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 2119152 times)
  2. What color is each planet? (viewed 891450 times)
  3. At what speed does the earth move around the sun? (viewed 565607 times)
  4. Is the Moon moving away from the Earth? When was this discovered? (viewed 544486 times)
  5. How far is each planet from Earth? (viewed 461166 times)
  6. When will Halley's Comet return? (viewed 413104 times)
  7. How many stars are there in our Galaxy (Milky Way)? (viewed 384232 times)
  8. How long does it take for the Sun's light to reach us? (viewed 382833 times)
  9. Why do the planets orbit the sun? (viewed 369148 times)
  10. What is the universe expanding into? (viewed 364538 times)
  11. How do you measure the distance between Earth and the Sun? (viewed 331985 times)
  12. Which planets have rings? (viewed 319932 times)
  13. Why do stars twinkle? (viewed 313592 times)
  14. Does the Moon rotate? Are there other moons that always keep one face toward their planet? (viewed 297317 times)
  15. How do I build a model rocket? (viewed 286338 times)
  16. What color is Venus? (viewed 270724 times)
  17. What is a white hole? (viewed 263904 times)
  18. Can you hear sounds in space? (viewed 245736 times)
  19. What is the life cycle of a star? (viewed 244078 times)
  20. What are the names of the earth, moon, sun, and solar system? (viewed 235075 times)
  21. What makes the Earth rotate? (viewed 226351 times)
  22. What is that ring (or rainbow) around the moon? (viewed 225655 times)
  23. What are shooting stars? (viewed 224113 times)
  24. What is the largest star? (viewed 221055 times)
  25. What do astronauts eat in space? Can they grow food? (viewed 206146 times)
  26. How do we know the age of the Universe and the Earth? (viewed 200719 times)
  27. Why do planets rotate? (viewed 200536 times)
  28. Can artificial gravity be created in space? (viewed 198660 times)
  29. Is the universe expanding faster than the speed of light? (viewed 195869 times)
  30. How does the location of sunrise and sunset change throughout the year? (viewed 186106 times)
  31. Where did the name 'Earth' come from? (viewed 177904 times)
  32. How can we see the Milky Way if we are inside it? (viewed 175331 times)
  33. What are the different kinds of astronomers? (viewed 174695 times)
  34. What would happen if we did not have a Moon? (viewed 173269 times)
  35. Why isn't the sky bright at night if the universe has so many stars? (viewed 172638 times)
  36. How many Earths fit into the Sun? (viewed 171602 times)
  37. Why is a day divided into 24 hours? (viewed 164867 times)
  38. How does the position of Moonrise and Moonset change? (viewed 159719 times)
  39. Who named the planets and who decides what to name them? (viewed 155110 times)
  40. Why are the Moon and Sun sometimes orange or red? (viewed 151189 times)
  41. When was the last time all 9 planets were aligned? (viewed 150438 times)
  42. Is Pluto a planet? (viewed 149263 times)
  43. Is the distance from the Earth to the Sun changing? (viewed 148213 times)
  44. Why do airplanes take longer to fly West than East? (viewed 146488 times)
  45. What is at the end of the Universe? (viewed 143821 times)
  46. How can I find the star I have "bought"? (viewed 139577 times)
  47. How much money is spent on space exploration? (viewed 139527 times)
  48. Why are there both high and low tides? (viewed 129954 times)
  49. How do astronauts take baths and use restrooms in space? (viewed 128086 times)
  50. What direction do planets rotate? (viewed 127546 times)
  51. What is the largest galaxy? (viewed 126673 times)
  52. Can we feel the Earth spin? (viewed 126515 times)
  53. Is the Sun expanding? Will it ever explode? (viewed 126105 times)
  54. How many known galaxies are there? (viewed 125448 times)
  55. What is a nova? (viewed 121406 times)
  56. Do stars move in the sky? (viewed 121202 times)
  57. Does your weight change between the poles and the equator? (viewed 121137 times)
  58. Can I buy a star? (viewed 115916 times)
  59. What are the advantages and disadvantages of using a telescope in space? (viewed 115631 times)
  60. Will the sun go supernova in six years and destroy Earth (as seen on Yahoo)? (viewed 113257 times)
  61. Why do all the planets orbit in the same plane? (viewed 112064 times)
  62. How are light and heavy elements formed? (viewed 111037 times)
  63. Are there telescopes that can see the flag and lunar rover on the Moon? (viewed 110691 times)
  64. What is the hottest time of day? (viewed 110646 times)
  65. How do stars move in the Galaxy? (viewed 109362 times)
  66. Does the Sun have a scientific name? (viewed 109146 times)
  67. What happens when galaxies collide? (viewed 108821 times)
  68. Why hasn't NASA gone back to the moon? (viewed 108736 times)
  69. Who first measured the speed of light? (viewed 107581 times)
  70. How do rockets work? (viewed 107267 times)
  71. Why do planets have elliptical orbits? (viewed 107114 times)
  72. What is the size of the Solar System? (viewed 106764 times)
  73. Will the magnetic field of the Earth reverse its direction in the future? Will this cause problems? (viewed 106461 times)
  74. What was there before the Big Bang and what is there outside of our universe? (viewed 105820 times)
  75. When is the next comet due to arrive? (viewed 105583 times)
  76. What would happen if an impact caused Earth to stop rotating? (viewed 105338 times)
  77. How much money do astronomers make? (viewed 105179 times)
  78. What is the physical difference between a star and a planet? (viewed 103836 times)
  79. How long does a solar eclipse last? (viewed 103743 times)
  80. Do black holes die? If so how? (viewed 103130 times)
  81. What will happen to life on Earth when the Sun becomes a red giant? (viewed 102981 times)
  82. How many constellations are there? (viewed 102162 times)
  83. How do you calculate the lifetime of the Sun? (viewed 102017 times)
  84. Does evolution contradict the second law of thermodynamics? (viewed 101775 times)
  85. What elements make up the Sun? (viewed 101632 times)
  86. What is the significance of the Tropic of Cancer, Tropic of Capricorn, Arctic Circle and Antarctic Circle? (viewed 100036 times)
  87. What is the observational difference between a star and a planet? (viewed 99725 times)
  88. Does the Sun rotate? (viewed 99636 times)
  89. Does the Sun move around the Milky Way? (viewed 98768 times)
  90. What's the difference between astronomy and astrology? (viewed 98438 times)
  91. What do astronauts do all day in the International Space Station? (viewed 97307 times)
  92. What is apparent magnitude? (viewed 94668 times)
  93. Which planet is most similar to Earth? (viewed 93435 times)
  94. Does gravity vary across the surface of the Earth? (viewed 92788 times)
  95. How many meteorites hit Earth each year? (viewed 92571 times)
  96. What would happen if the gravity on Earth was suddenly turned off? (viewed 91871 times)
  97. If Mars is only about 35-60 million miles away at close approach, why does it take 6-8 months to get there? (viewed 90445 times)
  98. What are constellations used for? (viewed 90374 times)
  99. How critical is the Earth-Sun distance in maintaining our average temperatures on Earth? (viewed 89721 times)
  100. How do astronomers use math in their jobs? (viewed 89305 times)
  101. Why do different stars appear with seasons? (viewed 88979 times)
  102. Why are stars and planets round? (viewed 88300 times)
  103. Is there a proof that Earth moves? (viewed 87767 times)
  104. Where did the Universe come from? (viewed 87737 times)
  105. Have astronomers discovered Earth's second moon? (viewed 87084 times)
  106. Does the Sun orbit the Earth as well as the Earth orbiting the Sun? (viewed 87022 times)
  107. Why is the Universe flat and not spherical? (viewed 86962 times)
  108. Why is the Moon so bright? (viewed 86840 times)
