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 2138058 times)
  2. What color is each planet? (viewed 926698 times)
  3. At what speed does the earth move around the sun? (viewed 595816 times)
  4. Is the Moon moving away from the Earth? When was this discovered? (viewed 574826 times)
  5. How far is each planet from Earth? (viewed 475936 times)
  6. When will Halley's Comet return? (viewed 431210 times)
  7. How long does it take for the Sun's light to reach us? (viewed 395532 times)
  8. How many stars are there in our Galaxy (Milky Way)? (viewed 390813 times)
  9. Why do the planets orbit the sun? (viewed 387265 times)
  10. What is the universe expanding into? (viewed 374649 times)
  11. How do you measure the distance between Earth and the Sun? (viewed 348156 times)
  12. Which planets have rings? (viewed 324435 times)
  13. Why do stars twinkle? (viewed 322704 times)
  14. Does the Moon rotate? Are there other moons that always keep one face toward their planet? (viewed 306483 times)
  15. How do I build a model rocket? (viewed 292327 times)
  16. Can you hear sounds in space? (viewed 280318 times)
  17. What color is Venus? (viewed 275717 times)
  18. What is a white hole? (viewed 269621 times)
  19. What is the life cycle of a star? (viewed 247212 times)
  20. What are the names of the earth, moon, sun, and solar system? (viewed 241546 times)
  21. What is that ring (or rainbow) around the moon? (viewed 238689 times)
  22. What are the different kinds of astronomers? (viewed 237633 times)
  23. What makes the Earth rotate? (viewed 236637 times)
  24. What are shooting stars? (viewed 232368 times)
  25. What is the largest star? (viewed 222435 times)
  26. How do we know the age of the Universe and the Earth? (viewed 216126 times)
  27. Can artificial gravity be created in space? (viewed 214604 times)
  28. What do astronauts eat in space? Can they grow food? (viewed 213276 times)
  29. Why do planets rotate? (viewed 211330 times)
  30. Is the universe expanding faster than the speed of light? (viewed 207382 times)
  31. How does the location of sunrise and sunset change throughout the year? (viewed 201367 times)
  32. How can we see the Milky Way if we are inside it? (viewed 187148 times)
  33. Where did the name 'Earth' come from? (viewed 181932 times)
  34. What would happen if we did not have a Moon? (viewed 178125 times)
  35. Why is a day divided into 24 hours? (viewed 175873 times)
  36. Why isn't the sky bright at night if the universe has so many stars? (viewed 175495 times)
  37. How does the position of Moonrise and Moonset change? (viewed 175090 times)
  38. How many Earths fit into the Sun? (viewed 173788 times)
  39. Who named the planets and who decides what to name them? (viewed 163909 times)
  40. Why do airplanes take longer to fly West than East? (viewed 161767 times)
  41. When was the last time all 9 planets were aligned? (viewed 161150 times)
  42. Why are the Moon and Sun sometimes orange or red? (viewed 160134 times)
  43. Is the distance from the Earth to the Sun changing? (viewed 152338 times)
  44. Is Pluto a planet? (viewed 151531 times)
  45. What is at the end of the Universe? (viewed 150430 times)
  46. How can I find the star I have "bought"? (viewed 148194 times)
  47. How much money is spent on space exploration? (viewed 145860 times)
  48. What is a nova? (viewed 138573 times)
  49. Does your weight change between the poles and the equator? (viewed 135627 times)
  50. How do astronauts take baths and use restrooms in space? (viewed 134787 times)
  51. Can we feel the Earth spin? (viewed 133352 times)
  52. Why are there both high and low tides? (viewed 131876 times)
  53. What direction do planets rotate? (viewed 131842 times)
  54. Is the Sun expanding? Will it ever explode? (viewed 130015 times)
  55. What is the largest galaxy? (viewed 127715 times)
  56. Do stars move in the sky? (viewed 127025 times)
  57. How many known galaxies are there? (viewed 126553 times)
  58. What are the advantages and disadvantages of using a telescope in space? (viewed 122723 times)
  59. Why do all the planets orbit in the same plane? (viewed 121665 times)
  60. Can I buy a star? (viewed 118786 times)
  61. How are light and heavy elements formed? (viewed 117770 times)
  62. Will the sun go supernova in six years and destroy Earth (as seen on Yahoo)? (viewed 116081 times)
  63. What is the physical difference between a star and a planet? (viewed 115756 times)
  64. Are there telescopes that can see the flag and lunar rover on the Moon? (viewed 115118 times)
  65. Why hasn't NASA gone back to the moon? (viewed 114604 times)
  66. Why do planets have elliptical orbits? (viewed 114515 times)
  67. Does the Sun have a scientific name? (viewed 113636 times)
  68. Who first measured the speed of light? (viewed 113354 times)
  69. How do stars move in the Galaxy? (viewed 112841 times)
  70. What happens when galaxies collide? (viewed 112158 times)
  71. What is the hottest time of day? (viewed 112057 times)
  72. How do rockets work? (viewed 111282 times)
  73. What is the significance of the Tropic of Cancer, Tropic of Capricorn, Arctic Circle and Antarctic Circle? (viewed 110333 times)
  74. What is the size of the Solar System? (viewed 109665 times)
  75. What would happen if an impact caused Earth to stop rotating? (viewed 108650 times)
  76. How much money do astronomers make? (viewed 108595 times)
  77. Does evolution contradict the second law of thermodynamics? (viewed 108409 times)
  78. Will the magnetic field of the Earth reverse its direction in the future? Will this cause problems? (viewed 107781 times)
  79. What was there before the Big Bang and what is there outside of our universe? (viewed 107656 times)
  80. What will happen to life on Earth when the Sun becomes a red giant? (viewed 107574 times)
  81. When is the next comet due to arrive? (viewed 107152 times)
  82. How do you calculate the lifetime of the Sun? (viewed 107140 times)
  83. How long does a solar eclipse last? (viewed 106036 times)
  84. What elements make up the Sun? (viewed 105753 times)
  85. What do astronauts do all day in the International Space Station? (viewed 105359 times)
  86. Do black holes die? If so how? (viewed 105278 times)
  87. How many constellations are there? (viewed 104317 times)
  88. What is the observational difference between a star and a planet? (viewed 104209 times)
  89. What's the difference between astronomy and astrology? (viewed 102613 times)
  90. Does gravity vary across the surface of the Earth? (viewed 101941 times)
  91. Does the Sun rotate? (viewed 101808 times)
  92. What would happen if the gravity on Earth was suddenly turned off? (viewed 101143 times)
  93. Does the Sun move around the Milky Way? (viewed 100146 times)
  94. What are constellations used for? (viewed 97692 times)
  95. What is apparent magnitude? (viewed 97355 times)
  96. How many meteorites hit Earth each year? (viewed 97319 times)
  97. Which planet is most similar to Earth? (viewed 96924 times)
  98. Why do different stars appear with seasons? (viewed 95545 times)
  99. What kind of schooling is necessary to become an astronomer? (viewed 95493 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 92940 times)
  101. How do astronomers use math in their jobs? (viewed 92880 times)
  102. Is there a proof that Earth moves? (viewed 92206 times)
  103. How critical is the Earth-Sun distance in maintaining our average temperatures on Earth? (viewed 91555 times)
  104. Where did the Universe come from? (viewed 91069 times)
  105. Why are stars and planets round? (viewed 90958 times)
  106. Does the Sun orbit the Earth as well as the Earth orbiting the Sun? (viewed 90858 times)
  107. Why is the Universe flat and not spherical? (viewed 90453 times)
  108. Why is the Moon so bright? (viewed 90161 times)
  109. What makes the wind? (viewed 89532 times)
