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 2122577 times)
  2. What color is each planet? (viewed 894685 times)
  3. At what speed does the earth move around the sun? (viewed 569023 times)
  4. Is the Moon moving away from the Earth? When was this discovered? (viewed 548824 times)
  5. How far is each planet from Earth? (viewed 462479 times)
  6. When will Halley's Comet return? (viewed 416478 times)
  7. How many stars are there in our Galaxy (Milky Way)? (viewed 385119 times)
  8. How long does it take for the Sun's light to reach us? (viewed 384292 times)
  9. Why do the planets orbit the sun? (viewed 370918 times)
  10. What is the universe expanding into? (viewed 366109 times)
  11. How do you measure the distance between Earth and the Sun? (viewed 333778 times)
  12. Which planets have rings? (viewed 320560 times)
  13. Why do stars twinkle? (viewed 314835 times)
  14. Does the Moon rotate? Are there other moons that always keep one face toward their planet? (viewed 298056 times)
  15. How do I build a model rocket? (viewed 287199 times)
  16. What color is Venus? (viewed 271200 times)
  17. What is a white hole? (viewed 264875 times)
  18. Can you hear sounds in space? (viewed 250242 times)
  19. What is the life cycle of a star? (viewed 244575 times)
  20. What are the names of the earth, moon, sun, and solar system? (viewed 235945 times)
  21. What makes the Earth rotate? (viewed 227822 times)
  22. What is that ring (or rainbow) around the moon? (viewed 227058 times)
  23. What are shooting stars? (viewed 225895 times)
  24. What is the largest star? (viewed 221268 times)
  25. What do astronauts eat in space? Can they grow food? (viewed 207008 times)
  26. How do we know the age of the Universe and the Earth? (viewed 202509 times)
  27. Why do planets rotate? (viewed 202142 times)
  28. Can artificial gravity be created in space? (viewed 200976 times)
  29. Is the universe expanding faster than the speed of light? (viewed 197598 times)
  30. How does the location of sunrise and sunset change throughout the year? (viewed 187945 times)
  31. What are the different kinds of astronomers? (viewed 186353 times)
  32. Where did the name 'Earth' come from? (viewed 178580 times)
  33. How can we see the Milky Way if we are inside it? (viewed 177193 times)
  34. What would happen if we did not have a Moon? (viewed 173852 times)
  35. Why isn't the sky bright at night if the universe has so many stars? (viewed 173101 times)
  36. How many Earths fit into the Sun? (viewed 171868 times)
  37. Why is a day divided into 24 hours? (viewed 166576 times)
  38. How does the position of Moonrise and Moonset change? (viewed 162076 times)
  39. Who named the planets and who decides what to name them? (viewed 156097 times)
  40. Why are the Moon and Sun sometimes orange or red? (viewed 154073 times)
  41. When was the last time all 9 planets were aligned? (viewed 152153 times)
  42. Is Pluto a planet? (viewed 149593 times)
  43. Why do airplanes take longer to fly West than East? (viewed 149338 times)
  44. Is the distance from the Earth to the Sun changing? (viewed 148725 times)
  45. What is at the end of the Universe? (viewed 144803 times)
  46. How can I find the star I have "bought"? (viewed 141049 times)
  47. How much money is spent on space exploration? (viewed 140366 times)
  48. Why are there both high and low tides? (viewed 130205 times)
  49. How do astronauts take baths and use restrooms in space? (viewed 128979 times)
  50. What direction do planets rotate? (viewed 128180 times)
  51. Can we feel the Earth spin? (viewed 127649 times)
  52. What is the largest galaxy? (viewed 126845 times)
  53. Is the Sun expanding? Will it ever explode? (viewed 126718 times)
  54. How many known galaxies are there? (viewed 125635 times)
  55. What is a nova? (viewed 124867 times)
  56. Does your weight change between the poles and the equator? (viewed 122749 times)
  57. Do stars move in the sky? (viewed 121532 times)
  58. Can I buy a star? (viewed 116434 times)
  59. What are the advantages and disadvantages of using a telescope in space? (viewed 116043 times)
  60. Will the sun go supernova in six years and destroy Earth (as seen on Yahoo)? (viewed 113760 times)
  61. Why do all the planets orbit in the same plane? (viewed 113453 times)
  62. How are light and heavy elements formed? (viewed 111641 times)
  63. Are there telescopes that can see the flag and lunar rover on the Moon? (viewed 111342 times)
  64. What is the hottest time of day? (viewed 110943 times)
  65. Does the Sun have a scientific name? (viewed 109959 times)
  66. Why hasn't NASA gone back to the moon? (viewed 109770 times)
  67. How do stars move in the Galaxy? (viewed 109760 times)
  68. What happens when galaxies collide? (viewed 109410 times)
  69. Who first measured the speed of light? (viewed 108428 times)
  70. Why do planets have elliptical orbits? (viewed 107943 times)
  71. How do rockets work? (viewed 107768 times)
  72. What is the size of the Solar System? (viewed 107105 times)
  73. Will the magnetic field of the Earth reverse its direction in the future? Will this cause problems? (viewed 106624 times)
  74. What was there before the Big Bang and what is there outside of our universe? (viewed 106140 times)
  75. What would happen if an impact caused Earth to stop rotating? (viewed 105877 times)
  76. When is the next comet due to arrive? (viewed 105872 times)
  77. How much money do astronomers make? (viewed 105719 times)
  78. What is the physical difference between a star and a planet? (viewed 105244 times)
  79. How long does a solar eclipse last? (viewed 104023 times)
  80. What will happen to life on Earth when the Sun becomes a red giant? (viewed 103632 times)
  81. Do black holes die? If so how? (viewed 103508 times)
  82. Does evolution contradict the second law of thermodynamics? (viewed 102796 times)
  83. How do you calculate the lifetime of the Sun? (viewed 102607 times)
  84. How many constellations are there? (viewed 102509 times)
  85. What elements make up the Sun? (viewed 102078 times)
  86. What is the significance of the Tropic of Cancer, Tropic of Capricorn, Arctic Circle and Antarctic Circle? (viewed 101215 times)
  87. What is the observational difference between a star and a planet? (viewed 100224 times)
  88. Does the Sun rotate? (viewed 99943 times)
  89. What's the difference between astronomy and astrology? (viewed 99134 times)
  90. Does the Sun move around the Milky Way? (viewed 98945 times)
  91. What do astronauts do all day in the International Space Station? (viewed 98092 times)
  92. What is apparent magnitude? (viewed 95036 times)
  93. Which planet is most similar to Earth? (viewed 93775 times)
  94. Does gravity vary across the surface of the Earth? (viewed 93726 times)
  95. How many meteorites hit Earth each year? (viewed 93305 times)
  96. What would happen if the gravity on Earth was suddenly turned off? (viewed 93101 times)
  97. What are constellations used for? (viewed 90987 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 90840 times)
  99. How critical is the Earth-Sun distance in maintaining our average temperatures on Earth? (viewed 89939 times)
  100. How do astronomers use math in their jobs? (viewed 89820 times)
  101. Why do different stars appear with seasons? (viewed 89436 times)
  102. Why are stars and planets round? (viewed 88670 times)
  103. Where did the Universe come from? (viewed 88349 times)
  104. Is there a proof that Earth moves? (viewed 88219 times)
  105. What kind of schooling is necessary to become an astronomer? (viewed 87862 times)
  106. Does the Sun orbit the Earth as well as the Earth orbiting the Sun? (viewed 87582 times)
  107. Why is the Moon so bright? (viewed 87549 times)
