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 2122267 times)
  2. What color is each planet? (viewed 894519 times)
  3. At what speed does the earth move around the sun? (viewed 568799 times)
  4. Is the Moon moving away from the Earth? When was this discovered? (viewed 548588 times)
  5. How far is each planet from Earth? (viewed 462407 times)
  6. When will Halley's Comet return? (viewed 416334 times)
  7. How many stars are there in our Galaxy (Milky Way)? (viewed 385071 times)
  8. How long does it take for the Sun's light to reach us? (viewed 384184 times)
  9. Why do the planets orbit the sun? (viewed 370794 times)
  10. What is the universe expanding into? (viewed 366016 times)
  11. How do you measure the distance between Earth and the Sun? (viewed 333665 times)
  12. Which planets have rings? (viewed 320500 times)
  13. Why do stars twinkle? (viewed 314753 times)
  14. Does the Moon rotate? Are there other moons that always keep one face toward their planet? (viewed 298002 times)
  15. How do I build a model rocket? (viewed 287139 times)
  16. What color is Venus? (viewed 271168 times)
  17. What is a white hole? (viewed 264814 times)
  18. Can you hear sounds in space? (viewed 250029 times)
  19. What is the life cycle of a star? (viewed 244525 times)
  20. What are the names of the earth, moon, sun, and solar system? (viewed 235880 times)
  21. What makes the Earth rotate? (viewed 227729 times)
  22. What is that ring (or rainbow) around the moon? (viewed 226968 times)
  23. What are shooting stars? (viewed 225796 times)
  24. What is the largest star? (viewed 221252 times)
  25. What do astronauts eat in space? Can they grow food? (viewed 206926 times)
  26. How do we know the age of the Universe and the Earth? (viewed 202380 times)
  27. Why do planets rotate? (viewed 202020 times)
  28. Can artificial gravity be created in space? (viewed 200805 times)
  29. Is the universe expanding faster than the speed of light? (viewed 197484 times)
  30. How does the location of sunrise and sunset change throughout the year? (viewed 187813 times)
  31. What are the different kinds of astronomers? (viewed 185370 times)
  32. Where did the name 'Earth' come from? (viewed 178543 times)
  33. How can we see the Milky Way if we are inside it? (viewed 177080 times)
  34. What would happen if we did not have a Moon? (viewed 173825 times)
  35. Why isn't the sky bright at night if the universe has so many stars? (viewed 173062 times)
  36. How many Earths fit into the Sun? (viewed 171851 times)
  37. Why is a day divided into 24 hours? (viewed 166460 times)
  38. How does the position of Moonrise and Moonset change? (viewed 162003 times)
  39. Who named the planets and who decides what to name them? (viewed 156041 times)
  40. Why are the Moon and Sun sometimes orange or red? (viewed 153926 times)
  41. When was the last time all 9 planets were aligned? (viewed 152049 times)
  42. Is Pluto a planet? (viewed 149570 times)
  43. Why do airplanes take longer to fly West than East? (viewed 149185 times)
  44. Is the distance from the Earth to the Sun changing? (viewed 148699 times)
  45. What is at the end of the Universe? (viewed 144755 times)
  46. How can I find the star I have "bought"? (viewed 140964 times)
  47. How much money is spent on space exploration? (viewed 140329 times)
  48. Why are there both high and low tides? (viewed 130185 times)
  49. How do astronauts take baths and use restrooms in space? (viewed 128902 times)
  50. What direction do planets rotate? (viewed 128131 times)
  51. Can we feel the Earth spin? (viewed 127571 times)
  52. What is the largest galaxy? (viewed 126835 times)
  53. Is the Sun expanding? Will it ever explode? (viewed 126694 times)
  54. How many known galaxies are there? (viewed 125623 times)
  55. What is a nova? (viewed 124798 times)
  56. Does your weight change between the poles and the equator? (viewed 122654 times)
  57. Do stars move in the sky? (viewed 121516 times)
  58. Can I buy a star? (viewed 116399 times)
  59. What are the advantages and disadvantages of using a telescope in space? (viewed 116023 times)
  60. Will the sun go supernova in six years and destroy Earth (as seen on Yahoo)? (viewed 113738 times)
  61. Why do all the planets orbit in the same plane? (viewed 113364 times)
  62. How are light and heavy elements formed? (viewed 111604 times)
  63. Are there telescopes that can see the flag and lunar rover on the Moon? (viewed 111307 times)
  64. What is the hottest time of day? (viewed 110926 times)
  65. Does the Sun have a scientific name? (viewed 109922 times)
  66. How do stars move in the Galaxy? (viewed 109741 times)
  67. Why hasn't NASA gone back to the moon? (viewed 109700 times)
  68. What happens when galaxies collide? (viewed 109389 times)
  69. Who first measured the speed of light? (viewed 108399 times)
  70. Why do planets have elliptical orbits? (viewed 107895 times)
  71. How do rockets work? (viewed 107736 times)
  72. What is the size of the Solar System? (viewed 107084 times)
  73. Will the magnetic field of the Earth reverse its direction in the future? Will this cause problems? (viewed 106613 times)
  74. What was there before the Big Bang and what is there outside of our universe? (viewed 106124 times)
  75. When is the next comet due to arrive? (viewed 105848 times)
  76. What would happen if an impact caused Earth to stop rotating? (viewed 105836 times)
  77. How much money do astronomers make? (viewed 105692 times)
  78. What is the physical difference between a star and a planet? (viewed 105161 times)
  79. How long does a solar eclipse last? (viewed 104004 times)
  80. What will happen to life on Earth when the Sun becomes a red giant? (viewed 103595 times)
  81. Do black holes die? If so how? (viewed 103488 times)
  82. Does evolution contradict the second law of thermodynamics? (viewed 102729 times)
  83. How do you calculate the lifetime of the Sun? (viewed 102564 times)
  84. How many constellations are there? (viewed 102494 times)
  85. What elements make up the Sun? (viewed 102061 times)
  86. What is the significance of the Tropic of Cancer, Tropic of Capricorn, Arctic Circle and Antarctic Circle? (viewed 101037 times)
  87. What is the observational difference between a star and a planet? (viewed 100197 times)
  88. Does the Sun rotate? (viewed 99930 times)
  89. What's the difference between astronomy and astrology? (viewed 99110 times)
  90. Does the Sun move around the Milky Way? (viewed 98939 times)
  91. What do astronauts do all day in the International Space Station? (viewed 98045 times)
  92. What is apparent magnitude? (viewed 95002 times)
  93. Which planet is most similar to Earth? (viewed 93752 times)
  94. Does gravity vary across the surface of the Earth? (viewed 93648 times)
  95. How many meteorites hit Earth each year? (viewed 93265 times)
  96. What would happen if the gravity on Earth was suddenly turned off? (viewed 93039 times)
  97. What are constellations used for? (viewed 90946 times)
  98. If Mars is only about 35-60 million miles away at close approach, why does it take 6-8 months to get there? (viewed 90802 times)
  99. How critical is the Earth-Sun distance in maintaining our average temperatures on Earth? (viewed 89922 times)
  100. How do astronomers use math in their jobs? (viewed 89786 times)
  101. Why do different stars appear with seasons? (viewed 89402 times)
  102. Why are stars and planets round? (viewed 88654 times)
  103. Where did the Universe come from? (viewed 88303 times)
  104. Is there a proof that Earth moves? (viewed 88183 times)
  105. What kind of schooling is necessary to become an astronomer? (viewed 87799 times)
  106. Does the Sun orbit the Earth as well as the Earth orbiting the Sun? (viewed 87552 times)
  107. Why is the Moon so bright? (viewed 87543 times)
  108. Why is the Universe flat and not spherical? (viewed 87495 times)
