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 2128729 times)
  2. What color is each planet? (viewed 903868 times)
  3. At what speed does the earth move around the sun? (viewed 578451 times)
  4. Is the Moon moving away from the Earth? When was this discovered? (viewed 557249 times)
  5. How far is each planet from Earth? (viewed 466163 times)
  6. When will Halley's Comet return? (viewed 420638 times)
  7. How long does it take for the Sun's light to reach us? (viewed 387599 times)
  8. How many stars are there in our Galaxy (Milky Way)? (viewed 387194 times)
  9. Why do the planets orbit the sun? (viewed 375223 times)
  10. What is the universe expanding into? (viewed 368936 times)
  11. How do you measure the distance between Earth and the Sun? (viewed 338725 times)
  12. Which planets have rings? (viewed 321831 times)
  13. Why do stars twinkle? (viewed 317959 times)
  14. Does the Moon rotate? Are there other moons that always keep one face toward their planet? (viewed 304046 times)
  15. How do I build a model rocket? (viewed 289440 times)
  16. What color is Venus? (viewed 272618 times)
  17. What is a white hole? (viewed 266390 times)
  18. Can you hear sounds in space? (viewed 257576 times)
  19. What is the life cycle of a star? (viewed 245431 times)
  20. What are the names of the earth, moon, sun, and solar system? (viewed 237575 times)
  21. What makes the Earth rotate? (viewed 230850 times)
  22. What is that ring (or rainbow) around the moon? (viewed 229585 times)
  23. What are shooting stars? (viewed 228143 times)
  24. What is the largest star? (viewed 221668 times)
  25. What do astronauts eat in space? Can they grow food? (viewed 209231 times)
  26. What are the different kinds of astronomers? (viewed 209193 times)
  27. How do we know the age of the Universe and the Earth? (viewed 208795 times)
  28. Can artificial gravity be created in space? (viewed 205618 times)
  29. Why do planets rotate? (viewed 205439 times)
  30. Is the universe expanding faster than the speed of light? (viewed 200647 times)
  31. How does the location of sunrise and sunset change throughout the year? (viewed 192176 times)
  32. How can we see the Milky Way if we are inside it? (viewed 180772 times)
  33. Where did the name 'Earth' come from? (viewed 179686 times)
  34. What would happen if we did not have a Moon? (viewed 175059 times)
  35. Why isn't the sky bright at night if the universe has so many stars? (viewed 173995 times)
  36. How many Earths fit into the Sun? (viewed 172371 times)
  37. Why is a day divided into 24 hours? (viewed 170010 times)
  38. How does the position of Moonrise and Moonset change? (viewed 165884 times)
  39. Who named the planets and who decides what to name them? (viewed 158307 times)
  40. Why are the Moon and Sun sometimes orange or red? (viewed 156559 times)
  41. When was the last time all 9 planets were aligned? (viewed 154787 times)
  42. Why do airplanes take longer to fly West than East? (viewed 153753 times)
  43. Is Pluto a planet? (viewed 150312 times)
  44. Is the distance from the Earth to the Sun changing? (viewed 149757 times)
  45. What is at the end of the Universe? (viewed 146485 times)
  46. How can I find the star I have "bought"? (viewed 143524 times)
  47. How much money is spent on space exploration? (viewed 141802 times)
  48. Why are there both high and low tides? (viewed 130734 times)
  49. What is a nova? (viewed 130606 times)
  50. How do astronauts take baths and use restrooms in space? (viewed 130544 times)
  51. Can we feel the Earth spin? (viewed 129611 times)
  52. What direction do planets rotate? (viewed 129399 times)
  53. Is the Sun expanding? Will it ever explode? (viewed 127791 times)
  54. What is the largest galaxy? (viewed 127151 times)
  55. Does your weight change between the poles and the equator? (viewed 126941 times)
  56. How many known galaxies are there? (viewed 125949 times)
  57. Do stars move in the sky? (viewed 122815 times)
  58. What are the advantages and disadvantages of using a telescope in space? (viewed 118100 times)
  59. Can I buy a star? (viewed 117211 times)
  60. Why do all the planets orbit in the same plane? (viewed 116054 times)
  61. Will the sun go supernova in six years and destroy Earth (as seen on Yahoo)? (viewed 114659 times)
  62. How are light and heavy elements formed? (viewed 113472 times)
  63. Are there telescopes that can see the flag and lunar rover on the Moon? (viewed 112612 times)
  64. Does the Sun have a scientific name? (viewed 111476 times)
  65. What is the hottest time of day? (viewed 111430 times)
  66. Why hasn't NASA gone back to the moon? (viewed 111284 times)
  67. How do stars move in the Galaxy? (viewed 110707 times)
  68. What happens when galaxies collide? (viewed 110264 times)
  69. Who first measured the speed of light? (viewed 110212 times)
  70. Why do planets have elliptical orbits? (viewed 109909 times)
  71. How do rockets work? (viewed 108901 times)
  72. What is the physical difference between a star and a planet? (viewed 108541 times)
  73. What is the size of the Solar System? (viewed 107920 times)
  74. What would happen if an impact caused Earth to stop rotating? (viewed 106985 times)
  75. Will the magnetic field of the Earth reverse its direction in the future? Will this cause problems? (viewed 106981 times)
  76. How much money do astronomers make? (viewed 106700 times)
  77. What was there before the Big Bang and what is there outside of our universe? (viewed 106631 times)
  78. When is the next comet due to arrive? (viewed 106256 times)
  79. What is the significance of the Tropic of Cancer, Tropic of Capricorn, Arctic Circle and Antarctic Circle? (viewed 105277 times)
  80. Does evolution contradict the second law of thermodynamics? (viewed 104932 times)
  81. What will happen to life on Earth when the Sun becomes a red giant? (viewed 104807 times)
  82. How long does a solar eclipse last? (viewed 104491 times)
  83. Do black holes die? If so how? (viewed 104178 times)
  84. How do you calculate the lifetime of the Sun? (viewed 103869 times)
  85. What elements make up the Sun? (viewed 103269 times)
  86. How many constellations are there? (viewed 103140 times)
  87. What is the observational difference between a star and a planet? (viewed 101458 times)
  88. Does the Sun rotate? (viewed 100505 times)
  89. What's the difference between astronomy and astrology? (viewed 100407 times)
  90. What do astronauts do all day in the International Space Station? (viewed 100201 times)
  91. Does the Sun move around the Milky Way? (viewed 99392 times)
  92. Does gravity vary across the surface of the Earth? (viewed 96360 times)
  93. What is apparent magnitude? (viewed 95783 times)
  94. What would happen if the gravity on Earth was suddenly turned off? (viewed 95497 times)
  95. Which planet is most similar to Earth? (viewed 94601 times)
  96. How many meteorites hit Earth each year? (viewed 94594 times)
  97. What are constellations used for? (viewed 92879 times)
  98. Why do different stars appear with seasons? (viewed 91569 times)
  99. If Mars is only about 35-60 million miles away at close approach, why does it take 6-8 months to get there? (viewed 91518 times)
  100. How do astronomers use math in their jobs? (viewed 90980 times)
  101. What kind of schooling is necessary to become an astronomer? (viewed 90757 times)
  102. How critical is the Earth-Sun distance in maintaining our average temperatures on Earth? (viewed 90500 times)
  103. Is there a proof that Earth moves? (viewed 89596 times)
  104. Why are stars and planets round? (viewed 89433 times)
  105. Where did the Universe come from? (viewed 89314 times)
  106. Does the Sun orbit the Earth as well as the Earth orbiting the Sun? (viewed 88606 times)
  107. Why is the Universe flat and not spherical? (viewed 88524 times)
  108. Why is the Moon so bright? (viewed 88482 times)
