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 2101545 times)
  2. What color is each planet? (viewed 858742 times)
  3. At what speed does the earth move around the sun? (viewed 543809 times)
  4. Is the Moon moving away from the Earth? When was this discovered? (viewed 523688 times)
  5. How far is each planet from Earth? (viewed 449682 times)
  6. When will Halley's Comet return? (viewed 388380 times)
  7. How many stars are there in our Galaxy (Milky Way)? (viewed 375874 times)
  8. How long does it take for the Sun's light to reach us? (viewed 369503 times)
  9. Why do the planets orbit the sun? (viewed 355754 times)
  10. What is the universe expanding into? (viewed 353652 times)
  11. How do you measure the distance between Earth and the Sun? (viewed 321232 times)
  12. Which planets have rings? (viewed 314769 times)
  13. Why do stars twinkle? (viewed 302532 times)
  14. Does the Moon rotate? Are there other moons that always keep one face toward their planet? (viewed 291232 times)
  15. How do I build a model rocket? (viewed 282058 times)
  16. What color is Venus? (viewed 266166 times)
  17. What is a white hole? (viewed 258458 times)
  18. What is the life cycle of a star? (viewed 241097 times)
  19. What are the names of the earth, moon, sun, and solar system? (viewed 228151 times)
  20. Can you hear sounds in space? (viewed 221639 times)
  21. What is the largest star? (viewed 219660 times)
  22. What is that ring (or rainbow) around the moon? (viewed 218099 times)
  23. What makes the Earth rotate? (viewed 216304 times)
  24. What are shooting stars? (viewed 214833 times)
  25. What do astronauts eat in space? Can they grow food? (viewed 197574 times)
  26. Why do planets rotate? (viewed 192273 times)
  27. How do we know the age of the Universe and the Earth? (viewed 189092 times)
  28. Can artificial gravity be created in space? (viewed 185788 times)
  29. Is the universe expanding faster than the speed of light? (viewed 184529 times)
  30. How does the location of sunrise and sunset change throughout the year? (viewed 175084 times)
  31. Where did the name 'Earth' come from? (viewed 172999 times)
  32. How many Earths fit into the Sun? (viewed 169329 times)
  33. What would happen if we did not have a Moon? (viewed 168542 times)
  34. How can we see the Milky Way if we are inside it? (viewed 166606 times)
  35. Why is a day divided into 24 hours? (viewed 156124 times)
  36. How does the position of Moonrise and Moonset change? (viewed 150556 times)
  37. Who named the planets and who decides what to name them? (viewed 148771 times)
  38. Is Pluto a planet? (viewed 147189 times)
  39. Is the distance from the Earth to the Sun changing? (viewed 145244 times)
  40. Why are the Moon and Sun sometimes orange or red? (viewed 142459 times)
  41. When was the last time all 9 planets were aligned? (viewed 141683 times)
  42. What is at the end of the Universe? (viewed 138148 times)
  43. Why do airplanes take longer to fly West than East? (viewed 133998 times)
  44. How much money is spent on space exploration? (viewed 133568 times)
  45. How can I find the star I have "bought"? (viewed 131001 times)
  46. Why are there both high and low tides? (viewed 128444 times)
  47. What is the largest galaxy? (viewed 125702 times)
  48. What are the different kinds of astronomers? (viewed 125290 times)
  49. How many known galaxies are there? (viewed 124079 times)
  50. What direction do planets rotate? (viewed 123477 times)
  51. Is the Sun expanding? Will it ever explode? (viewed 122661 times)
  52. How do astronauts take baths and use restrooms in space? (viewed 121458 times)
  53. Can we feel the Earth spin? (viewed 120879 times)
  54. Do stars move in the sky? (viewed 117522 times)
  55. Can I buy a star? (viewed 112507 times)
  56. Does your weight change between the poles and the equator? (viewed 111264 times)
  57. Will the sun go supernova in six years and destroy Earth (as seen on Yahoo)? (viewed 110687 times)
  58. What are the advantages and disadvantages of using a telescope in space? (viewed 109131 times)
  59. What is the hottest time of day? (viewed 107876 times)
  60. What is a nova? (viewed 107693 times)
  61. Are there telescopes that can see the flag and lunar rover on the Moon? (viewed 107271 times)
  62. How do stars move in the Galaxy? (viewed 106604 times)
  63. How are light and heavy elements formed? (viewed 106407 times)
  64. Why do all the planets orbit in the same plane? (viewed 105263 times)
  65. Will the magnetic field of the Earth reverse its direction in the future? Will this cause problems? (viewed 105224 times)
  66. Does the Sun have a scientific name? (viewed 104671 times)
  67. What happens when galaxies collide? (viewed 104576 times)
  68. When is the next comet due to arrive? (viewed 104244 times)
  69. What was there before the Big Bang and what is there outside of our universe? (viewed 103735 times)
  70. What is the size of the Solar System? (viewed 103578 times)
  71. Why hasn't NASA gone back to the moon? (viewed 102372 times)
  72. How do rockets work? (viewed 102276 times)
  73. Why do planets have elliptical orbits? (viewed 102039 times)
  74. Who first measured the speed of light? (viewed 101933 times)
  75. What would happen if an impact caused Earth to stop rotating? (viewed 101922 times)
  76. How long does a solar eclipse last? (viewed 101869 times)
  77. How much money do astronomers make? (viewed 101009 times)
  78. How many constellations are there? (viewed 99702 times)
  79. What will happen to life on Earth when the Sun becomes a red giant? (viewed 99050 times)
  80. Do black holes die? If so how? (viewed 98995 times)
  81. What elements make up the Sun? (viewed 98486 times)
  82. How do you calculate the lifetime of the Sun? (viewed 98241 times)
  83. Does the Sun move around the Milky Way? (viewed 97483 times)
  84. Does the Sun rotate? (viewed 97269 times)
  85. What is the observational difference between a star and a planet? (viewed 95770 times)
  86. What is the physical difference between a star and a planet? (viewed 94956 times)
  87. What is the significance of the Tropic of Cancer, Tropic of Capricorn, Arctic Circle and Antarctic Circle? (viewed 93957 times)
  88. Does evolution contradict the second law of thermodynamics? (viewed 93002 times)
  89. What is apparent magnitude? (viewed 92203 times)
  90. What's the difference between astronomy and astrology? (viewed 92003 times)
  91. What do astronauts do all day in the International Space Station? (viewed 90166 times)
  92. Which planet is most similar to Earth? (viewed 89719 times)
  93. How critical is the Earth-Sun distance in maintaining our average temperatures on Earth? (viewed 88430 times)
  94. If Mars is only about 35-60 million miles away at close approach, why does it take 6-8 months to get there? (viewed 88410 times)
  95. Does gravity vary across the surface of the Earth? (viewed 87807 times)
  96. How many meteorites hit Earth each year? (viewed 87036 times)
  97. How do astronomers use math in their jobs? (viewed 86022 times)
  98. Have astronomers discovered Earth's second moon? (viewed 85973 times)
  99. Why are stars and planets round? (viewed 85682 times)
  100. Why do different stars appear with seasons? (viewed 85397 times)
  101. What are constellations used for? (viewed 85071 times)
  102. Is there a proof that Earth moves? (viewed 85028 times)
  103. What would happen if the gravity on Earth was suddenly turned off? (viewed 84638 times)
  104. Where did the Universe come from? (viewed 84209 times)
  105. What would happen if an asteroid 10 kilometers across hit the Earth? (viewed 84051 times)
  106. Does the Sun orbit the Earth as well as the Earth orbiting the Sun? (viewed 83872 times)
  107. Why is the Moon so bright? (viewed 83573 times)
  108. Why is the Universe flat and not spherical? (viewed 83221 times)