  108. Why is the Universe flat and not spherical? (viewed 87530 times)
  109. Have astronomers discovered Earth's second moon? (viewed 87292 times)
  110. What makes the wind? (viewed 86897 times)
  111. What would happen if an asteroid 10 kilometers across hit the Earth? (viewed 86364 times)
  112. What is a singularity? (viewed 85776 times)
  113. How can a star burn with no oxygen? (viewed 84470 times)
  114. Where does the name "Milky Way" come from? (viewed 82022 times)
  115. Why does the Earth tilt back and forward once a year? (viewed 81865 times)
  116. What is the difference between a "star" and a "sun"? (viewed 81735 times)
  117. What are RA and DEC? (viewed 81557 times)
  118. What would happen if Earth had more than one moon? (viewed 80618 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 79997 times)
  120. Since Earth is spinning, why do we land in the same place when we jump or fall? (viewed 78370 times)
  121. What are the requirements for being a planet? (viewed 77952 times)
  122. What kind of rock is the moon made of? (viewed 77763 times)
  123. How many stars are born and die each day? (viewed 77266 times)
  124. Why aren't there any green stars? (viewed 77029 times)
  125. Did astronauts really go to the Moon, or is it a hoax? (viewed 76845 times)
  126. How are galaxies formed? (viewed 76491 times)
  127. Will the Sun become a black hole one day? (viewed 74358 times)
  128. How are black holes made? Could one be made close to us? (viewed 74281 times)
  129. What would happen if a supermassive black hole came close to the Earth? (viewed 73681 times)
  130. What is the density of a black hole? (viewed 73668 times)
  131. Who has landed on the moon? (viewed 73219 times)
  132. Why is the moon in a different place every night? (viewed 72180 times)
  133. What would you see from inside a black hole? (viewed 71608 times)
  134. Can moons have moons? (viewed 70967 times)
  135. Do most astronomers believe in God based on the available scientific evidence? (viewed 70953 times)
  136. What happens to a substance if its speed is more than the speed of light? (viewed 70372 times)
  137. Why can't you see stars during the day? (viewed 70316 times)
  138. How do rockets move in space? (viewed 70170 times)
  139. Can you fire a gun on the Moon? (viewed 69906 times)
  140. How do we weigh objects in space? (viewed 69860 times)
  141. How do astronomers measure the brightness of stars? (viewed 69853 times)
  142. How often does the Sun pass through a spiral arm in the Milky Way? (viewed 69674 times)
  143. How can the Universe expand faster than the speed of light during inflation? (viewed 69508 times)
  144. What would happen if you took off your helmet in space? (viewed 69379 times)
  145. What are some of the effects of solar flares on Earth? (viewed 69200 times)
  146. Does the Mediterranean sea have tides? (viewed 68868 times)
  147. How is astronomy impacted by trigonometry? (viewed 68420 times)
  148. When the Sun converts mass to energy, do the orbits of the planets change? (viewed 68360 times)
  149. How do we know the mass of the Earth and the Moon? (viewed 68082 times)
  150. Is it possible to measure the temperature of the Sun? (viewed 68036 times)
  151. How does the Sun compare to other stars? (viewed 67150 times)
  152. How do you measure a planet's mass? (viewed 66621 times)
  153. Why do stars change colour when they twinkle? (viewed 66613 times)
  154. What are the "dog days of summer"? (viewed 66438 times)
  155. How does the Moon stay "suspended" in the air? (viewed 66391 times)
  156. How are elements heavier than iron formed? (viewed 65831 times)
  157. What is the evidence supporting the nebula theory of Solar System formation? (viewed 65791 times)
  158. Why do we not have eclipses every month? (viewed 65318 times)
  159. What kinds of jobs do astronomers do? (viewed 65160 times)
  160. Does quantum entanglement imply faster than light communication? (viewed 64653 times)
  161. If the universe is infinite does that mean there is an infinite number of "me"s? (viewed 63844 times)
  162. What are black holes made of? (viewed 63548 times)
  163. What causes seasons? (viewed 63104 times)
  164. How did the stars get named? (viewed 62814 times)
  165. When can I see the Moon through the hole in the Pantheon? (viewed 62648 times)
  166. Why doesn't the earliest sunset occur on the shortest day of the year? (viewed 62645 times)
  167. Where does the name "Moon" come from? (viewed 62410 times)
  168. How did asteroids form and what is the difference between an asteroid and a comet? (viewed 62152 times)
  169. How fast is the Universe expanding? (viewed 62079 times)
  170. How long would it take the Earth to fall into the Sun? (viewed 61960 times)
  171. How do you measure the mass of a star? (viewed 61935 times)
  172. Where did the matter in the universe come from? (viewed 61840 times)
  173. Traveling at light speed, how long would it take to get to the nearest galaxy? (viewed 61709 times)
  174. What are Altitude and Azimuth? (viewed 61454 times)
  175. What's the best college for astronomy? (viewed 61435 times)
  176. Why do planets not twinkle? (viewed 61298 times)
  177. How does light pollution affect astronomers? (viewed 61144 times)
  178. Are there stars outside of galaxies? (viewed 61137 times)
  179. Why doesn't the length of each day change much around the solstices? (viewed 60830 times)
  180. What would happen to us if the sun went out for an hour? (viewed 60702 times)
  181. Where, in relation to the entire universe, is the Milky Way located? (viewed 60671 times)
  182. What is the mass of the Universe? (viewed 59900 times)
  183. What's the difference between dark matter and dark energy? (viewed 59093 times)
  184. How can I calculate the position or path of the Sun for a given time and location? (viewed 58475 times)
  185. Does the Moon rotate? (viewed 58450 times)
  186. Could there be life in the galaxies nearest to the Milky Way? (viewed 58313 times)
  187. Why does the Sun's apparent path through the sky change throughout the year? (viewed 58014 times)
  188. Why does the Earth have only one moon? (viewed 57907 times)
  189. Can any galaxies be seen with the naked eye? (viewed 57532 times)
  190. How does the parachute in a model rocket work? (viewed 56900 times)
  191. How does astronomy benefit humankind? (viewed 56842 times)
  192. What is the origin of spiral structure in galaxies? (viewed 56830 times)
  193. How close was the Moon to the Earth when it formed? (viewed 56643 times)
  194. How long does the supernova stage of a star last? (viewed 56318 times)
  195. What is the shape of the universe? (viewed 56185 times)
  196. What makes up most of the Universe? (viewed 56064 times)
  197. What is the largest structure in the universe? (viewed 55586 times)
  198. Why is looking out into space the same as looking back in time? (viewed 55301 times)
  199. Why isn't the summer solstice the hottest day of the year? (viewed 55066 times)
  200. What can we learn from the color of a star? (viewed 55024 times)
  201. Where are stars born? (viewed 54956 times)
  202. How do astronauts use math in their jobs? (viewed 54617 times)
  203. What is a star's "spectrum"? (viewed 54610 times)
  204. What is the size of a black hole? (viewed 54502 times)
  205. Are names given to black holes? (viewed 54435 times)
  206. Can you see satellites? (viewed 53963 times)
  207. Which constellation does our Sun belong to? (viewed 53730 times)
  208. If gravity is a "curvature of space" rather than a force, why do a ball and bullet follow different paths? (viewed 53569 times)
  209. How do we measure the size of the Moon and of the Sun? (viewed 53380 times)
  210. How do you calculate the azimuth and altitude of an object? (viewed 53358 times)