  109. Have astronomers discovered Earth's second moon? (viewed 87277 times)
  110. What makes the wind? (viewed 86852 times)
  111. What would happen if an asteroid 10 kilometers across hit the Earth? (viewed 86346 times)
  112. What is a singularity? (viewed 85751 times)
  113. How can a star burn with no oxygen? (viewed 84417 times)
  114. Where does the name "Milky Way" come from? (viewed 82013 times)
  115. Why does the Earth tilt back and forward once a year? (viewed 81846 times)
  116. What is the difference between a "star" and a "sun"? (viewed 81665 times)
  117. What are RA and DEC? (viewed 81533 times)
  118. What would happen if Earth had more than one moon? (viewed 80608 times)
  119. Considering the motion of the Earth, the solar system, and the galaxy, how fast am I moving while lying in bed asleep? (viewed 79975 times)
  120. Since Earth is spinning, why do we land in the same place when we jump or fall? (viewed 78313 times)
  121. What are the requirements for being a planet? (viewed 77924 times)
  122. What kind of rock is the moon made of? (viewed 77749 times)
  123. How many stars are born and die each day? (viewed 77235 times)
  124. Why aren't there any green stars? (viewed 77001 times)
  125. Did astronauts really go to the Moon, or is it a hoax? (viewed 76832 times)
  126. How are galaxies formed? (viewed 76476 times)
  127. Will the Sun become a black hole one day? (viewed 74306 times)
  128. How are black holes made? Could one be made close to us? (viewed 74260 times)
  129. What would happen if a supermassive black hole came close to the Earth? (viewed 73660 times)
  130. What is the density of a black hole? (viewed 73649 times)
  131. Who has landed on the moon? (viewed 73213 times)
  132. Why is the moon in a different place every night? (viewed 72148 times)
  133. What would you see from inside a black hole? (viewed 71598 times)
  134. Do most astronomers believe in God based on the available scientific evidence? (viewed 70933 times)
  135. Can moons have moons? (viewed 70931 times)
  136. What happens to a substance if its speed is more than the speed of light? (viewed 70329 times)
  137. Why can't you see stars during the day? (viewed 70288 times)
  138. How do rockets move in space? (viewed 70150 times)
  139. Can you fire a gun on the Moon? (viewed 69878 times)
  140. How do astronomers measure the brightness of stars? (viewed 69833 times)
  141. How do we weigh objects in space? (viewed 69823 times)
  142. How often does the Sun pass through a spiral arm in the Milky Way? (viewed 69633 times)
  143. How can the Universe expand faster than the speed of light during inflation? (viewed 69472 times)
  144. What would happen if you took off your helmet in space? (viewed 69338 times)
  145. What are some of the effects of solar flares on Earth? (viewed 69177 times)
  146. Does the Mediterranean sea have tides? (viewed 68804 times)
  147. How is astronomy impacted by trigonometry? (viewed 68406 times)
  148. When the Sun converts mass to energy, do the orbits of the planets change? (viewed 68120 times)
  149. How do we know the mass of the Earth and the Moon? (viewed 68059 times)
  150. Is it possible to measure the temperature of the Sun? (viewed 68014 times)
  151. How does the Sun compare to other stars? (viewed 67144 times)
  152. How do you measure a planet's mass? (viewed 66596 times)
  153. Why do stars change colour when they twinkle? (viewed 66592 times)
  154. What are the "dog days of summer"? (viewed 66428 times)
  155. How does the Moon stay "suspended" in the air? (viewed 66363 times)
  156. How are elements heavier than iron formed? (viewed 65811 times)
  157. What is the evidence supporting the nebula theory of Solar System formation? (viewed 65755 times)
  158. Why do we not have eclipses every month? (viewed 65302 times)
  159. What kinds of jobs do astronomers do? (viewed 65143 times)
  160. Does quantum entanglement imply faster than light communication? (viewed 64624 times)
  161. If the universe is infinite does that mean there is an infinite number of "me"s? (viewed 63821 times)
  162. What are black holes made of? (viewed 63535 times)
  163. What causes seasons? (viewed 63095 times)
  164. How did the stars get named? (viewed 62804 times)
  165. When can I see the Moon through the hole in the Pantheon? (viewed 62640 times)
  166. Why doesn't the earliest sunset occur on the shortest day of the year? (viewed 62633 times)
  167. Where does the name "Moon" come from? (viewed 62397 times)
  168. How did asteroids form and what is the difference between an asteroid and a comet? (viewed 62136 times)
  169. How fast is the Universe expanding? (viewed 62060 times)
  170. How long would it take the Earth to fall into the Sun? (viewed 61930 times)
  171. How do you measure the mass of a star? (viewed 61922 times)
  172. Where did the matter in the universe come from? (viewed 61809 times)
  173. Traveling at light speed, how long would it take to get to the nearest galaxy? (viewed 61679 times)
  174. What are Altitude and Azimuth? (viewed 61437 times)
  175. What's the best college for astronomy? (viewed 61428 times)
  176. Why do planets not twinkle? (viewed 61278 times)
  177. How does light pollution affect astronomers? (viewed 61118 times)
  178. Are there stars outside of galaxies? (viewed 61113 times)
  179. Why doesn't the length of each day change much around the solstices? (viewed 60821 times)
  180. What would happen to us if the sun went out for an hour? (viewed 60684 times)
  181. Where, in relation to the entire universe, is the Milky Way located? (viewed 60643 times)
  182. What is the mass of the Universe? (viewed 59886 times)
  183. What's the difference between dark matter and dark energy? (viewed 59058 times)
  184. How can I calculate the position or path of the Sun for a given time and location? (viewed 58460 times)
  185. Does the Moon rotate? (viewed 58439 times)
  186. Could there be life in the galaxies nearest to the Milky Way? (viewed 58304 times)
  187. Why does the Sun's apparent path through the sky change throughout the year? (viewed 57995 times)
  188. Why does the Earth have only one moon? (viewed 57901 times)
  189. Can any galaxies be seen with the naked eye? (viewed 57516 times)
  190. How does the parachute in a model rocket work? (viewed 56874 times)
  191. How does astronomy benefit humankind? (viewed 56810 times)
  192. What is the origin of spiral structure in galaxies? (viewed 56783 times)
  193. How close was the Moon to the Earth when it formed? (viewed 56622 times)
  194. How long does the supernova stage of a star last? (viewed 56302 times)
  195. What is the shape of the universe? (viewed 56174 times)
  196. What makes up most of the Universe? (viewed 56052 times)
  197. What is the largest structure in the universe? (viewed 55582 times)
  198. Why is looking out into space the same as looking back in time? (viewed 55263 times)
  199. Why isn't the summer solstice the hottest day of the year? (viewed 55040 times)
  200. What can we learn from the color of a star? (viewed 54998 times)
  201. Where are stars born? (viewed 54952 times)
  202. What is a star's "spectrum"? (viewed 54602 times)
  203. How do astronauts use math in their jobs? (viewed 54591 times)
  204. What is the size of a black hole? (viewed 54487 times)
  205. Are names given to black holes? (viewed 54429 times)
  206. Can you see satellites? (viewed 53957 times)
  207. Which constellation does our Sun belong to? (viewed 53720 times)
  208. If gravity is a "curvature of space" rather than a force, why do a ball and bullet follow different paths? (viewed 53536 times)
  209. How do we measure the size of the Moon and of the Sun? (viewed 53365 times)
  210. How do you calculate the azimuth and altitude of an object? (viewed 53340 times)
  211. How do the astronauts communicate in space if sound cannot travel in a vacuum? (viewed 52825 times)