  110. How can a star burn with no oxygen? (viewed 89488 times)
  111. What is the difference between a "star" and a "sun"? (viewed 89085 times)
  112. What would happen if an asteroid 10 kilometers across hit the Earth? (viewed 88838 times)
  113. What is a singularity? (viewed 88830 times)
  114. Have astronomers discovered Earth's second moon? (viewed 88192 times)
  115. What are the requirements for being a planet? (viewed 86177 times)
  116. Why does the Earth tilt back and forward once a year? (viewed 84312 times)
  117. What are RA and DEC? (viewed 84188 times)
  118. Where does the name "Milky Way" come from? (viewed 83689 times)
  119. Since Earth is spinning, why do we land in the same place when we jump or fall? (viewed 82762 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 82184 times)
  121. What would happen if Earth had more than one moon? (viewed 81906 times)
  122. How many stars are born and die each day? (viewed 81142 times)
  123. Why aren't there any green stars? (viewed 79363 times)
  124. What kind of rock is the moon made of? (viewed 78707 times)
  125. Why is the moon in a different place every night? (viewed 78430 times)
  126. Did astronauts really go to the Moon, or is it a hoax? (viewed 78154 times)
  127. How are galaxies formed? (viewed 78053 times)
  128. How do we weigh objects in space? (viewed 76365 times)
  129. Will the Sun become a black hole one day? (viewed 76341 times)
  130. What is the density of a black hole? (viewed 75844 times)
  131. How are black holes made? Could one be made close to us? (viewed 75690 times)
  132. What would happen if a supermassive black hole came close to the Earth? (viewed 75394 times)
  133. Who has landed on the moon? (viewed 73905 times)
  134. How do rockets move in space? (viewed 73526 times)
  135. Can moons have moons? (viewed 73478 times)
  136. What happens to a substance if its speed is more than the speed of light? (viewed 73271 times)
  137. Do most astronomers believe in God based on the available scientific evidence? (viewed 73225 times)
  138. What would you see from inside a black hole? (viewed 73095 times)
  139. Why can't you see stars during the day? (viewed 73039 times)
  140. Does the Mediterranean sea have tides? (viewed 72694 times)
  141. What would happen if you took off your helmet in space? (viewed 72664 times)
  142. How often does the Sun pass through a spiral arm in the Milky Way? (viewed 72523 times)
  143. How do astronomers measure the brightness of stars? (viewed 72367 times)
  144. When the Sun converts mass to energy, do the orbits of the planets change? (viewed 72360 times)
  145. What are some of the effects of solar flares on Earth? (viewed 71843 times)
  146. How can the Universe expand faster than the speed of light during inflation? (viewed 71780 times)
  147. Can you fire a gun on the Moon? (viewed 71638 times)
  148. What is the evidence supporting the nebula theory of Solar System formation? (viewed 71595 times)
  149. How do we know the mass of the Earth and the Moon? (viewed 71229 times)
  150. Why do we not have eclipses every month? (viewed 70712 times)
  151. How is astronomy impacted by trigonometry? (viewed 70637 times)
  152. Is it possible to measure the temperature of the Sun? (viewed 70065 times)
  153. How do you measure a planet's mass? (viewed 69909 times)
  154. How does the Moon stay "suspended" in the air? (viewed 69399 times)
  155. Why do stars change colour when they twinkle? (viewed 69337 times)
  156. How does the Sun compare to other stars? (viewed 69040 times)
  157. How are elements heavier than iron formed? (viewed 68947 times)
  158. What are the "dog days of summer"? (viewed 67460 times)
  159. Does quantum entanglement imply faster than light communication? (viewed 66353 times)
  160. What kinds of jobs do astronomers do? (viewed 66287 times)
  161. If the universe is infinite does that mean there is an infinite number of "me"s? (viewed 65481 times)
  162. How long would it take the Earth to fall into the Sun? (viewed 64855 times)
  163. Where does the name "Moon" come from? (viewed 64747 times)
  164. How did the stars get named? (viewed 64684 times)
  165. How do you measure the mass of a star? (viewed 64673 times)
  166. How does light pollution affect astronomers? (viewed 64670 times)
  167. What are black holes made of? (viewed 64488 times)
  168. Where did the matter in the universe come from? (viewed 64216 times)
  169. Why doesn't the earliest sunset occur on the shortest day of the year? (viewed 64081 times)
  170. What causes seasons? (viewed 64039 times)
  171. Are there stars outside of galaxies? (viewed 63940 times)
  172. Traveling at light speed, how long would it take to get to the nearest galaxy? (viewed 63883 times)
  173. How did asteroids form and what is the difference between an asteroid and a comet? (viewed 63875 times)
  174. What are Altitude and Azimuth? (viewed 63873 times)
  175. How fast is the Universe expanding? (viewed 63277 times)
  176. When can I see the Moon through the hole in the Pantheon? (viewed 63178 times)
  177. Why do planets not twinkle? (viewed 62442 times)
  178. What's the best college for astronomy? (viewed 62351 times)
  179. Where, in relation to the entire universe, is the Milky Way located? (viewed 62342 times)
  180. What would happen to us if the sun went out for an hour? (viewed 61893 times)
  181. What's the difference between dark matter and dark energy? (viewed 61780 times)
  182. Why doesn't the length of each day change much around the solstices? (viewed 61746 times)
  183. What is the mass of the Universe? (viewed 60865 times)
  184. Why does the Sun's apparent path through the sky change throughout the year? (viewed 60798 times)
  185. How does astronomy benefit humankind? (viewed 60427 times)
  186. Why is looking out into space the same as looking back in time? (viewed 60306 times)
  187. How can I calculate the position or path of the Sun for a given time and location? (viewed 60032 times)
  188. How does the parachute in a model rocket work? (viewed 59486 times)
  189. Why does the Earth have only one moon? (viewed 59407 times)
  190. Does the Moon rotate? (viewed 59372 times)
  191. Could there be life in the galaxies nearest to the Milky Way? (viewed 59275 times)
  192. What can we learn from the color of a star? (viewed 59092 times)
  193. What is the origin of spiral structure in galaxies? (viewed 59073 times)
  194. Can any galaxies be seen with the naked eye? (viewed 59028 times)
  195. How close was the Moon to the Earth when it formed? (viewed 58775 times)
  196. How long does the supernova stage of a star last? (viewed 58220 times)
  197. What makes up most of the Universe? (viewed 58125 times)
  198. How do the astronauts communicate in space if sound cannot travel in a vacuum? (viewed 57135 times)
  199. What is the shape of the universe? (viewed 56851 times)
  200. If gravity is a "curvature of space" rather than a force, why do a ball and bullet follow different paths? (viewed 56525 times)
  201. Why isn't the summer solstice the hottest day of the year? (viewed 56353 times)
  202. How do astronauts use math in their jobs? (viewed 56322 times)
  203. What is a star's "spectrum"? (viewed 56194 times)
  204. What is the largest structure in the universe? (viewed 55943 times)
  205. What is the size of a black hole? (viewed 55529 times)
  206. Where are stars born? (viewed 55442 times)
  207. How do we measure the size of the Moon and of the Sun? (viewed 55400 times)
  208. How do you calculate the azimuth and altitude of an object? (viewed 55274 times)
  209. What happens to a bullet fired on the moon? (viewed 55254 times)
  210. 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 55007 times)
  211. Which constellation does our Sun belong to? (viewed 54980 times)
  212. Are names given to black holes? (viewed 54908 times)