  109. What makes the wind? (viewed 87916 times)
  110. Have astronomers discovered Earth's second moon? (viewed 87603 times)
  111. What would happen if an asteroid 10 kilometers across hit the Earth? (viewed 87090 times)
  112. What is a singularity? (viewed 86522 times)
  113. How can a star burn with no oxygen? (viewed 86146 times)
  114. What is the difference between a "star" and a "sun"? (viewed 84701 times)
  115. Why does the Earth tilt back and forward once a year? (viewed 82664 times)
  116. Where does the name "Milky Way" come from? (viewed 82637 times)
  117. What are RA and DEC? (viewed 82535 times)
  118. What would happen if Earth had more than one moon? (viewed 81036 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 80771 times)
  120. What are the requirements for being a planet? (viewed 79838 times)
  121. Since Earth is spinning, why do we land in the same place when we jump or fall? (viewed 79792 times)
  122. How many stars are born and die each day? (viewed 78460 times)
  123. What kind of rock is the moon made of? (viewed 78079 times)
  124. Why aren't there any green stars? (viewed 77790 times)
  125. Did astronauts really go to the Moon, or is it a hoax? (viewed 77244 times)
  126. How are galaxies formed? (viewed 76905 times)
  127. Will the Sun become a black hole one day? (viewed 74954 times)
  128. How are black holes made? Could one be made close to us? (viewed 74746 times)
  129. What is the density of a black hole? (viewed 74409 times)
  130. What would happen if a supermassive black hole came close to the Earth? (viewed 74202 times)
  131. Why is the moon in a different place every night? (viewed 74148 times)
  132. Who has landed on the moon? (viewed 73439 times)
  133. What would you see from inside a black hole? (viewed 71979 times)
  134. Do most astronomers believe in God based on the available scientific evidence? (viewed 71830 times)
  135. How do we weigh objects in space? (viewed 71806 times)
  136. Can moons have moons? (viewed 71675 times)
  137. Why can't you see stars during the day? (viewed 71320 times)
  138. What happens to a substance if its speed is more than the speed of light? (viewed 71282 times)
  139. How do rockets move in space? (viewed 71178 times)
  140. How often does the Sun pass through a spiral arm in the Milky Way? (viewed 70706 times)
  141. Can you fire a gun on the Moon? (viewed 70673 times)
  142. Does the Mediterranean sea have tides? (viewed 70555 times)
  143. How do astronomers measure the brightness of stars? (viewed 70485 times)
  144. How can the Universe expand faster than the speed of light during inflation? (viewed 70337 times)
  145. What would happen if you took off your helmet in space? (viewed 70198 times)
  146. What are some of the effects of solar flares on Earth? (viewed 70117 times)
  147. When the Sun converts mass to energy, do the orbits of the planets change? (viewed 69720 times)
  148. How do we know the mass of the Earth and the Moon? (viewed 69040 times)
  149. How is astronomy impacted by trigonometry? (viewed 69033 times)
  150. Is it possible to measure the temperature of the Sun? (viewed 68789 times)
  151. Why do stars change colour when they twinkle? (viewed 67714 times)
  152. How does the Sun compare to other stars? (viewed 67625 times)
  153. How do you measure a planet's mass? (viewed 67536 times)
  154. What is the evidence supporting the nebula theory of Solar System formation? (viewed 67439 times)
  155. How does the Moon stay "suspended" in the air? (viewed 67153 times)
  156. Why do we not have eclipses every month? (viewed 67041 times)
  157. What are the "dog days of summer"? (viewed 66855 times)
  158. How are elements heavier than iron formed? (viewed 66700 times)
  159. What kinds of jobs do astronomers do? (viewed 65697 times)
  160. Does quantum entanglement imply faster than light communication? (viewed 65273 times)
  161. If the universe is infinite does that mean there is an infinite number of "me"s? (viewed 64377 times)
  162. What are black holes made of? (viewed 63859 times)
  163. What causes seasons? (viewed 63433 times)
  164. How did the stars get named? (viewed 63414 times)
  165. Why doesn't the earliest sunset occur on the shortest day of the year? (viewed 63130 times)
  166. Where does the name "Moon" come from? (viewed 63068 times)
  167. How long would it take the Earth to fall into the Sun? (viewed 62867 times)
  168. When can I see the Moon through the hole in the Pantheon? (viewed 62810 times)
  169. Where did the matter in the universe come from? (viewed 62674 times)
  170. How did asteroids form and what is the difference between an asteroid and a comet? (viewed 62546 times)
  171. How fast is the Universe expanding? (viewed 62485 times)
  172. How do you measure the mass of a star? (viewed 62461 times)
  173. What are Altitude and Azimuth? (viewed 62436 times)
  174. How does light pollution affect astronomers? (viewed 62395 times)
  175. Traveling at light speed, how long would it take to get to the nearest galaxy? (viewed 62314 times)
  176. Are there stars outside of galaxies? (viewed 62097 times)
  177. What's the best college for astronomy? (viewed 61785 times)
  178. Why do planets not twinkle? (viewed 61755 times)
  179. Where, in relation to the entire universe, is the Milky Way located? (viewed 61284 times)
  180. Why doesn't the length of each day change much around the solstices? (viewed 61138 times)
  181. What would happen to us if the sun went out for an hour? (viewed 61039 times)
  182. What is the mass of the Universe? (viewed 60248 times)
  183. What's the difference between dark matter and dark energy? (viewed 59936 times)
  184. How can I calculate the position or path of the Sun for a given time and location? (viewed 58959 times)
  185. Does the Moon rotate? (viewed 58766 times)
  186. Why does the Sun's apparent path through the sky change throughout the year? (viewed 58701 times)
  187. Could there be life in the galaxies nearest to the Milky Way? (viewed 58606 times)
  188. Why does the Earth have only one moon? (viewed 58378 times)
  189. How does astronomy benefit humankind? (viewed 58192 times)
  190. Can any galaxies be seen with the naked eye? (viewed 58046 times)
  191. How does the parachute in a model rocket work? (viewed 57790 times)
  192. What is the origin of spiral structure in galaxies? (viewed 57690 times)
  193. How close was the Moon to the Earth when it formed? (viewed 57443 times)
  194. How long does the supernova stage of a star last? (viewed 56934 times)
  195. Why is looking out into space the same as looking back in time? (viewed 56770 times)
  196. What makes up most of the Universe? (viewed 56695 times)
  197. What is the shape of the universe? (viewed 56406 times)
  198. What can we learn from the color of a star? (viewed 56071 times)
  199. What is the largest structure in the universe? (viewed 55727 times)
  200. Why isn't the summer solstice the hottest day of the year? (viewed 55581 times)
  201. How do astronauts use math in their jobs? (viewed 55272 times)
  202. Where are stars born? (viewed 55132 times)
  203. What is a star's "spectrum"? (viewed 55002 times)
  204. What is the size of a black hole? (viewed 54827 times)
  205. Are names given to black holes? (viewed 54585 times)
  206. If gravity is a "curvature of space" rather than a force, why do a ball and bullet follow different paths? (viewed 54471 times)
  207. Which constellation does our Sun belong to? (viewed 54223 times)
  208. Can you see satellites? (viewed 54173 times)
  209. How do you calculate the azimuth and altitude of an object? (viewed 54070 times)
  210. How do we measure the size of the Moon and of the Sun? (viewed 54066 times)
  211. How do the astronauts communicate in space if sound cannot travel in a vacuum? (viewed 54040 times)