  212. What happens to a bullet fired on the moon? (viewed 52765 times)
  213. How can I find the distance to the Sun on any given day? (viewed 52565 times)
  214. 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 52562 times)
  215. Are aliens or UFOs real? (viewed 52511 times)
  216. Why do we see stars? (viewed 52385 times)
  217. What other careers involve Astronomy besides Astronomer? (viewed 52312 times)
  218. How can I measure the distance of a star? (viewed 52042 times)
  219. Is the speed of light constant? (viewed 51519 times)
  220. Which hemisphere has the best view of the Milky Way? (viewed 51418 times)
  221. What are some astronomy science fair projects? (viewed 51400 times)
  222. Are there any asteroids on a collision course with Earth? (viewed 51060 times)
  223. How long has there been water on Earth? (viewed 50812 times)
  224. Why is the sky blue and not blue & purple? (viewed 50429 times)
  225. What would happen if the Moon fell out of its orbit around Earth? (viewed 50282 times)
  226. Is time travel possible? (viewed 50258 times)
  227. Why is twilight short near the equator? (viewed 50130 times)
  228. Are meteorites hot or cold when they hit Earth? (viewed 50072 times)
  229. Who discovered each planet? (viewed 50062 times)
  230. Would your weight change as you go underground? (viewed 49962 times)
  231. Why does the Moon look big on the horizon? (viewed 49869 times)
  232. Can we look back far enough in time to see the Big Bang? (viewed 49786 times)
  233. What do a galaxy's colors mean? Are they its true colors? (viewed 49654 times)
  234. If the Earth's rotation period is less than 24 hours, why don't our clocks fall out of sync with the Sun? (viewed 49577 times)
  235. Where did all the water in the universe come from? (viewed 49358 times)
  236. Why is it difficult to understand the expansion of the universe? (viewed 49181 times)
  237. What is a graviton? (viewed 48448 times)
  238. What is the difference between nutation and precession of the Earth? (viewed 48389 times)
  239. How is the time of sunrise calculated? (viewed 48306 times)
  240. What skills do astronomers need? (viewed 48182 times)
  241. If light has no mass, then what draws it into a black hole? (viewed 48163 times)
  242. What's the difference between astronomy and astrophysics? (viewed 48066 times)
  243. Are the planes of solar systems aligned with the plane of the Galaxy? (viewed 48019 times)
  244. How do we know what other planets (and stars, galaxies, etc.) are made of? (viewed 47048 times)
  245. What do I need to do to become an astronomer? (viewed 46564 times)
  246. Do dead stars still shine? (viewed 46217 times)
  247. Why do the size and brightness of the full moon change? (viewed 46064 times)
  248. How do gravitons escape black holes to tell the universe about their gravity? (viewed 45968 times)
  249. What is a wormhole? (viewed 45956 times)
  250. Do supermassive black holes cause galaxy rotation? (viewed 45863 times)
  251. How are black holes discovered? (viewed 45468 times)
  252. Where is the nearest black hole? (viewed 45276 times)
  253. Why does the Sun appear larger on the horizon than overhead? (viewed 45164 times)
  254. Will we get sucked into the black hole at the center of the Milky Way? (viewed 45132 times)
  255. The Moon slows the Earth's rotation, but how fast was it spinning billions of years ago? (viewed 44950 times)
  256. Can we find the place where the Big Bang happened? (viewed 44932 times)
  257. Why can't we see Venus at night when it is an inner planet? (viewed 44745 times)
  258. How do galaxies collide in an expanding universe? (viewed 44647 times)
  259. Is the Earth slowly getting larger? (viewed 44598 times)
  260. Why are there stars? (viewed 44560 times)
  261. Can I calculate the size of the Universe by converting light years to kilometres? (viewed 44547 times)
  262. Why are most months 30 or 31 days long? (viewed 44452 times)
  263. Why does Barnard 68 appear dark? (viewed 43941 times)
  264. Are Kuiper Belt Objects asteroids? Are large Kuiper Belt Objects planets? (viewed 42902 times)
  265. Why don't people walk upside-down on the bottom of the Earth? (viewed 42816 times)
  266. What is the best way to see the Milky Way? (viewed 42436 times)
  267. Was the Sun made in a supernova? (viewed 42317 times)
  268. What is the biggest crater recorded on Earth? (viewed 42273 times)
  269. Could the Universe have expanded faster than the speed of light at the Big Bang? (viewed 42257 times)
  270. Are there eclipses on other planets? (viewed 42236 times)
  271. Is there a "South Star"? (viewed 42131 times)
  272. Why does the location of sunrise change? (viewed 42052 times)
  273. Did life originate on Earth, or did it come from somewhere else? (viewed 42050 times)
  274. Has there been an experiment that measured speed faster than the speed of light in vacuum? (viewed 42010 times)
  275. How long could life on Earth survive if the Sun stopped shining? (viewed 42000 times)
  276. How much longer will the Earth last? (viewed 41884 times)
  277. How does Astronomy involve Chemistry? (viewed 41816 times)
  278. Why doesn't dark matter fall into a black hole? (viewed 41739 times)
  279. What is the difference between the "Doppler" redshift and the "gravitational" or "cosmological" redshift? (viewed 41707 times)
  280. How would the weather on Earth be different if it were a cube? (viewed 41551 times)
  281. Can I buy land on the Moon? (viewed 41371 times)
  282. What happens to spacetime inside a black hole? (viewed 41366 times)
  283. Can the acceleration of the Universe be analogous to apparent acceleration in a airplane? (viewed 41254 times)
  284. How much can the location of sunset differ from due West? (viewed 41209 times)
  285. Is the Moon hollow? (viewed 41084 times)
  286. Why does the Earth only see one side of the Moon? (viewed 41024 times)
  287. What happens when two black holes get too close? (viewed 41009 times)
  288. What's the biggest meteorite? (viewed 40735 times)
  289. What is time dilation? (viewed 40561 times)
  290. What color would Mars be if you were standing on it? (viewed 40478 times)
  291. What is the most distant known galaxy? (viewed 40333 times)
  292. What are the names of the three stars in Orion's belt? (viewed 40324 times)
  293. How can two moons of Saturn share the same orbit? (viewed 39995 times)
  294. What if the Earth rotated twice as fast? (viewed 39845 times)
  295. Could someone travel the universe in his or her own lifetime? (viewed 39600 times)
  296. Can terrestrial planets have rings? (viewed 39506 times)
  297. How long would it take for a mini-black hole to eat the Earth? (viewed 39435 times)
  298. Why do people draw stars with five points? (viewed 39244 times)
  299. How many Astronauts have been in space? (viewed 39214 times)
  300. What are "blue stragglers" in globular clusters? (viewed 38987 times)
  301. Is it possible to see the full Moon and the Sun simultaneously in high northern latitudes when the Sun doesn't set? (viewed 38955 times)
  302. How do we feel heat? (viewed 38906 times)
  303. Why do pictures of distant galaxies have higher resolution than those of nearby planets? (viewed 38810 times)
  304. What is the typical size of a visible shooting star? (viewed 38582 times)
  305. If a white dwarf is a "dead" star, why is it so hot? (viewed 38455 times)
  306. Why can we see the sun's image before sunrise and after sunset? (viewed 38429 times)
  307. How do we know that nuclear fusion is still going on in the Sun? (viewed 38342 times)
  308. Does Mt. Everest cast a shadow on the moon? (viewed 38256 times)
  309. Is the Great Wall the largest galaxy cluster? (viewed 38178 times)
  310. How fast does the Earth go at perihelion and aphelion? (viewed 38141 times)
  311. How does night and day work? (viewed 38073 times)
  312. Does the Sun have an iron surface? (viewed 37897 times)