  109. What kind of schooling is necessary to become an astronomer? (viewed 86552 times)
  110. What makes the wind? (viewed 86350 times)
  111. What would happen if an asteroid 10 kilometers across hit the Earth? (viewed 85999 times)
  112. What is a singularity? (viewed 85211 times)
  113. How can a star burn with no oxygen? (viewed 83558 times)
  114. Where does the name "Milky Way" come from? (viewed 81745 times)
  115. Why does the Earth tilt back and forward once a year? (viewed 81547 times)
  116. What are RA and DEC? (viewed 81118 times)
  117. What would happen if Earth had more than one moon? (viewed 80385 times)
  118. Considering the motion of the Earth, the solar system, and the galaxy, how fast am I moving while lying in bed asleep? (viewed 79634 times)
  119. What is the difference between a "star" and a "sun"? (viewed 78312 times)
  120. Since Earth is spinning, why do we land in the same place when we jump or fall? (viewed 77617 times)
  121. What kind of rock is the moon made of? (viewed 77608 times)
  122. What are the requirements for being a planet? (viewed 77358 times)
  123. Why aren't there any green stars? (viewed 76687 times)
  124. How many stars are born and die each day? (viewed 76673 times)
  125. Did astronauts really go to the Moon, or is it a hoax? (viewed 76547 times)
  126. How are galaxies formed? (viewed 76319 times)
  127. How are black holes made? Could one be made close to us? (viewed 74039 times)
  128. Will the Sun become a black hole one day? (viewed 73983 times)
  129. What would happen if a supermassive black hole came close to the Earth? (viewed 73375 times)
  130. What is the density of a black hole? (viewed 73277 times)
  131. Who has landed on the moon? (viewed 73080 times)
  132. What would you see from inside a black hole? (viewed 71330 times)
  133. Why is the moon in a different place every night? (viewed 71155 times)
  134. Do most astronomers believe in God based on the available scientific evidence? (viewed 70513 times)
  135. Can moons have moons? (viewed 70496 times)
  136. What happens to a substance if its speed is more than the speed of light? (viewed 69871 times)
  137. Why can't you see stars during the day? (viewed 69860 times)
  138. How do rockets move in space? (viewed 69669 times)
  139. How do astronomers measure the brightness of stars? (viewed 69612 times)
  140. Can you fire a gun on the Moon? (viewed 69568 times)
  141. How do we weigh objects in space? (viewed 69263 times)
  142. How often does the Sun pass through a spiral arm in the Milky Way? (viewed 69105 times)
  143. How can the Universe expand faster than the speed of light during inflation? (viewed 69006 times)
  144. What are some of the effects of solar flares on Earth? (viewed 68924 times)
  145. What would happen if you took off your helmet in space? (viewed 68716 times)
  146. How is astronomy impacted by trigonometry? (viewed 68153 times)
  147. Does the Mediterranean sea have tides? (viewed 67828 times)
  148. Is it possible to measure the temperature of the Sun? (viewed 67744 times)
  149. How do we know the mass of the Earth and the Moon? (viewed 67701 times)
  150. When the Sun converts mass to energy, do the orbits of the planets change? (viewed 67679 times)
  151. How does the Sun compare to other stars? (viewed 66997 times)
  152. How do you measure a planet's mass? (viewed 66233 times)
  153. Why do stars change colour when they twinkle? (viewed 66180 times)
  154. What are the "dog days of summer"? (viewed 66172 times)
  155. How does the Moon stay "suspended" in the air? (viewed 66013 times)
  156. How are elements heavier than iron formed? (viewed 65481 times)
  157. What is the evidence supporting the nebula theory of Solar System formation? (viewed 65362 times)
  158. What kinds of jobs do astronomers do? (viewed 64873 times)
  159. Why do we not have eclipses every month? (viewed 64866 times)
  160. Does quantum entanglement imply faster than light communication? (viewed 64274 times)
  161. If the universe is infinite does that mean there is an infinite number of "me"s? (viewed 63513 times)
  162. What are black holes made of? (viewed 63349 times)
  163. What causes seasons? (viewed 62996 times)
  164. How did the stars get named? (viewed 62561 times)
  165. When can I see the Moon through the hole in the Pantheon? (viewed 62545 times)
  166. Why doesn't the earliest sunset occur on the shortest day of the year? (viewed 62399 times)
  167. Where does the name "Moon" come from? (viewed 62079 times)
  168. How did asteroids form and what is the difference between an asteroid and a comet? (viewed 61953 times)
  169. How fast is the Universe expanding? (viewed 61800 times)
  170. How do you measure the mass of a star? (viewed 61686 times)
  171. How long would it take the Earth to fall into the Sun? (viewed 61506 times)
  172. Where did the matter in the universe come from? (viewed 61439 times)
  173. Traveling at light speed, how long would it take to get to the nearest galaxy? (viewed 61313 times)
  174. What's the best college for astronomy? (viewed 61225 times)
  175. What are Altitude and Azimuth? (viewed 61106 times)
  176. Why do planets not twinkle? (viewed 61047 times)
  177. Why doesn't the length of each day change much around the solstices? (viewed 60670 times)
  178. How does light pollution affect astronomers? (viewed 60628 times)
  179. Are there stars outside of galaxies? (viewed 60572 times)
  180. What would happen to us if the sun went out for an hour? (viewed 60502 times)
  181. Where, in relation to the entire universe, is the Milky Way located? (viewed 60292 times)
  182. What is the mass of the Universe? (viewed 59726 times)
  183. What's the difference between dark matter and dark energy? (viewed 58634 times)
  184. Does the Moon rotate? (viewed 58251 times)
  185. How can I calculate the position or path of the Sun for a given time and location? (viewed 58209 times)
  186. Could there be life in the galaxies nearest to the Milky Way? (viewed 58106 times)
  187. Why does the Sun's apparent path through the sky change throughout the year? (viewed 57704 times)
  188. Why does the Earth have only one moon? (viewed 57675 times)
  189. Can any galaxies be seen with the naked eye? (viewed 57270 times)
  190. How does the parachute in a model rocket work? (viewed 56553 times)
  191. How does astronomy benefit humankind? (viewed 56456 times)
  192. What is the origin of spiral structure in galaxies? (viewed 56370 times)
  193. What is the shape of the universe? (viewed 56026 times)
  194. How long does the supernova stage of a star last? (viewed 56018 times)
  195. How close was the Moon to the Earth when it formed? (viewed 56000 times)
  196. What makes up most of the Universe? (viewed 55816 times)
  197. What is the largest structure in the universe? (viewed 55520 times)
  198. Where are stars born? (viewed 54870 times)
  199. Why isn't the summer solstice the hottest day of the year? (viewed 54787 times)
  200. Why is looking out into space the same as looking back in time? (viewed 54658 times)
  201. What can we learn from the color of a star? (viewed 54596 times)
  202. What is a star's "spectrum"? (viewed 54454 times)
  203. What is the size of a black hole? (viewed 54349 times)
  204. How do astronauts use math in their jobs? (viewed 54331 times)
  205. Are names given to black holes? (viewed 54317 times)
  206. Can you see satellites? (viewed 53810 times)
  207. Which constellation does our Sun belong to? (viewed 53528 times)
  208. How do you calculate the azimuth and altitude of an object? (viewed 53144 times)
  209. How do we measure the size of the Moon and of the Sun? (viewed 53134 times)
  210. If gravity is a "curvature of space" rather than a force, why do a ball and bullet follow different paths? (viewed 53034 times)
  211. Are aliens or UFOs real? (viewed 52388 times)
  212. How can I find the distance to the Sun on any given day? (viewed 52364 times)