  211. How do the astronauts communicate in space if sound cannot travel in a vacuum? (viewed 52854 times)
  212. What happens to a bullet fired on the moon? (viewed 52785 times)
  213. Is the Moon seen as a crescent (and not a "boat") all over the world? Is the same phase of the moon visible from the Northern and Southern hemispheres? (viewed 52578 times)
  214. How can I find the distance to the Sun on any given day? (viewed 52574 times)
  215. Are aliens or UFOs real? (viewed 52520 times)
  216. Why do we see stars? (viewed 52398 times)
  217. What other careers involve Astronomy besides Astronomer? (viewed 52324 times)
  218. How can I measure the distance of a star? (viewed 52065 times)
  219. Is the speed of light constant? (viewed 51533 times)
  220. Which hemisphere has the best view of the Milky Way? (viewed 51437 times)
  221. What are some astronomy science fair projects? (viewed 51408 times)
  222. Are there any asteroids on a collision course with Earth? (viewed 51090 times)
  223. How long has there been water on Earth? (viewed 50817 times)
  224. Why is the sky blue and not blue & purple? (viewed 50470 times)
  225. What would happen if the Moon fell out of its orbit around Earth? (viewed 50302 times)
  226. Is time travel possible? (viewed 50271 times)
  227. Why is twilight short near the equator? (viewed 50162 times)
  228. Are meteorites hot or cold when they hit Earth? (viewed 50107 times)
  229. Who discovered each planet? (viewed 50069 times)
  230. Would your weight change as you go underground? (viewed 49981 times)
  231. Why does the Moon look big on the horizon? (viewed 49880 times)
  232. Can we look back far enough in time to see the Big Bang? (viewed 49802 times)
  233. What do a galaxy's colors mean? Are they its true colors? (viewed 49674 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 49593 times)
  235. Where did all the water in the universe come from? (viewed 49488 times)
  236. Why is it difficult to understand the expansion of the universe? (viewed 49189 times)
  237. What is a graviton? (viewed 48474 times)
  238. What is the difference between nutation and precession of the Earth? (viewed 48402 times)
  239. How is the time of sunrise calculated? (viewed 48323 times)
  240. What skills do astronomers need? (viewed 48204 times)
  241. If light has no mass, then what draws it into a black hole? (viewed 48170 times)
  242. What's the difference between astronomy and astrophysics? (viewed 48090 times)
  243. Are the planes of solar systems aligned with the plane of the Galaxy? (viewed 48043 times)
  244. How do we know what other planets (and stars, galaxies, etc.) are made of? (viewed 47074 times)
  245. What do I need to do to become an astronomer? (viewed 46574 times)
  246. Do dead stars still shine? (viewed 46226 times)
  247. Why do the size and brightness of the full moon change? (viewed 46088 times)
  248. How do gravitons escape black holes to tell the universe about their gravity? (viewed 45975 times)
  249. What is a wormhole? (viewed 45974 times)
  250. Do supermassive black holes cause galaxy rotation? (viewed 45898 times)
  251. How are black holes discovered? (viewed 45493 times)
  252. Where is the nearest black hole? (viewed 45281 times)
  253. Why does the Sun appear larger on the horizon than overhead? (viewed 45191 times)
  254. Will we get sucked into the black hole at the center of the Milky Way? (viewed 45143 times)
  255. The Moon slows the Earth's rotation, but how fast was it spinning billions of years ago? (viewed 44967 times)
  256. Can we find the place where the Big Bang happened? (viewed 44960 times)
  257. Why can't we see Venus at night when it is an inner planet? (viewed 44760 times)
  258. How do galaxies collide in an expanding universe? (viewed 44659 times)
  259. Is the Earth slowly getting larger? (viewed 44619 times)
  260. Why are there stars? (viewed 44570 times)
  261. Can I calculate the size of the Universe by converting light years to kilometres? (viewed 44553 times)
  262. Why are most months 30 or 31 days long? (viewed 44479 times)
  263. Why does Barnard 68 appear dark? (viewed 43964 times)
  264. Are Kuiper Belt Objects asteroids? Are large Kuiper Belt Objects planets? (viewed 42931 times)
  265. Why don't people walk upside-down on the bottom of the Earth? (viewed 42851 times)
  266. What is the best way to see the Milky Way? (viewed 42446 times)
  267. Was the Sun made in a supernova? (viewed 42326 times)
  268. What is the biggest crater recorded on Earth? (viewed 42280 times)
  269. Could the Universe have expanded faster than the speed of light at the Big Bang? (viewed 42278 times)
  270. Are there eclipses on other planets? (viewed 42261 times)
  271. Is there a "South Star"? (viewed 42139 times)
  272. Did life originate on Earth, or did it come from somewhere else? (viewed 42092 times)
  273. Why does the location of sunrise change? (viewed 42063 times)
  274. Has there been an experiment that measured speed faster than the speed of light in vacuum? (viewed 42034 times)
  275. How long could life on Earth survive if the Sun stopped shining? (viewed 42009 times)
  276. How much longer will the Earth last? (viewed 41893 times)
  277. How does Astronomy involve Chemistry? (viewed 41837 times)
  278. Why doesn't dark matter fall into a black hole? (viewed 41752 times)
  279. What is the difference between the "Doppler" redshift and the "gravitational" or "cosmological" redshift? (viewed 41721 times)
  280. How would the weather on Earth be different if it were a cube? (viewed 41576 times)
  281. Can the acceleration of the Universe be analogous to apparent acceleration in a airplane? (viewed 41403 times)
  282. What happens to spacetime inside a black hole? (viewed 41382 times)
  283. Can I buy land on the Moon? (viewed 41373 times)
  284. How much can the location of sunset differ from due West? (viewed 41232 times)
  285. Is the Moon hollow? (viewed 41096 times)
  286. Why does the Earth only see one side of the Moon? (viewed 41040 times)
  287. What happens when two black holes get too close? (viewed 41017 times)
  288. What's the biggest meteorite? (viewed 40739 times)
  289. What is time dilation? (viewed 40564 times)
  290. What color would Mars be if you were standing on it? (viewed 40485 times)
  291. What are the names of the three stars in Orion's belt? (viewed 40348 times)
  292. What is the most distant known galaxy? (viewed 40339 times)
  293. How can two moons of Saturn share the same orbit? (viewed 40003 times)
  294. What if the Earth rotated twice as fast? (viewed 39850 times)
  295. Could someone travel the universe in his or her own lifetime? (viewed 39613 times)
  296. Can terrestrial planets have rings? (viewed 39515 times)
  297. How long would it take for a mini-black hole to eat the Earth? (viewed 39443 times)
  298. Why do people draw stars with five points? (viewed 39260 times)
  299. How many Astronauts have been in space? (viewed 39226 times)
  300. What are "blue stragglers" in globular clusters? (viewed 39002 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 38967 times)
  302. How do we feel heat? (viewed 38921 times)
  303. Why do pictures of distant galaxies have higher resolution than those of nearby planets? (viewed 38812 times)
  304. What is the typical size of a visible shooting star? (viewed 38606 times)
  305. If a white dwarf is a "dead" star, why is it so hot? (viewed 38462 times)
  306. Why can we see the sun's image before sunrise and after sunset? (viewed 38461 times)
  307. How do we know that nuclear fusion is still going on in the Sun? (viewed 38351 times)
  308. Does Mt. Everest cast a shadow on the moon? (viewed 38262 times)
  309. Is the Great Wall the largest galaxy cluster? (viewed 38199 times)