  109. What makes the wind? (viewed 82450 times)
  110. What is a singularity? (viewed 82265 times)
  111. Where does the name "Milky Way" come from? (viewed 79869 times)
  112. Why does the Earth tilt back and forward once a year? (viewed 79346 times)
  113. What kind of schooling is necessary to become an astronomer? (viewed 79115 times)
  114. How can a star burn with no oxygen? (viewed 79097 times)
  115. What would happen if Earth had more than one moon? (viewed 78965 times)
  116. What are RA and DEC? (viewed 78596 times)
  117. Considering the motion of the Earth, the solar system, and the galaxy, how fast am I moving while lying in bed asleep? (viewed 77784 times)
  118. What kind of rock is the moon made of? (viewed 76722 times)
  119. Why isn't the sky bright at night if the universe has so many stars? (viewed 75671 times)
  120. Did astronauts really go to the Moon, or is it a hoax? (viewed 75084 times)
  121. Why aren't there any green stars? (viewed 74355 times)
  122. Since Earth is spinning, why do we land in the same place when we jump or fall? (viewed 74242 times)
  123. How are galaxies formed? (viewed 74132 times)
  124. How many stars are born and die each day? (viewed 73193 times)
  125. Who has landed on the moon? (viewed 72330 times)
  126. What is the difference between a "star" and a "sun"? (viewed 72208 times)
  127. How are black holes made? Could one be made close to us? (viewed 72161 times)
  128. Will the Sun become a black hole one day? (viewed 71415 times)
  129. What would happen if a supermassive black hole came close to the Earth? (viewed 71291 times)
  130. What is the density of a black hole? (viewed 70581 times)
  131. What are the requirements for being a planet? (viewed 69869 times)
  132. What would you see from inside a black hole? (viewed 69416 times)
  133. Do most astronomers believe in God based on the available scientific evidence? (viewed 68112 times)
  134. Can you fire a gun on the Moon? (viewed 67755 times)
  135. How do astronomers measure the brightness of stars? (viewed 67416 times)
  136. Can moons have moons? (viewed 67145 times)
  137. How do rockets move in space? (viewed 67088 times)
  138. What happens to a substance if its speed is more than the speed of light? (viewed 66956 times)
  139. Why can't you see stars during the day? (viewed 66944 times)
  140. How often does the Sun pass through a spiral arm in the Milky Way? (viewed 66874 times)
  141. What are some of the effects of solar flares on Earth? (viewed 66607 times)
  142. How do we weigh objects in space? (viewed 66233 times)
  143. Why is the moon in a different place every night? (viewed 66211 times)
  144. How can the Universe expand faster than the speed of light during inflation? (viewed 66133 times)
  145. Is it possible to measure the temperature of the Sun? (viewed 65972 times)
  146. How is astronomy impacted by trigonometry? (viewed 65664 times)
  147. How do we know the mass of the Earth and the Moon? (viewed 65482 times)
  148. When the Sun converts mass to energy, do the orbits of the planets change? (viewed 65257 times)
  149. How does the Sun compare to other stars? (viewed 65131 times)
  150. What are the "dog days of summer"? (viewed 65057 times)
  151. What would happen if you took off your helmet in space? (viewed 64535 times)
  152. How does the Moon stay "suspended" in the air? (viewed 63757 times)
  153. How do you measure a planet's mass? (viewed 63743 times)
  154. Why do stars change colour when they twinkle? (viewed 63701 times)
  155. What kinds of jobs do astronomers do? (viewed 63693 times)
  156. Does the Mediterranean sea have tides? (viewed 63180 times)
  157. How are elements heavier than iron formed? (viewed 62909 times)
  158. What are black holes made of? (viewed 62377 times)
  159. What causes seasons? (viewed 62211 times)
  160. When can I see the Moon through the hole in the Pantheon? (viewed 61830 times)
  161. If the universe is infinite does that mean there is an infinite number of "me"s? (viewed 61742 times)
  162. What is the evidence supporting the nebula theory of Solar System formation? (viewed 61614 times)
  163. Does quantum entanglement imply faster than light communication? (viewed 61528 times)
  164. Why doesn't the earliest sunset occur on the shortest day of the year? (viewed 61000 times)
  165. Why do we not have eclipses every month? (viewed 60844 times)
  166. How did the stars get named? (viewed 60804 times)
  167. How did asteroids form and what is the difference between an asteroid and a comet? (viewed 60349 times)
  168. How fast is the Universe expanding? (viewed 60302 times)
  169. Where does the name "Moon" come from? (viewed 60141 times)
  170. What's the best college for astronomy? (viewed 60050 times)
  171. Why doesn't the length of each day change much around the solstices? (viewed 59845 times)
  172. Why do planets not twinkle? (viewed 59557 times)
  173. What are Altitude and Azimuth? (viewed 59410 times)
  174. What would happen to us if the sun went out for an hour? (viewed 59341 times)
  175. Traveling at light speed, how long would it take to get to the nearest galaxy? (viewed 59145 times)
  176. How long would it take the Earth to fall into the Sun? (viewed 59080 times)
  177. How do you measure the mass of a star? (viewed 59072 times)
  178. Where did the matter in the universe come from? (viewed 58777 times)
  179. What is the mass of the Universe? (viewed 58531 times)
  180. Are there stars outside of galaxies? (viewed 58509 times)
  181. Where, in relation to the entire universe, is the Milky Way located? (viewed 57584 times)
  182. How does light pollution affect astronomers? (viewed 57530 times)
  183. Does the Moon rotate? (viewed 57511 times)
  184. Could there be life in the galaxies nearest to the Milky Way? (viewed 57110 times)
  185. How can I calculate the position or path of the Sun for a given time and location? (viewed 56571 times)
  186. Why does the Earth have only one moon? (viewed 56426 times)
  187. Why does the Sun's apparent path through the sky change throughout the year? (viewed 55807 times)
  188. Can any galaxies be seen with the naked eye? (viewed 55680 times)
  189. What is the shape of the universe? (viewed 55241 times)
  190. What's the difference between dark matter and dark energy? (viewed 55169 times)
  191. What is the largest structure in the universe? (viewed 55067 times)
  192. How does the parachute in a model rocket work? (viewed 54494 times)
  193. What is the origin of spiral structure in galaxies? (viewed 54404 times)
  194. Where are stars born? (viewed 54240 times)
  195. How long does the supernova stage of a star last? (viewed 53731 times)
  196. How close was the Moon to the Earth when it formed? (viewed 53715 times)
  197. Are names given to black holes? (viewed 53658 times)
  198. How does astronomy benefit humankind? (viewed 53551 times)
  199. What makes up most of the Universe? (viewed 53472 times)
  200. What is the size of a black hole? (viewed 53070 times)
  201. Can you see satellites? (viewed 53018 times)
  202. How do astronauts use math in their jobs? (viewed 52715 times)
  203. What is a star's "spectrum"? (viewed 52706 times)
  204. Why isn't the summer solstice the hottest day of the year? (viewed 52681 times)
  205. Which constellation does our Sun belong to? (viewed 52015 times)
  206. How do you calculate the azimuth and altitude of an object? (viewed 51796 times)
  207. How do we measure the size of the Moon and of the Sun? (viewed 51690 times)
  208. Are aliens or UFOs real? (viewed 51590 times)
  209. What can we learn from the color of a star? (viewed 51539 times)
  210. Why do we see stars? (viewed 51010 times)
  211. How can I find the distance to the Sun on any given day? (viewed 50876 times)
  212. What are some astronomy science fair projects? (viewed 50713 times)
  213. How can I measure the distance of a star? (viewed 50703 times)