  212. What happens to a bullet fired on the moon? (viewed 53625 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 53382 times)
  214. How can I find the distance to the Sun on any given day? (viewed 53047 times)
  215. What other careers involve Astronomy besides Astronomer? (viewed 52919 times)
  216. Why do we see stars? (viewed 52816 times)
  217. Are aliens or UFOs real? (viewed 52779 times)
  218. How can I measure the distance of a star? (viewed 52461 times)
  219. Which hemisphere has the best view of the Milky Way? (viewed 52244 times)
  220. Is the speed of light constant? (viewed 51917 times)
  221. What are some astronomy science fair projects? (viewed 51602 times)
  222. Are there any asteroids on a collision course with Earth? (viewed 51584 times)
  223. How long has there been water on Earth? (viewed 51331 times)
  224. Why is the sky blue and not blue & purple? (viewed 51179 times)
  225. Why is twilight short near the equator? (viewed 51104 times)
  226. Where did all the water in the universe come from? (viewed 51042 times)
  227. Are meteorites hot or cold when they hit Earth? (viewed 50931 times)
  228. What would happen if the Moon fell out of its orbit around Earth? (viewed 50798 times)
  229. Would your weight change as you go underground? (viewed 50606 times)
  230. Is time travel possible? (viewed 50547 times)
  231. What do a galaxy's colors mean? Are they its true colors? (viewed 50488 times)
  232. Who discovered each planet? (viewed 50323 times)
  233. Can we look back far enough in time to see the Big Bang? (viewed 50267 times)
  234. Why does the Moon look big on the horizon? (viewed 50208 times)
  235. If the Earth's rotation period is less than 24 hours, why don't our clocks fall out of sync with the Sun? (viewed 49947 times)
  236. Why is it difficult to understand the expansion of the universe? (viewed 49449 times)
  237. What skills do astronomers need? (viewed 49185 times)
  238. What is the difference between nutation and precession of the Earth? (viewed 49119 times)
  239. How is the time of sunrise calculated? (viewed 49028 times)
  240. Are the planes of solar systems aligned with the plane of the Galaxy? (viewed 48867 times)
  241. What is a graviton? (viewed 48835 times)
  242. What's the difference between astronomy and astrophysics? (viewed 48688 times)
  243. If light has no mass, then what draws it into a black hole? (viewed 48431 times)
  244. How do we know what other planets (and stars, galaxies, etc.) are made of? (viewed 48033 times)
  245. What do I need to do to become an astronomer? (viewed 46869 times)
  246. Why do the size and brightness of the full moon change? (viewed 46583 times)
  247. Do dead stars still shine? (viewed 46501 times)
  248. Do supermassive black holes cause galaxy rotation? (viewed 46492 times)
  249. How do gravitons escape black holes to tell the universe about their gravity? (viewed 46435 times)
  250. What is a wormhole? (viewed 46270 times)
  251. How are black holes discovered? (viewed 46002 times)
  252. Why does the Sun appear larger on the horizon than overhead? (viewed 45865 times)
  253. Why are most months 30 or 31 days long? (viewed 45649 times)
  254. Can we find the place where the Big Bang happened? (viewed 45583 times)
  255. The Moon slows the Earth's rotation, but how fast was it spinning billions of years ago? (viewed 45452 times)
  256. Where is the nearest black hole? (viewed 45403 times)
  257. Will we get sucked into the black hole at the center of the Milky Way? (viewed 45351 times)
  258. Why can't we see Venus at night when it is an inner planet? (viewed 45109 times)
  259. Why are there stars? (viewed 45080 times)
  260. Is the Earth slowly getting larger? (viewed 45072 times)
  261. How do galaxies collide in an expanding universe? (viewed 44951 times)
  262. Can I calculate the size of the Universe by converting light years to kilometres? (viewed 44772 times)
  263. Why does Barnard 68 appear dark? (viewed 44290 times)
  264. Why don't people walk upside-down on the bottom of the Earth? (viewed 43728 times)
  265. Can the acceleration of the Universe be analogous to apparent acceleration in a airplane? (viewed 43634 times)
  266. Are Kuiper Belt Objects asteroids? Are large Kuiper Belt Objects planets? (viewed 43621 times)
  267. Did life originate on Earth, or did it come from somewhere else? (viewed 43186 times)
  268. What is the best way to see the Milky Way? (viewed 42849 times)
  269. Are there eclipses on other planets? (viewed 42845 times)
  270. Could the Universe have expanded faster than the speed of light at the Big Bang? (viewed 42765 times)
  271. Is there a "South Star"? (viewed 42664 times)
  272. How does Astronomy involve Chemistry? (viewed 42599 times)
  273. Why does the location of sunrise change? (viewed 42538 times)
  274. Has there been an experiment that measured speed faster than the speed of light in vacuum? (viewed 42524 times)
  275. Was the Sun made in a supernova? (viewed 42499 times)
  276. What is the biggest crater recorded on Earth? (viewed 42457 times)
  277. How long could life on Earth survive if the Sun stopped shining? (viewed 42341 times)
  278. What is the difference between the "Doppler" redshift and the "gravitational" or "cosmological" redshift? (viewed 42311 times)
  279. How would the weather on Earth be different if it were a cube? (viewed 42105 times)
  280. Why doesn't dark matter fall into a black hole? (viewed 42081 times)
  281. How much longer will the Earth last? (viewed 42073 times)
  282. How much can the location of sunset differ from due West? (viewed 41961 times)
  283. What happens to spacetime inside a black hole? (viewed 41700 times)
  284. Can I buy land on the Moon? (viewed 41501 times)
  285. Why does the Earth only see one side of the Moon? (viewed 41278 times)
  286. Is the Moon hollow? (viewed 41255 times)
  287. What happens when two black holes get too close? (viewed 41184 times)
  288. What are the names of the three stars in Orion's belt? (viewed 40877 times)
  289. What's the biggest meteorite? (viewed 40830 times)
  290. What is time dilation? (viewed 40710 times)
  291. What color would Mars be if you were standing on it? (viewed 40698 times)
  292. What is the most distant known galaxy? (viewed 40500 times)
  293. What if the Earth rotated twice as fast? (viewed 40370 times)
  294. How can two moons of Saturn share the same orbit? (viewed 40249 times)
  295. Could someone travel the universe in his or her own lifetime? (viewed 39944 times)
  296. Why do people draw stars with five points? (viewed 39862 times)
  297. Can terrestrial planets have rings? (viewed 39773 times)
  298. How do we feel heat? (viewed 39641 times)
  299. How long would it take for a mini-black hole to eat the Earth? (viewed 39576 times)
  300. Is it possible to see the full Moon and the Sun simultaneously in high northern latitudes when the Sun doesn't set? (viewed 39497 times)
  301. How many Astronauts have been in space? (viewed 39446 times)
  302. What are "blue stragglers" in globular clusters? (viewed 39364 times)
  303. Why can we see the sun's image before sunrise and after sunset? (viewed 39166 times)
  304. Why do pictures of distant galaxies have higher resolution than those of nearby planets? (viewed 39015 times)
  305. What is the typical size of a visible shooting star? (viewed 38793 times)
  306. How fast does the Earth go at perihelion and aphelion? (viewed 38775 times)
  307. If a white dwarf is a "dead" star, why is it so hot? (viewed 38701 times)
  308. How do we know that nuclear fusion is still going on in the Sun? (viewed 38682 times)
  309. Is the Great Wall the largest galaxy cluster? (viewed 38473 times)
  310. Does Mt. Everest cast a shadow on the moon? (viewed 38468 times)
  311. Does the Sun have an iron surface? (viewed 38402 times)
  312. Is the Sun always up for exactly 12 hours at the equator? (viewed 38356 times)