  313. Can a person go into a black hole and come out alive? (viewed 37828 times)
  314. What is a dimension? (viewed 37790 times)
  315. Why are Saturn's rings flat? (viewed 37772 times)
  316. Can you see the future as you fall into a black hole? (viewed 37684 times)
  317. What is the speed of gravity? (viewed 37587 times)
  318. Can I communicate faster than light? (viewed 37579 times)
  319. On which days can I see the Moon in the evening / morning and why is this so? (viewed 37558 times)
  320. Where do planetary rings come from, and what are they made of? (viewed 37548 times)
  321. Do you think it's possible to maintain life on other planets? (viewed 37501 times)
  322. Is the Sun always up for exactly 12 hours at the equator? (viewed 37442 times)
  323. What is Earthrise over the Moon? (viewed 37328 times)
  324. What can I use for fuel in my homemade rocket? (viewed 37305 times)
  325. How big is the universe? (viewed 37254 times)
  326. Where is the supernova remnant that led to our solar system? (viewed 37211 times)
  327. Who (and when) discovered that the earth's axis is on a 23 degree tilt? (viewed 37201 times)
  328. Why do clocks turn in the opposite direction from the Earth and Moon? (viewed 37157 times)
  329. What is the approximate GPA needed in High School in Math and Science to be an astronomer? (viewed 37077 times)
  330. Are all stars the same? (viewed 36982 times)
  331. How do we determine the age of the universe? (viewed 36849 times)
  332. What companies or businesses can astronomers work for? (viewed 36731 times)
  333. Is there really a 10th planet? (viewed 36729 times)
  334. Why is sea water salty, and not lake water? (viewed 36608 times)
  335. What would happen to the Earth if an asteroid hit the Moon? (viewed 36342 times)
  336. How many stars can I see? (viewed 36279 times)
  337. Does the Coriolis force determine which way my toilet drains? Does it affect black holes? (viewed 36226 times)
  338. Is there a beginning and an end to a galaxy's life? (viewed 36213 times)
  339. How do I tell which planet is which? (viewed 36176 times)
  340. If the universe is 15 billion years old, how can it be larger than 15 billion light years across? (viewed 36112 times)
  341. How can the universe be "flat"? We're 3D! (viewed 35830 times)
  342. How do we know the Milky Way is a spiral galaxy? (viewed 35819 times)
  343. Do the Sun's or Earth's magnetic field reverse? (viewed 35715 times)
  344. How are photons created and destroyed? (viewed 35648 times)
  345. How do we define distance in an expanding universe? (viewed 35645 times)
  346. How can I find my age on another planet? (viewed 35295 times)
  347. Is Andromeda part of the Milky Way? Where can I find them in the sky? (viewed 35036 times)
  348. Why are there blue shifted galaxies? (viewed 34884 times)
  349. Why have star signs shifted by one constellation? (viewed 34854 times)
  350. Why do humans want to go in space? (viewed 34585 times)
  351. How does the brightness of a star depend on its distance from us? (viewed 34555 times)
  352. What was that really big falling star that I saw? (viewed 34506 times)
  353. What is the pattern to the distances between each planet and the sun? (viewed 34420 times)
  354. Can a lunar and a solar eclipse happen in the same month? When will this happen next? (viewed 34410 times)
  355. How are planets detected around other stars? (viewed 34406 times)
  356. What would happen if two stars collided? (viewed 34305 times)
  357. Who came up with the name "black hole"? (viewed 34260 times)
  358. What kind of eyepieces do I need to look at planets? (viewed 34172 times)
  359. What is the significance of the second focus of elliptical orbits of planets in our Solar System? (viewed 34163 times)
  360. How do astronauts communicate with their families from space? (viewed 34122 times)
  361. How can we estimate the number of Earth-like planets in the Galaxy? (viewed 34087 times)
  362. Is the Earth at the centre of the Universe? (viewed 34066 times)
  363. Will we ever stop having solar eclipses because of the moon's motion away from the Earth? (viewed 34048 times)
  364. When we look back to the Big Bang, why don't we see the universe as a tiny speck of matter? (viewed 34032 times)
  365. Is there a simple formula to calculate solar eclipse timings from any position on Earth? (viewed 34004 times)
  366. Why don't astronomers use everyday units to measure distances (what is an AU or a pc)? (viewed 33823 times)
  367. How is it that we see farther out in space (farther back in time) than in the past? (viewed 33640 times)
  368. Will the Moon be invisible in 500 million years? (viewed 33558 times)
  369. Are Earth and the Moon "twin planets"? (viewed 33321 times)
  370. How dangerous are the asteroids? (viewed 33209 times)
  371. Which American colleges teach astronomy? (viewed 33203 times)
  372. How do I become both an astronaut and an astronomer? (viewed 33158 times)
  373. Why is our solar system so different from all the others we've found? (viewed 33147 times)
  374. Why is Uranus tipped on its side? (viewed 33010 times)
  375. Can we colonize other planets? (viewed 32876 times)
  376. How hot is each one of the layers of the sun? (viewed 32850 times)
  377. Why can't a plane fly slowly and let the Earth pass underneath? (viewed 32509 times)
  378. How do sunrise and sunset times change with altitude? (viewed 32483 times)
  379. What are quasars made of? (viewed 32175 times)
  380. Can you describe a day on the job as an astronomer? (viewed 32152 times)
  381. How can I calculate distances between stars? (viewed 32142 times)
  382. Why do constellations look the same after several years even though all the stars are moving? (viewed 32112 times)
  383. Why do astronauts in space need to exercise? (viewed 31993 times)
  384. Why are there no craters on Earth? Did all the meteorites miss us? (viewed 31978 times)
  385. Why doesn't gravity change the speed of light? (viewed 31907 times)
  386. Is the universe really like an expanding balloon? (viewed 31854 times)
  387. Is it true that the Sun burns off a billion tons of gas every 5 seconds? (viewed 31826 times)
  388. Is the gravitational force exerted by the Earth on the Moon equal to the centripetal force acting on the Moon? (viewed 31620 times)
  389. Is it possible to count the stars? (viewed 31610 times)
  390. What is dark matter? (viewed 31608 times)
  391. Is the Local Group expanding along with the entire Universe? (viewed 31541 times)
  392. Is time travel possible using merging black holes? (viewed 31510 times)
  393. Can superheavy elements (such as Z=116 or 118) be formed in a supernova? Can we observe them? (viewed 31399 times)
  394. What is happening just around the black hole in the center of the Milky Way? (viewed 31387 times)
  395. Did the speed of light change over the history of the universe? (viewed 31252 times)
  396. How big a change in the Earth's orbit would be required to destroy all life? (viewed 31192 times)
  397. Can we see dead stars with the naked eye? (viewed 31176 times)
  398. How can we distinguish a star's "real" color from the change in color that we observe due to the star's motion? (viewed 31112 times)
  399. How do we measure distances to other stars? (viewed 31058 times)
  400. How do I make a scale model of the Solar System? (viewed 30901 times)
  401. What happens when an antimatter black hole collides with a matter blackhole? (viewed 30895 times)
  402. Are time machines possible? (viewed 30810 times)
  403. How many moles of stars are in the known universe? (viewed 30443 times)
  404. How are galaxy distances inferred from their recessional velocities? (viewed 30222 times)
  405. How can we tell what the interiors of planets are like? (viewed 30083 times)
  406. Why is the time between two successive full moons different from the lunar synodic month? (viewed 30020 times)