  214. Why is looking out into space the same as looking back in time? (viewed 50631 times)
  215. What other careers involve Astronomy besides Astronomer? (viewed 50515 times)
  216. Is the speed of light constant? (viewed 50265 times)
  217. What happens to a bullet fired on the moon? (viewed 50225 times)
  218. If gravity is a "curvature of space" rather than a force, why do a ball and bullet follow different paths? (viewed 50197 times)
  219. 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 49636 times)
  220. Are there any asteroids on a collision course with Earth? (viewed 49498 times)
  221. How long has there been water on Earth? (viewed 49450 times)
  222. Is time travel possible? (viewed 49420 times)
  223. Who discovered each planet? (viewed 49115 times)
  224. Which hemisphere has the best view of the Milky Way? (viewed 49018 times)
  225. How do the astronauts communicate in space if sound cannot travel in a vacuum? (viewed 48986 times)
  226. If the Earth's rotation period is less than 24 hours, why don't our clocks fall out of sync with the Sun? (viewed 48664 times)
  227. What would happen if the Moon fell out of its orbit around Earth? (viewed 48605 times)
  228. Why does the Moon look big on the horizon? (viewed 48354 times)
  229. Why is the sky blue and not blue & purple? (viewed 48265 times)
  230. Would your weight change as you go underground? (viewed 48113 times)
  231. Can we look back far enough in time to see the Big Bang? (viewed 47873 times)
  232. Why is it difficult to understand the expansion of the universe? (viewed 47519 times)
  233. Are meteorites hot or cold when they hit Earth? (viewed 47484 times)
  234. What is a graviton? (viewed 47198 times)
  235. What do a galaxy's colors mean? Are they its true colors? (viewed 47036 times)
  236. If light has no mass, then what draws it into a black hole? (viewed 46925 times)
  237. Why is twilight short near the equator? (viewed 46895 times)
  238. What is the difference between nutation and precession of the Earth? (viewed 46816 times)
  239. Are the planes of solar systems aligned with the plane of the Galaxy? (viewed 46208 times)
  240. How is the time of sunrise calculated? (viewed 45990 times)
  241. What's the difference between astronomy and astrophysics? (viewed 45804 times)
  242. What skills do astronomers need? (viewed 45746 times)
  243. Where did all the water in the universe come from? (viewed 45605 times)
  244. What do I need to do to become an astronomer? (viewed 45369 times)
  245. Do dead stars still shine? (viewed 45237 times)
  246. Where is the nearest black hole? (viewed 44750 times)
  247. How do gravitons escape black holes to tell the universe about their gravity? (viewed 44457 times)
  248. Do supermassive black holes cause galaxy rotation? (viewed 44353 times)
  249. Why do the size and brightness of the full moon change? (viewed 44195 times)
  250. Will we get sucked into the black hole at the center of the Milky Way? (viewed 44175 times)
  251. What is a wormhole? (viewed 44000 times)
  252. How are black holes discovered? (viewed 43862 times)
  253. How do we know what other planets (and stars, galaxies, etc.) are made of? (viewed 43732 times)
  254. Why can't we see Venus at night when it is an inner planet? (viewed 43726 times)
  255. Can I calculate the size of the Universe by converting light years to kilometres? (viewed 43675 times)
  256. How do galaxies collide in an expanding universe? (viewed 43485 times)
  257. The Moon slows the Earth's rotation, but how fast was it spinning billions of years ago? (viewed 43173 times)
  258. Is the Earth slowly getting larger? (viewed 42971 times)
  259. Why are there stars? (viewed 42936 times)
  260. Why does the Sun appear larger on the horizon than overhead? (viewed 42869 times)
  261. Why does Barnard 68 appear dark? (viewed 42864 times)
  262. Can we find the place where the Big Bang happened? (viewed 42339 times)
  263. What is the biggest crater recorded on Earth? (viewed 41832 times)
  264. Was the Sun made in a supernova? (viewed 41633 times)
  265. How much longer will the Earth last? (viewed 41026 times)
  266. Why are most months 30 or 31 days long? (viewed 40871 times)
  267. Are Kuiper Belt Objects asteroids? Are large Kuiper Belt Objects planets? (viewed 40827 times)
  268. Why does the location of sunrise change? (viewed 40818 times)
  269. Can I buy land on the Moon? (viewed 40808 times)
  270. Has there been an experiment that measured speed faster than the speed of light in vacuum? (viewed 40774 times)
  271. Could the Universe have expanded faster than the speed of light at the Big Bang? (viewed 40620 times)
  272. Why doesn't dark matter fall into a black hole? (viewed 40564 times)
  273. Are there eclipses on other planets? (viewed 40522 times)
  274. Is the Moon hollow? (viewed 40509 times)
  275. Is there a "South Star"? (viewed 40454 times)
  276. What happens when two black holes get too close? (viewed 40330 times)
  277. What's the biggest meteorite? (viewed 40292 times)
  278. What is the best way to see the Milky Way? (viewed 40284 times)
  279. How would the weather on Earth be different if it were a cube? (viewed 40209 times)
  280. What happens to spacetime inside a black hole? (viewed 40067 times)
  281. What is time dilation? (viewed 40015 times)
  282. Why does the Earth only see one side of the Moon? (viewed 39952 times)
  283. What is the difference between the "Doppler" redshift and the "gravitational" or "cosmological" redshift? (viewed 39909 times)
  284. What color would Mars be if you were standing on it? (viewed 39799 times)
  285. Why don't people walk upside-down on the bottom of the Earth? (viewed 39745 times)
  286. What is the most distant known galaxy? (viewed 39717 times)
  287. Did life originate on Earth, or did it come from somewhere else? (viewed 39646 times)
  288. How does Astronomy involve Chemistry? (viewed 39513 times)
  289. How can two moons of Saturn share the same orbit? (viewed 39180 times)
  290. How long could life on Earth survive if the Sun stopped shining? (viewed 38860 times)
  291. How much can the location of sunset differ from due West? (viewed 38787 times)
  292. How long would it take for a mini-black hole to eat the Earth? (viewed 38694 times)
  293. Can terrestrial planets have rings? (viewed 38647 times)
  294. What are the names of the three stars in Orion's belt? (viewed 38630 times)
  295. How many Astronauts have been in space? (viewed 38429 times)
  296. Could someone travel the universe in his or her own lifetime? (viewed 38293 times)
  297. Why do pictures of distant galaxies have higher resolution than those of nearby planets? (viewed 38246 times)
  298. What if the Earth rotated twice as fast? (viewed 38174 times)
  299. What are "blue stragglers" in globular clusters? (viewed 37772 times)
  300. What is the typical size of a visible shooting star? (viewed 37705 times)
  301. Does Mt. Everest cast a shadow on the moon? (viewed 37655 times)
  302. Why do people draw stars with five points? (viewed 37585 times)
  303. If a white dwarf is a "dead" star, why is it so hot? (viewed 37381 times)
  304. Is the Great Wall the largest galaxy cluster? (viewed 37201 times)
  305. Is it possible to see the full Moon and the Sun simultaneously in high northern latitudes when the Sun doesn't set? (viewed 37199 times)
  306. How does night and day work? (viewed 37127 times)
  307. How do we know that nuclear fusion is still going on in the Sun? (viewed 37111 times)
  308. What is the speed of gravity? (viewed 37066 times)
  309. What can I use for fuel in my homemade rocket? (viewed 36940 times)
  310. How do we feel heat? (viewed 36897 times)
  311. Can a person go into a black hole and come out alive? (viewed 36851 times)
  312. How big is the universe? (viewed 36847 times)
  313. How fast does the Earth go at perihelion and aphelion? (viewed 36804 times)
