What would an "open geometry" for the universe look like? (viewed 20322 times)
  640. What kinds of star clusters are there? (viewed 20230 times)
  641. Why is the Cosmic Microwave Background not absorbed by interstellar hydrogen? (viewed 20105 times)
  642. Why aren't discoveries of extrasolar planets reported on the news? (viewed 20101 times)
  643. How do astronomers come up with their facts? (viewed 20096 times)
  644. Why don't astronauts sublimate in space? (viewed 20086 times)
  645. How do photons from distant objects maintain enough energy to reach us? (viewed 20086 times)
  646. How do bars form in spiral galaxies? (viewed 20075 times)
  647. How did Mars get so dusty? (viewed 20048 times)
  648. What are collections of galaxies called? (viewed 20015 times)
  649. Can HST see the Oort cloud? (viewed 19922 times)
  650. Do electrons age? (viewed 19917 times)
  651. Can we make a movie of the Milky Way galaxy's rotation? (viewed 19826 times)
  652. Can the Space Shuttle abort and return to Earth before reaching orbit? (viewed 19775 times)
  653. How long is twilight on the Moon? (viewed 19771 times)
  654. Will astronauts ever be able to go ice-skating on Europa? (viewed 19686 times)
  655. How does melting a material reset its radioactive clock? (viewed 19669 times)
  656. Does the shuttle worry about space junk? (viewed 19630 times)
  657. Why don't all neutron stars become pulsars? (viewed 19580 times)
  658. Where can I see Newton's original reflecting telescope? (viewed 19566 times)
  659. Why do supernova remnants look like rings rather than spheres? (viewed 19561 times)
  660. How do you classify galaxies? (viewed 19544 times)
  661. If photons have zero mass, why do they feel the effects of gravity? (viewed 19486 times)
  662. How can we understand the meaning of large numbers like "a million million?" (viewed 19459 times)
  663. What is the best time of the year to see eclipses? (viewed 19402 times)
  664. Why doesn't SETI concentrate its observations to the nearby stars and the solar systems that we are discovering? (viewed 19392 times)
  665. What causes a particle to decay? (viewed 19337 times)
  666. Will the next generation telescope OWL be able to detect an Earth like extrasolar planet? (viewed 19312 times)
  667. Why is it called astronomy when all the other sciences end in -ology? (viewed 19266 times)
  668. How does the color index of a star relate to its actual color? (viewed 19200 times)
  669. How can I nominate myself for a Nobel Prize in Physics? (viewed 19194 times)
  670. How long has humanity known that we live in a galaxy similar to others in the Universe? (viewed 19164 times)
  671. Will the Leonid meteor shower go away? (viewed 19122 times)
  672. What are "curled" dimensions? (viewed 19025 times)
  673. If nothing can escape a black hole, why do some black holes have jets? (viewed 18943 times)
  674. Is light of different colors affected differently by gravity? (viewed 18934 times)
  675. How does interferometry work? (viewed 18865 times)
  676. Do asteroids ever do anything good in the Solar System? (viewed 18840 times)
  677. What was that eclipse I saw in the sky? (viewed 18827 times)
  678. How do distant galaxies differ from those nearby? (viewed 18787 times)
  679. Does the temperature of matter increase as it is accelerated to relativistic speeds? (viewed 18779 times)
  680. Are black holes spherical? (viewed 18768 times)
  681. What kind of interference must astronomers contend with when observing? (viewed 18765 times)
  682. What would happen if you went back in time and killed your grandmother? (viewed 18759 times)
  683. Wouldn't the vast distances of space distort SETI signals into unintelligeble forms? (viewed 18708 times)
  684. How do we find out about the star formation histories of galaxies? (viewed 18700 times)
  685. Why will fusion wait until hydrogen is gone before starting to fuse heavier atoms? (viewed 18614 times)
  686. Can astronomers observe anything when the moon is full? (viewed 18592 times)
  687. How can I watch the Perseid meteor shower? (viewed 18565 times)
  688. What do stellar classifications mean? (viewed 18519 times)