  213. Can you see satellites? (viewed 54550 times)
  214. How can I find the distance to the Sun on any given day? (viewed 54182 times)
  215. What other careers involve Astronomy besides Astronomer? (viewed 53767 times)
  216. Why do we see stars? (viewed 53494 times)
  217. Which hemisphere has the best view of the Milky Way? (viewed 53474 times)
  218. Are aliens or UFOs real? (viewed 53278 times)
  219. Where did all the water in the universe come from? (viewed 53193 times)
  220. How can I measure the distance of a star? (viewed 53129 times)
  221. Why is twilight short near the equator? (viewed 52874 times)
  222. Is the speed of light constant? (viewed 52813 times)
  223. Are meteorites hot or cold when they hit Earth? (viewed 52445 times)
  224. Are there any asteroids on a collision course with Earth? (viewed 52330 times)
  225. Why is the sky blue and not blue & purple? (viewed 52319 times)
  226. How long has there been water on Earth? (viewed 52236 times)
  227. What do a galaxy's colors mean? Are they its true colors? (viewed 52083 times)
  228. What are some astronomy science fair projects? (viewed 51958 times)
  229. What would happen if the Moon fell out of its orbit around Earth? (viewed 51898 times)
  230. Would your weight change as you go underground? (viewed 51742 times)
  231. Can we look back far enough in time to see the Big Bang? (viewed 51134 times)
  232. Is time travel possible? (viewed 51019 times)
  233. Why does the Moon look big on the horizon? (viewed 50879 times)
  234. Who discovered each planet? (viewed 50850 times)
  235. How is the time of sunrise calculated? (viewed 50616 times)
  236. What skills do astronomers need? (viewed 50554 times)
  237. If the Earth's rotation period is less than 24 hours, why don't our clocks fall out of sync with the Sun? (viewed 50548 times)
  238. Are the planes of solar systems aligned with the plane of the Galaxy? (viewed 50397 times)
  239. How do we know what other planets (and stars, galaxies, etc.) are made of? (viewed 50315 times)
  240. What is the difference between nutation and precession of the Earth? (viewed 50066 times)
  241. Why is it difficult to understand the expansion of the universe? (viewed 49930 times)
  242. What's the difference between astronomy and astrophysics? (viewed 49684 times)
  243. What is a graviton? (viewed 49512 times)
  244. If light has no mass, then what draws it into a black hole? (viewed 49102 times)
  245. Why do the size and brightness of the full moon change? (viewed 47870 times)
  246. Why are most months 30 or 31 days long? (viewed 47671 times)
  247. Do supermassive black holes cause galaxy rotation? (viewed 47562 times)
  248. What do I need to do to become an astronomer? (viewed 47502 times)
  249. How do gravitons escape black holes to tell the universe about their gravity? (viewed 47230 times)
  250. What is a wormhole? (viewed 47118 times)
  251. Why does the Sun appear larger on the horizon than overhead? (viewed 47052 times)
  252. Can we find the place where the Big Bang happened? (viewed 46998 times)
  253. Do dead stars still shine? (viewed 46978 times)
  254. How are black holes discovered? (viewed 46942 times)
  255. Can the acceleration of the Universe be analogous to apparent acceleration in a airplane? (viewed 46535 times)
  256. The Moon slows the Earth's rotation, but how fast was it spinning billions of years ago? (viewed 46521 times)
  257. Why are there stars? (viewed 46110 times)
  258. Is the Earth slowly getting larger? (viewed 45967 times)
  259. Will we get sucked into the black hole at the center of the Milky Way? (viewed 45918 times)
  260. Why can't we see Venus at night when it is an inner planet? (viewed 45804 times)
  261. Where is the nearest black hole? (viewed 45696 times)
  262. Why don't people walk upside-down on the bottom of the Earth? (viewed 45648 times)
  263. How do galaxies collide in an expanding universe? (viewed 45536 times)
  264. Can I calculate the size of the Universe by converting light years to kilometres? (viewed 45123 times)
  265. Did life originate on Earth, or did it come from somewhere else? (viewed 44899 times)
  266. Are Kuiper Belt Objects asteroids? Are large Kuiper Belt Objects planets? (viewed 44753 times)
  267. Why does Barnard 68 appear dark? (viewed 44687 times)
  268. Are there eclipses on other planets? (viewed 44103 times)
  269. Could the Universe have expanded faster than the speed of light at the Big Bang? (viewed 43619 times)
  270. How does Astronomy involve Chemistry? (viewed 43584 times)
  271. What is the best way to see the Milky Way? (viewed 43540 times)
  272. Is there a "South Star"? (viewed 43536 times)
  273. Why does the location of sunrise change? (viewed 43463 times)
  274. How long could life on Earth survive if the Sun stopped shining? (viewed 43436 times)
  275. What is the difference between the "Doppler" redshift and the "gravitational" or "cosmological" redshift? (viewed 43381 times)
  276. Has there been an experiment that measured speed faster than the speed of light in vacuum? (viewed 43320 times)
  277. How much can the location of sunset differ from due West? (viewed 43225 times)
  278. What happens to spacetime inside a black hole? (viewed 42942 times)
  279. How would the weather on Earth be different if it were a cube? (viewed 42887 times)
  280. Was the Sun made in a supernova? (viewed 42833 times)
  281. What is the biggest crater recorded on Earth? (viewed 42714 times)
  282. Why doesn't dark matter fall into a black hole? (viewed 42634 times)
  283. How much longer will the Earth last? (viewed 42511 times)
  284. Why does the Earth only see one side of the Moon? (viewed 41803 times)
  285. What are the names of the three stars in Orion's belt? (viewed 41796 times)
  286. Can I buy land on the Moon? (viewed 41775 times)
  287. What happens when two black holes get too close? (viewed 41516 times)
  288. Is the Moon hollow? (viewed 41509 times)
  289. What if the Earth rotated twice as fast? (viewed 41296 times)
  290. What is time dilation? (viewed 41079 times)
  291. What color would Mars be if you were standing on it? (viewed 41069 times)
  292. What's the biggest meteorite? (viewed 41015 times)
  293. Why do people draw stars with five points? (viewed 40862 times)
  294. How do we feel heat? (viewed 40757 times)
  295. What is the most distant known galaxy? (viewed 40742 times)
  296. How can two moons of Saturn share the same orbit? (viewed 40714 times)
  297. Could someone travel the universe in his or her own lifetime? (viewed 40678 times)
  298. Why can we see the sun's image before sunrise and after sunset? (viewed 40669 times)
  299. Is it possible to see the full Moon and the Sun simultaneously in high northern latitudes when the Sun doesn't set? (viewed 40510 times)
  300. Can terrestrial planets have rings? (viewed 40341 times)
  301. What are "blue stragglers" in globular clusters? (viewed 39954 times)
  302. How fast does the Earth go at perihelion and aphelion? (viewed 39954 times)
  303. How long would it take for a mini-black hole to eat the Earth? (viewed 39905 times)
  304. Is the Sun always up for exactly 12 hours at the equator? (viewed 39872 times)
  305. How do we know that nuclear fusion is still going on in the Sun? (viewed 39819 times)
  306. How many Astronauts have been in space? (viewed 39789 times)
  307. How do we define distance in an expanding universe? (viewed 39586 times)
  308. Do you think it's possible to maintain life on other planets? (viewed 39554 times)
  309. Why do clocks turn in the opposite direction from the Earth and Moon? (viewed 39508 times)
  310. Does the Sun have an iron surface? (viewed 39424 times)
  311. Why do pictures of distant galaxies have higher resolution than those of nearby planets? (viewed 39363 times)
  312. Why are Saturn's rings flat? (viewed 39327 times)