  314. Can the acceleration of the Universe be analogous to apparent acceleration in a airplane? (viewed 36687 times)
  315. Where is the supernova remnant that led to our solar system? (viewed 36674 times)
  316. What is Earthrise over the Moon? (viewed 36642 times)
  317. What is a dimension? (viewed 36579 times)
  318. Can I communicate faster than light? (viewed 36551 times)
  319. Where do planetary rings come from, and what are they made of? (viewed 36408 times)
  320. On which days can I see the Moon in the evening / morning and why is this so? (viewed 36280 times)
  321. Can you see the future as you fall into a black hole? (viewed 36239 times)
  322. What is the approximate GPA needed in High School in Math and Science to be an astronomer? (viewed 36086 times)
  323. Why are Saturn's rings flat? (viewed 35995 times)
  324. Is there really a 10th planet? (viewed 35976 times)
  325. Does the Sun have an iron surface? (viewed 35844 times)
  326. Why is sea water salty, and not lake water? (viewed 35777 times)
  327. What would happen to the Earth if an asteroid hit the Moon? (viewed 35765 times)
  328. Are all stars the same? (viewed 35745 times)
  329. How many stars can I see? (viewed 35730 times)
  330. Why can we see the sun's image before sunrise and after sunset? (viewed 35666 times)
  331. How do I tell which planet is which? (viewed 35662 times)
  332. Does the Coriolis force determine which way my toilet drains? Does it affect black holes? (viewed 35544 times)
  333. How do we determine the age of the universe? (viewed 35487 times)
  334. Who (and when) discovered that the earth's axis is on a 23 degree tilt? (viewed 35466 times)
  335. What companies or businesses can astronomers work for? (viewed 35417 times)
  336. Do you think it's possible to maintain life on other planets? (viewed 35399 times)
  337. Do the Sun's or Earth's magnetic field reverse? (viewed 35222 times)
  338. Is the Sun always up for exactly 12 hours at the equator? (viewed 34970 times)
  339. Is there a beginning and an end to a galaxy's life? (viewed 34929 times)
  340. If the universe is 15 billion years old, how can it be larger than 15 billion light years across? (viewed 34881 times)
  341. How can I find my age on another planet? (viewed 34551 times)
  342. Is Andromeda part of the Milky Way? Where can I find them in the sky? (viewed 34398 times)
  343. How do we know the Milky Way is a spiral galaxy? (viewed 34217 times)
  344. How do we define distance in an expanding universe? (viewed 34162 times)
  345. Why do clocks turn in the opposite direction from the Earth and Moon? (viewed 34140 times)
  346. What was that really big falling star that I saw? (viewed 34106 times)
  347. Why have star signs shifted by one constellation? (viewed 34105 times)
  348. How can the universe be "flat"? We're 3D! (viewed 33726 times)
  349. How are photons created and destroyed? (viewed 33670 times)
  350. When we look back to the Big Bang, why don't we see the universe as a tiny speck of matter? (viewed 33440 times)
  351. How does the brightness of a star depend on its distance from us? (viewed 33391 times)
  352. Who came up with the name "black hole"? (viewed 33336 times)
  353. Why do humans want to go in space? (viewed 33328 times)
  354. Is the Earth at the centre of the Universe? (viewed 33315 times)
  355. What would happen if two stars collided? (viewed 33298 times)
  356. Why don't astronomers use everyday units to measure distances (what is an AU or a pc)? (viewed 33272 times)
  357. What is the pattern to the distances between each planet and the sun? (viewed 33256 times)
  358. How can we estimate the number of Earth-like planets in the Galaxy? (viewed 33180 times)
  359. What is the significance of the second focus of elliptical orbits of planets in our Solar System? (viewed 33128 times)
  360. Is there a simple formula to calculate solar eclipse timings from any position on Earth? (viewed 33121 times)
  361. How do astronauts communicate with their families from space? (viewed 33075 times)
  362. How are planets detected around other stars? (viewed 33001 times)
  363. Can a lunar and a solar eclipse happen in the same month? When will this happen next? (viewed 32997 times)
  364. Are Earth and the Moon "twin planets"? (viewed 32900 times)
  365. How is it that we see farther out in space (farther back in time) than in the past? (viewed 32834 times)
  366. Will the Moon be invisible in 500 million years? (viewed 32819 times)
  367. Which American colleges teach astronomy? (viewed 32653 times)
  368. How dangerous are the asteroids? (viewed 32623 times)
  369. Will we ever stop having solar eclipses because of the moon's motion away from the Earth? (viewed 32606 times)
  370. Why is our solar system so different from all the others we've found? (viewed 32487 times)
  371. Can we colonize other planets? (viewed 32431 times)
  372. Why are there blue shifted galaxies? (viewed 32347 times)
  373. Why is Uranus tipped on its side? (viewed 32211 times)
  374. What kind of eyepieces do I need to look at planets? (viewed 32109 times)
  375. How do I become both an astronaut and an astronomer? (viewed 31756 times)
  376. How can I calculate distances between stars? (viewed 31705 times)
  377. What are quasars made of? (viewed 31660 times)
  378. Why doesn't gravity change the speed of light? (viewed 31407 times)
  379. Why do constellations look the same after several years even though all the stars are moving? (viewed 31213 times)
  380. Is it possible to count the stars? (viewed 31197 times)
  381. Is time travel possible using merging black holes? (viewed 31171 times)
  382. Why do astronauts in space need to exercise? (viewed 31043 times)
  383. Why are there no craters on Earth? Did all the meteorites miss us? (viewed 30999 times)
  384. How do sunrise and sunset times change with altitude? (viewed 30990 times)
  385. What is happening just around the black hole in the center of the Milky Way? (viewed 30941 times)
  386. Is the gravitational force exerted by the Earth on the Moon equal to the centripetal force acting on the Moon? (viewed 30860 times)
  387. What is dark matter? (viewed 30785 times)
  388. How hot is each one of the layers of the sun? (viewed 30620 times)
  389. Did the speed of light change over the history of the universe? (viewed 30608 times)
  390. How can we distinguish a star's "real" color from the change in color that we observe due to the star's motion? (viewed 30602 times)
  391. Can we see dead stars with the naked eye? (viewed 30571 times)
  392. How big a change in the Earth's orbit would be required to destroy all life? (viewed 30552 times)
  393. How do we measure distances to other stars? (viewed 30397 times)
  394. Can superheavy elements (such as Z=116 or 118) be formed in a supernova? Can we observe them? (viewed 30346 times)
  395. Is it true that the Sun burns off a billion tons of gas every 5 seconds? (viewed 30337 times)
  396. Are time machines possible? (viewed 30289 times)
  397. What happens when an antimatter black hole collides with a matter blackhole? (viewed 30264 times)
  398. Is the universe really like an expanding balloon? (viewed 30154 times)
  399. How do I make a scale model of the Solar System? (viewed 30125 times)
  400. How many moles of stars are in the known universe? (viewed 29839 times)
  401. Is there any limitation to what a black hole can "suck" in? (viewed 29655 times)
  402. How are galaxy distances inferred from their recessional velocities? (viewed 29432 times)
  403. Can you describe a day on the job as an astronomer? (viewed 29431 times)
  404. What's that dark spot on the Sun? (viewed 29274 times)
  405. What is the farthest in space that we have gone? (viewed 29044 times)
  406. How can I tell if the rock I found is a meteorite? (viewed 28998 times)
  407. How can we tell what the interiors of planets are like? (viewed 28994 times)