  213. What happens to a bullet fired on the moon? (viewed 52361 times)
  214. How do the astronauts communicate in space if sound cannot travel in a vacuum? (viewed 52316 times)
  215. Why do we see stars? (viewed 52214 times)
  216. Is the Moon seen as a crescent (and not a "boat") all over the world? Is the same phase of the moon visible from the Northern and Southern hemispheres? (viewed 52100 times)
  217. What other careers involve Astronomy besides Astronomer? (viewed 52058 times)
  218. How can I measure the distance of a star? (viewed 51866 times)
  219. Is the speed of light constant? (viewed 51342 times)
  220. What are some astronomy science fair projects? (viewed 51310 times)
  221. Which hemisphere has the best view of the Milky Way? (viewed 51034 times)
  222. Are there any asteroids on a collision course with Earth? (viewed 50831 times)
  223. How long has there been water on Earth? (viewed 50650 times)
  224. Is time travel possible? (viewed 50143 times)
  225. Why is the sky blue and not blue & purple? (viewed 50087 times)
  226. What would happen if the Moon fell out of its orbit around Earth? (viewed 49967 times)
  227. Who discovered each planet? (viewed 49963 times)
  228. Are meteorites hot or cold when they hit Earth? (viewed 49691 times)
  229. Why does the Moon look big on the horizon? (viewed 49676 times)
  230. Would your weight change as you go underground? (viewed 49669 times)
  231. Why is twilight short near the equator? (viewed 49647 times)
  232. Can we look back far enough in time to see the Big Bang? (viewed 49531 times)
  233. If the Earth's rotation period is less than 24 hours, why don't our clocks fall out of sync with the Sun? (viewed 49416 times)
  234. What do a galaxy's colors mean? Are they its true colors? (viewed 49296 times)
  235. Why is it difficult to understand the expansion of the universe? (viewed 49020 times)
  236. Where did all the water in the universe come from? (viewed 48789 times)
  237. What is a graviton? (viewed 48265 times)
  238. What is the difference between nutation and precession of the Earth? (viewed 48207 times)
  239. If light has no mass, then what draws it into a black hole? (viewed 48005 times)
  240. How is the time of sunrise calculated? (viewed 47995 times)
  241. What skills do astronomers need? (viewed 47856 times)
  242. What's the difference between astronomy and astrophysics? (viewed 47772 times)
  243. Are the planes of solar systems aligned with the plane of the Galaxy? (viewed 47713 times)
  244. How do we know what other planets (and stars, galaxies, etc.) are made of? (viewed 46638 times)
  245. What do I need to do to become an astronomer? (viewed 46422 times)
  246. Do dead stars still shine? (viewed 46082 times)
  247. Why do the size and brightness of the full moon change? (viewed 45721 times)
  248. How do gravitons escape black holes to tell the universe about their gravity? (viewed 45719 times)
  249. What is a wormhole? (viewed 45717 times)
  250. Do supermassive black holes cause galaxy rotation? (viewed 45613 times)
  251. How are black holes discovered? (viewed 45265 times)
  252. Where is the nearest black hole? (viewed 45197 times)
  253. Will we get sucked into the black hole at the center of the Milky Way? (viewed 45014 times)
  254. The Moon slows the Earth's rotation, but how fast was it spinning billions of years ago? (viewed 44707 times)
  255. Why does the Sun appear larger on the horizon than overhead? (viewed 44678 times)
  256. Can we find the place where the Big Bang happened? (viewed 44642 times)
  257. Why can't we see Venus at night when it is an inner planet? (viewed 44508 times)
  258. How do galaxies collide in an expanding universe? (viewed 44489 times)
  259. Can I calculate the size of the Universe by converting light years to kilometres? (viewed 44417 times)
  260. Is the Earth slowly getting larger? (viewed 44360 times)
  261. Why are there stars? (viewed 44333 times)
  262. Why are most months 30 or 31 days long? (viewed 43931 times)
  263. Why does Barnard 68 appear dark? (viewed 43784 times)
  264. Are Kuiper Belt Objects asteroids? Are large Kuiper Belt Objects planets? (viewed 42587 times)
  265. Why don't people walk upside-down on the bottom of the Earth? (viewed 42337 times)
  266. Was the Sun made in a supernova? (viewed 42220 times)
  267. What is the biggest crater recorded on Earth? (viewed 42208 times)
  268. What is the best way to see the Milky Way? (viewed 42165 times)
  269. Could the Universe have expanded faster than the speed of light at the Big Bang? (viewed 42038 times)
  270. Are there eclipses on other planets? (viewed 41940 times)
  271. Is there a "South Star"? (viewed 41900 times)
  272. Why does the location of sunrise change? (viewed 41890 times)
  273. Has there been an experiment that measured speed faster than the speed of light in vacuum? (viewed 41853 times)
  274. How long could life on Earth survive if the Sun stopped shining? (viewed 41802 times)
  275. How much longer will the Earth last? (viewed 41775 times)
  276. Did life originate on Earth, or did it come from somewhere else? (viewed 41722 times)
  277. Why doesn't dark matter fall into a black hole? (viewed 41569 times)
  278. How does Astronomy involve Chemistry? (viewed 41534 times)
  279. What is the difference between the "Doppler" redshift and the "gravitational" or "cosmological" redshift? (viewed 41472 times)
  280. How would the weather on Earth be different if it were a cube? (viewed 41353 times)
  281. Can I buy land on the Moon? (viewed 41292 times)
  282. What happens to spacetime inside a black hole? (viewed 41189 times)
  283. Is the Moon hollow? (viewed 40990 times)
  284. What happens when two black holes get too close? (viewed 40914 times)
  285. Why does the Earth only see one side of the Moon? (viewed 40893 times)
  286. How much can the location of sunset differ from due West? (viewed 40841 times)
  287. What's the biggest meteorite? (viewed 40664 times)
  288. Can the acceleration of the Universe be analogous to apparent acceleration in a airplane? (viewed 40542 times)
  289. What is time dilation? (viewed 40478 times)
  290. What color would Mars be if you were standing on it? (viewed 40388 times)
  291. What is the most distant known galaxy? (viewed 40242 times)
  292. What are the names of the three stars in Orion's belt? (viewed 40038 times)
  293. How can two moons of Saturn share the same orbit? (viewed 39852 times)
  294. What if the Earth rotated twice as fast? (viewed 39628 times)
  295. Could someone travel the universe in his or her own lifetime? (viewed 39410 times)
  296. Can terrestrial planets have rings? (viewed 39362 times)
  297. How long would it take for a mini-black hole to eat the Earth? (viewed 39326 times)
  298. How many Astronauts have been in space? (viewed 39107 times)
  299. Why do people draw stars with five points? (viewed 38981 times)
  300. What are "blue stragglers" in globular clusters? (viewed 38809 times)
  301. Why do pictures of distant galaxies have higher resolution than those of nearby planets? (viewed 38724 times)
  302. How do we feel heat? (viewed 38641 times)
  303. Is it possible to see the full Moon and the Sun simultaneously in high northern latitudes when the Sun doesn't set? (viewed 38624 times)
  304. What is the typical size of a visible shooting star? (viewed 38426 times)
  305. If a white dwarf is a "dead" star, why is it so hot? (viewed 38332 times)
  306. How do we know that nuclear fusion is still going on in the Sun? (viewed 38172 times)
  307. Does Mt. Everest cast a shadow on the moon? (viewed 38150 times)
  308. Is the Great Wall the largest galaxy cluster? (viewed 38038 times)
  309. Why can we see the sun's image before sunrise and after sunset? (viewed 38003 times)
  310. How fast does the Earth go at perihelion and aphelion? (viewed 37968 times)
  311. How does night and day work? (viewed 37942 times)