  313. Do you think it's possible to maintain life on other planets? (viewed 38296 times)
  314. Why are Saturn's rings flat? (viewed 38291 times)
  315. How does night and day work? (viewed 38281 times)
  316. What is a dimension? (viewed 38173 times)
  317. Can you see the future as you fall into a black hole? (viewed 38079 times)
  318. Can a person go into a black hole and come out alive? (viewed 38044 times)
  319. On which days can I see the Moon in the evening / morning and why is this so? (viewed 38012 times)
  320. Why do clocks turn in the opposite direction from the Earth and Moon? (viewed 37938 times)
  321. Who (and when) discovered that the earth's axis is on a 23 degree tilt? (viewed 37864 times)
  322. Can I communicate faster than light? (viewed 37843 times)
  323. Where do planetary rings come from, and what are they made of? (viewed 37815 times)
  324. What is the speed of gravity? (viewed 37745 times)
  325. What is Earthrise over the Moon? (viewed 37578 times)
  326. What can I use for fuel in my homemade rocket? (viewed 37389 times)
  327. Are all stars the same? (viewed 37378 times)
  328. Where is the supernova remnant that led to our solar system? (viewed 37370 times)
  329. How big is the universe? (viewed 37355 times)
  330. What companies or businesses can astronomers work for? (viewed 37327 times)
  331. What is the approximate GPA needed in High School in Math and Science to be an astronomer? (viewed 37321 times)
  332. How do we determine the age of the universe? (viewed 37212 times)
  333. Is there really a 10th planet? (viewed 36987 times)
  334. Why is sea water salty, and not lake water? (viewed 36901 times)
  335. Is there a beginning and an end to a galaxy's life? (viewed 36607 times)
  336. Does the Coriolis force determine which way my toilet drains? Does it affect black holes? (viewed 36550 times)
  337. If the universe is 15 billion years old, how can it be larger than 15 billion light years across? (viewed 36495 times)
  338. What would happen to the Earth if an asteroid hit the Moon? (viewed 36481 times)
  339. How many stars can I see? (viewed 36433 times)
  340. How can the universe be "flat"? We're 3D! (viewed 36408 times)
  341. How do I tell which planet is which? (viewed 36318 times)
  342. How do we know the Milky Way is a spiral galaxy? (viewed 36238 times)
  343. How do we define distance in an expanding universe? (viewed 36150 times)
  344. How are photons created and destroyed? (viewed 36112 times)
  345. Do the Sun's or Earth's magnetic field reverse? (viewed 35864 times)
  346. How can I find my age on another planet? (viewed 35523 times)
  347. Why are there blue shifted galaxies? (viewed 35513 times)
  348. Is Andromeda part of the Milky Way? Where can I find them in the sky? (viewed 35216 times)
  349. Why have star signs shifted by one constellation? (viewed 35137 times)
  350. Why do humans want to go in space? (viewed 34962 times)
  351. How does the brightness of a star depend on its distance from us? (viewed 34889 times)
  352. Can a lunar and a solar eclipse happen in the same month? When will this happen next? (viewed 34834 times)
  353. What is the pattern to the distances between each planet and the sun? (viewed 34798 times)
  354. How are planets detected around other stars? (viewed 34757 times)
  355. What kind of eyepieces do I need to look at planets? (viewed 34721 times)
  356. What was that really big falling star that I saw? (viewed 34613 times)
  357. What is the significance of the second focus of elliptical orbits of planets in our Solar System? (viewed 34611 times)
  358. Will we ever stop having solar eclipses because of the moon's motion away from the Earth? (viewed 34526 times)
  359. Who came up with the name "black hole"? (viewed 34523 times)
  360. What would happen if two stars collided? (viewed 34487 times)
  361. How can we estimate the number of Earth-like planets in the Galaxy? (viewed 34438 times)
  362. How do astronauts communicate with their families from space? (viewed 34384 times)
  363. Is the Earth at the centre of the Universe? (viewed 34229 times)
  364. Is there a simple formula to calculate solar eclipse timings from any position on Earth? (viewed 34202 times)
  365. When we look back to the Big Bang, why don't we see the universe as a tiny speck of matter? (viewed 34186 times)
  366. Why don't astronomers use everyday units to measure distances (what is an AU or a pc)? (viewed 33969 times)
  367. How is it that we see farther out in space (farther back in time) than in the past? (viewed 33927 times)
  368. Why can't a plane fly slowly and let the Earth pass underneath? (viewed 33858 times)
  369. Will the Moon be invisible in 500 million years? (viewed 33740 times)
  370. How do I become both an astronaut and an astronomer? (viewed 33536 times)
  371. Are Earth and the Moon "twin planets"? (viewed 33421 times)
  372. How hot is each one of the layers of the sun? (viewed 33399 times)
  373. How dangerous are the asteroids? (viewed 33371 times)
  374. Which American colleges teach astronomy? (viewed 33325 times)
  375. Why is our solar system so different from all the others we've found? (viewed 33295 times)
  376. Can you describe a day on the job as an astronomer? (viewed 33290 times)
  377. Why is Uranus tipped on its side? (viewed 33204 times)
  378. Can we colonize other planets? (viewed 32994 times)
  379. How do sunrise and sunset times change with altitude? (viewed 32873 times)
  380. Is the Local Group expanding along with the entire Universe? (viewed 32760 times)
  381. Why do constellations look the same after several years even though all the stars are moving? (viewed 32493 times)
  382. What are quasars made of? (viewed 32318 times)
  383. Is it true that the Sun burns off a billion tons of gas every 5 seconds? (viewed 32290 times)
  384. How can I calculate distances between stars? (viewed 32269 times)
  385. Is the universe really like an expanding balloon? (viewed 32262 times)
  386. Why do astronauts in space need to exercise? (viewed 32214 times)
  387. Why are there no craters on Earth? Did all the meteorites miss us? (viewed 32198 times)
  388. Why doesn't gravity change the speed of light? (viewed 32022 times)
  389. Is the gravitational force exerted by the Earth on the Moon equal to the centripetal force acting on the Moon? (viewed 31953 times)
  390. What is dark matter? (viewed 31834 times)
  391. Can superheavy elements (such as Z=116 or 118) be formed in a supernova? Can we observe them? (viewed 31780 times)
  392. Is it possible to count the stars? (viewed 31741 times)
  393. Is time travel possible using merging black holes? (viewed 31595 times)
  394. What is happening just around the black hole in the center of the Milky Way? (viewed 31499 times)
  395. Did the speed of light change over the history of the universe? (viewed 31389 times)
  396. How big a change in the Earth's orbit would be required to destroy all life? (viewed 31368 times)
  397. Can we see dead stars with the naked eye? (viewed 31362 times)
  398. How do we measure distances to other stars? (viewed 31244 times)
  399. How can we distinguish a star's "real" color from the change in color that we observe due to the star's motion? (viewed 31244 times)
  400. How do I make a scale model of the Solar System? (viewed 31105 times)
  401. What happens when an antimatter black hole collides with a matter blackhole? (viewed 31045 times)
  402. Are time machines possible? (viewed 30898 times)
  403. How many moles of stars are in the known universe? (viewed 30617 times)
  404. Why is the time between two successive full moons different from the lunar synodic month? (viewed 30465 times)
  405. How are galaxy distances inferred from their recessional velocities? (viewed 30433 times)
  406. How can we tell what the interiors of planets are like? (viewed 30351 times)