  407. What happens when you change the mass of a White Dwarf or Neutron Star? (viewed 30007 times)
  408. Is there any limitation to what a black hole can "suck" in? (viewed 29982 times)
  409. What is the farthest in space that we have gone? (viewed 29867 times)
  410. What do "homogeneity" and "isotropy" mean? (viewed 29840 times)
  411. Does the Milky Way spin counter-clockwise? If so, do all spiral galaxies spin in this direction and why? (viewed 29684 times)
  412. How can we know that there are other galaxies if we cannot leave ours? (viewed 29625 times)
  413. What's that dark spot on the Sun? (viewed 29573 times)
  414. What would happen if a human were exposed to space without wearing a spacesuit? (viewed 29555 times)
  415. What are the closest and/or brightest stars? (viewed 29524 times)
  416. Can astronauts produce water in space? (viewed 29516 times)
  417. How can I tell if the rock I found is a meteorite? (viewed 29495 times)
  418. Will the seasons change due to precession? (viewed 29483 times)
  419. How was the starting point for the Julian Date system chosen? (viewed 29407 times)
  420. Aren't jobs in astronomy scarce? (viewed 29363 times)
  421. Do astronomers believe in astrology? (viewed 29208 times)
  422. How do we know if the universe will keep expanding forever? (viewed 29200 times)
  423. Why does the SETI project search for radio signals? (viewed 29163 times)
  424. Did I see the Aurora Borealis as a child? (viewed 29148 times)
  425. How long does it take the Big Dipper to move in the sky? (viewed 29120 times)
  426. What are the facts about the Star of Bethlehem? (viewed 29053 times)
  427. Don't tachyons travel faster than light? (viewed 29038 times)
  428. Why do most moons orbit their planets at the equator? (viewed 29009 times)
  429. Could an astronaut or satellite fall into a black hole that we didn't know about? (viewed 28981 times)
  430. Why do we study black holes? (viewed 28978 times)
  431. Do we see the same stars from above and below the equator? (viewed 28953 times)
  432. When are there 5 Sundays in February? (viewed 28900 times)
  433. What are the atmospheres of Mars and Pluto like? (viewed 28871 times)
  434. Wouldn't the Big Bang theory be considered a hypothesis and not a theory? (viewed 28797 times)
  435. Can you use an infinite line of reflectors to send light to the edge of the Universe? (viewed 28492 times)
  436. Was I hit by a meteorite? (viewed 28489 times)
  437. Has anyone made a map of the Milky Way? (viewed 28487 times)
  438. Do you believe in UFOs? (viewed 28451 times)
  439. What colors are visible through an amateur telescope? (viewed 28427 times)
  440. Could you tell me about the life cycle of galaxies? (viewed 28417 times)
  441. What does the term "visible universe" mean? (viewed 28416 times)
  442. How are galaxies named? (viewed 28385 times)
  443. How can geometry be different in space? (viewed 28310 times)
  444. Why are the compositions of comets and asteroids different? (viewed 28012 times)
  445. What's the best thing about being an astronomer? (viewed 27804 times)
  446. How do asteroids, meteors and comets disappear? (viewed 27748 times)
  447. Why do so many of the world's UFO sightings happen in America? (viewed 27700 times)
  448. How much time do astronomers spend looking through telescopes? (viewed 27636 times)
  449. Will winter and summer constellations change due to abnormal warmth or cold on Earth? (viewed 27598 times)
  450. How do astronomers measure the radius of a star? (viewed 27560 times)
  451. Can two lunar eclipses occur in the same month? (viewed 27530 times)
  452. How will the two black holes that are going to collide affect Earth? (viewed 27432 times)
  453. How can we see galaxies if their stars are so faint? (viewed 27419 times)
  454. Have there been other Big Bangs before? (viewed 27406 times)
  455. How do I explain to my children why the Moon has phases? (viewed 27272 times)
  456. Can life exist on the recently discovered extrasolar planets? (viewed 27173 times)
  457. How are galaxies and solar systems similar? (viewed 27158 times)
  458. How close do you have to come to the Earth to be influenced by its gravity? (viewed 27106 times)
  459. Is the Milky Way a collision of two galaxies? (viewed 27015 times)
  460. Is there a project I can do on black holes? (viewed 27006 times)
  461. What is the origin of the stellar classification system "OBAFGKM"? (viewed 27005 times)
  462. How can we measure distances to more stars? (viewed 26905 times)
  463. Could you escape from a black hole if you were able to go faster than the speed of light? (viewed 26853 times)
  464. Do the magnitudes and colors of stars ever change? (viewed 26815 times)
  465. How do scientists slow light down? (viewed 26813 times)
  466. Is infinite temperature possible? (viewed 26616 times)
  467. How close does a supernova need to be to damage the Earth's environment? (viewed 26595 times)
  468. Do we know everything about the Sun? (viewed 26586 times)
  469. Do asteroids hit the sun? (viewed 26535 times)
  470. Can "tired light theory" explain the observed redshifts of galaxies? (viewed 26500 times)
  471. What supernova created the Crab nebula? (viewed 26471 times)
  472. Is it worthwhile to continue the search for extraterrestrial life? (viewed 26429 times)
  473. Can one star orbit another? (viewed 26413 times)
  474. Can double stars have planets? (viewed 26324 times)
  475. What causes gamma ray bursts? (viewed 26298 times)
  476. How far does a galaxy extend? (viewed 26266 times)
  477. Does the Moon look different in the northern and southern hemispheres? (viewed 26137 times)
  478. How do I polar align my telescope? (viewed 26093 times)
  479. What will happen to the Milky Way in the future? (viewed 26041 times)
  480. Can astronauts play musical instruments in space? (viewed 26013 times)
  481. Is there such a thing as hyperspace? (viewed 25998 times)
  482. What type of energy does a black hole have? (viewed 25970 times)
  483. Which way does the sun travel in the southern hemisphere? (viewed 25938 times)
  484. What happens to the material that has been sucked into a black hole? (viewed 25931 times)
  485. What is sidereal time? (viewed 25923 times)
  486. What is the farthest Northern Latitude in which the Magellanic Clouds can be seen? (viewed 25915 times)
  487. Why do the explosions of Type Ia supernovae have a more predictable spectrum than those of regular Type II supernovae? (viewed 25828 times)
  488. Is there oxygen in the atmospheres of other planets? (viewed 25809 times)
  489. What is a Cepheid variable? (viewed 25752 times)
  490. Which part of the sky did the famous 'wow' signal originate from? (viewed 25737 times)
  491. What is "nothing", from a scientific point of view? (viewed 25735 times)
  492. How will a change in the speed of light affect the evolution of the Universe? (viewed 25691 times)
  493. What's the object I saw that moved across the sky and then got very bright? (viewed 25687 times)
  494. Why did the Pioneer and Voyager take only 2 years to reach Jupiter, while Galileo and Cassini took more than 5 years? (viewed 25667 times)
  495. Can a human give birth in space? (viewed 25655 times)
  496. How different would the night sky have looked in 40,000 B.C.? (viewed 25576 times)
  497. Is there sound coming from the Sun? (viewed 25572 times)
  498. How do we know what parameters to use when simulating the collision of the Milky Way and Andromeda? (viewed 25447 times)
  499. Why do we assume that the universe is homogeneous? (viewed 25425 times)
  500. When did people discover that the Sun is a star? (viewed 25368 times)
  501. How do we know that sunspots are associated with the Sun's magnetic field? (viewed 25354 times)
  502. Why is the shadow on the Moon the shape it is? (viewed 25339 times)