  312. Can a person go into a black hole and come out alive? (viewed 37718 times)
  313. Does the Sun have an iron surface? (viewed 37632 times)
  314. What is a dimension? (viewed 37613 times)
  315. Why are Saturn's rings flat? (viewed 37527 times)
  316. What is the speed of gravity? (viewed 37507 times)
  317. Can you see the future as you fall into a black hole? (viewed 37500 times)
  318. Can I communicate faster than light? (viewed 37412 times)
  319. Where do planetary rings come from, and what are they made of? (viewed 37410 times)
  320. On which days can I see the Moon in the evening / morning and why is this so? (viewed 37363 times)
  321. What is Earthrise over the Moon? (viewed 37241 times)
  322. What can I use for fuel in my homemade rocket? (viewed 37235 times)
  323. How big is the universe? (viewed 37198 times)
  324. Do you think it's possible to maintain life on other planets? (viewed 37196 times)
  325. Where is the supernova remnant that led to our solar system? (viewed 37133 times)
  326. Is the Sun always up for exactly 12 hours at the equator? (viewed 37120 times)
  327. What is the approximate GPA needed in High School in Math and Science to be an astronomer? (viewed 36956 times)
  328. Who (and when) discovered that the earth's axis is on a 23 degree tilt? (viewed 36915 times)
  329. Are all stars the same? (viewed 36830 times)
  330. Why do clocks turn in the opposite direction from the Earth and Moon? (viewed 36712 times)
  331. How do we determine the age of the universe? (viewed 36673 times)
  332. Is there really a 10th planet? (viewed 36636 times)
  333. What companies or businesses can astronomers work for? (viewed 36556 times)
  334. Why is sea water salty, and not lake water? (viewed 36477 times)
  335. What would happen to the Earth if an asteroid hit the Moon? (viewed 36263 times)
  336. How many stars can I see? (viewed 36187 times)
  337. Does the Coriolis force determine which way my toilet drains? Does it affect black holes? (viewed 36114 times)
  338. How do I tell which planet is which? (viewed 36101 times)
  339. Is there a beginning and an end to a galaxy's life? (viewed 35976 times)
  340. If the universe is 15 billion years old, how can it be larger than 15 billion light years across? (viewed 35957 times)
  341. Do the Sun's or Earth's magnetic field reverse? (viewed 35654 times)
  342. How do we know the Milky Way is a spiral galaxy? (viewed 35632 times)
  343. How can the universe be "flat"? We're 3D! (viewed 35514 times)
  344. How do we define distance in an expanding universe? (viewed 35422 times)
  345. How are photons created and destroyed? (viewed 35407 times)
  346. How can I find my age on another planet? (viewed 35213 times)
  347. Is Andromeda part of the Milky Way? Where can I find them in the sky? (viewed 34939 times)
  348. Why have star signs shifted by one constellation? (viewed 34736 times)
  349. Why are there blue shifted galaxies? (viewed 34465 times)
  350. What was that really big falling star that I saw? (viewed 34442 times)
  351. How does the brightness of a star depend on its distance from us? (viewed 34424 times)
  352. Why do humans want to go in space? (viewed 34420 times)
  353. What is the pattern to the distances between each planet and the sun? (viewed 34249 times)
  354. How are planets detected around other stars? (viewed 34238 times)
  355. Can a lunar and a solar eclipse happen in the same month? When will this happen next? (viewed 34182 times)
  356. What would happen if two stars collided? (viewed 34149 times)
  357. Who came up with the name "black hole"? (viewed 34129 times)
  358. What is the significance of the second focus of elliptical orbits of planets in our Solar System? (viewed 34009 times)
  359. Is the Earth at the centre of the Universe? (viewed 33979 times)
  360. How do astronauts communicate with their families from space? (viewed 33979 times)
  361. When we look back to the Big Bang, why don't we see the universe as a tiny speck of matter? (viewed 33961 times)
  362. How can we estimate the number of Earth-like planets in the Galaxy? (viewed 33954 times)
  363. What kind of eyepieces do I need to look at planets? (viewed 33874 times)
  364. Is there a simple formula to calculate solar eclipse timings from any position on Earth? (viewed 33866 times)
  365. Will we ever stop having solar eclipses because of the moon's motion away from the Earth? (viewed 33818 times)
  366. Why don't astronomers use everyday units to measure distances (what is an AU or a pc)? (viewed 33745 times)
  367. How is it that we see farther out in space (farther back in time) than in the past? (viewed 33507 times)
  368. Will the Moon be invisible in 500 million years? (viewed 33439 times)
  369. Are Earth and the Moon "twin planets"? (viewed 33253 times)
  370. Which American colleges teach astronomy? (viewed 33129 times)
  371. How dangerous are the asteroids? (viewed 33120 times)
  372. Why is our solar system so different from all the others we've found? (viewed 33061 times)
  373. How do I become both an astronaut and an astronomer? (viewed 32966 times)
  374. Why is Uranus tipped on its side? (viewed 32925 times)
  375. Can we colonize other planets? (viewed 32817 times)
  376. How hot is each one of the layers of the sun? (viewed 32657 times)
  377. How do sunrise and sunset times change with altitude? (viewed 32278 times)
  378. What are quasars made of? (viewed 32096 times)
  379. How can I calculate distances between stars? (viewed 32082 times)
  380. Why do constellations look the same after several years even though all the stars are moving? (viewed 31974 times)
  381. Why do astronauts in space need to exercise? (viewed 31896 times)
  382. Why are there no craters on Earth? Did all the meteorites miss us? (viewed 31887 times)
  383. Why doesn't gravity change the speed of light? (viewed 31834 times)
  384. Can you describe a day on the job as an astronomer? (viewed 31726 times)
  385. Why can't a plane fly slowly and let the Earth pass underneath? (viewed 31720 times)
  386. Is the universe really like an expanding balloon? (viewed 31643 times)
  387. Is it true that the Sun burns off a billion tons of gas every 5 seconds? (viewed 31564 times)
  388. Is it possible to count the stars? (viewed 31551 times)
  389. What is dark matter? (viewed 31499 times)
  390. Is the gravitational force exerted by the Earth on the Moon equal to the centripetal force acting on the Moon? (viewed 31497 times)
  391. Is time travel possible using merging black holes? (viewed 31460 times)
  392. What is happening just around the black hole in the center of the Milky Way? (viewed 31328 times)
  393. Can superheavy elements (such as Z=116 or 118) be formed in a supernova? Can we observe them? (viewed 31262 times)
  394. Did the speed of light change over the history of the universe? (viewed 31161 times)
  395. How big a change in the Earth's orbit would be required to destroy all life? (viewed 31103 times)
  396. Can we see dead stars with the naked eye? (viewed 31086 times)
  397. How can we distinguish a star's "real" color from the change in color that we observe due to the star's motion? (viewed 31041 times)
  398. Is the Local Group expanding along with the entire Universe? (viewed 31034 times)
  399. How do we measure distances to other stars? (viewed 30959 times)
  400. What happens when an antimatter black hole collides with a matter blackhole? (viewed 30816 times)
  401. How do I make a scale model of the Solar System? (viewed 30812 times)
  402. Are time machines possible? (viewed 30755 times)
  403. How many moles of stars are in the known universe? (viewed 30347 times)
  404. How are galaxy distances inferred from their recessional velocities? (viewed 30127 times)
  405. How can we tell what the interiors of planets are like? (viewed 29950 times)
  406. Is there any limitation to what a black hole can "suck" in? (viewed 29936 times)