  407. What happens when you change the mass of a White Dwarf or Neutron Star? (viewed 30296 times)
  408. Does the Milky Way spin counter-clockwise? If so, do all spiral galaxies spin in this direction and why? (viewed 30216 times)
  409. What do "homogeneity" and "isotropy" mean? (viewed 30161 times)
  410. What would happen if a human were exposed to space without wearing a spacesuit? (viewed 30126 times)
  411. What is the farthest in space that we have gone? (viewed 30063 times)
  412. Is there any limitation to what a black hole can "suck" in? (viewed 30058 times)
  413. Will the seasons change due to precession? (viewed 29892 times)
  414. Do we see the same stars from above and below the equator? (viewed 29836 times)
  415. How can we know that there are other galaxies if we cannot leave ours? (viewed 29803 times)
  416. Can astronauts produce water in space? (viewed 29769 times)
  417. What are the closest and/or brightest stars? (viewed 29762 times)
  418. How was the starting point for the Julian Date system chosen? (viewed 29710 times)
  419. How can I tell if the rock I found is a meteorite? (viewed 29672 times)
  420. Aren't jobs in astronomy scarce? (viewed 29659 times)
  421. What's that dark spot on the Sun? (viewed 29646 times)
  422. How do we know if the universe will keep expanding forever? (viewed 29512 times)
  423. Do astronomers believe in astrology? (viewed 29412 times)
  424. Why does the SETI project search for radio signals? (viewed 29389 times)
  425. How long does it take the Big Dipper to move in the sky? (viewed 29376 times)
  426. Did I see the Aurora Borealis as a child? (viewed 29359 times)
  427. What are the facts about the Star of Bethlehem? (viewed 29192 times)
  428. Why do we study black holes? (viewed 29151 times)
  429. Why do most moons orbit their planets at the equator? (viewed 29149 times)
  430. When are there 5 Sundays in February? (viewed 29132 times)
  431. Don't tachyons travel faster than light? (viewed 29131 times)
  432. Could an astronaut or satellite fall into a black hole that we didn't know about? (viewed 29044 times)
  433. What are the atmospheres of Mars and Pluto like? (viewed 29030 times)
  434. Wouldn't the Big Bang theory be considered a hypothesis and not a theory? (viewed 29013 times)
  435. Do you believe in UFOs? (viewed 28860 times)
  436. Can you use an infinite line of reflectors to send light to the edge of the Universe? (viewed 28776 times)
  437. What does the term "visible universe" mean? (viewed 28696 times)
  438. Could you tell me about the life cycle of galaxies? (viewed 28627 times)
  439. What colors are visible through an amateur telescope? (viewed 28583 times)
  440. Has anyone made a map of the Milky Way? (viewed 28577 times)
  441. Was I hit by a meteorite? (viewed 28574 times)
  442. How are galaxies named? (viewed 28530 times)
  443. How can geometry be different in space? (viewed 28464 times)
  444. Why are the compositions of comets and asteroids different? (viewed 28194 times)
  445. Why do so many of the world's UFO sightings happen in America? (viewed 28106 times)
  446. What's the best thing about being an astronomer? (viewed 28071 times)
  447. How do asteroids, meteors and comets disappear? (viewed 27916 times)
  448. Can two lunar eclipses occur in the same month? (viewed 27843 times)
  449. How much time do astronomers spend looking through telescopes? (viewed 27776 times)
  450. How do astronomers measure the radius of a star? (viewed 27748 times)
  451. Will winter and summer constellations change due to abnormal warmth or cold on Earth? (viewed 27685 times)
  452. How can we see galaxies if their stars are so faint? (viewed 27550 times)
  453. How will the two black holes that are going to collide affect Earth? (viewed 27512 times)
  454. Have there been other Big Bangs before? (viewed 27499 times)
  455. How do I explain to my children why the Moon has phases? (viewed 27471 times)
  456. What is the origin of the stellar classification system "OBAFGKM"? (viewed 27449 times)
  457. Does the Moon look different in the northern and southern hemispheres? (viewed 27442 times)
  458. How are galaxies and solar systems similar? (viewed 27346 times)
  459. Can life exist on the recently discovered extrasolar planets? (viewed 27239 times)
  460. How close do you have to come to the Earth to be influenced by its gravity? (viewed 27210 times)
  461. Is there a project I can do on black holes? (viewed 27176 times)
  462. Is the Milky Way a collision of two galaxies? (viewed 27125 times)
  463. Do the magnitudes and colors of stars ever change? (viewed 27073 times)
  464. How can we measure distances to more stars? (viewed 27035 times)
  465. Could you escape from a black hole if you were able to go faster than the speed of light? (viewed 26969 times)
  466. How do scientists slow light down? (viewed 26932 times)
  467. Do asteroids hit the sun? (viewed 26831 times)
  468. Is infinite temperature possible? (viewed 26734 times)
  469. How close does a supernova need to be to damage the Earth's environment? (viewed 26725 times)
  470. Do we know everything about the Sun? (viewed 26696 times)
  471. Can "tired light theory" explain the observed redshifts of galaxies? (viewed 26656 times)
  472. Is it worthwhile to continue the search for extraterrestrial life? (viewed 26644 times)
  473. What supernova created the Crab nebula? (viewed 26635 times)
  474. Can double stars have planets? (viewed 26536 times)
  475. Can one star orbit another? (viewed 26512 times)
  476. What causes gamma ray bursts? (viewed 26481 times)
  477. How far does a galaxy extend? (viewed 26373 times)
  478. How do I polar align my telescope? (viewed 26195 times)
  479. What will happen to the Milky Way in the future? (viewed 26195 times)
  480. Can astronauts play musical instruments in space? (viewed 26171 times)
  481. Can a human give birth in space? (viewed 26147 times)
  482. Which part of the sky did the famous 'wow' signal originate from? (viewed 26127 times)
  483. Is there oxygen in the atmospheres of other planets? (viewed 26120 times)
  484. What is sidereal time? (viewed 26090 times)
  485. Which way does the sun travel in the southern hemisphere? (viewed 26079 times)
  486. Is there such a thing as hyperspace? (viewed 26070 times)
  487. What type of energy does a black hole have? (viewed 26069 times)
  488. What is the farthest Northern Latitude in which the Magellanic Clouds can be seen? (viewed 26047 times)
  489. What happens to the material that has been sucked into a black hole? (viewed 25997 times)
  490. Why do the explosions of Type Ia supernovae have a more predictable spectrum than those of regular Type II supernovae? (viewed 25928 times)
  491. What is a Cepheid variable? (viewed 25921 times)
  492. What is "nothing", from a scientific point of view? (viewed 25899 times)
  493. Why did the Pioneer and Voyager take only 2 years to reach Jupiter, while Galileo and Cassini took more than 5 years? (viewed 25897 times)
  494. Is there sound coming from the Sun? (viewed 25872 times)
  495. What's the object I saw that moved across the sky and then got very bright? (viewed 25849 times)
  496. How different would the night sky have looked in 40,000 B.C.? (viewed 25807 times)
  497. How will a change in the speed of light affect the evolution of the Universe? (viewed 25786 times)
  498. When did people discover that the Sun is a star? (viewed 25658 times)
  499. Why do we assume that the universe is homogeneous? (viewed 25566 times)
  500. How do we know what parameters to use when simulating the collision of the Milky Way and Andromeda? (viewed 25534 times)
  501. Why is the shadow on the Moon the shape it is? (viewed 25523 times)
  502. Are planetary nebulae the result of supernovae? (viewed 25477 times)
  503. How do we know that sunspots are associated with the Sun's magnetic field? (viewed 25459 times)