  408. What are the closest and/or brightest stars? (viewed 28909 times)
  409. What happens when you change the mass of a White Dwarf or Neutron Star? (viewed 28888 times)
  410. How can we know that there are other galaxies if we cannot leave ours? (viewed 28837 times)
  411. Could an astronaut or satellite fall into a black hole that we didn't know about? (viewed 28699 times)
  412. Can astronauts produce water in space? (viewed 28641 times)
  413. Will the seasons change due to precession? (viewed 28620 times)
  414. What are the facts about the Star of Bethlehem? (viewed 28615 times)
  415. Did I see the Aurora Borealis as a child? (viewed 28594 times)
  416. Don't tachyons travel faster than light? (viewed 28552 times)
  417. Is the Local Group expanding along with the entire Universe? (viewed 28532 times)
  418. Why do most moons orbit their planets at the equator? (viewed 28518 times)
  419. Why is the time between two successive full moons different from the lunar synodic month? (viewed 28508 times)
  420. Do astronomers believe in astrology? (viewed 28504 times)
  421. What are the atmospheres of Mars and Pluto like? (viewed 28413 times)
  422. Aren't jobs in astronomy scarce? (viewed 28405 times)
  423. How long does it take the Big Dipper to move in the sky? (viewed 28396 times)
  424. How was the starting point for the Julian Date system chosen? (viewed 28365 times)
  425. Why does the SETI project search for radio signals? (viewed 28340 times)
  426. What do "homogeneity" and "isotropy" mean? (viewed 28261 times)
  427. Has anyone made a map of the Milky Way? (viewed 28206 times)
  428. When are there 5 Sundays in February? (viewed 28199 times)
  429. Why do we study black holes? (viewed 28133 times)
  430. Was I hit by a meteorite? (viewed 28132 times)
  431. Wouldn't the Big Bang theory be considered a hypothesis and not a theory? (viewed 28109 times)
  432. How do we know if the universe will keep expanding forever? (viewed 28053 times)
  433. How are galaxies named? (viewed 28006 times)
  434. What does the term "visible universe" mean? (viewed 27869 times)
  435. What colors are visible through an amateur telescope? (viewed 27824 times)
  436. How can geometry be different in space? (viewed 27778 times)
  437. Does the Milky Way spin counter-clockwise? If so, do all spiral galaxies spin in this direction and why? (viewed 27626 times)
  438. Why can't a plane fly slowly and let the Earth pass underneath? (viewed 27510 times)
  439. Could you tell me about the life cycle of galaxies? (viewed 27477 times)
  440. Why are the compositions of comets and asteroids different? (viewed 27432 times)
  441. Can you use an infinite line of reflectors to send light to the edge of the Universe? (viewed 27394 times)
  442. Do you believe in UFOs? (viewed 27349 times)
  443. Will winter and summer constellations change due to abnormal warmth or cold on Earth? (viewed 27268 times)
  444. How do asteroids, meteors and comets disappear? (viewed 27264 times)
  445. How much time do astronomers spend looking through telescopes? (viewed 27143 times)
  446. How will the two black holes that are going to collide affect Earth? (viewed 27133 times)
  447. Have there been other Big Bangs before? (viewed 27044 times)
  448. How can we see galaxies if their stars are so faint? (viewed 26900 times)
  449. Can life exist on the recently discovered extrasolar planets? (viewed 26893 times)
  450. What's the best thing about being an astronomer? (viewed 26892 times)
  451. Do we see the same stars from above and below the equator? (viewed 26744 times)
  452. How close do you have to come to the Earth to be influenced by its gravity? (viewed 26708 times)
  453. How do astronomers measure the radius of a star? (viewed 26703 times)
  454. Is the Milky Way a collision of two galaxies? (viewed 26604 times)
  455. How do I explain to my children why the Moon has phases? (viewed 26545 times)
  456. How are galaxies and solar systems similar? (viewed 26539 times)
  457. Is there a project I can do on black holes? (viewed 26529 times)
  458. Can two lunar eclipses occur in the same month? (viewed 26505 times)
  459. How can we measure distances to more stars? (viewed 26503 times)
  460. Could you escape from a black hole if you were able to go faster than the speed of light? (viewed 26363 times)
  461. Why do so many of the world's UFO sightings happen in America? (viewed 26282 times)
  462. Is infinite temperature possible? (viewed 26260 times)
  463. How do scientists slow light down? (viewed 26250 times)
  464. Do we know everything about the Sun? (viewed 26240 times)
  465. How close does a supernova need to be to damage the Earth's environment? (viewed 26107 times)
  466. Do the magnitudes and colors of stars ever change? (viewed 26009 times)
  467. Can one star orbit another? (viewed 25984 times)
  468. Can "tired light theory" explain the observed redshifts of galaxies? (viewed 25925 times)
  469. How far does a galaxy extend? (viewed 25828 times)
  470. Is it worthwhile to continue the search for extraterrestrial life? (viewed 25779 times)
  471. How do I polar align my telescope? (viewed 25748 times)
  472. What supernova created the Crab nebula? (viewed 25727 times)
  473. Is there such a thing as hyperspace? (viewed 25697 times)
  474. Can double stars have planets? (viewed 25654 times)
  475. What happens to the material that has been sucked into a black hole? (viewed 25627 times)
  476. What type of energy does a black hole have? (viewed 25577 times)
  477. What causes gamma ray bursts? (viewed 25561 times)
  478. What is the origin of the stellar classification system "OBAFGKM"? (viewed 25554 times)
  479. Do asteroids hit the sun? (viewed 25553 times)
  480. What will happen to the Milky Way in the future? (viewed 25508 times)
  481. What is the farthest Northern Latitude in which the Magellanic Clouds can be seen? (viewed 25499 times)
  482. Why do the explosions of Type Ia supernovae have a more predictable spectrum than those of regular Type II supernovae? (viewed 25492 times)
  483. Can astronauts play musical instruments in space? (viewed 25452 times)
  484. What is sidereal time? (viewed 25411 times)
  485. Which way does the sun travel in the southern hemisphere? (viewed 25367 times)
  486. How will a change in the speed of light affect the evolution of the Universe? (viewed 25313 times)
  487. How do we know what parameters to use when simulating the collision of the Milky Way and Andromeda? (viewed 25131 times)
  488. Is there oxygen in the atmospheres of other planets? (viewed 25099 times)
  489. What's the object I saw that moved across the sky and then got very bright? (viewed 25058 times)
  490. What is "nothing", from a scientific point of view? (viewed 24985 times)
  491. How do we know that sunspots are associated with the Sun's magnetic field? (viewed 24983 times)
  492. Why did the Pioneer and Voyager take only 2 years to reach Jupiter, while Galileo and Cassini took more than 5 years? (viewed 24950 times)
  493. How different would the night sky have looked in 40,000 B.C.? (viewed 24911 times)
  494. What is a Cepheid variable? (viewed 24884 times)
  495. Are there any dark stars or dark galaxies made of dark matter? (viewed 24837 times)
  496. Why do we assume that the universe is homogeneous? (viewed 24835 times)
  497. Was Stonehenge built to mark solar phenomena? (viewed 24786 times)
  498. Is there sound coming from the Sun? (viewed 24775 times)
  499. What calculations go into predicting eclipses? (viewed 24726 times)
  500. Is there a list of the sizes of different kinds of stars? (viewed 24693 times)
  501. Why is the shadow on the Moon the shape it is? (viewed 24678 times)
  502. When unmanned spacecraft accelerate in space, what causes them to slow down? (viewed 24644 times)
  503. What is a Dyson Sphere? (viewed 24642 times)