  407. What happens when you change the mass of a White Dwarf or Neutron Star? (viewed 29860 times)
  408. Why is the time between two successive full moons different from the lunar synodic month? (viewed 29812 times)
  409. What is the farthest in space that we have gone? (viewed 29751 times)
  410. What do "homogeneity" and "isotropy" mean? (viewed 29669 times)
  411. What's that dark spot on the Sun? (viewed 29522 times)
  412. How can we know that there are other galaxies if we cannot leave ours? (viewed 29517 times)
  413. What are the closest and/or brightest stars? (viewed 29443 times)
  414. Does the Milky Way spin counter-clockwise? If so, do all spiral galaxies spin in this direction and why? (viewed 29423 times)
  415. How can I tell if the rock I found is a meteorite? (viewed 29410 times)
  416. Can astronauts produce water in space? (viewed 29405 times)
  417. Will the seasons change due to precession? (viewed 29379 times)
  418. How was the starting point for the Julian Date system chosen? (viewed 29253 times)
  419. Aren't jobs in astronomy scarce? (viewed 29220 times)
  420. Do astronomers believe in astrology? (viewed 29094 times)
  421. How do we know if the universe will keep expanding forever? (viewed 29067 times)
  422. Did I see the Aurora Borealis as a child? (viewed 29055 times)
  423. Why does the SETI project search for radio signals? (viewed 29052 times)
  424. How long does it take the Big Dipper to move in the sky? (viewed 29021 times)
  425. What are the facts about the Star of Bethlehem? (viewed 28985 times)
  426. Don't tachyons travel faster than light? (viewed 28982 times)
  427. Could an astronaut or satellite fall into a black hole that we didn't know about? (viewed 28938 times)
  428. Why do most moons orbit their planets at the equator? (viewed 28935 times)
  429. Why do we study black holes? (viewed 28882 times)
  430. What are the atmospheres of Mars and Pluto like? (viewed 28795 times)
  431. When are there 5 Sundays in February? (viewed 28774 times)
  432. Wouldn't the Big Bang theory be considered a hypothesis and not a theory? (viewed 28708 times)
  433. Do we see the same stars from above and below the equator? (viewed 28587 times)
  434. Has anyone made a map of the Milky Way? (viewed 28446 times)
  435. Was I hit by a meteorite? (viewed 28440 times)
  436. Can you use an infinite line of reflectors to send light to the edge of the Universe? (viewed 28338 times)
  437. What does the term "visible universe" mean? (viewed 28326 times)
  438. How are galaxies named? (viewed 28316 times)
  439. What colors are visible through an amateur telescope? (viewed 28313 times)
  440. Could you tell me about the life cycle of galaxies? (viewed 28306 times)
  441. Do you believe in UFOs? (viewed 28275 times)
  442. How can geometry be different in space? (viewed 28218 times)
  443. Why are the compositions of comets and asteroids different? (viewed 27941 times)
  444. What's the best thing about being an astronomer? (viewed 27671 times)
  445. How do asteroids, meteors and comets disappear? (viewed 27659 times)
  446. How much time do astronomers spend looking through telescopes? (viewed 27574 times)
  447. Will winter and summer constellations change due to abnormal warmth or cold on Earth? (viewed 27554 times)
  448. Why do so many of the world's UFO sightings happen in America? (viewed 27487 times)
  449. How do astronomers measure the radius of a star? (viewed 27461 times)
  450. Can two lunar eclipses occur in the same month? (viewed 27394 times)
  451. How will the two black holes that are going to collide affect Earth? (viewed 27391 times)
  452. Have there been other Big Bangs before? (viewed 27359 times)
  453. How can we see galaxies if their stars are so faint? (viewed 27355 times)
  454. How do I explain to my children why the Moon has phases? (viewed 27158 times)
  455. Can life exist on the recently discovered extrasolar planets? (viewed 27124 times)
  456. How are galaxies and solar systems similar? (viewed 27069 times)
  457. How close do you have to come to the Earth to be influenced by its gravity? (viewed 27047 times)
  458. Is the Milky Way a collision of two galaxies? (viewed 26959 times)
  459. Is there a project I can do on black holes? (viewed 26921 times)
  460. How can we measure distances to more stars? (viewed 26846 times)
  461. What is the origin of the stellar classification system "OBAFGKM"? (viewed 26827 times)
  462. Could you escape from a black hole if you were able to go faster than the speed of light? (viewed 26791 times)
  463. How do scientists slow light down? (viewed 26734 times)
  464. Do the magnitudes and colors of stars ever change? (viewed 26688 times)
  465. Is infinite temperature possible? (viewed 26559 times)
  466. Do we know everything about the Sun? (viewed 26530 times)
  467. How close does a supernova need to be to damage the Earth's environment? (viewed 26519 times)
  468. Can "tired light theory" explain the observed redshifts of galaxies? (viewed 26420 times)
  469. Do asteroids hit the sun? (viewed 26390 times)
  470. What supernova created the Crab nebula? (viewed 26387 times)
  471. Can one star orbit another? (viewed 26362 times)
  472. Is it worthwhile to continue the search for extraterrestrial life? (viewed 26354 times)
  473. Can double stars have planets? (viewed 26202 times)
  474. What causes gamma ray bursts? (viewed 26202 times)
  475. How far does a galaxy extend? (viewed 26194 times)
  476. How do I polar align my telescope? (viewed 26034 times)
  477. What will happen to the Milky Way in the future? (viewed 25959 times)
  478. Is there such a thing as hyperspace? (viewed 25949 times)
  479. Can astronauts play musical instruments in space? (viewed 25913 times)
  480. What type of energy does a black hole have? (viewed 25906 times)
  481. What happens to the material that has been sucked into a black hole? (viewed 25893 times)
  482. What is the farthest Northern Latitude in which the Magellanic Clouds can be seen? (viewed 25850 times)
  483. Which way does the sun travel in the southern hemisphere? (viewed 25850 times)
  484. What is sidereal time? (viewed 25831 times)
  485. Why do the explosions of Type Ia supernovae have a more predictable spectrum than those of regular Type II supernovae? (viewed 25772 times)
  486. Is there oxygen in the atmospheres of other planets? (viewed 25719 times)
  487. What is a Cepheid variable? (viewed 25671 times)
  488. What is "nothing", from a scientific point of view? (viewed 25645 times)
  489. How will a change in the speed of light affect the evolution of the Universe? (viewed 25632 times)
  490. What's the object I saw that moved across the sky and then got very bright? (viewed 25577 times)
  491. Why did the Pioneer and Voyager take only 2 years to reach Jupiter, while Galileo and Cassini took more than 5 years? (viewed 25563 times)
  492. Which part of the sky did the famous 'wow' signal originate from? (viewed 25557 times)
  493. How different would the night sky have looked in 40,000 B.C.? (viewed 25472 times)
  494. Is there sound coming from the Sun? (viewed 25447 times)
  495. How do we know what parameters to use when simulating the collision of the Milky Way and Andromeda? (viewed 25384 times)
  496. Can a human give birth in space? (viewed 25366 times)
  497. Why do we assume that the universe is homogeneous? (viewed 25347 times)
  498. How do we know that sunspots are associated with the Sun's magnetic field? (viewed 25290 times)
  499. Does the Moon look different in the northern and southern hemispheres? (viewed 25266 times)
  500. When did people discover that the Sun is a star? (viewed 25240 times)
  501. Why is the shadow on the Moon the shape it is? (viewed 25207 times)
  502. Are there any dark stars or dark galaxies made of dark matter? (viewed 25171 times)
  503. Are planetary nebulae the result of supernovae? (viewed 25159 times)