  504. If we invented special suits could we ever go to the sun? (viewed 25433 times)
  505. When unmanned spacecraft accelerate in space, what causes them to slow down? (viewed 25428 times)
  506. Are there any dark stars or dark galaxies made of dark matter? (viewed 25331 times)
  507. What calculations go into predicting eclipses? (viewed 25306 times)
  508. What is the difference between homogeneity and isotropy? (viewed 25302 times)
  509. What is our galaxy's halo made of, and how was it formed? (viewed 25231 times)
  510. Was Stonehenge built to mark solar phenomena? (viewed 25224 times)
  511. Can I see a quasar? (viewed 25158 times)
  512. Is there a list of the sizes of different kinds of stars? (viewed 25157 times)
  513. What process would bring about a quark star? (viewed 25118 times)
  514. How many sunspots can the Sun have at once? (viewed 25072 times)
  515. How are asteroid compositions and classifications determined? (viewed 25036 times)
  516. What's so exciting about the new planet around 55 Cancri? (viewed 25026 times)
  517. Did a giant impact cause the Dark Ages? (viewed 25001 times)
  518. Can I see details on Venus? (viewed 24957 times)
  519. Can any comparison be made between spiral galaxies and hurricanes? (viewed 24949 times)
  520. What is a Dyson Sphere? (viewed 24947 times)
  521. Have gravitational waves been proven to exist? (viewed 24935 times)
  522. Why are there more maria on the near side of the Moon? (viewed 24837 times)
  523. What equipment do I need for astrophotography? (viewed 24741 times)
  524. What happened to the girl who named Pluto? (viewed 24737 times)
  525. What happened to all the black holes that were around in the early universe? (viewed 24733 times)
  526. How is it proved that the Universe is expanding? (viewed 24666 times)
  527. Would the biggest airplanes cause tsunamis if they crashed? (viewed 24656 times)
  528. Does Cerenkov radiation travel faster than light? (viewed 24637 times)
  529. Why are there active volcanos on Io? (viewed 24629 times)
  530. Why are telescopes kept in cold conditions? (viewed 24613 times)
  531. Is there any possibility that the Solar System or the Universe is in a black hole? (viewed 24524 times)
  532. How big is the Hubble Ultra Deep Field image? (viewed 24429 times)
  533. If clocks run slow in a gravitational field, how can we know the true age of the Solar System and Universe? (viewed 24371 times)
  534. How can we compare dark matter and dark energy? (viewed 24330 times)
  535. How big was the Sun when it first "fired up"? (viewed 24316 times)
  536. If the Universe was infinitely dense at the Big Bang, why didn't time stand still? (viewed 24284 times)
  537. How long do supernova remnants last? (viewed 24225 times)
  538. What caused Shoemaker-Levy 9 to split up? (viewed 24187 times)
  539. Why do photos of space taken from space never show any stars? (viewed 24165 times)
  540. Could we send a space mission to a comet? (viewed 24151 times)
  541. How do solar flares affect airline pilots? (viewed 24122 times)
  542. Why doesn't light from distant galaxies reach us instantaneously? (viewed 24067 times)
  543. Can you give me advice on buying a telescope? (viewed 24007 times)
  544. How are sunspots formed? (viewed 24002 times)
  545. Could we be seeing dead stars? (viewed 23978 times)
  546. How does the Earth compare in size to the entire universe at the present epoch? (viewed 23891 times)
  547. Could a different theory of gravity explain the dark matter mystery? (viewed 23880 times)
  548. Why doesn't NASA build rotating spacecraft to simulate gravity? (viewed 23811 times)
  549. As the universe expands, why don't galaxies get stretched out? (viewed 23798 times)
  550. Where does the kinetic energy of infalling bodies come from? (viewed 23793 times)
  551. Can I build an instrument to measure the size of the Sun and of the Moon? (viewed 23780 times)
  552. How many comets are currently orbiting our sun? (viewed 23722 times)
  553. Can you tell time by the Big Dipper? (viewed 23667 times)
  554. Why is the Hubble Space Telescope in space? (viewed 23654 times)
  555. How can I contribute to science as an amateur astronomer? (viewed 23637 times)
  556. Why is it important to study meteorites? (viewed 23628 times)
  557. Did I really hear a meteor? (viewed 23587 times)
  558. How do we know that superclusters are the largest structures in the universe? (viewed 23535 times)
  559. Why are telescopes located in remote places? (viewed 23489 times)
  560. How powerful are quasars? (viewed 23486 times)
  561. Would extraterrestrial civilizations know that there is life on Earth? (viewed 23478 times)
  562. Are the asteroids the remains of a planet which broke apart? (viewed 23428 times)
  563. How is the Cepheid yardstick validated? (viewed 23385 times)
  564. Do unmanned spacecraft like Voyager travel in straight lines? (viewed 23310 times)
  565. How do unmanned space probes avoid running into things? (viewed 23299 times)
  566. Do the Earth's magnetic poles ever change places? (viewed 23274 times)
  567. Did time go slower just after the Big Bang? (viewed 23269 times)
  568. Can supernovae hinder the formation of life in galaxies? (viewed 23200 times)
  569. Why are stars of different masses? (viewed 23199 times)
  570. Are there any new craters on the moon? (viewed 23199 times)
  571. What would happen if there was a collision between two white dwarfs? (viewed 23196 times)
  572. Do galaxies orbit around anything? (viewed 23193 times)
  573. What kind of instruments are used to detect extrasolar planets? (viewed 23110 times)
  574. Do similar laws of physics throughout the Universe imply that all life must be like life on Earth? (viewed 23107 times)
  575. How could galaxies have gotten so far away in only 15 billion years? (viewed 23095 times)
  576. How do planets capture satellites? (viewed 23090 times)
  577. How do I become an astronomical artist? (viewed 23089 times)
  578. Why can't relative velocities add up to more than the speed of light? (viewed 23050 times)
  579. Could there have been multiple Big Bangs at different places in the universe? (viewed 22956 times)
  580. How are astronomy and poetry linked? (viewed 22931 times)
  581. What kind of telescope should I use for astrophotography? (viewed 22919 times)
  582. Could dark energy come from matter anti-matter pairs forming spontaneously and then annihilating? (viewed 22826 times)
  583. Why is NASA shutting down the Hubble Space Telescope? (viewed 22738 times)
  584. Can I listen to the SETI@home radio signal? (viewed 22733 times)
  585. How can you tell if a crescent moon is preceding or following a new-moon phase? (viewed 22673 times)
  586. Does the Sun have any heavy elements? (viewed 22624 times)
  587. Are the properties of extrasolar planets known? (viewed 22564 times)
  588. What class of spiral galaxy is the Milky Way? (viewed 22487 times)
  589. A line drawn perpendicular to a line through the tips of the horns of the crescent moon doesn't point to the Sun! Why not? (viewed 22473 times)
  590. Can the theory of formation of the solar system explain all the observables? (viewed 22442 times)
  591. Will we discover an 11th planet? What would it be called? (viewed 22432 times)
  592. What month was it when Odysseus saw Orion in 1000BC? (viewed 22353 times)
  593. How do astronomers observe the Sun's interior? (viewed 22287 times)
  594. What makes a satellite geosyncronise itself with Earth's orbit? (viewed 22084 times)
  595. Why does one side of Mars look more catastrophic than the other? (viewed 22073 times)
  596. Where was the water in the big bang? (viewed 22065 times)
  597. Why does the apparent density of galaxies drop off at larger distances? (viewed 22064 times)
  598. Is it possible for amateurs to do optical interferometry? (viewed 22021 times)
  599. Would a planet near the galactic center have a brighter night sky? (viewed 21985 times)