  504. What's so exciting about the new planet around 55 Cancri? (viewed 24621 times)
  505. What process would bring about a quark star? (viewed 24611 times)
  506. Have gravitational waves been proven to exist? (viewed 24528 times)
  507. Did a giant impact cause the Dark Ages? (viewed 24522 times)
  508. What is the difference between homogeneity and isotropy? (viewed 24505 times)
  509. Which part of the sky did the famous 'wow' signal originate from? (viewed 24480 times)
  510. If we invented special suits could we ever go to the sun? (viewed 24473 times)
  511. When did people discover that the Sun is a star? (viewed 24449 times)
  512. How many sunspots can the Sun have at once? (viewed 24414 times)
  513. Can I see a quasar? (viewed 24385 times)
  514. Are planetary nebulae the result of supernovae? (viewed 24379 times)
  515. Can I see details on Venus? (viewed 24329 times)
  516. How are asteroid compositions and classifications determined? (viewed 24279 times)
  517. Can any comparison be made between spiral galaxies and hurricanes? (viewed 24251 times)
  518. What is our galaxy's halo made of, and how was it formed? (viewed 24229 times)
  519. Why are there active volcanos on Io? (viewed 24214 times)
  520. Is there any possibility that the Solar System or the Universe is in a black hole? (viewed 24133 times)
  521. What equipment do I need for astrophotography? (viewed 24091 times)
  522. Does Cerenkov radiation travel faster than light? (viewed 24058 times)
  523. How is it proved that the Universe is expanding? (viewed 24008 times)
  524. Can a human give birth in space? (viewed 23958 times)
  525. How big was the Sun when it first "fired up"? (viewed 23925 times)
  526. What happened to all the black holes that were around in the early universe? (viewed 23856 times)
  527. Why are there more maria on the near side of the Moon? (viewed 23823 times)
  528. If clocks run slow in a gravitational field, how can we know the true age of the Solar System and Universe? (viewed 23789 times)
  529. How can we compare dark matter and dark energy? (viewed 23781 times)
  530. Could we send a space mission to a comet? (viewed 23761 times)
  531. What caused Shoemaker-Levy 9 to split up? (viewed 23754 times)
  532. Could we be seeing dead stars? (viewed 23698 times)
  533. Why are telescopes kept in cold conditions? (viewed 23669 times)
  534. Why do photos of space taken from space never show any stars? (viewed 23644 times)
  535. How are sunspots formed? (viewed 23575 times)
  536. If the Universe was infinitely dense at the Big Bang, why didn't time stand still? (viewed 23571 times)
  537. How long do supernova remnants last? (viewed 23527 times)
  538. How do solar flares affect airline pilots? (viewed 23503 times)
  539. Would the biggest airplanes cause tsunamis if they crashed? (viewed 23451 times)
  540. Why doesn't light from distant galaxies reach us instantaneously? (viewed 23447 times)
  541. How many comets are currently orbiting our sun? (viewed 23378 times)
  542. As the universe expands, why don't galaxies get stretched out? (viewed 23374 times)
  543. Why is the Hubble Space Telescope in space? (viewed 23342 times)
  544. What happened to the girl who named Pluto? (viewed 23341 times)
  545. Could a different theory of gravity explain the dark matter mystery? (viewed 23299 times)
  546. How does the Earth compare in size to the entire universe at the present epoch? (viewed 23262 times)
  547. How do we know that superclusters are the largest structures in the universe? (viewed 23233 times)
  548. Can you tell time by the Big Dipper? (viewed 23183 times)
  549. Why doesn't NASA build rotating spacecraft to simulate gravity? (viewed 23172 times)
  550. How powerful are quasars? (viewed 23093 times)
  551. Can you give me advice on buying a telescope? (viewed 23082 times)
  552. Would extraterrestrial civilizations know that there is life on Earth? (viewed 23043 times)
  553. Can I build an instrument to measure the size of the Sun and of the Moon? (viewed 22907 times)
  554. Where does the kinetic energy of infalling bodies come from? (viewed 22875 times)
  555. How is the Cepheid yardstick validated? (viewed 22872 times)
  556. Did I really hear a meteor? (viewed 22827 times)
  557. Can supernovae hinder the formation of life in galaxies? (viewed 22799 times)
  558. What would happen if there was a collision between two white dwarfs? (viewed 22769 times)
  559. Are there any new craters on the moon? (viewed 22729 times)
  560. Do unmanned spacecraft like Voyager travel in straight lines? (viewed 22723 times)
  561. Why are stars of different masses? (viewed 22705 times)
  562. How do planets capture satellites? (viewed 22660 times)
  563. Did time go slower just after the Big Bang? (viewed 22617 times)
  564. Why is it important to study meteorites? (viewed 22615 times)
  565. How big is the Hubble Ultra Deep Field image? (viewed 22602 times)
  566. Do galaxies orbit around anything? (viewed 22590 times)
  567. Do similar laws of physics throughout the Universe imply that all life must be like life on Earth? (viewed 22586 times)
  568. What kind of instruments are used to detect extrasolar planets? (viewed 22577 times)
  569. How do I become an astronomical artist? (viewed 22512 times)
  570. Why are telescopes located in remote places? (viewed 22505 times)
  571. Could there have been multiple Big Bangs at different places in the universe? (viewed 22292 times)
  572. How can I contribute to science as an amateur astronomer? (viewed 22260 times)
  573. Are the properties of extrasolar planets known? (viewed 22211 times)
  574. Do the Earth's magnetic poles ever change places? (viewed 22195 times)
  575. What kind of telescope should I use for astrophotography? (viewed 22192 times)
  576. Are the asteroids the remains of a planet which broke apart? (viewed 22191 times)
  577. How could galaxies have gotten so far away in only 15 billion years? (viewed 22148 times)
  578. How are astronomy and poetry linked? (viewed 22141 times)
  579. How can you tell if a crescent moon is preceding or following a new-moon phase? (viewed 22118 times)
  580. Why is NASA shutting down the Hubble Space Telescope? (viewed 22116 times)
  581. Can I listen to the SETI@home radio signal? (viewed 22112 times)
  582. Does the Sun have any heavy elements? (viewed 22083 times)
  583. Could dark energy come from matter anti-matter pairs forming spontaneously and then annihilating? (viewed 22077 times)
  584. Does the Moon look different in the northern and southern hemispheres? (viewed 22065 times)
  585. What would happen if a human were exposed to space without wearing a spacesuit? (viewed 21998 times)
  586. What month was it when Odysseus saw Orion in 1000BC? (viewed 21980 times)
  587. Will we discover an 11th planet? What would it be called? (viewed 21973 times)
  588. Can the theory of formation of the solar system explain all the observables? (viewed 21947 times)
  589. A line drawn perpendicular to a line through the tips of the horns of the crescent moon doesn't point to the Sun! Why not? (viewed 21763 times)
  590. What class of spiral galaxy is the Milky Way? (viewed 21760 times)
  591. How do unmanned space probes avoid running into things? (viewed 21753 times)
  592. Why can't relative velocities add up to more than the speed of light? (viewed 21735 times)
  593. Why does one side of Mars look more catastrophic than the other? (viewed 21704 times)
  594. Why does the apparent density of galaxies drop off at larger distances? (viewed 21636 times)
  595. What makes a satellite geosyncronise itself with Earth's orbit? (viewed 21615 times)
  596. Would a planet near the galactic center have a brighter night sky? (viewed 21588 times)
  597. What is the solar cycle? (viewed 21531 times)
  598. Is it possible for amateurs to do optical interferometry? (viewed 21377 times)