  504. When unmanned spacecraft accelerate in space, what causes them to slow down? (viewed 25148 times)
  505. What calculations go into predicting eclipses? (viewed 25118 times)
  506. If we invented special suits could we ever go to the sun? (viewed 25100 times)
  507. Was Stonehenge built to mark solar phenomena? (viewed 25062 times)
  508. What is the difference between homogeneity and isotropy? (viewed 25037 times)
  509. Is there a list of the sizes of different kinds of stars? (viewed 25026 times)
  510. What is our galaxy's halo made of, and how was it formed? (viewed 25003 times)
  511. What process would bring about a quark star? (viewed 24957 times)
  512. Can I see a quasar? (viewed 24896 times)
  513. What's so exciting about the new planet around 55 Cancri? (viewed 24893 times)
  514. What is a Dyson Sphere? (viewed 24846 times)
  515. How many sunspots can the Sun have at once? (viewed 24840 times)
  516. Did a giant impact cause the Dark Ages? (viewed 24839 times)
  517. How are asteroid compositions and classifications determined? (viewed 24798 times)
  518. Have gravitational waves been proven to exist? (viewed 24778 times)
  519. Can I see details on Venus? (viewed 24738 times)
  520. Can any comparison be made between spiral galaxies and hurricanes? (viewed 24675 times)
  521. Why are there more maria on the near side of the Moon? (viewed 24530 times)
  522. Why are there active volcanos on Io? (viewed 24504 times)
  523. What equipment do I need for astrophotography? (viewed 24488 times)
  524. Does Cerenkov radiation travel faster than light? (viewed 24463 times)
  525. How is it proved that the Universe is expanding? (viewed 24448 times)
  526. What happened to all the black holes that were around in the early universe? (viewed 24400 times)
  527. Is there any possibility that the Solar System or the Universe is in a black hole? (viewed 24394 times)
  528. Why are telescopes kept in cold conditions? (viewed 24264 times)
  529. What happened to the girl who named Pluto? (viewed 24234 times)
  530. Would the biggest airplanes cause tsunamis if they crashed? (viewed 24225 times)
  531. If clocks run slow in a gravitational field, how can we know the true age of the Solar System and Universe? (viewed 24189 times)
  532. How big was the Sun when it first "fired up"? (viewed 24175 times)
  533. How can we compare dark matter and dark energy? (viewed 24145 times)
  534. If the Universe was infinitely dense at the Big Bang, why didn't time stand still? (viewed 24061 times)
  535. What caused Shoemaker-Levy 9 to split up? (viewed 24036 times)
  536. Could we send a space mission to a comet? (viewed 24022 times)
  537. Why do photos of space taken from space never show any stars? (viewed 24019 times)
  538. How long do supernova remnants last? (viewed 23983 times)
  539. How do solar flares affect airline pilots? (viewed 23896 times)
  540. Could we be seeing dead stars? (viewed 23891 times)
  541. Why doesn't light from distant galaxies reach us instantaneously? (viewed 23873 times)
  542. How are sunspots formed? (viewed 23860 times)
  543. How big is the Hubble Ultra Deep Field image? (viewed 23750 times)
  544. Could a different theory of gravity explain the dark matter mystery? (viewed 23700 times)
  545. Can you give me advice on buying a telescope? (viewed 23692 times)
  546. How does the Earth compare in size to the entire universe at the present epoch? (viewed 23690 times)
  547. As the universe expands, why don't galaxies get stretched out? (viewed 23648 times)
  548. Why doesn't NASA build rotating spacecraft to simulate gravity? (viewed 23608 times)
  549. How many comets are currently orbiting our sun? (viewed 23606 times)
  550. What would happen if a human were exposed to space without wearing a spacesuit? (viewed 23590 times)
  551. Why is the Hubble Space Telescope in space? (viewed 23543 times)
  552. Can you tell time by the Big Dipper? (viewed 23519 times)
  553. Where does the kinetic energy of infalling bodies come from? (viewed 23488 times)
  554. Can I build an instrument to measure the size of the Sun and of the Moon? (viewed 23476 times)
  555. How do we know that superclusters are the largest structures in the universe? (viewed 23433 times)
  556. How powerful are quasars? (viewed 23363 times)
  557. Would extraterrestrial civilizations know that there is life on Earth? (viewed 23293 times)
  558. Did I really hear a meteor? (viewed 23277 times)
  559. Why is it important to study meteorites? (viewed 23244 times)
  560. How is the Cepheid yardstick validated? (viewed 23221 times)
  561. Why are telescopes located in remote places? (viewed 23091 times)
  562. What would happen if there was a collision between two white dwarfs? (viewed 23078 times)
  563. Do unmanned spacecraft like Voyager travel in straight lines? (viewed 23078 times)
  564. Can supernovae hinder the formation of life in galaxies? (viewed 23069 times)
  565. Did time go slower just after the Big Bang? (viewed 23056 times)
  566. Are there any new craters on the moon? (viewed 23038 times)
  567. Why are stars of different masses? (viewed 23018 times)
  568. How can I contribute to science as an amateur astronomer? (viewed 22989 times)
  569. Do galaxies orbit around anything? (viewed 22978 times)
  570. Do the Earth's magnetic poles ever change places? (viewed 22959 times)
  571. How do planets capture satellites? (viewed 22940 times)
  572. Do similar laws of physics throughout the Universe imply that all life must be like life on Earth? (viewed 22940 times)
  573. Are the asteroids the remains of a planet which broke apart? (viewed 22938 times)
  574. How do I become an astronomical artist? (viewed 22914 times)
  575. What kind of instruments are used to detect extrasolar planets? (viewed 22888 times)
  576. How could galaxies have gotten so far away in only 15 billion years? (viewed 22760 times)
  577. Could there have been multiple Big Bangs at different places in the universe? (viewed 22752 times)
  578. How do unmanned space probes avoid running into things? (viewed 22720 times)
  579. How are astronomy and poetry linked? (viewed 22709 times)
  580. Why can't relative velocities add up to more than the speed of light? (viewed 22631 times)
  581. What kind of telescope should I use for astrophotography? (viewed 22624 times)
  582. Could dark energy come from matter anti-matter pairs forming spontaneously and then annihilating? (viewed 22550 times)
  583. Why is NASA shutting down the Hubble Space Telescope? (viewed 22543 times)
  584. Can I listen to the SETI@home radio signal? (viewed 22524 times)
  585. How can you tell if a crescent moon is preceding or following a new-moon phase? (viewed 22508 times)
  586. Are the properties of extrasolar planets known? (viewed 22463 times)
  587. Does the Sun have any heavy elements? (viewed 22434 times)
  588. Will we discover an 11th planet? What would it be called? (viewed 22289 times)
  589. What class of spiral galaxy is the Milky Way? (viewed 22255 times)
  590. Can the theory of formation of the solar system explain all the observables? (viewed 22250 times)
  591. A line drawn perpendicular to a line through the tips of the horns of the crescent moon doesn't point to the Sun! Why not? (viewed 22233 times)
  592. What month was it when Odysseus saw Orion in 1000BC? (viewed 22227 times)
  593. How do astronomers observe the Sun's interior? (viewed 21985 times)
  594. Why does one side of Mars look more catastrophic than the other? (viewed 21946 times)
  595. What makes a satellite geosyncronise itself with Earth's orbit? (viewed 21935 times)
  596. Why does the apparent density of galaxies drop off at larger distances? (viewed 21899 times)
  597. Would a planet near the galactic center have a brighter night sky? (viewed 21848 times)
  598. Is it possible for amateurs to do optical interferometry? (viewed 21749 times)
  599. What is the solar cycle? (viewed 21697 times)