  600. Could we send a manned mission to the outer planets? (viewed 21952 times)
  601. Do stars' orbits in galaxies obey Kepler's Laws? (viewed 21801 times)
  602. What is the solar cycle? (viewed 21758 times)
  603. How can water be chemically trapped in rocks? (viewed 21706 times)
  604. Can other terrestrial moons be (or have been) stable? (viewed 21687 times)
  605. Why was the Platonic year named after Plato? (viewed 21668 times)
  606. Why do spacecraft need heat shields coming back to Earth but not leaving? (viewed 21618 times)
  607. How are supernovae discovered? (viewed 21594 times)
  608. What would the Big Crunch look like to an observer on Earth? (viewed 21572 times)
  609. Why are accretion disks flat? (viewed 21546 times)
  610. Can a black hole come back to the visual universe through a "little bang"? (viewed 21513 times)
  611. What is meant by "stopping down a telescope"? (viewed 21467 times)
  612. Does inflation allow for an infinite number of universes? (viewed 21452 times)
  613. Could our position in the universe affect our perceptions of the expansion? (viewed 21401 times)
  614. Why doesn't the hydrogen on Jupiter explode? (viewed 21363 times)
  615. How can the Sun have such a strong gravitational field if it's made of gasses? (viewed 21243 times)
  616. Did I find a rock that came from the Moon? (viewed 21148 times)
  617. Have astronomers observed any phenomena that could be produced by extraterrestrial civilizations? (viewed 21138 times)
  618. What is the SU(3) quark model? (viewed 21096 times)
  619. Can gravitational lensing from intervening galaxies cause the observed ripples in the Cosmic Microwave Background? (viewed 21068 times)
  620. Does a photon observe other photons moving past it at the speed of light? (viewed 21029 times)
  621. Will I be able to see the shadow of the Moon streaking towards me in a total solar eclipse? (viewed 20904 times)
  622. What's new with the Big Bang? (viewed 20802 times)
  623. Could photons be dark matter? (viewed 20734 times)
  624. How can we find galaxies behind the Milky Way? (viewed 20707 times)
  625. Is it possible to build a cheap device to measure declination? (viewed 20668 times)
  626. Why search for only Earth-like life on other planets? (viewed 20654 times)
  627. Why can we have solar eclipses? (viewed 20649 times)
  628. How fast do particles travel in space? (viewed 20616 times)
  629. If comets are boiling away, why are there any left? (viewed 20607 times)
  630. Why is the WMAP picture of the CMB an ellipse? (viewed 20581 times)
  631. Where can I find information on the moons of other planets? (viewed 20551 times)
  632. Why do some eclipses take longer than others? (viewed 20528 times)
  633. How much power is contained in a beam of light? (viewed 20479 times)
  634. Why is pressure broadening greater in low mass stars than in high mass stars? (viewed 20335 times)
  635. What are the boundaries of the constellations? (viewed 20259 times)
  636. What would an "open geometry" for the universe look like? (viewed 20246 times)
  637. Do constellations looks the same from space? (viewed 20222 times)
  638. Can planets collide with one another? (viewed 20216 times)
  639. Did the Sumerians measure precession? (viewed 20211 times)
  640. What kinds of star clusters are there? (viewed 20116 times)
  641. Why is the Cosmic Microwave Background not absorbed by interstellar hydrogen? (viewed 20059 times)
  642. How do astronomers come up with their facts? (viewed 20045 times)
  643. Why aren't discoveries of extrasolar planets reported on the news? (viewed 20039 times)
  644. Why don't astronauts sublimate in space? (viewed 19999 times)
  645. How do bars form in spiral galaxies? (viewed 19997 times)
  646. How do photons from distant objects maintain enough energy to reach us? (viewed 19987 times)
  647. How did Mars get so dusty? (viewed 19882 times)
  648. Can HST see the Oort cloud? (viewed 19877 times)
  649. Do electrons age? (viewed 19850 times)
  650. What are collections of galaxies called? (viewed 19767 times)
  651. Can we make a movie of the Milky Way galaxy's rotation? (viewed 19736 times)
  652. Can the Space Shuttle abort and return to Earth before reaching orbit? (viewed 19731 times)
  653. How long is twilight on the Moon? (viewed 19659 times)
  654. Does the shuttle worry about space junk? (viewed 19569 times)
  655. Will astronauts ever be able to go ice-skating on Europa? (viewed 19557 times)
  656. How does melting a material reset its radioactive clock? (viewed 19540 times)
  657. Why do supernova remnants look like rings rather than spheres? (viewed 19489 times)
  658. Where can I see Newton's original reflecting telescope? (viewed 19468 times)
  659. How do you classify galaxies? (viewed 19459 times)
  660. Why don't all neutron stars become pulsars? (viewed 19442 times)
  661. How can we understand the meaning of large numbers like "a million million?" (viewed 19354 times)
  662. Why doesn't SETI concentrate its observations to the nearby stars and the solar systems that we are discovering? (viewed 19321 times)
  663. What is the best time of the year to see eclipses? (viewed 19300 times)
  664. Will the next generation telescope OWL be able to detect an Earth like extrasolar planet? (viewed 19221 times)
  665. What causes a particle to decay? (viewed 19215 times)
  666. How can I nominate myself for a Nobel Prize in Physics? (viewed 19120 times)
  667. How long has humanity known that we live in a galaxy similar to others in the Universe? (viewed 19085 times)
  668. Will the Leonid meteor shower go away? (viewed 19053 times)
  669. Why is it called astronomy when all the other sciences end in -ology? (viewed 19051 times)
  670. How does the color index of a star relate to its actual color? (viewed 18960 times)
  671. What are "curled" dimensions? (viewed 18948 times)
  672. If photons have zero mass, why do they feel the effects of gravity? (viewed 18918 times)
  673. Is light of different colors affected differently by gravity? (viewed 18879 times)
  674. What was that eclipse I saw in the sky? (viewed 18777 times)
  675. How does interferometry work? (viewed 18772 times)
  676. If nothing can escape a black hole, why do some black holes have jets? (viewed 18731 times)
  677. How do distant galaxies differ from those nearby? (viewed 18706 times)
  678. Do asteroids ever do anything good in the Solar System? (viewed 18682 times)
  679. Does the temperature of matter increase as it is accelerated to relativistic speeds? (viewed 18668 times)
  680. What kind of interference must astronomers contend with when observing? (viewed 18645 times)
  681. What would happen if you went back in time and killed your grandmother? (viewed 18637 times)
  682. How do we find out about the star formation histories of galaxies? (viewed 18626 times)
  683. Are black holes spherical? (viewed 18624 times)
  684. Wouldn't the vast distances of space distort SETI signals into unintelligeble forms? (viewed 18601 times)
  685. Can astronomers observe anything when the moon is full? (viewed 18554 times)
  686. Why will fusion wait until hydrogen is gone before starting to fuse heavier atoms? (viewed 18481 times)
  687. How can I watch the Perseid meteor shower? (viewed 18478 times)
  688. Do we really observe the edges of galaxies at different epochs? (viewed 18404 times)
  689. What do stellar classifications mean? (viewed 18389 times)
  690. Can you tell me the characteristics of W, R, N and S type stars? (viewed 18366 times)
  691. How are astronauts trained for weightlessness? (viewed 18296 times)
  692. What is the three-body problem? (viewed 18260 times)
  693. Why aren't accretion disks around giant stars as hot as accretion disks around black holes? (viewed 18210 times)
  694. If the universe is "bounded" today, could it one day become "unbounded"? (viewed 18032 times)