  313. If a white dwarf is a "dead" star, why is it so hot? (viewed 39261 times)
  314. What is the typical size of a visible shooting star? (viewed 39164 times)
  315. Can you see the future as you fall into a black hole? (viewed 39020 times)
  316. Can a person go into a black hole and come out alive? (viewed 38982 times)
  317. On which days can I see the Moon in the evening / morning and why is this so? (viewed 38886 times)
  318. Who (and when) discovered that the earth's axis is on a 23 degree tilt? (viewed 38878 times)
  319. Is the Great Wall the largest galaxy cluster? (viewed 38869 times)
  320. Does Mt. Everest cast a shadow on the moon? (viewed 38827 times)
  321. What is a dimension? (viewed 38814 times)
  322. How does night and day work? (viewed 38619 times)
  323. Where do planetary rings come from, and what are they made of? (viewed 38470 times)
  324. Are all stars the same? (viewed 38394 times)
  325. Can I communicate faster than light? (viewed 38319 times)
  326. What is the speed of gravity? (viewed 38064 times)
  327. How do we determine the age of the universe? (viewed 38040 times)
  328. What companies or businesses can astronomers work for? (viewed 38011 times)
  329. What is Earthrise over the Moon? (viewed 37999 times)
  330. What is the approximate GPA needed in High School in Math and Science to be an astronomer? (viewed 37790 times)
  331. Where is the supernova remnant that led to our solar system? (viewed 37685 times)
  332. How can the universe be "flat"? We're 3D! (viewed 37602 times)
  333. What can I use for fuel in my homemade rocket? (viewed 37556 times)
  334. How big is the universe? (viewed 37528 times)
  335. Why is sea water salty, and not lake water? (viewed 37345 times)
  336. Is there a beginning and an end to a galaxy's life? (viewed 37323 times)
  337. Is there really a 10th planet? (viewed 37294 times)
  338. If the universe is 15 billion years old, how can it be larger than 15 billion light years across? (viewed 37166 times)
  339. How do we know the Milky Way is a spiral galaxy? (viewed 37073 times)
  340. Does the Coriolis force determine which way my toilet drains? Does it affect black holes? (viewed 37031 times)
  341. How are photons created and destroyed? (viewed 37026 times)
  342. What would happen to the Earth if an asteroid hit the Moon? (viewed 36776 times)
  343. Why can't a plane fly slowly and let the Earth pass underneath? (viewed 36755 times)
  344. How many stars can I see? (viewed 36677 times)
  345. Why are there blue shifted galaxies? (viewed 36624 times)
  346. How do I tell which planet is which? (viewed 36519 times)
  347. Do the Sun's or Earth's magnetic field reverse? (viewed 36091 times)
  348. How can I find my age on another planet? (viewed 36078 times)
  349. How are planets detected around other stars? (viewed 35960 times)
  350. Can a lunar and a solar eclipse happen in the same month? When will this happen next? (viewed 35895 times)
  351. How does the brightness of a star depend on its distance from us? (viewed 35868 times)
  352. What kind of eyepieces do I need to look at planets? (viewed 35847 times)
  353. What is the pattern to the distances between each planet and the sun? (viewed 35774 times)
  354. Why do humans want to go in space? (viewed 35747 times)
  355. Why have star signs shifted by one constellation? (viewed 35635 times)
  356. Will we ever stop having solar eclipses because of the moon's motion away from the Earth? (viewed 35589 times)
  357. Is Andromeda part of the Milky Way? Where can I find them in the sky? (viewed 35561 times)
  358. What is the significance of the second focus of elliptical orbits of planets in our Solar System? (viewed 35404 times)
  359. How hot is each one of the layers of the sun? (viewed 35069 times)
  360. Can you describe a day on the job as an astronomer? (viewed 35063 times)
  361. Who came up with the name "black hole"? (viewed 35019 times)
  362. How do astronauts communicate with their families from space? (viewed 35008 times)
  363. How can we estimate the number of Earth-like planets in the Galaxy? (viewed 34939 times)
  364. What would happen if two stars collided? (viewed 34826 times)
  365. What was that really big falling star that I saw? (viewed 34805 times)
  366. Is there a simple formula to calculate solar eclipse timings from any position on Earth? (viewed 34570 times)
  367. Is the Earth at the centre of the Universe? (viewed 34563 times)
  368. When we look back to the Big Bang, why don't we see the universe as a tiny speck of matter? (viewed 34463 times)
  369. Why don't astronomers use everyday units to measure distances (what is an AU or a pc)? (viewed 34417 times)
  370. How is it that we see farther out in space (farther back in time) than in the past? (viewed 34412 times)
  371. Is the Local Group expanding along with the entire Universe? (viewed 34367 times)
  372. How do I become both an astronaut and an astronomer? (viewed 34321 times)
  373. Will the Moon be invisible in 500 million years? (viewed 34092 times)
  374. How do sunrise and sunset times change with altitude? (viewed 33697 times)
  375. Why is our solar system so different from all the others we've found? (viewed 33669 times)
  376. Why is Uranus tipped on its side? (viewed 33655 times)
  377. Are Earth and the Moon "twin planets"? (viewed 33647 times)
  378. How dangerous are the asteroids? (viewed 33623 times)
  379. Which American colleges teach astronomy? (viewed 33572 times)
  380. Can we colonize other planets? (viewed 33199 times)
  381. Why do constellations look the same after several years even though all the stars are moving? (viewed 33092 times)
  382. Is it true that the Sun burns off a billion tons of gas every 5 seconds? (viewed 33057 times)
  383. Is the universe really like an expanding balloon? (viewed 32972 times)
  384. Why are there no craters on Earth? Did all the meteorites miss us? (viewed 32945 times)
  385. Is the gravitational force exerted by the Earth on the Moon equal to the centripetal force acting on the Moon? (viewed 32754 times)
  386. Why do astronauts in space need to exercise? (viewed 32642 times)
  387. What are quasars made of? (viewed 32594 times)
  388. How can I calculate distances between stars? (viewed 32529 times)
  389. Can superheavy elements (such as Z=116 or 118) be formed in a supernova? Can we observe them? (viewed 32327 times)
  390. Why doesn't gravity change the speed of light? (viewed 32237 times)
  391. What is dark matter? (viewed 32215 times)
  392. Is it possible to count the stars? (viewed 31902 times)
  393. How big a change in the Earth's orbit would be required to destroy all life? (viewed 31877 times)
  394. Is time travel possible using merging black holes? (viewed 31774 times)
  395. Why is the time between two successive full moons different from the lunar synodic month? (viewed 31701 times)
  396. What is happening just around the black hole in the center of the Milky Way? (viewed 31701 times)
  397. Can we see dead stars with the naked eye? (viewed 31692 times)
  398. Did the speed of light change over the history of the universe? (viewed 31640 times)
  399. How do we measure distances to other stars? (viewed 31623 times)
  400. Does the Milky Way spin counter-clockwise? If so, do all spiral galaxies spin in this direction and why? (viewed 31563 times)
  401. How can we distinguish a star's "real" color from the change in color that we observe due to the star's motion? (viewed 31511 times)
  402. How do I make a scale model of the Solar System? (viewed 31478 times)
  403. What happens when an antimatter black hole collides with a matter blackhole? (viewed 31310 times)
  404. Do we see the same stars from above and below the equator? (viewed 31283 times)
  405. What would happen if a human were exposed to space without wearing a spacesuit? (viewed 31238 times)