  600. Where was the water in the big bang? (viewed 21662 times)
  601. Could we send a manned mission to the outer planets? (viewed 21642 times)
  602. Do stars' orbits in galaxies obey Kepler's Laws? (viewed 21608 times)
  603. Can other terrestrial moons be (or have been) stable? (viewed 21569 times)
  604. Why was the Platonic year named after Plato? (viewed 21505 times)
  605. How are supernovae discovered? (viewed 21483 times)
  606. Can a black hole come back to the visual universe through a "little bang"? (viewed 21422 times)
  607. What would the Big Crunch look like to an observer on Earth? (viewed 21413 times)
  608. Does inflation allow for an infinite number of universes? (viewed 21346 times)
  609. Why are accretion disks flat? (viewed 21309 times)
  610. How can water be chemically trapped in rocks? (viewed 21299 times)
  611. Could our position in the universe affect our perceptions of the expansion? (viewed 21295 times)
  612. What is meant by "stopping down a telescope"? (viewed 21291 times)
  613. Why do spacecraft need heat shields coming back to Earth but not leaving? (viewed 21260 times)
  614. Why doesn't the hydrogen on Jupiter explode? (viewed 21204 times)
  615. Did I find a rock that came from the Moon? (viewed 20991 times)
  616. Have astronomers observed any phenomena that could be produced by extraterrestrial civilizations? (viewed 20985 times)
  617. How can the Sun have such a strong gravitational field if it's made of gasses? (viewed 20954 times)
  618. What is the SU(3) quark model? (viewed 20948 times)
  619. Does a photon observe other photons moving past it at the speed of light? (viewed 20946 times)
  620. Can gravitational lensing from intervening galaxies cause the observed ripples in the Cosmic Microwave Background? (viewed 20924 times)
  621. What's new with the Big Bang? (viewed 20664 times)
  622. Will I be able to see the shadow of the Moon streaking towards me in a total solar eclipse? (viewed 20625 times)
  623. Could photons be dark matter? (viewed 20566 times)
  624. Is it possible to build a cheap device to measure declination? (viewed 20534 times)
  625. Why can we have solar eclipses? (viewed 20519 times)
  626. How can we find galaxies behind the Milky Way? (viewed 20490 times)
  627. If comets are boiling away, why are there any left? (viewed 20488 times)
  628. How fast do particles travel in space? (viewed 20440 times)
  629. Why do some eclipses take longer than others? (viewed 20426 times)
  630. Why search for only Earth-like life on other planets? (viewed 20404 times)
  631. Where can I find information on the moons of other planets? (viewed 20370 times)
  632. How much power is contained in a beam of light? (viewed 20294 times)
  633. Why is the WMAP picture of the CMB an ellipse? (viewed 20261 times)
  634. Why is pressure broadening greater in low mass stars than in high mass stars? (viewed 20204 times)
  635. What would an "open geometry" for the universe look like? (viewed 20104 times)
  636. What are the boundaries of the constellations? (viewed 20073 times)
  637. Did the Sumerians measure precession? (viewed 20024 times)
  638. What kinds of star clusters are there? (viewed 19993 times)
  639. Why is the Cosmic Microwave Background not absorbed by interstellar hydrogen? (viewed 19963 times)
  640. How do astronomers come up with their facts? (viewed 19958 times)
  641. Why aren't discoveries of extrasolar planets reported on the news? (viewed 19930 times)
  642. How do bars form in spiral galaxies? (viewed 19886 times)
  643. Why don't astronauts sublimate in space? (viewed 19856 times)
  644. How do photons from distant objects maintain enough energy to reach us? (viewed 19820 times)
  645. Can HST see the Oort cloud? (viewed 19789 times)
  646. Can planets collide with one another? (viewed 19741 times)
  647. Do electrons age? (viewed 19728 times)
  648. Do constellations looks the same from space? (viewed 19704 times)
  649. Can the Space Shuttle abort and return to Earth before reaching orbit? (viewed 19628 times)
  650. Can we make a movie of the Milky Way galaxy's rotation? (viewed 19619 times)
  651. How did Mars get so dusty? (viewed 19572 times)
  652. How long is twilight on the Moon? (viewed 19510 times)
  653. Does the shuttle worry about space junk? (viewed 19441 times)
  654. What are collections of galaxies called? (viewed 19435 times)
  655. How does melting a material reset its radioactive clock? (viewed 19410 times)
  656. Why do supernova remnants look like rings rather than spheres? (viewed 19364 times)
  657. Will astronauts ever be able to go ice-skating on Europa? (viewed 19323 times)
  658. How do you classify galaxies? (viewed 19313 times)
  659. Where can I see Newton's original reflecting telescope? (viewed 19291 times)
  660. Why don't all neutron stars become pulsars? (viewed 19247 times)
  661. What is the best time of the year to see eclipses? (viewed 19178 times)
  662. Why doesn't SETI concentrate its observations to the nearby stars and the solar systems that we are discovering? (viewed 19177 times)
  663. How can we understand the meaning of large numbers like "a million million?" (viewed 19146 times)
  664. Will the next generation telescope OWL be able to detect an Earth like extrasolar planet? (viewed 19088 times)
  665. What causes a particle to decay? (viewed 19063 times)
  666. How can I nominate myself for a Nobel Prize in Physics? (viewed 18982 times)
  667. How long has humanity known that we live in a galaxy similar to others in the Universe? (viewed 18952 times)
  668. Will the Leonid meteor shower go away? (viewed 18939 times)
  669. What are "curled" dimensions? (viewed 18817 times)
  670. Is light of different colors affected differently by gravity? (viewed 18796 times)
  671. What was that eclipse I saw in the sky? (viewed 18698 times)
  672. How does interferometry work? (viewed 18655 times)
  673. How do distant galaxies differ from those nearby? (viewed 18573 times)
  674. How does the color index of a star relate to its actual color? (viewed 18552 times)
  675. Does the temperature of matter increase as it is accelerated to relativistic speeds? (viewed 18548 times)
  676. Why is it called astronomy when all the other sciences end in -ology? (viewed 18546 times)
  677. Do asteroids ever do anything good in the Solar System? (viewed 18536 times)
  678. How do we find out about the star formation histories of galaxies? (viewed 18529 times)
  679. Can astronomers observe anything when the moon is full? (viewed 18462 times)
  680. Wouldn't the vast distances of space distort SETI signals into unintelligeble forms? (viewed 18422 times)
  681. If nothing can escape a black hole, why do some black holes have jets? (viewed 18413 times)
  682. What kind of interference must astronomers contend with when observing? (viewed 18358 times)
  683. Are black holes spherical? (viewed 18350 times)
  684. What would happen if you went back in time and killed your grandmother? (viewed 18349 times)
  685. Why will fusion wait until hydrogen is gone before starting to fuse heavier atoms? (viewed 18271 times)
  686. Do we really observe the edges of galaxies at different epochs? (viewed 18267 times)
  687. What do stellar classifications mean? (viewed 18257 times)
  688. Can you tell me the characteristics of W, R, N and S type stars? (viewed 18247 times)
  689. How are astronauts trained for weightlessness? (viewed 18169 times)
  690. How can I watch the Perseid meteor shower? (viewed 18165 times)
  691. If photons have zero mass, why do they feel the effects of gravity? (viewed 18103 times)
  692. What is the three-body problem? (viewed 18077 times)
  693. Why aren't accretion disks around giant stars as hot as accretion disks around black holes? (viewed 17994 times)
  694. If the universe is "bounded" today, could it one day become "unbounded"? (viewed 17910 times)
  695. Will the diameter of a cluster of galaxies change with redshift? (viewed 17860 times)