  695. Will the diameter of a cluster of galaxies change with redshift? (viewed 18001 times)
  696. Is cosmic expansion happening on microscopic scales? (viewed 17838 times)
  697. How can I find out if the new moon has been sighted? (viewed 17700 times)
  698. Could neutrinos be dark matter? (viewed 17542 times)
  699. Do we have to worry about relativity when studying galactic objects? (viewed 17499 times)
  700. When measuring the expansion of the universe, do astronomers consider that they're seeing how galaxies moved long ago, not today? (viewed 17407 times)
  701. What kinds of cancer research have been done in space? (viewed 17351 times)
  702. Does lunar gardening really work? (viewed 17270 times)
  703. How does a star take mass from another star? (viewed 17228 times)
  704. How do supernovae show us that the Universe's expansion is accelerating? (viewed 17182 times)
  705. Could the Universe's dark matter be made up of black holes? (viewed 17090 times)
  706. How can you tell the difference between single and multiple extrasolar planets? (viewed 17031 times)
  707. What is Hot Dark Matter theory? (viewed 16962 times)
  708. Is it a coincidence that we can have total solar eclipses? Are there other planets which also have them? (viewed 16675 times)
  709. What happens to the helium formed in the sun? (viewed 16624 times)
  710. Is the green flash real? (viewed 16580 times)
  711. What is the photoelectric effect? Why can't multiple low-frequency photons free an electron? (viewed 16469 times)
  712. How do we know the density of some extrasolar planets? (viewed 16464 times)
  713. How does libration allow us to see more than 50% of the Moon? (viewed 16456 times)
  714. How can observations of the distant universe prove that the expansion is accelerating *now*? (viewed 16435 times)
  715. Is light blueshifted when it is gravitationally lensed? (viewed 16307 times)
  716. Do binary or triple star systems form together? (viewed 16246 times)
  717. No matter how fast the universe is expanding, shouldn't gravity eventually make it recollapse? (viewed 16221 times)
  718. What percent of the time can astronomers observe without interference from the Moon? (viewed 15993 times)
  719. What do meteorites tell us about life on other planets? (viewed 15976 times)
  720. Why is it easier to see a star if you look slightly to the side? (viewed 15918 times)
  721. Can we prove that the Moon isn't hollow? (viewed 15744 times)
  722. If the sun went out and our atmosphere froze solid, what color would it be? (viewed 15736 times)
  723. Could matter-anti-matter repulsion power the expansion of the universe? (viewed 15731 times)
  724. Why doesn't the ammonia and methane in Jupiter's atmosphere sink into the core? (viewed 15524 times)
  725. Are there any 'lonely galaxies'? (viewed 15348 times)
  726. How do we detect incoming meteorites? (viewed 15343 times)
  727. What was different on Mars in the past to allow liquid water to be present? (viewed 15261 times)
  728. When will Hale-Bopp return? (viewed 15139 times)
  729. Why don't skydivers burn up like meteors? (viewed 15111 times)
  730. Has anyone ever seen a star "turn on"? (viewed 14889 times)
  731. How has light from 13 billion years ago not passed us by? (viewed 14731 times)
  732. During close approaches, can Mars appear in our sky as large as the Moon? (viewed 14618 times)
  733. Why are craters round? (viewed 14471 times)
  734. How are planets affected by the Hot Ionised Medium? (viewed 14415 times)
  735. Can the sun rise from the west on Mars? (viewed 14090 times)
  736. What are the largest radio wavelengths observed from radio sources in the sky? (viewed 13965 times)
  737. Why was Mir burnt up in the atmosphere? (viewed 13959 times)
  738. What time is sunrise/sunset or moonrise/moonset at my location? (viewed 13917 times)
  739. How can we discern different galaxies/clusters along the same line of sight? (viewed 13858 times)
  740. What is the relationship between the width of a star trail on a photo and the star's intensity? (viewed 13423 times)
  741. Can we harvest H & O from space to make water? (viewed 13168 times)
  742. 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 13149 times)
  743. Why does Titan, in spite of being smaller than Mars, have an atmosphere more dense than Earth's? (viewed 12727 times)
  744. What is between the Oort cloud and the closest star? (viewed 12662 times)
  745. Could a planetary system survive if its star merged with another, or if its star went supernova? (viewed 11806 times)
  746. Are there solar tides? (viewed 11767 times)
  747. Does weightlessness affect hunger? (viewed 11591 times)
  748. Is Earth-moon tidal friction causing global warming? (viewed 11306 times)
  749. What happens to the Earth as the moon gets farther away and will it ever go away entirely? (viewed 11287 times)
  750. Do planets radiate noise? (viewed 11066 times)
  751. Is the moon spherical? (viewed 10986 times)
  752. Is dark energy affected by black holes? (viewed 10792 times)
  753. What would happen if a nuclear-powered shuttle exploded? (viewed 10569 times)
  754. Why is the Moon higher in the sky in winter and lower in the summer? (viewed 10532 times)
  755. Where are the protons and electrons in a Neutron Star? (viewed 10161 times)
  756. Is the Moon always visible during winter on the North Pole? (viewed 9768 times)
  757. Wait, I'm still confused why information can't travel faster than the speed of light. (viewed 9731 times)
  758. Do more meteorites fall at low latitudes? (viewed 9617 times)
  759. Did the Moon or planets form in a manner similar to that of Earth? (viewed 9588 times)
  760. Will Comet Elenin (C/2010 X1) affect the Earth on its close approach in Fall 2011? (viewed 9483 times)
  761. What are the possible ends of the universe? (viewed 9478 times)
  762. Will the Pioneer and Voyager probes ever leave the Milky Way? (viewed 9469 times)
  763. If there are infinity universes, will every thing that is possible happen? (viewed 9341 times)
  764. Is it sensible to consider terraforming Mars? (viewed 9309 times)
  765. What color are meteors? (viewed 8952 times)
  766. Where is everybody? (viewed 8564 times)
  767. Why does Mars have a dusty atmosphere? (viewed 8150 times)
  768. The naming of Mars (viewed 8022 times)
  769. Does the singularity in a black hole create a new Universe? (viewed 8001 times)
  770. If I were traveling through space, could I see distant galaxies with my own eyes? (viewed 7974 times)
  771. Is the reddish dust of Mars biogenic? (viewed 7834 times)
  772. Where is the Spitzer Space Telescope? (viewed 7224 times)
  773. When will humans travel to Mars and revisit the Moon? (viewed 7079 times)
  774. Does the particles involved in a star's final core collapse travel faster than the speed of light? (viewed 6421 times)
  775. How likely is it for a planet to transit its star? (viewed 6399 times)
  776. Why do astronomers use telescopes? (viewed 6307 times)
  777. When is the best time to observe zodiacal light? (viewed 6225 times)
  778. What causes the aurora? (viewed 6168 times)
  779. How did a transit of Venus provide astronomers with the first measurement of the Earth-Sun distance? (viewed 5126 times)
  780. Can the Sun be closer to the Earth than any planet is to Earth? (viewed 4460 times)
  781. Cosmologists say the expansion of the universe is accelerating, what is driving this? (viewed 3937 times)
  782. Can we hear sound on Titan? (viewed 3760 times)
  783. Does the direction of the moon's crescent change through the night? (viewed 3582 times)
  784. What do all the angles in a table for a planet's orbit mean? (viewed 3437 times)
  785. How do I maximize my chances of seeing shooting stars? (viewed 2777 times)
  786. Are exoplanets real? (viewed 2420 times)
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