  503. When unmanned spacecraft accelerate in space, what causes them to slow down? (viewed 25260 times)
  504. Are planetary nebulae the result of supernovae? (viewed 25252 times)
  505. If we invented special suits could we ever go to the sun? (viewed 25233 times)
  506. Are there any dark stars or dark galaxies made of dark matter? (viewed 25229 times)
  507. What calculations go into predicting eclipses? (viewed 25171 times)
  508. What is the difference between homogeneity and isotropy? (viewed 25132 times)
  509. Was Stonehenge built to mark solar phenomena? (viewed 25117 times)
  510. What is our galaxy's halo made of, and how was it formed? (viewed 25097 times)
  511. Is there a list of the sizes of different kinds of stars? (viewed 25063 times)
  512. What process would bring about a quark star? (viewed 25022 times)
  513. Can I see a quasar? (viewed 24982 times)
  514. What's so exciting about the new planet around 55 Cancri? (viewed 24937 times)
  515. How many sunspots can the Sun have at once? (viewed 24914 times)
  516. Did a giant impact cause the Dark Ages? (viewed 24893 times)
  517. What is a Dyson Sphere? (viewed 24883 times)
  518. How are asteroid compositions and classifications determined? (viewed 24873 times)
  519. Have gravitational waves been proven to exist? (viewed 24841 times)
  520. Can I see details on Venus? (viewed 24827 times)
  521. Can any comparison be made between spiral galaxies and hurricanes? (viewed 24780 times)
  522. Why are there more maria on the near side of the Moon? (viewed 24627 times)
  523. What equipment do I need for astrophotography? (viewed 24565 times)
  524. Why are there active volcanos on Io? (viewed 24562 times)
  525. Does Cerenkov radiation travel faster than light? (viewed 24536 times)
  526. How is it proved that the Universe is expanding? (viewed 24520 times)
  527. What happened to all the black holes that were around in the early universe? (viewed 24505 times)
  528. Is there any possibility that the Solar System or the Universe is in a black hole? (viewed 24454 times)
  529. What happened to the girl who named Pluto? (viewed 24409 times)
  530. Why are telescopes kept in cold conditions? (viewed 24370 times)
  531. Would the biggest airplanes cause tsunamis if they crashed? (viewed 24369 times)
  532. If clocks run slow in a gravitational field, how can we know the true age of the Solar System and Universe? (viewed 24246 times)
  533. How big was the Sun when it first "fired up"? (viewed 24221 times)
  534. How can we compare dark matter and dark energy? (viewed 24206 times)
  535. If the Universe was infinitely dense at the Big Bang, why didn't time stand still? (viewed 24137 times)
  536. What caused Shoemaker-Levy 9 to split up? (viewed 24087 times)
  537. Why do photos of space taken from space never show any stars? (viewed 24069 times)
  538. Could we send a space mission to a comet? (viewed 24063 times)
  539. How long do supernova remnants last? (viewed 24062 times)
  540. How do solar flares affect airline pilots? (viewed 23970 times)
  541. Why doesn't light from distant galaxies reach us instantaneously? (viewed 23942 times)
  542. How big is the Hubble Ultra Deep Field image? (viewed 23933 times)
  543. Could we be seeing dead stars? (viewed 23923 times)
  544. How are sunspots formed? (viewed 23896 times)
  545. Can you give me advice on buying a telescope? (viewed 23806 times)
  546. Could a different theory of gravity explain the dark matter mystery? (viewed 23767 times)
  547. How does the Earth compare in size to the entire universe at the present epoch? (viewed 23759 times)
  548. As the universe expands, why don't galaxies get stretched out? (viewed 23715 times)
  549. Why doesn't NASA build rotating spacecraft to simulate gravity? (viewed 23670 times)
  550. How many comets are currently orbiting our sun? (viewed 23643 times)
  551. Where does the kinetic energy of infalling bodies come from? (viewed 23589 times)
  552. Why is the Hubble Space Telescope in space? (viewed 23588 times)
  553. Can I build an instrument to measure the size of the Sun and of the Moon? (viewed 23584 times)
  554. Can you tell time by the Big Dipper? (viewed 23574 times)
  555. How do we know that superclusters are the largest structures in the universe? (viewed 23470 times)
  556. How powerful are quasars? (viewed 23416 times)
  557. Did I really hear a meteor? (viewed 23374 times)
  558. Would extraterrestrial civilizations know that there is life on Earth? (viewed 23345 times)
  559. Why is it important to study meteorites? (viewed 23337 times)
  560. How is the Cepheid yardstick validated? (viewed 23290 times)
  561. Why are telescopes located in remote places? (viewed 23215 times)
  562. Do unmanned spacecraft like Voyager travel in straight lines? (viewed 23177 times)
  563. Did time go slower just after the Big Bang? (viewed 23131 times)
  564. What would happen if there was a collision between two white dwarfs? (viewed 23117 times)
  565. How can I contribute to science as an amateur astronomer? (viewed 23114 times)
  566. Can supernovae hinder the formation of life in galaxies? (viewed 23101 times)
  567. Are there any new craters on the moon? (viewed 23099 times)
  568. Why are stars of different masses? (viewed 23076 times)
  569. Are the asteroids the remains of a planet which broke apart? (viewed 23062 times)
  570. Do the Earth's magnetic poles ever change places? (viewed 23055 times)
  571. Do galaxies orbit around anything? (viewed 23052 times)
  572. Do similar laws of physics throughout the Universe imply that all life must be like life on Earth? (viewed 23000 times)
  573. How do planets capture satellites? (viewed 22991 times)
  574. How do I become an astronomical artist? (viewed 22976 times)
  575. What kind of instruments are used to detect extrasolar planets? (viewed 22938 times)
  576. How do unmanned space probes avoid running into things? (viewed 22905 times)
  577. How could galaxies have gotten so far away in only 15 billion years? (viewed 22857 times)
  578. Could there have been multiple Big Bangs at different places in the universe? (viewed 22818 times)
  579. How are astronomy and poetry linked? (viewed 22783 times)
  580. Why can't relative velocities add up to more than the speed of light? (viewed 22767 times)
  581. What kind of telescope should I use for astrophotography? (viewed 22717 times)
  582. Could dark energy come from matter anti-matter pairs forming spontaneously and then annihilating? (viewed 22647 times)
  583. Why is NASA shutting down the Hubble Space Telescope? (viewed 22618 times)
  584. Can I listen to the SETI@home radio signal? (viewed 22598 times)
  585. How can you tell if a crescent moon is preceding or following a new-moon phase? (viewed 22569 times)
  586. Does the Sun have any heavy elements? (viewed 22499 times)
  587. Are the properties of extrasolar planets known? (viewed 22498 times)
  588. What class of spiral galaxy is the Milky Way? (viewed 22347 times)
  589. Will we discover an 11th planet? What would it be called? (viewed 22343 times)
  590. A line drawn perpendicular to a line through the tips of the horns of the crescent moon doesn't point to the Sun! Why not? (viewed 22338 times)
  591. Can the theory of formation of the solar system explain all the observables? (viewed 22304 times)
  592. What month was it when Odysseus saw Orion in 1000BC? (viewed 22275 times)
  593. How do astronomers observe the Sun's interior? (viewed 22070 times)
  594. What makes a satellite geosyncronise itself with Earth's orbit? (viewed 21996 times)
  595. Why does one side of Mars look more catastrophic than the other? (viewed 21995 times)
  596. Why does the apparent density of galaxies drop off at larger distances? (viewed 21961 times)
  597. Would a planet near the galactic center have a brighter night sky? (viewed 21896 times)
  598. Is it possible for amateurs to do optical interferometry? (viewed 21837 times)