  406. How can we tell what the interiors of planets are like? (viewed 31232 times)
  407. Are time machines possible? (viewed 31079 times)
  408. How many moles of stars are in the known universe? (viewed 30945 times)
  409. What happens when you change the mass of a White Dwarf or Neutron Star? (viewed 30917 times)
  410. What do "homogeneity" and "isotropy" mean? (viewed 30914 times)
  411. How are galaxy distances inferred from their recessional velocities? (viewed 30793 times)
  412. What is the farthest in space that we have gone? (viewed 30654 times)
  413. Will the seasons change due to precession? (viewed 30392 times)
  414. Can astronauts produce water in space? (viewed 30294 times)
  415. How can we know that there are other galaxies if we cannot leave ours? (viewed 30242 times)
  416. Is there any limitation to what a black hole can "suck" in? (viewed 30223 times)
  417. How was the starting point for the Julian Date system chosen? (viewed 30211 times)
  418. How do we know if the universe will keep expanding forever? (viewed 30131 times)
  419. What are the closest and/or brightest stars? (viewed 30057 times)
  420. Aren't jobs in astronomy scarce? (viewed 30055 times)
  421. Does the Moon look different in the northern and southern hemispheres? (viewed 29961 times)
  422. How can I tell if the rock I found is a meteorite? (viewed 29942 times)
  423. Why does the SETI project search for radio signals? (viewed 29894 times)
  424. What's that dark spot on the Sun? (viewed 29876 times)
  425. How long does it take the Big Dipper to move in the sky? (viewed 29833 times)
  426. Why do we study black holes? (viewed 29813 times)
  427. Do astronomers believe in astrology? (viewed 29786 times)
  428. Did I see the Aurora Borealis as a child? (viewed 29615 times)
  429. When are there 5 Sundays in February? (viewed 29545 times)
  430. Why do most moons orbit their planets at the equator? (viewed 29476 times)
  431. What are the facts about the Star of Bethlehem? (viewed 29425 times)
  432. Do you believe in UFOs? (viewed 29422 times)
  433. Wouldn't the Big Bang theory be considered a hypothesis and not a theory? (viewed 29421 times)
  434. Don't tachyons travel faster than light? (viewed 29339 times)
  435. What are the atmospheres of Mars and Pluto like? (viewed 29316 times)
  436. Can you use an infinite line of reflectors to send light to the edge of the Universe? (viewed 29299 times)
  437. Could an astronaut or satellite fall into a black hole that we didn't know about? (viewed 29206 times)
  438. Could you tell me about the life cycle of galaxies? (viewed 29060 times)
  439. What does the term "visible universe" mean? (viewed 29055 times)
  440. What colors are visible through an amateur telescope? (viewed 28927 times)
  441. Was I hit by a meteorite? (viewed 28768 times)
  442. How can geometry be different in space? (viewed 28754 times)
  443. How are galaxies named? (viewed 28750 times)
  444. Has anyone made a map of the Milky Way? (viewed 28744 times)
  445. Why do so many of the world's UFO sightings happen in America? (viewed 28735 times)
  446. Why are the compositions of comets and asteroids different? (viewed 28696 times)
  447. What's the best thing about being an astronomer? (viewed 28471 times)
  448. Can two lunar eclipses occur in the same month? (viewed 28440 times)
  449. How do astronomers measure the radius of a star? (viewed 28360 times)
  450. What is the origin of the stellar classification system "OBAFGKM"? (viewed 28319 times)
  451. How do asteroids, meteors and comets disappear? (viewed 28259 times)
  452. How much time do astronomers spend looking through telescopes? (viewed 28008 times)
  453. How do I explain to my children why the Moon has phases? (viewed 27905 times)
  454. Will winter and summer constellations change due to abnormal warmth or cold on Earth? (viewed 27896 times)
  455. How can we see galaxies if their stars are so faint? (viewed 27849 times)
  456. Have there been other Big Bangs before? (viewed 27715 times)
  457. How will the two black holes that are going to collide affect Earth? (viewed 27685 times)
  458. How are galaxies and solar systems similar? (viewed 27673 times)
  459. Do asteroids hit the sun? (viewed 27485 times)
  460. Is there a project I can do on black holes? (viewed 27468 times)
  461. Do the magnitudes and colors of stars ever change? (viewed 27452 times)
  462. How close do you have to come to the Earth to be influenced by its gravity? (viewed 27418 times)
  463. Can life exist on the recently discovered extrasolar planets? (viewed 27365 times)
  464. How can we measure distances to more stars? (viewed 27314 times)
  465. Is the Milky Way a collision of two galaxies? (viewed 27284 times)
  466. Could you escape from a black hole if you were able to go faster than the speed of light? (viewed 27212 times)
  467. How do scientists slow light down? (viewed 27146 times)
  468. Can a human give birth in space? (viewed 27131 times)
  469. What supernova created the Crab nebula? (viewed 27006 times)
  470. How close does a supernova need to be to damage the Earth's environment? (viewed 26970 times)
  471. Is it worthwhile to continue the search for extraterrestrial life? (viewed 26964 times)
  472. Is infinite temperature possible? (viewed 26959 times)
  473. Can "tired light theory" explain the observed redshifts of galaxies? (viewed 26932 times)
  474. What causes gamma ray bursts? (viewed 26929 times)
  475. Can double stars have planets? (viewed 26895 times)
  476. Do we know everything about the Sun? (viewed 26846 times)
  477. Is there oxygen in the atmospheres of other planets? (viewed 26780 times)
  478. Can one star orbit another? (viewed 26686 times)
  479. Which part of the sky did the famous 'wow' signal originate from? (viewed 26661 times)
  480. How far does a galaxy extend? (viewed 26550 times)
  481. Why did the Pioneer and Voyager take only 2 years to reach Jupiter, while Galileo and Cassini took more than 5 years? (viewed 26493 times)
  482. Can astronauts play musical instruments in space? (viewed 26482 times)
  483. What will happen to the Milky Way in the future? (viewed 26469 times)
  484. What is sidereal time? (viewed 26399 times)
  485. How do I polar align my telescope? (viewed 26363 times)
  486. Which way does the sun travel in the southern hemisphere? (viewed 26349 times)
  487. What type of energy does a black hole have? (viewed 26287 times)
  488. What is the farthest Northern Latitude in which the Magellanic Clouds can be seen? (viewed 26235 times)
  489. Is there such a thing as hyperspace? (viewed 26223 times)
  490. Is there sound coming from the Sun? (viewed 26216 times)
  491. What is a Cepheid variable? (viewed 26212 times)
  492. What is "nothing", from a scientific point of view? (viewed 26178 times)
  493. What happens to the material that has been sucked into a black hole? (viewed 26171 times)
  494. When did people discover that the Sun is a star? (viewed 26164 times)
  495. How different would the night sky have looked in 40,000 B.C.? (viewed 26154 times)
  496. What's the object I saw that moved across the sky and then got very bright? (viewed 26153 times)
  497. Why do the explosions of Type Ia supernovae have a more predictable spectrum than those of regular Type II supernovae? (viewed 26097 times)
  498. Are planetary nebulae the result of supernovae? (viewed 26080 times)
  499. How will a change in the speed of light affect the evolution of the Universe? (viewed 25975 times)
  500. Why is the shadow on the Moon the shape it is? (viewed 25927 times)
  501. Why do we assume that the universe is homogeneous? (viewed 25816 times)
  502. If we invented special suits could we ever go to the sun? (viewed 25744 times)
  503. How do we know that sunspots are associated with the Sun's magnetic field? (viewed 25738 times)