  310. How fast does the Earth go at perihelion and aphelion? (viewed 38155 times)
  311. How does night and day work? (viewed 38083 times)
  312. Does the Sun have an iron surface? (viewed 37907 times)
  313. Can a person go into a black hole and come out alive? (viewed 37839 times)
  314. What is a dimension? (viewed 37805 times)
  315. Why are Saturn's rings flat? (viewed 37792 times)
  316. Can you see the future as you fall into a black hole? (viewed 37702 times)
  317. What is the speed of gravity? (viewed 37598 times)
  318. Can I communicate faster than light? (viewed 37588 times)
  319. On which days can I see the Moon in the evening / morning and why is this so? (viewed 37571 times)
  320. Do you think it's possible to maintain life on other planets? (viewed 37559 times)
  321. Where do planetary rings come from, and what are they made of? (viewed 37554 times)
  322. Is the Sun always up for exactly 12 hours at the equator? (viewed 37472 times)
  323. What is Earthrise over the Moon? (viewed 37336 times)
  324. What can I use for fuel in my homemade rocket? (viewed 37307 times)
  325. How big is the universe? (viewed 37257 times)
  326. Where is the supernova remnant that led to our solar system? (viewed 37214 times)
  327. Who (and when) discovered that the earth's axis is on a 23 degree tilt? (viewed 37210 times)
  328. Why do clocks turn in the opposite direction from the Earth and Moon? (viewed 37189 times)
  329. What is the approximate GPA needed in High School in Math and Science to be an astronomer? (viewed 37084 times)
  330. Are all stars the same? (viewed 37001 times)
  331. How do we determine the age of the universe? (viewed 36860 times)
  332. What companies or businesses can astronomers work for? (viewed 36745 times)
  333. Is there really a 10th planet? (viewed 36735 times)
  334. Why is sea water salty, and not lake water? (viewed 36616 times)
  335. What would happen to the Earth if an asteroid hit the Moon? (viewed 36344 times)
  336. How many stars can I see? (viewed 36285 times)
  337. Is there a beginning and an end to a galaxy's life? (viewed 36237 times)
  338. Does the Coriolis force determine which way my toilet drains? Does it affect black holes? (viewed 36236 times)
  339. How do I tell which planet is which? (viewed 36182 times)
  340. If the universe is 15 billion years old, how can it be larger than 15 billion light years across? (viewed 36121 times)
  341. How can the universe be "flat"? We're 3D! (viewed 35853 times)
  342. How do we know the Milky Way is a spiral galaxy? (viewed 35830 times)
  343. Do the Sun's or Earth's magnetic field reverse? (viewed 35722 times)
  344. How are photons created and destroyed? (viewed 35669 times)
  345. How do we define distance in an expanding universe? (viewed 35660 times)
  346. How can I find my age on another planet? (viewed 35299 times)
  347. Is Andromeda part of the Milky Way? Where can I find them in the sky? (viewed 35041 times)
  348. Why are there blue shifted galaxies? (viewed 34920 times)
  349. Why have star signs shifted by one constellation? (viewed 34870 times)
  350. Why do humans want to go in space? (viewed 34593 times)
  351. How does the brightness of a star depend on its distance from us? (viewed 34559 times)
  352. What was that really big falling star that I saw? (viewed 34510 times)
  353. What is the pattern to the distances between each planet and the sun? (viewed 34432 times)
  354. Can a lunar and a solar eclipse happen in the same month? When will this happen next? (viewed 34419 times)
  355. How are planets detected around other stars? (viewed 34415 times)
  356. What would happen if two stars collided? (viewed 34315 times)
  357. Who came up with the name "black hole"? (viewed 34269 times)
  358. What kind of eyepieces do I need to look at planets? (viewed 34186 times)
  359. What is the significance of the second focus of elliptical orbits of planets in our Solar System? (viewed 34172 times)
  360. How do astronauts communicate with their families from space? (viewed 34130 times)
  361. How can we estimate the number of Earth-like planets in the Galaxy? (viewed 34103 times)
  362. Is the Earth at the centre of the Universe? (viewed 34077 times)
  363. Will we ever stop having solar eclipses because of the moon's motion away from the Earth? (viewed 34069 times)
  364. When we look back to the Big Bang, why don't we see the universe as a tiny speck of matter? (viewed 34035 times)
  365. Is there a simple formula to calculate solar eclipse timings from any position on Earth? (viewed 34015 times)
  366. Why don't astronomers use everyday units to measure distances (what is an AU or a pc)? (viewed 33827 times)
  367. How is it that we see farther out in space (farther back in time) than in the past? (viewed 33647 times)
  368. Will the Moon be invisible in 500 million years? (viewed 33564 times)
  369. Are Earth and the Moon "twin planets"? (viewed 33328 times)
  370. How dangerous are the asteroids? (viewed 33238 times)
  371. Which American colleges teach astronomy? (viewed 33209 times)
  372. How do I become both an astronaut and an astronomer? (viewed 33173 times)
  373. Why is our solar system so different from all the others we've found? (viewed 33156 times)
  374. Why is Uranus tipped on its side? (viewed 33019 times)
  375. Can we colonize other planets? (viewed 32879 times)
  376. How hot is each one of the layers of the sun? (viewed 32860 times)
  377. Why can't a plane fly slowly and let the Earth pass underneath? (viewed 32560 times)
  378. How do sunrise and sunset times change with altitude? (viewed 32496 times)
  379. Can you describe a day on the job as an astronomer? (viewed 32191 times)
  380. What are quasars made of? (viewed 32178 times)
  381. How can I calculate distances between stars? (viewed 32143 times)
  382. Why do constellations look the same after several years even though all the stars are moving? (viewed 32115 times)
  383. Why do astronauts in space need to exercise? (viewed 31999 times)
  384. Why are there no craters on Earth? Did all the meteorites miss us? (viewed 31986 times)
  385. Why doesn't gravity change the speed of light? (viewed 31911 times)
  386. Is the universe really like an expanding balloon? (viewed 31872 times)
  387. Is it true that the Sun burns off a billion tons of gas every 5 seconds? (viewed 31852 times)
  388. Is the gravitational force exerted by the Earth on the Moon equal to the centripetal force acting on the Moon? (viewed 31623 times)
  389. What is dark matter? (viewed 31619 times)
  390. Is it possible to count the stars? (viewed 31612 times)
  391. Is the Local Group expanding along with the entire Universe? (viewed 31603 times)
  392. Is time travel possible using merging black holes? (viewed 31513 times)
  393. Can superheavy elements (such as Z=116 or 118) be formed in a supernova? Can we observe them? (viewed 31408 times)
  394. What is happening just around the black hole in the center of the Milky Way? (viewed 31391 times)
  395. Did the speed of light change over the history of the universe? (viewed 31257 times)
  396. How big a change in the Earth's orbit would be required to destroy all life? (viewed 31201 times)
  397. Can we see dead stars with the naked eye? (viewed 31185 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 31117 times)
  399. How do we measure distances to other stars? (viewed 31066 times)
  400. How do I make a scale model of the Solar System? (viewed 30911 times)
  401. What happens when an antimatter black hole collides with a matter blackhole? (viewed 30900 times)
  402. Are time machines possible? (viewed 30814 times)
  403. How many moles of stars are in the known universe? (viewed 30445 times)