  599. Can other terrestrial moons be (or have been) stable? (viewed 21287 times)
  600. How are supernovae discovered? (viewed 21270 times)
  601. Can a black hole come back to the visual universe through a "little bang"? (viewed 21268 times)
  602. How do astronomers observe the Sun's interior? (viewed 21256 times)
  603. Why was the Platonic year named after Plato? (viewed 21238 times)
  604. Do stars' orbits in galaxies obey Kepler's Laws? (viewed 21208 times)
  605. Could we send a manned mission to the outer planets? (viewed 21142 times)
  606. What would the Big Crunch look like to an observer on Earth? (viewed 21133 times)
  607. Where was the water in the big bang? (viewed 21110 times)
  608. Does inflation allow for an infinite number of universes? (viewed 21107 times)
  609. Could our position in the universe affect our perceptions of the expansion? (viewed 21085 times)
  610. What is meant by "stopping down a telescope"? (viewed 20975 times)
  611. Why doesn't the hydrogen on Jupiter explode? (viewed 20892 times)
  612. Why are accretion disks flat? (viewed 20850 times)
  613. Does a photon observe other photons moving past it at the speed of light? (viewed 20739 times)
  614. Did I find a rock that came from the Moon? (viewed 20694 times)
  615. Can gravitational lensing from intervening galaxies cause the observed ripples in the Cosmic Microwave Background? (viewed 20666 times)
  616. Have astronomers observed any phenomena that could be produced by extraterrestrial civilizations? (viewed 20619 times)
  617. What is the SU(3) quark model? (viewed 20576 times)
  618. Why do spacecraft need heat shields coming back to Earth but not leaving? (viewed 20529 times)
  619. How can water be chemically trapped in rocks? (viewed 20491 times)
  620. How can the Sun have such a strong gravitational field if it's made of gasses? (viewed 20482 times)
  621. What's new with the Big Bang? (viewed 20397 times)
  622. Is it possible to build a cheap device to measure declination? (viewed 20247 times)
  623. If comets are boiling away, why are there any left? (viewed 20230 times)
  624. Could photons be dark matter? (viewed 20201 times)
  625. Why do some eclipses take longer than others? (viewed 20194 times)
  626. Why can we have solar eclipses? (viewed 20191 times)
  627. Will I be able to see the shadow of the Moon streaking towards me in a total solar eclipse? (viewed 20182 times)
  628. How fast do particles travel in space? (viewed 20135 times)
  629. Why search for only Earth-like life on other planets? (viewed 20124 times)
  630. How can we find galaxies behind the Milky Way? (viewed 20073 times)
  631. Where can I find information on the moons of other planets? (viewed 20062 times)
  632. Why is pressure broadening greater in low mass stars than in high mass stars? (viewed 19902 times)
  633. How much power is contained in a beam of light? (viewed 19874 times)
  634. What would an "open geometry" for the universe look like? (viewed 19841 times)
  635. What are the boundaries of the constellations? (viewed 19806 times)
  636. Why is the Cosmic Microwave Background not absorbed by interstellar hydrogen? (viewed 19770 times)
  637. How do astronomers come up with their facts? (viewed 19744 times)
  638. Why aren't discoveries of extrasolar planets reported on the news? (viewed 19714 times)
  639. Did the Sumerians measure precession? (viewed 19665 times)
  640. How do bars form in spiral galaxies? (viewed 19636 times)
  641. What kinds of star clusters are there? (viewed 19622 times)
  642. Can HST see the Oort cloud? (viewed 19617 times)
  643. Why is the WMAP picture of the CMB an ellipse? (viewed 19590 times)
  644. Why don't astronauts sublimate in space? (viewed 19554 times)
  645. Do electrons age? (viewed 19499 times)
  646. How do photons from distant objects maintain enough energy to reach us? (viewed 19451 times)
  647. Can the Space Shuttle abort and return to Earth before reaching orbit? (viewed 19447 times)
  648. Can we make a movie of the Milky Way galaxy's rotation? (viewed 19374 times)
  649. How long is twilight on the Moon? (viewed 19276 times)
  650. Does the shuttle worry about space junk? (viewed 19191 times)
  651. Why do supernova remnants look like rings rather than spheres? (viewed 19093 times)
  652. How does melting a material reset its radioactive clock? (viewed 19086 times)
  653. How did Mars get so dusty? (viewed 19037 times)
  654. How do you classify galaxies? (viewed 18979 times)
  655. Where can I see Newton's original reflecting telescope? (viewed 18969 times)
  656. What is the best time of the year to see eclipses? (viewed 18940 times)
  657. Why doesn't SETI concentrate its observations to the nearby stars and the solar systems that we are discovering? (viewed 18874 times)
  658. Do constellations looks the same from space? (viewed 18849 times)
  659. Will the next generation telescope OWL be able to detect an Earth like extrasolar planet? (viewed 18806 times)
  660. Will astronauts ever be able to go ice-skating on Europa? (viewed 18771 times)
  661. What causes a particle to decay? (viewed 18732 times)
  662. How can we understand the meaning of large numbers like "a million million?" (viewed 18730 times)
  663. Will the Leonid meteor shower go away? (viewed 18728 times)
  664. Why don't all neutron stars become pulsars? (viewed 18703 times)
  665. How can I nominate myself for a Nobel Prize in Physics? (viewed 18697 times)
  666. How long has humanity known that we live in a galaxy similar to others in the Universe? (viewed 18687 times)
  667. Can planets collide with one another? (viewed 18660 times)
  668. Is light of different colors affected differently by gravity? (viewed 18603 times)
  669. What are collections of galaxies called? (viewed 18563 times)
  670. What are "curled" dimensions? (viewed 18558 times)
  671. What was that eclipse I saw in the sky? (viewed 18530 times)
  672. How does interferometry work? (viewed 18413 times)
  673. How do we find out about the star formation histories of galaxies? (viewed 18323 times)
  674. Does the temperature of matter increase as it is accelerated to relativistic speeds? (viewed 18290 times)
  675. How do distant galaxies differ from those nearby? (viewed 18284 times)
  676. Can astronomers observe anything when the moon is full? (viewed 18256 times)
  677. Do asteroids ever do anything good in the Solar System? (viewed 18244 times)
  678. Wouldn't the vast distances of space distort SETI signals into unintelligeble forms? (viewed 18028 times)
  679. Do we really observe the edges of galaxies at different epochs? (viewed 18018 times)
  680. Can you tell me the characteristics of W, R, N and S type stars? (viewed 17999 times)
  681. What do stellar classifications mean? (viewed 17969 times)
  682. Why is it called astronomy when all the other sciences end in -ology? (viewed 17960 times)
  683. Why will fusion wait until hydrogen is gone before starting to fuse heavier atoms? (viewed 17927 times)
  684. What kind of interference must astronomers contend with when observing? (viewed 17911 times)
  685. How are astronauts trained for weightlessness? (viewed 17858 times)
  686. What would happen if you went back in time and killed your grandmother? (viewed 17853 times)
  687. How can I watch the Perseid meteor shower? (viewed 17845 times)
  688. If nothing can escape a black hole, why do some black holes have jets? (viewed 17841 times)
  689. Are black holes spherical? (viewed 17758 times)
  690. How does the color index of a star relate to its actual color? (viewed 17709 times)
  691. Will the diameter of a cluster of galaxies change with redshift? (viewed 17598 times)
  692. Why aren't accretion disks around giant stars as hot as accretion disks around black holes? (viewed 17574 times)
  693. If the universe is "bounded" today, could it one day become "unbounded"? (viewed 17551 times)