  504. When unmanned spacecraft accelerate in space, what causes them to slow down? (viewed 25735 times)
  505. How do we know what parameters to use when simulating the collision of the Milky Way and Andromeda? (viewed 25710 times)
  506. What is our galaxy's halo made of, and how was it formed? (viewed 25670 times)
  507. What is the difference between homogeneity and isotropy? (viewed 25638 times)
  508. What calculations go into predicting eclipses? (viewed 25558 times)
  509. Are there any dark stars or dark galaxies made of dark matter? (viewed 25518 times)
  510. Can I see a quasar? (viewed 25410 times)
  511. How many sunspots can the Sun have at once? (viewed 25392 times)
  512. How are asteroid compositions and classifications determined? (viewed 25385 times)
  513. Was Stonehenge built to mark solar phenomena? (viewed 25355 times)
  514. Is there a list of the sizes of different kinds of stars? (viewed 25346 times)
  515. What process would bring about a quark star? (viewed 25294 times)
  516. Why are there more maria on the near side of the Moon? (viewed 25252 times)
  517. Can any comparison be made between spiral galaxies and hurricanes? (viewed 25242 times)
  518. Can I see details on Venus? (viewed 25235 times)
  519. What happened to the girl who named Pluto? (viewed 25202 times)
  520. Did a giant impact cause the Dark Ages? (viewed 25175 times)
  521. What's so exciting about the new planet around 55 Cancri? (viewed 25168 times)
  522. How big is the Hubble Ultra Deep Field image? (viewed 25162 times)
  523. What is a Dyson Sphere? (viewed 25069 times)
  524. Have gravitational waves been proven to exist? (viewed 25066 times)
  525. Would the biggest airplanes cause tsunamis if they crashed? (viewed 25053 times)
  526. What happened to all the black holes that were around in the early universe? (viewed 25051 times)
  527. Why are telescopes kept in cold conditions? (viewed 24998 times)
  528. What equipment do I need for astrophotography? (viewed 24973 times)
  529. How is it proved that the Universe is expanding? (viewed 24932 times)
  530. If clocks run slow in a gravitational field, how can we know the true age of the Solar System and Universe? (viewed 24874 times)
  531. Does Cerenkov radiation travel faster than light? (viewed 24863 times)
  532. Why are there active volcanos on Io? (viewed 24830 times)
  533. Is there any possibility that the Solar System or the Universe is in a black hole? (viewed 24722 times)
  534. If the Universe was infinitely dense at the Big Bang, why didn't time stand still? (viewed 24688 times)
  535. How long do supernova remnants last? (viewed 24515 times)
  536. How can we compare dark matter and dark energy? (viewed 24511 times)
  537. How big was the Sun when it first "fired up"? (viewed 24485 times)
  538. What caused Shoemaker-Levy 9 to split up? (viewed 24371 times)
  539. How do solar flares affect airline pilots? (viewed 24358 times)
  540. Why do photos of space taken from space never show any stars? (viewed 24352 times)
  541. Could we send a space mission to a comet? (viewed 24343 times)
  542. Can you give me advice on buying a telescope? (viewed 24320 times)
  543. Why doesn't light from distant galaxies reach us instantaneously? (viewed 24259 times)
  544. How are sunspots formed? (viewed 24212 times)
  545. How can I contribute to science as an amateur astronomer? (viewed 24196 times)
  546. How does the Earth compare in size to the entire universe at the present epoch? (viewed 24173 times)
  547. Why is it important to study meteorites? (viewed 24168 times)
  548. Why doesn't NASA build rotating spacecraft to simulate gravity? (viewed 24153 times)
  549. Can I build an instrument to measure the size of the Sun and of the Moon? (viewed 24149 times)
  550. How do unmanned space probes avoid running into things? (viewed 24120 times)
  551. Why are telescopes located in remote places? (viewed 24101 times)
  552. Could a different theory of gravity explain the dark matter mystery? (viewed 24096 times)
  553. Could we be seeing dead stars? (viewed 24090 times)
  554. Where does the kinetic energy of infalling bodies come from? (viewed 24073 times)
  555. As the universe expands, why don't galaxies get stretched out? (viewed 23993 times)
  556. Are the asteroids the remains of a planet which broke apart? (viewed 23944 times)
  557. How many comets are currently orbiting our sun? (viewed 23918 times)
  558. Did I really hear a meteor? (viewed 23897 times)
  559. Can you tell time by the Big Dipper? (viewed 23838 times)
  560. Why is the Hubble Space Telescope in space? (viewed 23776 times)
  561. Would extraterrestrial civilizations know that there is life on Earth? (viewed 23674 times)
  562. How do we know that superclusters are the largest structures in the universe? (viewed 23665 times)
  563. How powerful are quasars? (viewed 23618 times)
  564. How is the Cepheid yardstick validated? (viewed 23614 times)
  565. Do the Earth's magnetic poles ever change places? (viewed 23601 times)
  566. Do unmanned spacecraft like Voyager travel in straight lines? (viewed 23566 times)
  567. Why can't relative velocities add up to more than the speed of light? (viewed 23498 times)
  568. Do galaxies orbit around anything? (viewed 23496 times)
  569. Did time go slower just after the Big Bang? (viewed 23485 times)
  570. Why are stars of different masses? (viewed 23452 times)
  571. How could galaxies have gotten so far away in only 15 billion years? (viewed 23426 times)
  572. Can supernovae hinder the formation of life in galaxies? (viewed 23400 times)
  573. Are there any new craters on the moon? (viewed 23382 times)
  574. What kind of instruments are used to detect extrasolar planets? (viewed 23378 times)
  575. What would happen if there was a collision between two white dwarfs? (viewed 23344 times)
  576. How do I become an astronomical artist? (viewed 23322 times)
  577. Do similar laws of physics throughout the Universe imply that all life must be like life on Earth? (viewed 23298 times)
  578. How do planets capture satellites? (viewed 23273 times)
  579. How are astronomy and poetry linked? (viewed 23220 times)
  580. What kind of telescope should I use for astrophotography? (viewed 23216 times)
  581. Could there have been multiple Big Bangs at different places in the universe? (viewed 23209 times)
  582. Could dark energy come from matter anti-matter pairs forming spontaneously and then annihilating? (viewed 23061 times)
  583. How do astronomers observe the Sun's interior? (viewed 23037 times)
  584. Can I listen to the SETI@home radio signal? (viewed 22947 times)
  585. Why is NASA shutting down the Hubble Space Telescope? (viewed 22929 times)
  586. How can you tell if a crescent moon is preceding or following a new-moon phase? (viewed 22902 times)
  587. Does the Sun have any heavy elements? (viewed 22841 times)
  588. 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 22769 times)
  589. Can the theory of formation of the solar system explain all the observables? (viewed 22735 times)
  590. What class of spiral galaxy is the Milky Way? (viewed 22708 times)
  591. Are the properties of extrasolar planets known? (viewed 22703 times)
  592. Will we discover an 11th planet? What would it be called? (viewed 22640 times)
  593. What month was it when Odysseus saw Orion in 1000BC? (viewed 22508 times)
  594. Where was the water in the big bang? (viewed 22466 times)
  595. Could we send a manned mission to the outer planets? (viewed 22413 times)
  596. Is it possible for amateurs to do optical interferometry? (viewed 22327 times)
  597. What makes a satellite geosyncronise itself with Earth's orbit? (viewed 22309 times)
  598. How can water be chemically trapped in rocks? (viewed 22284 times)
  599. Why do spacecraft need heat shields coming back to Earth but not leaving? (viewed 22269 times)