  404. How are galaxy distances inferred from their recessional velocities? (viewed 30229 times)
  405. How can we tell what the interiors of planets are like? (viewed 30095 times)
  406. Why is the time between two successive full moons different from the lunar synodic month? (viewed 30036 times)
  407. What happens when you change the mass of a White Dwarf or Neutron Star? (viewed 30010 times)
  408. Is there any limitation to what a black hole can "suck" in? (viewed 29984 times)
  409. What is the farthest in space that we have gone? (viewed 29869 times)
  410. What do "homogeneity" and "isotropy" mean? (viewed 29853 times)
  411. Does the Milky Way spin counter-clockwise? If so, do all spiral galaxies spin in this direction and why? (viewed 29699 times)
  412. How can we know that there are other galaxies if we cannot leave ours? (viewed 29632 times)
  413. What would happen if a human were exposed to space without wearing a spacesuit? (viewed 29582 times)
  414. What's that dark spot on the Sun? (viewed 29577 times)
  415. Can astronauts produce water in space? (viewed 29533 times)
  416. What are the closest and/or brightest stars? (viewed 29527 times)
  417. How can I tell if the rock I found is a meteorite? (viewed 29498 times)
  418. Will the seasons change due to precession? (viewed 29492 times)
  419. How was the starting point for the Julian Date system chosen? (viewed 29411 times)
  420. Aren't jobs in astronomy scarce? (viewed 29374 times)
  421. How do we know if the universe will keep expanding forever? (viewed 29218 times)
  422. Do astronomers believe in astrology? (viewed 29217 times)
  423. Why does the SETI project search for radio signals? (viewed 29171 times)
  424. Did I see the Aurora Borealis as a child? (viewed 29153 times)
  425. How long does it take the Big Dipper to move in the sky? (viewed 29123 times)
  426. What are the facts about the Star of Bethlehem? (viewed 29062 times)
  427. Don't tachyons travel faster than light? (viewed 29040 times)
  428. Why do most moons orbit their planets at the equator? (viewed 29011 times)
  429. Do we see the same stars from above and below the equator? (viewed 28992 times)
  430. Could an astronaut or satellite fall into a black hole that we didn't know about? (viewed 28986 times)
  431. Why do we study black holes? (viewed 28983 times)
  432. When are there 5 Sundays in February? (viewed 28905 times)
  433. What are the atmospheres of Mars and Pluto like? (viewed 28874 times)
  434. Wouldn't the Big Bang theory be considered a hypothesis and not a theory? (viewed 28804 times)
  435. Can you use an infinite line of reflectors to send light to the edge of the Universe? (viewed 28501 times)
  436. Was I hit by a meteorite? (viewed 28493 times)
  437. Has anyone made a map of the Milky Way? (viewed 28488 times)
  438. Do you believe in UFOs? (viewed 28483 times)
  439. What colors are visible through an amateur telescope? (viewed 28432 times)
  440. Could you tell me about the life cycle of galaxies? (viewed 28424 times)
  441. What does the term "visible universe" mean? (viewed 28421 times)
  442. How are galaxies named? (viewed 28391 times)
  443. How can geometry be different in space? (viewed 28315 times)
  444. Why are the compositions of comets and asteroids different? (viewed 28042 times)
  445. What's the best thing about being an astronomer? (viewed 27820 times)
  446. How do asteroids, meteors and comets disappear? (viewed 27765 times)
  447. Why do so many of the world's UFO sightings happen in America? (viewed 27721 times)
  448. How much time do astronomers spend looking through telescopes? (viewed 27642 times)
  449. Will winter and summer constellations change due to abnormal warmth or cold on Earth? (viewed 27601 times)
  450. How do astronomers measure the radius of a star? (viewed 27570 times)
  451. Can two lunar eclipses occur in the same month? (viewed 27539 times)
  452. How will the two black holes that are going to collide affect Earth? (viewed 27433 times)
  453. How can we see galaxies if their stars are so faint? (viewed 27422 times)
  454. Have there been other Big Bangs before? (viewed 27408 times)
  455. How do I explain to my children why the Moon has phases? (viewed 27283 times)
  456. Can life exist on the recently discovered extrasolar planets? (viewed 27177 times)
  457. How are galaxies and solar systems similar? (viewed 27162 times)
  458. How close do you have to come to the Earth to be influenced by its gravity? (viewed 27110 times)
  459. What is the origin of the stellar classification system "OBAFGKM"? (viewed 27021 times)
  460. Is the Milky Way a collision of two galaxies? (viewed 27017 times)
  461. Is there a project I can do on black holes? (viewed 27007 times)
  462. How can we measure distances to more stars? (viewed 26906 times)
  463. Could you escape from a black hole if you were able to go faster than the speed of light? (viewed 26860 times)
  464. Do the magnitudes and colors of stars ever change? (viewed 26821 times)
  465. How do scientists slow light down? (viewed 26817 times)
  466. Is infinite temperature possible? (viewed 26620 times)
  467. How close does a supernova need to be to damage the Earth's environment? (viewed 26599 times)
  468. Do we know everything about the Sun? (viewed 26588 times)
  469. Do asteroids hit the sun? (viewed 26562 times)
  470. Can "tired light theory" explain the observed redshifts of galaxies? (viewed 26508 times)
  471. What supernova created the Crab nebula? (viewed 26481 times)
  472. Is it worthwhile to continue the search for extraterrestrial life? (viewed 26441 times)
  473. Can one star orbit another? (viewed 26413 times)
  474. Can double stars have planets? (viewed 26332 times)
  475. What causes gamma ray bursts? (viewed 26306 times)
  476. How far does a galaxy extend? (viewed 26270 times)
  477. Does the Moon look different in the northern and southern hemispheres? (viewed 26161 times)
  478. How do I polar align my telescope? (viewed 26095 times)
  479. What will happen to the Milky Way in the future? (viewed 26044 times)
  480. Can astronauts play musical instruments in space? (viewed 26019 times)
  481. Is there such a thing as hyperspace? (viewed 26000 times)
  482. What type of energy does a black hole have? (viewed 25975 times)
  483. Which way does the sun travel in the southern hemisphere? (viewed 25944 times)
  484. What happens to the material that has been sucked into a black hole? (viewed 25935 times)
  485. What is sidereal time? (viewed 25932 times)
  486. What is the farthest Northern Latitude in which the Magellanic Clouds can be seen? (viewed 25922 times)
  487. Why do the explosions of Type Ia supernovae have a more predictable spectrum than those of regular Type II supernovae? (viewed 25833 times)
  488. Is there oxygen in the atmospheres of other planets? (viewed 25818 times)
  489. What is a Cepheid variable? (viewed 25763 times)
  490. Which part of the sky did the famous 'wow' signal originate from? (viewed 25761 times)
  491. What is "nothing", from a scientific point of view? (viewed 25744 times)
  492. What's the object I saw that moved across the sky and then got very bright? (viewed 25695 times)
  493. How will a change in the speed of light affect the evolution of the Universe? (viewed 25695 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 25688 times)
  495. Can a human give birth in space? (viewed 25670 times)
  496. How different would the night sky have looked in 40,000 B.C.? (viewed 25582 times)
  497. Is there sound coming from the Sun? (viewed 25577 times)
  498. How do we know what parameters to use when simulating the collision of the Milky Way and Andromeda? (viewed 25449 times)
  499. Why do we assume that the universe is homogeneous? (viewed 25431 times)