  599. Where was the water in the big bang? (viewed 21759 times)
  600. Could we send a manned mission to the outer planets? (viewed 21755 times)
  601. What is the solar cycle? (viewed 21722 times)
  602. Do stars' orbits in galaxies obey Kepler's Laws? (viewed 21680 times)
  603. Can other terrestrial moons be (or have been) stable? (viewed 21611 times)
  604. Why was the Platonic year named after Plato? (viewed 21562 times)
  605. How are supernovae discovered? (viewed 21531 times)
  606. What would the Big Crunch look like to an observer on Earth? (viewed 21467 times)
  607. Can a black hole come back to the visual universe through a "little bang"? (viewed 21456 times)
  608. How can water be chemically trapped in rocks? (viewed 21435 times)
  609. Why are accretion disks flat? (viewed 21406 times)
  610. Why do spacecraft need heat shields coming back to Earth but not leaving? (viewed 21395 times)
  611. Does inflation allow for an infinite number of universes? (viewed 21381 times)
  612. What is meant by "stopping down a telescope"? (viewed 21350 times)
  613. Could our position in the universe affect our perceptions of the expansion? (viewed 21342 times)
  614. Why doesn't the hydrogen on Jupiter explode? (viewed 21257 times)
  615. Did I find a rock that came from the Moon? (viewed 21045 times)
  616. Have astronomers observed any phenomena that could be produced by extraterrestrial civilizations? (viewed 21045 times)
  617. How can the Sun have such a strong gravitational field if it's made of gasses? (viewed 21032 times)
  618. What is the SU(3) quark model? (viewed 20996 times)
  619. Can gravitational lensing from intervening galaxies cause the observed ripples in the Cosmic Microwave Background? (viewed 20984 times)
  620. Does a photon observe other photons moving past it at the speed of light? (viewed 20977 times)
  621. Will I be able to see the shadow of the Moon streaking towards me in a total solar eclipse? (viewed 20723 times)
  622. What's new with the Big Bang? (viewed 20717 times)
  623. Could photons be dark matter? (viewed 20620 times)
  624. Is it possible to build a cheap device to measure declination? (viewed 20580 times)
  625. How can we find galaxies behind the Milky Way? (viewed 20575 times)
  626. Why can we have solar eclipses? (viewed 20562 times)
  627. If comets are boiling away, why are there any left? (viewed 20526 times)
  628. How fast do particles travel in space? (viewed 20513 times)
  629. Why search for only Earth-like life on other planets? (viewed 20501 times)
  630. Why do some eclipses take longer than others? (viewed 20460 times)
  631. Where can I find information on the moons of other planets? (viewed 20439 times)
  632. Why is the WMAP picture of the CMB an ellipse? (viewed 20398 times)
  633. How much power is contained in a beam of light? (viewed 20358 times)
  634. Why is pressure broadening greater in low mass stars than in high mass stars? (viewed 20249 times)
  635. What would an "open geometry" for the universe look like? (viewed 20157 times)
  636. What are the boundaries of the constellations? (viewed 20129 times)
  637. Did the Sumerians measure precession? (viewed 20078 times)
  638. What kinds of star clusters are there? (viewed 20037 times)
  639. Why is the Cosmic Microwave Background not absorbed by interstellar hydrogen? (viewed 19998 times)
  640. How do astronomers come up with their facts? (viewed 19989 times)
  641. Why aren't discoveries of extrasolar planets reported on the news? (viewed 19967 times)
  642. How do bars form in spiral galaxies? (viewed 19931 times)
  643. Why don't astronauts sublimate in space? (viewed 19910 times)
  644. Can planets collide with one another? (viewed 19903 times)
  645. How do photons from distant objects maintain enough energy to reach us? (viewed 19873 times)
  646. Can HST see the Oort cloud? (viewed 19817 times)
  647. Do constellations looks the same from space? (viewed 19814 times)
  648. Do electrons age? (viewed 19768 times)
  649. Can the Space Shuttle abort and return to Earth before reaching orbit? (viewed 19670 times)
  650. How did Mars get so dusty? (viewed 19669 times)
  651. Can we make a movie of the Milky Way galaxy's rotation? (viewed 19661 times)
  652. How long is twilight on the Moon? (viewed 19555 times)
  653. What are collections of galaxies called? (viewed 19535 times)
  654. Does the shuttle worry about space junk? (viewed 19485 times)
  655. How does melting a material reset its radioactive clock? (viewed 19449 times)
  656. Will astronauts ever be able to go ice-skating on Europa? (viewed 19424 times)
  657. Why do supernova remnants look like rings rather than spheres? (viewed 19410 times)
  658. Where can I see Newton's original reflecting telescope? (viewed 19356 times)
  659. How do you classify galaxies? (viewed 19354 times)
  660. Why don't all neutron stars become pulsars? (viewed 19316 times)
  661. Why doesn't SETI concentrate its observations to the nearby stars and the solar systems that we are discovering? (viewed 19236 times)
  662. What is the best time of the year to see eclipses? (viewed 19222 times)
  663. How can we understand the meaning of large numbers like "a million million?" (viewed 19217 times)
  664. Will the next generation telescope OWL be able to detect an Earth like extrasolar planet? (viewed 19140 times)
  665. What causes a particle to decay? (viewed 19102 times)
  666. How can I nominate myself for a Nobel Prize in Physics? (viewed 19035 times)
  667. How long has humanity known that we live in a galaxy similar to others in the Universe? (viewed 18994 times)
  668. Will the Leonid meteor shower go away? (viewed 18977 times)
  669. What are "curled" dimensions? (viewed 18865 times)
  670. Is light of different colors affected differently by gravity? (viewed 18827 times)
  671. What was that eclipse I saw in the sky? (viewed 18727 times)
  672. How does the color index of a star relate to its actual color? (viewed 18708 times)
  673. How does interferometry work? (viewed 18704 times)
  674. Why is it called astronomy when all the other sciences end in -ology? (viewed 18668 times)
  675. How do distant galaxies differ from those nearby? (viewed 18622 times)
  676. Does the temperature of matter increase as it is accelerated to relativistic speeds? (viewed 18594 times)
  677. Do asteroids ever do anything good in the Solar System? (viewed 18581 times)
  678. How do we find out about the star formation histories of galaxies? (viewed 18563 times)
  679. If nothing can escape a black hole, why do some black holes have jets? (viewed 18549 times)
  680. Can astronomers observe anything when the moon is full? (viewed 18493 times)
  681. Wouldn't the vast distances of space distort SETI signals into unintelligeble forms? (viewed 18486 times)
  682. What would happen if you went back in time and killed your grandmother? (viewed 18454 times)
  683. Are black holes spherical? (viewed 18454 times)
  684. What kind of interference must astronomers contend with when observing? (viewed 18441 times)
  685. If photons have zero mass, why do they feel the effects of gravity? (viewed 18366 times)
  686. How can I watch the Perseid meteor shower? (viewed 18353 times)
  687. Why will fusion wait until hydrogen is gone before starting to fuse heavier atoms? (viewed 18338 times)
  688. Do we really observe the edges of galaxies at different epochs? (viewed 18315 times)
  689. What do stellar classifications mean? (viewed 18295 times)
  690. Can you tell me the characteristics of W, R, N and S type stars? (viewed 18289 times)
  691. How are astronauts trained for weightlessness? (viewed 18214 times)
  692. What is the three-body problem? (viewed 18142 times)
  693. Why aren't accretion disks around giant stars as hot as accretion disks around black holes? (viewed 18081 times)
  694. If the universe is "bounded" today, could it one day become "unbounded"? (viewed 17954 times)