  600. Why does the apparent density of galaxies drop off at larger distances? (viewed 22245 times)
  601. Why does one side of Mars look more catastrophic than the other? (viewed 22203 times)
  602. Would a planet near the galactic center have a brighter night sky? (viewed 22139 times)
  603. Do stars' orbits in galaxies obey Kepler's Laws? (viewed 22042 times)
  604. Why are accretion disks flat? (viewed 21936 times)
  605. Can other terrestrial moons be (or have been) stable? (viewed 21851 times)
  606. Why was the Platonic year named after Plato? (viewed 21843 times)
  607. What is the solar cycle? (viewed 21831 times)
  608. What would the Big Crunch look like to an observer on Earth? (viewed 21759 times)
  609. How are supernovae discovered? (viewed 21718 times)
  610. How can the Sun have such a strong gravitational field if it's made of gasses? (viewed 21694 times)
  611. What is meant by "stopping down a telescope"? (viewed 21629 times)
  612. Can a black hole come back to the visual universe through a "little bang"? (viewed 21614 times)
  613. Does inflation allow for an infinite number of universes? (viewed 21589 times)
  614. Why doesn't the hydrogen on Jupiter explode? (viewed 21560 times)
  615. Could our position in the universe affect our perceptions of the expansion? (viewed 21510 times)
  616. Did I find a rock that came from the Moon? (viewed 21318 times)
  617. Have astronomers observed any phenomena that could be produced by extraterrestrial civilizations? (viewed 21309 times)
  618. What is the SU(3) quark model? (viewed 21267 times)
  619. Can gravitational lensing from intervening galaxies cause the observed ripples in the Cosmic Microwave Background? (viewed 21218 times)
  620. Will I be able to see the shadow of the Moon streaking towards me in a total solar eclipse? (viewed 21157 times)
  621. Does a photon observe other photons moving past it at the speed of light? (viewed 21134 times)
  622. What's new with the Big Bang? (viewed 20945 times)
  623. How can we find galaxies behind the Milky Way? (viewed 20944 times)
  624. Could photons be dark matter? (viewed 20943 times)
  625. How fast do particles travel in space? (viewed 20897 times)
  626. Why is the WMAP picture of the CMB an ellipse? (viewed 20856 times)
  627. Can planets collide with one another? (viewed 20853 times)
  628. Why search for only Earth-like life on other planets? (viewed 20829 times)
  629. Why can we have solar eclipses? (viewed 20819 times)
  630. Is it possible to build a cheap device to measure declination? (viewed 20793 times)
  631. If comets are boiling away, why are there any left? (viewed 20763 times)
  632. Do constellations looks the same from space? (viewed 20749 times)
  633. Where can I find information on the moons of other planets? (viewed 20741 times)
  634. How much power is contained in a beam of light? (viewed 20708 times)
  635. Why do some eclipses take longer than others? (viewed 20664 times)
  636. Why is pressure broadening greater in low mass stars than in high mass stars? (viewed 20545 times)
  637. Did the Sumerians measure precession? (viewed 20418 times)
  638. What are the boundaries of the constellations? (viewed 20417 times)
  639. What would an "open geometry" for the universe look like? (viewed 20402 times)
  640. What kinds of star clusters are there? (viewed 20328 times)
  641. What are collections of galaxies called? (viewed 20236 times)
  642. How did Mars get so dusty? (viewed 20187 times)
  643. How do photons from distant objects maintain enough energy to reach us? (viewed 20182 times)
  644. Why aren't discoveries of extrasolar planets reported on the news? (viewed 20165 times)
  645. Why don't astronauts sublimate in space? (viewed 20163 times)
  646. Why is the Cosmic Microwave Background not absorbed by interstellar hydrogen? (viewed 20150 times)
  647. How do astronomers come up with their facts? (viewed 20150 times)
  648. How do bars form in spiral galaxies? (viewed 20141 times)
  649. If photons have zero mass, why do they feel the effects of gravity? (viewed 20037 times)
  650. Do electrons age? (viewed 19978 times)
  651. Can HST see the Oort cloud? (viewed 19975 times)
  652. Can we make a movie of the Milky Way galaxy's rotation? (viewed 19896 times)
  653. How long is twilight on the Moon? (viewed 19831 times)
  654. Can the Space Shuttle abort and return to Earth before reaching orbit? (viewed 19828 times)
  655. Will astronauts ever be able to go ice-skating on Europa? (viewed 19786 times)
  656. How does melting a material reset its radioactive clock? (viewed 19767 times)
  657. Why don't all neutron stars become pulsars? (viewed 19739 times)
  658. Does the shuttle worry about space junk? (viewed 19694 times)
  659. Where can I see Newton's original reflecting telescope? (viewed 19649 times)
  660. How do you classify galaxies? (viewed 19634 times)
  661. Why do supernova remnants look like rings rather than spheres? (viewed 19634 times)
  662. How can we understand the meaning of large numbers like "a million million?" (viewed 19556 times)
  663. Why doesn't SETI concentrate its observations to the nearby stars and the solar systems that we are discovering? (viewed 19463 times)
  664. What is the best time of the year to see eclipses? (viewed 19462 times)
  665. Why is it called astronomy when all the other sciences end in -ology? (viewed 19443 times)
  666. How does the color index of a star relate to its actual color? (viewed 19443 times)
  667. What causes a particle to decay? (viewed 19429 times)
  668. Will the next generation telescope OWL be able to detect an Earth like extrasolar planet? (viewed 19397 times)
  669. How can I nominate myself for a Nobel Prize in Physics? (viewed 19278 times)
  670. How long has humanity known that we live in a galaxy similar to others in the Universe? (viewed 19243 times)
  671. If nothing can escape a black hole, why do some black holes have jets? (viewed 19201 times)
  672. Are black holes spherical? (viewed 19198 times)
  673. Will the Leonid meteor shower go away? (viewed 19194 times)
  674. What are "curled" dimensions? (viewed 19100 times)
  675. Is light of different colors affected differently by gravity? (viewed 19000 times)
  676. Do asteroids ever do anything good in the Solar System? (viewed 18963 times)
  677. How does interferometry work? (viewed 18952 times)
  678. What would happen if you went back in time and killed your grandmother? (viewed 18885 times)
  679. How do distant galaxies differ from those nearby? (viewed 18883 times)
  680. What kind of interference must astronomers contend with when observing? (viewed 18877 times)
  681. What was that eclipse I saw in the sky? (viewed 18872 times)
  682. Does the temperature of matter increase as it is accelerated to relativistic speeds? (viewed 18855 times)
  683. Wouldn't the vast distances of space distort SETI signals into unintelligeble forms? (viewed 18778 times)
  684. How do we find out about the star formation histories of galaxies? (viewed 18759 times)
  685. Why will fusion wait until hydrogen is gone before starting to fuse heavier atoms? (viewed 18717 times)
  686. How can I watch the Perseid meteor shower? (viewed 18640 times)
  687. Can astronomers observe anything when the moon is full? (viewed 18638 times)
  688. What do stellar classifications mean? (viewed 18620 times)
  689. Do we really observe the edges of galaxies at different epochs? (viewed 18560 times)
  690. Why aren't accretion disks around giant stars as hot as accretion disks around black holes? (viewed 18517 times)
  691. Can you tell me the characteristics of W, R, N and S type stars? (viewed 18500 times)
  692. How are astronauts trained for weightlessness? (viewed 18499 times)
  693. What is the three-body problem? (viewed 18433 times)
  694. If the universe is "bounded" today, could it one day become "unbounded"? (viewed 18213 times)