  500. When did people discover that the Sun is a star? (viewed 25376 times)
  501. How do we know that sunspots are associated with the Sun's magnetic field? (viewed 25356 times)
  502. Why is the shadow on the Moon the shape it is? (viewed 25343 times)
  503. When unmanned spacecraft accelerate in space, what causes them to slow down? (viewed 25268 times)
  504. Are planetary nebulae the result of supernovae? (viewed 25257 times)
  505. If we invented special suits could we ever go to the sun? (viewed 25238 times)
  506. Are there any dark stars or dark galaxies made of dark matter? (viewed 25233 times)
  507. What calculations go into predicting eclipses? (viewed 25176 times)
  508. What is the difference between homogeneity and isotropy? (viewed 25140 times)
  509. Was Stonehenge built to mark solar phenomena? (viewed 25118 times)
  510. What is our galaxy's halo made of, and how was it formed? (viewed 25103 times)
  511. Is there a list of the sizes of different kinds of stars? (viewed 25065 times)
  512. What process would bring about a quark star? (viewed 25027 times)
  513. Can I see a quasar? (viewed 24988 times)
  514. What's so exciting about the new planet around 55 Cancri? (viewed 24940 times)
  515. How many sunspots can the Sun have at once? (viewed 24916 times)
  516. Did a giant impact cause the Dark Ages? (viewed 24897 times)
  517. How are asteroid compositions and classifications determined? (viewed 24889 times)
  518. What is a Dyson Sphere? (viewed 24886 times)
  519. Have gravitational waves been proven to exist? (viewed 24843 times)
  520. Can I see details on Venus? (viewed 24833 times)
  521. Can any comparison be made between spiral galaxies and hurricanes? (viewed 24790 times)
  522. Why are there more maria on the near side of the Moon? (viewed 24636 times)
  523. What equipment do I need for astrophotography? (viewed 24572 times)
  524. Why are there active volcanos on Io? (viewed 24566 times)
  525. Does Cerenkov radiation travel faster than light? (viewed 24537 times)
  526. How is it proved that the Universe is expanding? (viewed 24523 times)
  527. What happened to all the black holes that were around in the early universe? (viewed 24520 times)
  528. Is there any possibility that the Solar System or the Universe is in a black hole? (viewed 24455 times)
  529. What happened to the girl who named Pluto? (viewed 24422 times)
  530. Would the biggest airplanes cause tsunamis if they crashed? (viewed 24389 times)
  531. Why are telescopes kept in cold conditions? (viewed 24374 times)
  532. If clocks run slow in a gravitational field, how can we know the true age of the Solar System and Universe? (viewed 24251 times)
  533. How big was the Sun when it first "fired up"? (viewed 24228 times)
  534. How can we compare dark matter and dark energy? (viewed 24208 times)
  535. If the Universe was infinitely dense at the Big Bang, why didn't time stand still? (viewed 24141 times)
  536. What caused Shoemaker-Levy 9 to split up? (viewed 24106 times)
  537. Could we send a space mission to a comet? (viewed 24079 times)
  538. Why do photos of space taken from space never show any stars? (viewed 24071 times)
  539. How long do supernova remnants last? (viewed 24071 times)
  540. How do solar flares affect airline pilots? (viewed 23976 times)
  541. How big is the Hubble Ultra Deep Field image? (viewed 23952 times)
  542. Why doesn't light from distant galaxies reach us instantaneously? (viewed 23951 times)
  543. Could we be seeing dead stars? (viewed 23926 times)
  544. How are sunspots formed? (viewed 23902 times)
  545. Can you give me advice on buying a telescope? (viewed 23818 times)
  546. Could a different theory of gravity explain the dark matter mystery? (viewed 23771 times)
  547. How does the Earth compare in size to the entire universe at the present epoch? (viewed 23768 times)
  548. As the universe expands, why don't galaxies get stretched out? (viewed 23721 times)
  549. Why doesn't NASA build rotating spacecraft to simulate gravity? (viewed 23674 times)
  550. How many comets are currently orbiting our sun? (viewed 23660 times)
  551. Where does the kinetic energy of infalling bodies come from? (viewed 23603 times)
  552. Can I build an instrument to measure the size of the Sun and of the Moon? (viewed 23596 times)
  553. Why is the Hubble Space Telescope in space? (viewed 23590 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 23472 times)
  556. How powerful are quasars? (viewed 23419 times)
  557. Did I really hear a meteor? (viewed 23394 times)
  558. Why is it important to study meteorites? (viewed 23347 times)
  559. Would extraterrestrial civilizations know that there is life on Earth? (viewed 23347 times)
  560. How is the Cepheid yardstick validated? (viewed 23293 times)
  561. Why are telescopes located in remote places? (viewed 23227 times)
  562. Do unmanned spacecraft like Voyager travel in straight lines? (viewed 23183 times)
  563. Did time go slower just after the Big Bang? (viewed 23132 times)
  564. How can I contribute to science as an amateur astronomer? (viewed 23122 times)
  565. What would happen if there was a collision between two white dwarfs? (viewed 23118 times)
  566. Are there any new craters on the moon? (viewed 23110 times)
  567. Can supernovae hinder the formation of life in galaxies? (viewed 23104 times)
  568. Are the asteroids the remains of a planet which broke apart? (viewed 23083 times)
  569. Why are stars of different masses? (viewed 23080 times)
  570. Do the Earth's magnetic poles ever change places? (viewed 23063 times)
  571. Do galaxies orbit around anything? (viewed 23053 times)
  572. Do similar laws of physics throughout the Universe imply that all life must be like life on Earth? (viewed 23001 times)
  573. How do planets capture satellites? (viewed 22994 times)
  574. How do I become an astronomical artist? (viewed 22979 times)
  575. What kind of instruments are used to detect extrasolar planets? (viewed 22943 times)
  576. How do unmanned space probes avoid running into things? (viewed 22913 times)
  577. How could galaxies have gotten so far away in only 15 billion years? (viewed 22868 times)
  578. Could there have been multiple Big Bangs at different places in the universe? (viewed 22823 times)
  579. How are astronomy and poetry linked? (viewed 22786 times)
  580. Why can't relative velocities add up to more than the speed of light? (viewed 22777 times)
  581. What kind of telescope should I use for astrophotography? (viewed 22735 times)
  582. Could dark energy come from matter anti-matter pairs forming spontaneously and then annihilating? (viewed 22654 times)
  583. Why is NASA shutting down the Hubble Space Telescope? (viewed 22620 times)
  584. Can I listen to the SETI@home radio signal? (viewed 22603 times)
  585. How can you tell if a crescent moon is preceding or following a new-moon phase? (viewed 22572 times)
  586. Does the Sun have any heavy elements? (viewed 22506 times)
  587. Are the properties of extrasolar planets known? (viewed 22500 times)
  588. What class of spiral galaxy is the Milky Way? (viewed 22358 times)
  589. Will we discover an 11th planet? What would it be called? (viewed 22345 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 22343 times)
  591. Can the theory of formation of the solar system explain all the observables? (viewed 22309 times)
  592. What month was it when Odysseus saw Orion in 1000BC? (viewed 22277 times)
  593. How do astronomers observe the Sun's interior? (viewed 22081 times)
  594. Why does one side of Mars look more catastrophic than the other? (viewed 22004 times)
  595. What makes a satellite geosyncronise itself with Earth's orbit? (viewed 21999 times)