  689. Do we really observe the edges of galaxies at different epochs? (viewed 18479 times)
  690. Can you tell me the characteristics of W, R, N and S type stars? (viewed 18439 times)
  691. How are astronauts trained for weightlessness? (viewed 18385 times)
  692. Why aren't accretion disks around giant stars as hot as accretion disks around black holes? (viewed 18362 times)
  693. What is the three-body problem? (viewed 18361 times)
  694. If the universe is "bounded" today, could it one day become "unbounded"? (viewed 18137 times)
  695. Will the diameter of a cluster of galaxies change with redshift? (viewed 18093 times)
  696. Is cosmic expansion happening on microscopic scales? (viewed 17956 times)
  697. How can I find out if the new moon has been sighted? (viewed 17753 times)
  698. When measuring the expansion of the universe, do astronomers consider that they're seeing how galaxies moved long ago, not today? (viewed 17703 times)
  699. Could neutrinos be dark matter? (viewed 17645 times)
  700. Do we have to worry about relativity when studying galactic objects? (viewed 17593 times)
  701. How do supernovae show us that the Universe's expansion is accelerating? (viewed 17484 times)
  702. Does lunar gardening really work? (viewed 17470 times)
  703. What kinds of cancer research have been done in space? (viewed 17428 times)
  704. What happens to the helium formed in the sun? (viewed 17414 times)
  705. How does a star take mass from another star? (viewed 17293 times)
  706. Could the Universe's dark matter be made up of black holes? (viewed 17203 times)
  707. How can you tell the difference between single and multiple extrasolar planets? (viewed 17082 times)
  708. What is Hot Dark Matter theory? (viewed 17043 times)
  709. Is it a coincidence that we can have total solar eclipses? Are there other planets which also have them? (viewed 16811 times)
  710. How do we know the density of some extrasolar planets? (viewed 16744 times)
  711. Is the green flash real? (viewed 16682 times)
  712. What is the photoelectric effect? Why can't multiple low-frequency photons free an electron? (viewed 16669 times)
  713. How does libration allow us to see more than 50% of the Moon? (viewed 16514 times)
  714. How can observations of the distant universe prove that the expansion is accelerating *now*? (viewed 16492 times)
  715. Is light blueshifted when it is gravitationally lensed? (viewed 16366 times)
  716. Do binary or triple star systems form together? (viewed 16320 times)
  717. No matter how fast the universe is expanding, shouldn't gravity eventually make it recollapse? (viewed 16285 times)
  718. What do meteorites tell us about life on other planets? (viewed 16098 times)
  719. Why is it easier to see a star if you look slightly to the side? (viewed 16051 times)
  720. What percent of the time can astronomers observe without interference from the Moon? (viewed 16042 times)
  721. Can we prove that the Moon isn't hollow? (viewed 15980 times)
  722. If the sun went out and our atmosphere froze solid, what color would it be? (viewed 15912 times)
  723. Could matter-anti-matter repulsion power the expansion of the universe? (viewed 15800 times)
  724. What time is sunrise/sunset or moonrise/moonset at my location? (viewed 15697 times)
  725. How has light from 13 billion years ago not passed us by? (viewed 15638 times)
  726. Why doesn't the ammonia and methane in Jupiter's atmosphere sink into the core? (viewed 15608 times)
  727. How do we detect incoming meteorites? (viewed 15522 times)
  728. What was different on Mars in the past to allow liquid water to be present? (viewed 15419 times)
  729. Are there any 'lonely galaxies'? (viewed 15408 times)
  730. When will Hale-Bopp return? (viewed 15357 times)
  731. Why don't skydivers burn up like meteors? (viewed 15300 times)
  732. Has anyone ever seen a star "turn on"? (viewed 15094 times)
  733. 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 14958 times)
  734. Why are craters round? (viewed 14749 times)
  735. During close approaches, can Mars appear in our sky as large as the Moon? (viewed 14658 times)
  736. How are planets affected by the Hot Ionised Medium? (viewed 14470 times)