  695. What happens to the helium formed in the sun? (viewed 18180 times)
  696. Will the diameter of a cluster of galaxies change with redshift? (viewed 18167 times)
  697. Is cosmic expansion happening on microscopic scales? (viewed 18034 times)
  698. When measuring the expansion of the universe, do astronomers consider that they're seeing how galaxies moved long ago, not today? (viewed 18009 times)
  699. How do supernovae show us that the Universe's expansion is accelerating? (viewed 17855 times)
  700. How can I find out if the new moon has been sighted? (viewed 17804 times)
  701. Could neutrinos be dark matter? (viewed 17733 times)
  702. Do we have to worry about relativity when studying galactic objects? (viewed 17654 times)
  703. Does lunar gardening really work? (viewed 17649 times)
  704. What kinds of cancer research have been done in space? (viewed 17491 times)
  705. How does a star take mass from another star? (viewed 17362 times)
  706. Could the Universe's dark matter be made up of black holes? (viewed 17309 times)
  707. How can you tell the difference between single and multiple extrasolar planets? (viewed 17141 times)
  708. What is Hot Dark Matter theory? (viewed 17110 times)
  709. Is it a coincidence that we can have total solar eclipses? Are there other planets which also have them? (viewed 16930 times)
  710. How do we know the density of some extrasolar planets? (viewed 16883 times)
  711. What is the photoelectric effect? Why can't multiple low-frequency photons free an electron? (viewed 16797 times)
  712. Is the green flash real? (viewed 16780 times)
  713. What time is sunrise/sunset or moonrise/moonset at my location? (viewed 16657 times)
  714. How does libration allow us to see more than 50% of the Moon? (viewed 16587 times)
  715. How can observations of the distant universe prove that the expansion is accelerating *now*? (viewed 16556 times)
  716. Is light blueshifted when it is gravitationally lensed? (viewed 16438 times)
  717. Do binary or triple star systems form together? (viewed 16432 times)
  718. No matter how fast the universe is expanding, shouldn't gravity eventually make it recollapse? (viewed 16345 times)
  719. What do meteorites tell us about life on other planets? (viewed 16235 times)
  720. Why is it easier to see a star if you look slightly to the side? (viewed 16177 times)
  721. Can we prove that the Moon isn't hollow? (viewed 16137 times)
  722. What percent of the time can astronomers observe without interference from the Moon? (viewed 16090 times)
  723. 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 16083 times)
  724. If the sun went out and our atmosphere froze solid, what color would it be? (viewed 16065 times)
  725. How has light from 13 billion years ago not passed us by? (viewed 16008 times)
  726. Could matter-anti-matter repulsion power the expansion of the universe? (viewed 15856 times)
  727. Why doesn't the ammonia and methane in Jupiter's atmosphere sink into the core? (viewed 15725 times)
  728. How do we detect incoming meteorites? (viewed 15606 times)
  729. What was different on Mars in the past to allow liquid water to be present? (viewed 15593 times)
  730. When will Hale-Bopp return? (viewed 15511 times)
  731. Why don't skydivers burn up like meteors? (viewed 15495 times)
  732. Are there any 'lonely galaxies'? (viewed 15470 times)
  733. Has anyone ever seen a star "turn on"? (viewed 15290 times)
  734. Why are craters round? (viewed 14967 times)
  735. During close approaches, can Mars appear in our sky as large as the Moon? (viewed 14702 times)
  736. How are planets affected by the Hot Ionised Medium? (viewed 14525 times)
  737. Can the sun rise from the west on Mars? (viewed 14449 times)
  738. What are the largest radio wavelengths observed from radio sources in the sky? (viewed 14123 times)
  739. Why was Mir burnt up in the atmosphere? (viewed 14079 times)
  740. How can we discern different galaxies/clusters along the same line of sight? (viewed 13957 times)
  741. What is the relationship between the width of a star trail on a photo and the star's intensity? (viewed 13529 times)
  742. Can we harvest H & O from space to make water? (viewed 13466 times)
  743. Why does Titan, in spite of being smaller than Mars, have an atmosphere more dense than Earth's? (viewed 13366 times)
  744. What is between the Oort cloud and the closest star? (viewed 12889 times)
  745. What happens to the Earth as the moon gets farther away and will it ever go away entirely? (viewed 12186 times)
  746. Could a planetary system survive if its star merged with another, or if its star went supernova? (viewed 12052 times)
  747. Are there solar tides? (viewed 11937 times)
  748. Does weightlessness affect hunger? (viewed 11698 times)
  749. Is Earth-moon tidal friction causing global warming? (viewed 11585 times)
  750. Is the moon spherical? (viewed 11380 times)
  751. Do planets radiate noise? (viewed 11367 times)
  752. Why is the Moon higher in the sky in winter and lower in the summer? (viewed 11269 times)
  753. Is dark energy affected by black holes? (viewed 11068 times)
  754. Where are the protons and electrons in a Neutron Star? (viewed 10828 times)
  755. What would happen if a nuclear-powered shuttle exploded? (viewed 10710 times)
  756. Is the Moon always visible during winter on the North Pole? (viewed 10643 times)
  757. Wait, I'm still confused why information can't travel faster than the speed of light. (viewed 10232 times)
  758. Will the Pioneer and Voyager probes ever leave the Milky Way? (viewed 9795 times)
  759. Do more meteorites fall at low latitudes? (viewed 9777 times)
  760. Will Comet Elenin (C/2010 X1) affect the Earth on its close approach in Fall 2011? (viewed 9740 times)
  761. Did the Moon or planets form in a manner similar to that of Earth? (viewed 9720 times)
  762. What are the possible ends of the universe? (viewed 9687 times)
  763. If there are infinity universes, will every thing that is possible happen? (viewed 9499 times)
  764. Is it sensible to consider terraforming Mars? (viewed 9418 times)
  765. What color are meteors? (viewed 9197 times)
  766. Where is everybody? (viewed 8683 times)
  767. Why does Mars have a dusty atmosphere? (viewed 8364 times)
  768. Does the singularity in a black hole create a new Universe? (viewed 8216 times)
  769. The naming of Mars (viewed 8197 times)
  770. If I were traveling through space, could I see distant galaxies with my own eyes? (viewed 8159 times)
  771. Is the reddish dust of Mars biogenic? (viewed 8020 times)
  772. Where is the Spitzer Space Telescope? (viewed 7463 times)
  773. Why do astronomers use telescopes? (viewed 7405 times)
  774. When will humans travel to Mars and revisit the Moon? (viewed 7181 times)
  775. How likely is it for a planet to transit its star? (viewed 6741 times)
  776. What causes the aurora? (viewed 6621 times)
  777. Does the particles involved in a star's final core collapse travel faster than the speed of light? (viewed 6516 times)
  778. When is the best time to observe zodiacal light? (viewed 6362 times)
  779. How did a transit of Venus provide astronomers with the first measurement of the Earth-Sun distance? (viewed 5423 times)
  780. Can the Sun be closer to the Earth than any planet is to Earth? (viewed 4870 times)
  781. Cosmologists say the expansion of the universe is accelerating, what is driving this? (viewed 4200 times)
  782. Can we hear sound on Titan? (viewed 3951 times)
  783. Does the direction of the moon's crescent change through the night? (viewed 3806 times)
  784. What do all the angles in a table for a planet's orbit mean? (viewed 3645 times)
  785. How do I maximize my chances of seeing shooting stars? (viewed 3103 times)
  786. Are exoplanets real? (viewed 2623 times)
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