  596. Why does the apparent density of galaxies drop off at larger distances? (viewed 21964 times)
  597. Would a planet near the galactic center have a brighter night sky? (viewed 21897 times)
  598. Is it possible for amateurs to do optical interferometry? (viewed 21843 times)
  599. Where was the water in the big bang? (viewed 21767 times)
  600. Could we send a manned mission to the outer planets? (viewed 21761 times)
  601. What is the solar cycle? (viewed 21723 times)
  602. Do stars' orbits in galaxies obey Kepler's Laws? (viewed 21682 times)
  603. Can other terrestrial moons be (or have been) stable? (viewed 21614 times)
  604. Why was the Platonic year named after Plato? (viewed 21565 times)
  605. How are supernovae discovered? (viewed 21531 times)
  606. What would the Big Crunch look like to an observer on Earth? (viewed 21471 times)
  607. Can a black hole come back to the visual universe through a "little bang"? (viewed 21459 times)
  608. How can water be chemically trapped in rocks? (viewed 21442 times)
  609. Why are accretion disks flat? (viewed 21410 times)
  610. Why do spacecraft need heat shields coming back to Earth but not leaving? (viewed 21399 times)
  611. Does inflation allow for an infinite number of universes? (viewed 21385 times)
  612. What is meant by "stopping down a telescope"? (viewed 21355 times)
  613. Could our position in the universe affect our perceptions of the expansion? (viewed 21343 times)
  614. Why doesn't the hydrogen on Jupiter explode? (viewed 21262 times)
  615. Did I find a rock that came from the Moon? (viewed 21047 times)
  616. Have astronomers observed any phenomena that could be produced by extraterrestrial civilizations? (viewed 21046 times)
  617. How can the Sun have such a strong gravitational field if it's made of gasses? (viewed 21035 times)
  618. What is the SU(3) quark model? (viewed 21001 times)
  619. Can gravitational lensing from intervening galaxies cause the observed ripples in the Cosmic Microwave Background? (viewed 20987 times)
  620. Does a photon observe other photons moving past it at the speed of light? (viewed 20980 times)
  621. Will I be able to see the shadow of the Moon streaking towards me in a total solar eclipse? (viewed 20738 times)
  622. What's new with the Big Bang? (viewed 20719 times)
  623. Could photons be dark matter? (viewed 20624 times)
  624. Is it possible to build a cheap device to measure declination? (viewed 20581 times)
  625. How can we find galaxies behind the Milky Way? (viewed 20579 times)
  626. Why can we have solar eclipses? (viewed 20564 times)
  627. If comets are boiling away, why are there any left? (viewed 20536 times)
  628. How fast do particles travel in space? (viewed 20516 times)
  629. Why search for only Earth-like life on other planets? (viewed 20507 times)
  630. Why do some eclipses take longer than others? (viewed 20464 times)
  631. Where can I find information on the moons of other planets? (viewed 20443 times)
  632. Why is the WMAP picture of the CMB an ellipse? (viewed 20404 times)
  633. How much power is contained in a beam of light? (viewed 20361 times)
  634. Why is pressure broadening greater in low mass stars than in high mass stars? (viewed 20255 times)
  635. What would an "open geometry" for the universe look like? (viewed 20161 times)
  636. What are the boundaries of the constellations? (viewed 20133 times)
  637. Did the Sumerians measure precession? (viewed 20083 times)
  638. What kinds of star clusters are there? (viewed 20039 times)
  639. Why is the Cosmic Microwave Background not absorbed by interstellar hydrogen? (viewed 20000 times)
  640. How do astronomers come up with their facts? (viewed 19992 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. Can planets collide with one another? (viewed 19912 times)
  644. Why don't astronauts sublimate in space? (viewed 19911 times)
  645. How do photons from distant objects maintain enough energy to reach us? (viewed 19878 times)
  646. Do constellations looks the same from space? (viewed 19821 times)
  647. Can HST see the Oort cloud? (viewed 19817 times)
  648. Do electrons age? (viewed 19770 times)
  649. How did Mars get so dusty? (viewed 19680 times)
  650. Can the Space Shuttle abort and return to Earth before reaching orbit? (viewed 19670 times)
  651. Can we make a movie of the Milky Way galaxy's rotation? (viewed 19663 times)
  652. How long is twilight on the Moon? (viewed 19561 times)
  653. What are collections of galaxies called? (viewed 19544 times)
  654. Does the shuttle worry about space junk? (viewed 19488 times)
  655. How does melting a material reset its radioactive clock? (viewed 19453 times)
  656. Will astronauts ever be able to go ice-skating on Europa? (viewed 19434 times)
  657. Why do supernova remnants look like rings rather than spheres? (viewed 19412 times)
  658. How do you classify galaxies? (viewed 19358 times)
  659. Where can I see Newton's original reflecting telescope? (viewed 19358 times)
  660. Why don't all neutron stars become pulsars? (viewed 19321 times)
  661. Why doesn't SETI concentrate its observations to the nearby stars and the solar systems that we are discovering? (viewed 19238 times)
  662. How can we understand the meaning of large numbers like "a million million?" (viewed 19227 times)
  663. What is the best time of the year to see eclipses? (viewed 19226 times)
  664. Will the next generation telescope OWL be able to detect an Earth like extrasolar planet? (viewed 19142 times)
  665. What causes a particle to decay? (viewed 19108 times)
  666. How can I nominate myself for a Nobel Prize in Physics? (viewed 19039 times)
  667. How long has humanity known that we live in a galaxy similar to others in the Universe? (viewed 18995 times)
  668. Will the Leonid meteor shower go away? (viewed 18983 times)
  669. What are "curled" dimensions? (viewed 18867 times)
  670. Is light of different colors affected differently by gravity? (viewed 18828 times)
  671. What was that eclipse I saw in the sky? (viewed 18729 times)
  672. How does the color index of a star relate to its actual color? (viewed 18716 times)
  673. How does interferometry work? (viewed 18704 times)
  674. Why is it called astronomy when all the other sciences end in -ology? (viewed 18676 times)
  675. How do distant galaxies differ from those nearby? (viewed 18625 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 18588 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 18557 times)
  680. Can astronomers observe anything when the moon is full? (viewed 18495 times)
  681. Wouldn't the vast distances of space distort SETI signals into unintelligeble forms? (viewed 18490 times)
  682. Are black holes spherical? (viewed 18462 times)
  683. What would happen if you went back in time and killed your grandmother? (viewed 18461 times)
  684. What kind of interference must astronomers contend with when observing? (viewed 18449 times)
  685. If photons have zero mass, why do they feel the effects of gravity? (viewed 18381 times)
  686. How can I watch the Perseid meteor shower? (viewed 18356 times)
  687. Why will fusion wait until hydrogen is gone before starting to fuse heavier atoms? (viewed 18348 times)
  688. Do we really observe the edges of galaxies at different epochs? (viewed 18316 times)
  689. What do stellar classifications mean? (viewed 18297 times)
  690. Can you tell me the characteristics of W, R, N and S type stars? (viewed 18292 times)
  691. How are astronauts trained for weightlessness? (viewed 18217 times)
  692. What is the three-body problem? (viewed 18145 times)
  693. Why aren't accretion disks around giant stars as hot as accretion disks around black holes? (viewed 18087 times)