  737. Can the sun rise from the west on Mars? (viewed 14278 times)
  738. What are the largest radio wavelengths observed from radio sources in the sky? (viewed 14051 times)
  739. Why was Mir burnt up in the atmosphere? (viewed 14020 times)
  740. How can we discern different galaxies/clusters along the same line of sight? (viewed 13910 times)
  741. What is the relationship between the width of a star trail on a photo and the star's intensity? (viewed 13478 times)
  742. Can we harvest H & O from space to make water? (viewed 13323 times)
  743. Why does Titan, in spite of being smaller than Mars, have an atmosphere more dense than Earth's? (viewed 12981 times)
  744. What is between the Oort cloud and the closest star? (viewed 12774 times)
  745. Could a planetary system survive if its star merged with another, or if its star went supernova? (viewed 11941 times)
  746. Are there solar tides? (viewed 11851 times)
  747. What happens to the Earth as the moon gets farther away and will it ever go away entirely? (viewed 11783 times)
  748. Does weightlessness affect hunger? (viewed 11645 times)
  749. Is Earth-moon tidal friction causing global warming? (viewed 11460 times)
  750. Do planets radiate noise? (viewed 11227 times)
  751. Is the moon spherical? (viewed 11172 times)
  752. Is dark energy affected by black holes? (viewed 10922 times)
  753. Why is the Moon higher in the sky in winter and lower in the summer? (viewed 10881 times)
  754. What would happen if a nuclear-powered shuttle exploded? (viewed 10645 times)
  755. Where are the protons and electrons in a Neutron Star? (viewed 10527 times)
  756. Is the Moon always visible during winter on the North Pole? (viewed 10225 times)
  757. Wait, I'm still confused why information can't travel faster than the speed of light. (viewed 9956 times)
  758. Do more meteorites fall at low latitudes? (viewed 9699 times)
  759. Did the Moon or planets form in a manner similar to that of Earth? (viewed 9655 times)
  760. Will the Pioneer and Voyager probes ever leave the Milky Way? (viewed 9611 times)
  761. Will Comet Elenin (C/2010 X1) affect the Earth on its close approach in Fall 2011? (viewed 9608 times)
  762. What are the possible ends of the universe? (viewed 9587 times)
  763. If there are infinity universes, will every thing that is possible happen? (viewed 9422 times)
  764. Is it sensible to consider terraforming Mars? (viewed 9367 times)
  765. What color are meteors? (viewed 9040 times)
  766. Where is everybody? (viewed 8624 times)
  767. Why does Mars have a dusty atmosphere? (viewed 8258 times)
  768. Does the singularity in a black hole create a new Universe? (viewed 8125 times)
  769. The naming of Mars (viewed 8119 times)
  770. If I were traveling through space, could I see distant galaxies with my own eyes? (viewed 8073 times)
  771. Is the reddish dust of Mars biogenic? (viewed 7914 times)
  772. Where is the Spitzer Space Telescope? (viewed 7356 times)
  773. When will humans travel to Mars and revisit the Moon? (viewed 7121 times)
  774. Why do astronomers use telescopes? (viewed 6882 times)
  775. How likely is it for a planet to transit its star? (viewed 6557 times)
  776. Does the particles involved in a star's final core collapse travel faster than the speed of light? (viewed 6466 times)
  777. What causes the aurora? (viewed 6420 times)
  778. When is the best time to observe zodiacal light? (viewed 6298 times)
  779. How did a transit of Venus provide astronomers with the first measurement of the Earth-Sun distance? (viewed 5272 times)
  780. Can the Sun be closer to the Earth than any planet is to Earth? (viewed 4674 times)
  781. Cosmologists say the expansion of the universe is accelerating, what is driving this? (viewed 4086 times)
  782. Can we hear sound on Titan? (viewed 3848 times)
  783. Does the direction of the moon's crescent change through the night? (viewed 3695 times)
  784. What do all the angles in a table for a planet's orbit mean? (viewed 3552 times)
  785. How do I maximize my chances of seeing shooting stars? (viewed 2930 times)
  786. Are exoplanets real? (viewed 2525 times)
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