  696. Is cosmic expansion happening on microscopic scales? (viewed 17719 times)
  697. How can I find out if the new moon has been sighted? (viewed 17596 times)
  698. Do we have to worry about relativity when studying galactic objects? (viewed 17400 times)
  699. Could neutrinos be dark matter? (viewed 17331 times)
  700. What kinds of cancer research have been done in space? (viewed 17221 times)
  701. How does a star take mass from another star? (viewed 17130 times)
  702. How can you tell the difference between single and multiple extrasolar planets? (viewed 16931 times)
  703. Could the Universe's dark matter be made up of black holes? (viewed 16928 times)
  704. Does lunar gardening really work? (viewed 16898 times)
  705. When measuring the expansion of the universe, do astronomers consider that they're seeing how galaxies moved long ago, not today? (viewed 16861 times)
  706. What is Hot Dark Matter theory? (viewed 16852 times)
  707. How do supernovae show us that the Universe's expansion is accelerating? (viewed 16709 times)
  708. Is it a coincidence that we can have total solar eclipses? Are there other planets which also have them? (viewed 16415 times)
  709. How does libration allow us to see more than 50% of the Moon? (viewed 16353 times)
  710. Is the green flash real? (viewed 16334 times)
  711. How can observations of the distant universe prove that the expansion is accelerating *now*? (viewed 16305 times)
  712. How do we know the density of some extrasolar planets? (viewed 16243 times)
  713. Is light blueshifted when it is gravitationally lensed? (viewed 16193 times)
  714. What is the photoelectric effect? Why can't multiple low-frequency photons free an electron? (viewed 16184 times)
  715. Do binary or triple star systems form together? (viewed 16153 times)
  716. No matter how fast the universe is expanding, shouldn't gravity eventually make it recollapse? (viewed 16114 times)
  717. What percent of the time can astronomers observe without interference from the Moon? (viewed 15902 times)
  718. What do meteorites tell us about life on other planets? (viewed 15844 times)
  719. Why is it easier to see a star if you look slightly to the side? (viewed 15721 times)
  720. What happens to the helium formed in the sun? (viewed 15719 times)
  721. Could matter-anti-matter repulsion power the expansion of the universe? (viewed 15618 times)
  722. If the sun went out and our atmosphere froze solid, what color would it be? (viewed 15468 times)
  723. Can we prove that the Moon isn't hollow? (viewed 15437 times)
  724. Why doesn't the ammonia and methane in Jupiter's atmosphere sink into the core? (viewed 15351 times)
  725. Are there any 'lonely galaxies'? (viewed 15230 times)
  726. How do we detect incoming meteorites? (viewed 15110 times)
  727. What was different on Mars in the past to allow liquid water to be present? (viewed 14990 times)
  728. When will Hale-Bopp return? (viewed 14851 times)
  729. Why don't skydivers burn up like meteors? (viewed 14761 times)
  730. Has anyone ever seen a star "turn on"? (viewed 14576 times)
  731. During close approaches, can Mars appear in our sky as large as the Moon? (viewed 14543 times)
  732. How are planets affected by the Hot Ionised Medium? (viewed 14312 times)
  733. How has light from 13 billion years ago not passed us by? (viewed 14225 times)
  734. Why are craters round? (viewed 14134 times)
  735. Can the sun rise from the west on Mars? (viewed 13875 times)
  736. Why was Mir burnt up in the atmosphere? (viewed 13853 times)
  737. What are the largest radio wavelengths observed from radio sources in the sky? (viewed 13834 times)
  738. How can we discern different galaxies/clusters along the same line of sight? (viewed 13738 times)
  739. What is the relationship between the width of a star trail on a photo and the star's intensity? (viewed 13307 times)
  740. Can we harvest H & O from space to make water? (viewed 12862 times)
  741. What is between the Oort cloud and the closest star? (viewed 12517 times)
  742. Why does Titan, in spite of being smaller than Mars, have an atmosphere more dense than Earth's? (viewed 12415 times)
  743. What time is sunrise/sunset or moonrise/moonset at my location? (viewed 12329 times)
  744. Could a planetary system survive if its star merged with another, or if its star went supernova? (viewed 11648 times)
  745. Are there solar tides? (viewed 11605 times)
  746. Does weightlessness affect hunger? (viewed 11511 times)
  747. Is Earth-moon tidal friction causing global warming? (viewed 11045 times)
  748. The Moon and Sun are the same apparent size in the sky. The Moon is moving away from us at 3.8 centimeters/year. Isn't it improbable that we live in an epoch in which they appear the same size in the sky? (viewed 11027 times)
  749. Do planets radiate noise? (viewed 10807 times)
  750. Is the moon spherical? (viewed 10653 times)
  751. What happens to the Earth as the moon gets farther away and will it ever go away entirely? (viewed 10593 times)
  752. What would happen if a nuclear-powered shuttle exploded? (viewed 10412 times)
  753. Is dark energy affected by black holes? (viewed 10408 times)
  754. Why is the Moon higher in the sky in winter and lower in the summer? (viewed 9841 times)
  755. Where are the protons and electrons in a Neutron Star? (viewed 9728 times)
  756. Did the Moon or planets form in a manner similar to that of Earth? (viewed 9467 times)
  757. Do more meteorites fall at low latitudes? (viewed 9465 times)
  758. Wait, I'm still confused why information can't travel faster than the speed of light. (viewed 9326 times)
  759. What are the possible ends of the universe? (viewed 9313 times)
  760. Will Comet Elenin (C/2010 X1) affect the Earth on its close approach in Fall 2011? (viewed 9302 times)
  761. Is it sensible to consider terraforming Mars? (viewed 9214 times)
  762. Is the Moon always visible during winter on the North Pole? (viewed 9206 times)
  763. Will the Pioneer and Voyager probes ever leave the Milky Way? (viewed 9198 times)
  764. If there are infinity universes, will every thing that is possible happen? (viewed 9183 times)
  765. What color are meteors? (viewed 8761 times)
  766. Where is everybody? (viewed 8456 times)
  767. Why does Mars have a dusty atmosphere? (viewed 7956 times)
  768. The naming of Mars (viewed 7863 times)
  769. If I were traveling through space, could I see distant galaxies with my own eyes? (viewed 7836 times)
  770. Does the singularity in a black hole create a new Universe? (viewed 7756 times)
  771. Is the reddish dust of Mars biogenic? (viewed 7601 times)
  772. Where is the Spitzer Space Telescope? (viewed 7086 times)
  773. When will humans travel to Mars and revisit the Moon? (viewed 6995 times)
  774. Does the particles involved in a star's final core collapse travel faster than the speed of light? (viewed 6341 times)
  775. When is the best time to observe zodiacal light? (viewed 6102 times)
  776. How likely is it for a planet to transit its star? (viewed 6014 times)
  777. What causes the aurora? (viewed 5897 times)
  778. Why do astronomers use telescopes? (viewed 5814 times)
  779. How did a transit of Venus provide astronomers with the first measurement of the Earth-Sun distance? (viewed 4853 times)
  780. Can the Sun be closer to the Earth than any planet is to Earth? (viewed 4180 times)
  781. Cosmologists say the expansion of the universe is accelerating, what is driving this? (viewed 3699 times)
  782. Can we hear sound on Titan? (viewed 3642 times)
  783. Does the direction of the moon's crescent change through the night? (viewed 3443 times)
  784. What do all the angles in a table for a planet's orbit mean? (viewed 3205 times)
  785. How do I maximize my chances of seeing shooting stars? (viewed 2515 times)
  786. Are exoplanets real? (viewed 2242 times)
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