  694. Is cosmic expansion happening on microscopic scales? (viewed 17463 times)
  695. What is the three-body problem? (viewed 17433 times)
  696. How can I find out if the new moon has been sighted? (viewed 17382 times)
  697. Do we have to worry about relativity when studying galactic objects? (viewed 17173 times)
  698. Could neutrinos be dark matter? (viewed 16994 times)
  699. What kinds of cancer research have been done in space? (viewed 16972 times)
  700. How does a star take mass from another star? (viewed 16904 times)
  701. How can you tell the difference between single and multiple extrasolar planets? (viewed 16700 times)
  702. What is Hot Dark Matter theory? (viewed 16596 times)
  703. Could the Universe's dark matter be made up of black holes? (viewed 16587 times)
  704. Does lunar gardening really work? (viewed 16165 times)
  705. How does libration allow us to see more than 50% of the Moon? (viewed 16150 times)
  706. How can observations of the distant universe prove that the expansion is accelerating *now*? (viewed 16071 times)
  707. Is it a coincidence that we can have total solar eclipses? Are there other planets which also have them? (viewed 16047 times)
  708. Is light blueshifted when it is gravitationally lensed? (viewed 15956 times)
  709. Do binary or triple star systems form together? (viewed 15950 times)
  710. If photons have zero mass, why do they feel the effects of gravity? (viewed 15930 times)
  711. No matter how fast the universe is expanding, shouldn't gravity eventually make it recollapse? (viewed 15892 times)
  712. When measuring the expansion of the universe, do astronomers consider that they're seeing how galaxies moved long ago, not today? (viewed 15814 times)
  713. Is the green flash real? (viewed 15741 times)
  714. What percent of the time can astronomers observe without interference from the Moon? (viewed 15706 times)
  715. What is the photoelectric effect? Why can't multiple low-frequency photons free an electron? (viewed 15683 times)
  716. How do we know the density of some extrasolar planets? (viewed 15615 times)
  717. What do meteorites tell us about life on other planets? (viewed 15602 times)
  718. Could matter-anti-matter repulsion power the expansion of the universe? (viewed 15421 times)
  719. Why is it easier to see a star if you look slightly to the side? (viewed 15381 times)
  720. How do supernovae show us that the Universe's expansion is accelerating? (viewed 15369 times)
  721. Are there any 'lonely galaxies'? (viewed 14991 times)
  722. Why doesn't the ammonia and methane in Jupiter's atmosphere sink into the core? (viewed 14983 times)
  723. If the sun went out and our atmosphere froze solid, what color would it be? (viewed 14879 times)
  724. Can we prove that the Moon isn't hollow? (viewed 14795 times)
  725. How do we detect incoming meteorites? (viewed 14670 times)
  726. What was different on Mars in the past to allow liquid water to be present? (viewed 14537 times)
  727. During close approaches, can Mars appear in our sky as large as the Moon? (viewed 14374 times)
  728. When will Hale-Bopp return? (viewed 14309 times)
  729. Why don't skydivers burn up like meteors? (viewed 14116 times)
  730. How are planets affected by the Hot Ionised Medium? (viewed 14105 times)
  731. Has anyone ever seen a star "turn on"? (viewed 13983 times)
  732. What happens to the helium formed in the sun? (viewed 13789 times)
  733. Why was Mir burnt up in the atmosphere? (viewed 13639 times)
  734. How can we discern different galaxies/clusters along the same line of sight? (viewed 13572 times)
  735. What are the largest radio wavelengths observed from radio sources in the sky? (viewed 13569 times)
  736. Can the sun rise from the west on Mars? (viewed 13371 times)
  737. How has light from 13 billion years ago not passed us by? (viewed 13250 times)
  738. Why are craters round? (viewed 13240 times)
  739. What is the relationship between the width of a star trail on a photo and the star's intensity? (viewed 13144 times)
  740. Can we harvest H & O from space to make water? (viewed 12281 times)
  741. What is between the Oort cloud and the closest star? (viewed 12165 times)
  742. Why does Titan, in spite of being smaller than Mars, have an atmosphere more dense than Earth's? (viewed 11667 times)
  743. Does weightlessness affect hunger? (viewed 11318 times)
  744. Are there solar tides? (viewed 11280 times)
  745. Could a planetary system survive if its star merged with another, or if its star went supernova? (viewed 11263 times)
  746. Do planets radiate noise? (viewed 10458 times)
  747. What time is sunrise/sunset or moonrise/moonset at my location? (viewed 10418 times)
  748. Is Earth-moon tidal friction causing global warming? (viewed 10411 times)
  749. Is the moon spherical? (viewed 10080 times)
  750. What would happen if a nuclear-powered shuttle exploded? (viewed 10079 times)
  751. Is dark energy affected by black holes? (viewed 9806 times)
  752. What happens to the Earth as the moon gets farther away and will it ever go away entirely? (viewed 9420 times)
  753. Did the Moon or planets form in a manner similar to that of Earth? (viewed 9239 times)
  754. Do more meteorites fall at low latitudes? (viewed 9126 times)
  755. Is it sensible to consider terraforming Mars? (viewed 8996 times)
  756. If there are infinity universes, will every thing that is possible happen? (viewed 8919 times)
  757. Why is the Moon higher in the sky in winter and lower in the summer? (viewed 8904 times)
  758. Will Comet Elenin (C/2010 X1) affect the Earth on its close approach in Fall 2011? (viewed 8895 times)
  759. What are the possible ends of the universe? (viewed 8850 times)
  760. Where are the protons and electrons in a Neutron Star? (viewed 8804 times)
  761. Will the Pioneer and Voyager probes ever leave the Milky Way? (viewed 8738 times)
  762. 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 8706 times)
  763. What color are meteors? (viewed 8423 times)
  764. Wait, I'm still confused why information can't travel faster than the speed of light. (viewed 8351 times)
  765. Where is everybody? (viewed 8231 times)
  766. Is the Moon always visible during winter on the North Pole? (viewed 8222 times)
  767. Why does Mars have a dusty atmosphere? (viewed 7594 times)
  768. If I were traveling through space, could I see distant galaxies with my own eyes? (viewed 7544 times)
  769. The naming of Mars (viewed 7532 times)
  770. Does the singularity in a black hole create a new Universe? (viewed 7402 times)
  771. Is the reddish dust of Mars biogenic? (viewed 7218 times)
  772. When will humans travel to Mars and revisit the Moon? (viewed 6814 times)
  773. Where is the Spitzer Space Telescope? (viewed 6801 times)
  774. Does the particles involved in a star's final core collapse travel faster than the speed of light? (viewed 6138 times)
  775. When is the best time to observe zodiacal light? (viewed 5867 times)
  776. How likely is it for a planet to transit its star? (viewed 5239 times)
  777. Why do astronomers use telescopes? (viewed 4848 times)
  778. What causes the aurora? (viewed 4545 times)
  779. How did a transit of Venus provide astronomers with the first measurement of the Earth-Sun distance? (viewed 4371 times)
  780. Can the Sun be closer to the Earth than any planet is to Earth? (viewed 3512 times)
  781. Can we hear sound on Titan? (viewed 3371 times)
  782. Cosmologists say the expansion of the universe is accelerating, what is driving this? (viewed 3265 times)
  783. Does the direction of the moon's crescent change through the night? (viewed 3113 times)
  784. What do all the angles in a table for a planet's orbit mean? (viewed 2858 times)
  785. How do I maximize my chances of seeing shooting stars? (viewed 2079 times)
  786. Are exoplanets real? (viewed 1844 times)
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