  694. If the universe is "bounded" today, could it one day become "unbounded"? (viewed 17959 times)
  695. Will the diameter of a cluster of galaxies change with redshift? (viewed 17923 times)
  696. Is cosmic expansion happening on microscopic scales? (viewed 17761 times)
  697. How can I find out if the new moon has been sighted? (viewed 17639 times)
  698. Could neutrinos be dark matter? (viewed 17448 times)
  699. Do we have to worry about relativity when studying galactic objects? (viewed 17436 times)
  700. What kinds of cancer research have been done in space? (viewed 17264 times)
  701. How does a star take mass from another star? (viewed 17165 times)
  702. When measuring the expansion of the universe, do astronomers consider that they're seeing how galaxies moved long ago, not today? (viewed 17061 times)
  703. Does lunar gardening really work? (viewed 17033 times)
  704. Could the Universe's dark matter be made up of black holes? (viewed 16991 times)
  705. How can you tell the difference between single and multiple extrasolar planets? (viewed 16964 times)
  706. How do supernovae show us that the Universe's expansion is accelerating? (viewed 16896 times)
  707. What is Hot Dark Matter theory? (viewed 16893 times)
  708. Is it a coincidence that we can have total solar eclipses? Are there other planets which also have them? (viewed 16507 times)
  709. Is the green flash real? (viewed 16427 times)
  710. How does libration allow us to see more than 50% of the Moon? (viewed 16394 times)
  711. How can observations of the distant universe prove that the expansion is accelerating *now*? (viewed 16365 times)
  712. How do we know the density of some extrasolar planets? (viewed 16324 times)
  713. What is the photoelectric effect? Why can't multiple low-frequency photons free an electron? (viewed 16294 times)
  714. Is light blueshifted when it is gravitationally lensed? (viewed 16240 times)
  715. Do binary or triple star systems form together? (viewed 16184 times)
  716. No matter how fast the universe is expanding, shouldn't gravity eventually make it recollapse? (viewed 16156 times)
  717. What happens to the helium formed in the sun? (viewed 16004 times)
  718. What percent of the time can astronomers observe without interference from the Moon? (viewed 15942 times)
  719. What do meteorites tell us about life on other planets? (viewed 15881 times)
  720. Why is it easier to see a star if you look slightly to the side? (viewed 15787 times)
  721. Could matter-anti-matter repulsion power the expansion of the universe? (viewed 15665 times)
  722. If the sun went out and our atmosphere froze solid, what color would it be? (viewed 15553 times)
  723. Can we prove that the Moon isn't hollow? (viewed 15550 times)
  724. Why doesn't the ammonia and methane in Jupiter's atmosphere sink into the core? (viewed 15428 times)
  725. Are there any 'lonely galaxies'? (viewed 15273 times)
  726. How do we detect incoming meteorites? (viewed 15188 times)
  727. What was different on Mars in the past to allow liquid water to be present? (viewed 15080 times)
  728. When will Hale-Bopp return? (viewed 14955 times)
  729. Why don't skydivers burn up like meteors? (viewed 14884 times)
  730. Has anyone ever seen a star "turn on"? (viewed 14694 times)
  731. During close approaches, can Mars appear in our sky as large as the Moon? (viewed 14573 times)
  732. How has light from 13 billion years ago not passed us by? (viewed 14395 times)
  733. How are planets affected by the Hot Ionised Medium? (viewed 14359 times)
  734. Why are craters round? (viewed 14260 times)
  735. Can the sun rise from the west on Mars? (viewed 13953 times)
  736. Why was Mir burnt up in the atmosphere? (viewed 13888 times)
  737. What are the largest radio wavelengths observed from radio sources in the sky? (viewed 13879 times)
  738. How can we discern different galaxies/clusters along the same line of sight? (viewed 13788 times)
  739. What is the relationship between the width of a star trail on a photo and the star's intensity? (viewed 13354 times)
  740. What time is sunrise/sunset or moonrise/moonset at my location? (viewed 13171 times)
  741. Can we harvest H & O from space to make water? (viewed 12970 times)
  742. What is between the Oort cloud and the closest star? (viewed 12571 times)
  743. Why does Titan, in spite of being smaller than Mars, have an atmosphere more dense than Earth's? (viewed 12532 times)
  744. Could a planetary system survive if its star merged with another, or if its star went supernova? (viewed 11705 times)
  745. Are there solar tides? (viewed 11681 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 11626 times)
  747. Does weightlessness affect hunger? (viewed 11549 times)
  748. Is Earth-moon tidal friction causing global warming? (viewed 11139 times)
  749. Do planets radiate noise? (viewed 10883 times)
  750. What happens to the Earth as the moon gets farther away and will it ever go away entirely? (viewed 10828 times)
  751. Is the moon spherical? (viewed 10775 times)
  752. Is dark energy affected by black holes? (viewed 10551 times)
  753. What would happen if a nuclear-powered shuttle exploded? (viewed 10461 times)
  754. Why is the Moon higher in the sky in winter and lower in the summer? (viewed 10056 times)
  755. Where are the protons and electrons in a Neutron Star? (viewed 9873 times)
  756. Do more meteorites fall at low latitudes? (viewed 9512 times)
  757. Did the Moon or planets form in a manner similar to that of Earth? (viewed 9509 times)
  758. Wait, I'm still confused why information can't travel faster than the speed of light. (viewed 9485 times)
  759. Is the Moon always visible during winter on the North Pole? (viewed 9408 times)
  760. What are the possible ends of the universe? (viewed 9377 times)
  761. Will Comet Elenin (C/2010 X1) affect the Earth on its close approach in Fall 2011? (viewed 9366 times)
  762. Will the Pioneer and Voyager probes ever leave the Milky Way? (viewed 9275 times)
  763. Is it sensible to consider terraforming Mars? (viewed 9263 times)
  764. If there are infinity universes, will every thing that is possible happen? (viewed 9239 times)
  765. What color are meteors? (viewed 8835 times)
  766. Where is everybody? (viewed 8498 times)
  767. Why does Mars have a dusty atmosphere? (viewed 8029 times)
  768. The naming of Mars (viewed 7924 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 7847 times)
  771. Is the reddish dust of Mars biogenic? (viewed 7684 times)
  772. Where is the Spitzer Space Telescope? (viewed 7124 times)
  773. When will humans travel to Mars and revisit the Moon? (viewed 7035 times)
  774. Does the particles involved in a star's final core collapse travel faster than the speed of light? (viewed 6378 times)
  775. How likely is it for a planet to transit its star? (viewed 6155 times)
  776. When is the best time to observe zodiacal light? (viewed 6152 times)
  777. What causes the aurora? (viewed 6002 times)
  778. Why do astronomers use telescopes? (viewed 5941 times)
  779. How did a transit of Venus provide astronomers with the first measurement of the Earth-Sun distance? (viewed 4947 times)
  780. Can the Sun be closer to the Earth than any planet is to Earth? (viewed 4320 times)
  781. Cosmologists say the expansion of the universe is accelerating, what is driving this? (viewed 3781 times)
  782. Can we hear sound on Titan? (viewed 3684 times)
  783. Does the direction of the moon's crescent change through the night? (viewed 3491 times)
  784. What do all the angles in a table for a planet's orbit mean? (viewed 3262 times)
  785. How do I maximize my chances of seeing shooting stars? (viewed 2618 times)
  786. Are exoplanets real? (viewed 2309 times)
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