  695. Will the diameter of a cluster of galaxies change with redshift? (viewed 17917 times)
  696. Is cosmic expansion happening on microscopic scales? (viewed 17760 times)
  697. How can I find out if the new moon has been sighted? (viewed 17637 times)
  698. Could neutrinos be dark matter? (viewed 17444 times)
  699. Do we have to worry about relativity when studying galactic objects? (viewed 17434 times)
  700. What kinds of cancer research have been done in space? (viewed 17260 times)
  701. How does a star take mass from another star? (viewed 17160 times)
  702. When measuring the expansion of the universe, do astronomers consider that they're seeing how galaxies moved long ago, not today? (viewed 17047 times)
  703. Does lunar gardening really work? (viewed 17023 times)
  704. Could the Universe's dark matter be made up of black holes? (viewed 16986 times)
  705. How can you tell the difference between single and multiple extrasolar planets? (viewed 16960 times)
  706. What is Hot Dark Matter theory? (viewed 16891 times)
  707. How do supernovae show us that the Universe's expansion is accelerating? (viewed 16874 times)
  708. Is it a coincidence that we can have total solar eclipses? Are there other planets which also have them? (viewed 16500 times)
  709. Is the green flash real? (viewed 16423 times)
  710. How does libration allow us to see more than 50% of the Moon? (viewed 16390 times)
  711. How can observations of the distant universe prove that the expansion is accelerating *now*? (viewed 16363 times)
  712. How do we know the density of some extrasolar planets? (viewed 16320 times)
  713. What is the photoelectric effect? Why can't multiple low-frequency photons free an electron? (viewed 16283 times)
  714. Is light blueshifted when it is gravitationally lensed? (viewed 16237 times)
  715. Do binary or triple star systems form together? (viewed 16182 times)
  716. No matter how fast the universe is expanding, shouldn't gravity eventually make it recollapse? (viewed 16154 times)
  717. What happens to the helium formed in the sun? (viewed 15979 times)
  718. What percent of the time can astronomers observe without interference from the Moon? (viewed 15939 times)
  719. What do meteorites tell us about life on other planets? (viewed 15877 times)
  720. Why is it easier to see a star if you look slightly to the side? (viewed 15782 times)
  721. Could matter-anti-matter repulsion power the expansion of the universe? (viewed 15664 times)
  722. If the sun went out and our atmosphere froze solid, what color would it be? (viewed 15546 times)
  723. Can we prove that the Moon isn't hollow? (viewed 15533 times)
  724. Why doesn't the ammonia and methane in Jupiter's atmosphere sink into the core? (viewed 15425 times)
  725. Are there any 'lonely galaxies'? (viewed 15272 times)
  726. How do we detect incoming meteorites? (viewed 15180 times)
  727. What was different on Mars in the past to allow liquid water to be present? (viewed 15068 times)
  728. When will Hale-Bopp return? (viewed 14941 times)
  729. Why don't skydivers burn up like meteors? (viewed 14857 times)
  730. Has anyone ever seen a star "turn on"? (viewed 14689 times)
  731. During close approaches, can Mars appear in our sky as large as the Moon? (viewed 14571 times)
  732. How has light from 13 billion years ago not passed us by? (viewed 14380 times)
  733. How are planets affected by the Hot Ionised Medium? (viewed 14359 times)
  734. Why are craters round? (viewed 14252 times)
  735. Can the sun rise from the west on Mars? (viewed 13948 times)
  736. Why was Mir burnt up in the atmosphere? (viewed 13887 times)
  737. What are the largest radio wavelengths observed from radio sources in the sky? (viewed 13878 times)
  738. How can we discern different galaxies/clusters along the same line of sight? (viewed 13787 times)
  739. What is the relationship between the width of a star trail on a photo and the star's intensity? (viewed 13349 times)
  740. What time is sunrise/sunset or moonrise/moonset at my location? (viewed 13154 times)
  741. Can we harvest H & O from space to make water? (viewed 12954 times)
  742. What is between the Oort cloud and the closest star? (viewed 12569 times)
  743. Why does Titan, in spite of being smaller than Mars, have an atmosphere more dense than Earth's? (viewed 12518 times)
  744. Could a planetary system survive if its star merged with another, or if its star went supernova? (viewed 11702 times)
  745. Are there solar tides? (viewed 11672 times)
  746. 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 11576 times)
  747. Does weightlessness affect hunger? (viewed 11547 times)
  748. Is Earth-moon tidal friction causing global warming? (viewed 11135 times)
  749. Do planets radiate noise? (viewed 10878 times)
  750. What happens to the Earth as the moon gets farther away and will it ever go away entirely? (viewed 10812 times)
  751. Is the moon spherical? (viewed 10770 times)
  752. Is dark energy affected by black holes? (viewed 10537 times)
  753. What would happen if a nuclear-powered shuttle exploded? (viewed 10460 times)
  754. Why is the Moon higher in the sky in winter and lower in the summer? (viewed 10048 times)
  755. Where are the protons and electrons in a Neutron Star? (viewed 9861 times)
  756. Do more meteorites fall at low latitudes? (viewed 9510 times)
  757. Did the Moon or planets form in a manner similar to that of Earth? (viewed 9507 times)
  758. Wait, I'm still confused why information can't travel faster than the speed of light. (viewed 9465 times)
  759. Is the Moon always visible during winter on the North Pole? (viewed 9392 times)
  760. What are the possible ends of the universe? (viewed 9371 times)
  761. Will Comet Elenin (C/2010 X1) affect the Earth on its close approach in Fall 2011? (viewed 9360 times)
  762. Will the Pioneer and Voyager probes ever leave the Milky Way? (viewed 9272 times)
  763. Is it sensible to consider terraforming Mars? (viewed 9261 times)
  764. If there are infinity universes, will every thing that is possible happen? (viewed 9235 times)
  765. What color are meteors? (viewed 8820 times)
  766. Where is everybody? (viewed 8491 times)
  767. Why does Mars have a dusty atmosphere? (viewed 8027 times)
  768. The naming of Mars (viewed 7921 times)
  769. If I were traveling through space, could I see distant galaxies with my own eyes? (viewed 7888 times)
  770. Does the singularity in a black hole create a new Universe? (viewed 7839 times)
  771. Is the reddish dust of Mars biogenic? (viewed 7673 times)
  772. Where is the Spitzer Space Telescope? (viewed 7122 times)
  773. When will humans travel to Mars and revisit the Moon? (viewed 7034 times)
  774. Does the particles involved in a star's final core collapse travel faster than the speed of light? (viewed 6375 times)
  775. When is the best time to observe zodiacal light? (viewed 6152 times)
  776. How likely is it for a planet to transit its star? (viewed 6143 times)
  777. What causes the aurora? (viewed 5996 times)
  778. Why do astronomers use telescopes? (viewed 5938 times)
  779. How did a transit of Venus provide astronomers with the first measurement of the Earth-Sun distance? (viewed 4945 times)
  780. Can the Sun be closer to the Earth than any planet is to Earth? (viewed 4310 times)
  781. Cosmologists say the expansion of the universe is accelerating, what is driving this? (viewed 3774 times)
  782. Can we hear sound on Titan? (viewed 3683 times)
  783. Does the direction of the moon's crescent change through the night? (viewed 3490 times)
  784. What do all the angles in a table for a planet's orbit mean? (viewed 3256 times)
  785. How do I maximize my chances of seeing shooting stars? (viewed 2612 times)
  786. Are exoplanets real? (viewed 2306 times)
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