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 2101744 times)
  2. What color is each planet? (viewed 859264 times)
  3. At what speed does the earth move around the sun? (viewed 544297 times)
  4. Is the Moon moving away from the Earth? When was this discovered? (viewed 524115 times)
  5. How far is each planet from Earth? (viewed 449917 times)
  6. When will Halley's Comet return? (viewed 389170 times)
  7. How many stars are there in our Galaxy (Milky Way)? (viewed 376084 times)
  8. How long does it take for the Sun's light to reach us? (viewed 369772 times)
  9. Why do the planets orbit the sun? (viewed 356002 times)
  10. What is the universe expanding into? (viewed 353856 times)
  11. How do you measure the distance between Earth and the Sun? (viewed 321416 times)
  12. Which planets have rings? (viewed 314875 times)
  13. Why do stars twinkle? (viewed 302719 times)
  14. Does the Moon rotate? Are there other moons that always keep one face toward their planet? (viewed 291411 times)
  15. How do I build a model rocket? (viewed 282109 times)
  16. What color is Venus? (viewed 266257 times)
  17. What is a white hole? (viewed 258554 times)
  18. What is the life cycle of a star? (viewed 241140 times)
  19. What are the names of the earth, moon, sun, and solar system? (viewed 228346 times)
  20. Can you hear sounds in space? (viewed 222013 times)
  21. What is the largest star? (viewed 219688 times)
  22. What is that ring (or rainbow) around the moon? (viewed 218327 times)
  23. What makes the Earth rotate? (viewed 216501 times)
  24. What are shooting stars? (viewed 215046 times)
  25. What do astronauts eat in space? Can they grow food? (viewed 197672 times)
  26. Why do planets rotate? (viewed 192448 times)
  27. How do we know the age of the Universe and the Earth? (viewed 189339 times)
  28. Can artificial gravity be created in space? (viewed 186023 times)
  29. Is the universe expanding faster than the speed of light? (viewed 184748 times)
  30. How does the location of sunrise and sunset change throughout the year? (viewed 175241 times)
  31. Where did the name 'Earth' come from? (viewed 173107 times)
  32. How many Earths fit into the Sun? (viewed 169374 times)
  33. What would happen if we did not have a Moon? (viewed 168689 times)
  34. How can we see the Milky Way if we are inside it? (viewed 166751 times)
  35. Why is a day divided into 24 hours? (viewed 156276 times)
  36. How does the position of Moonrise and Moonset change? (viewed 150765 times)
  37. Who named the planets and who decides what to name them? (viewed 148885 times)
  38. Is Pluto a planet? (viewed 147224 times)
  39. Is the distance from the Earth to the Sun changing? (viewed 145299 times)
  40. Why are the Moon and Sun sometimes orange or red? (viewed 142777 times)
  41. When was the last time all 9 planets were aligned? (viewed 141947 times)
  42. What is at the end of the Universe? (viewed 138270 times)
  43. Why do airplanes take longer to fly West than East? (viewed 134191 times)
  44. How much money is spent on space exploration? (viewed 133660 times)
  45. How can I find the star I have "bought"? (viewed 131111 times)
  46. Why are there both high and low tides? (viewed 128470 times)
  47. What are the different kinds of astronomers? (viewed 126350 times)
  48. What is the largest galaxy? (viewed 125721 times)
  49. How many known galaxies are there? (viewed 124109 times)
  50. What direction do planets rotate? (viewed 123570 times)
  51. Is the Sun expanding? Will it ever explode? (viewed 122737 times)
  52. How do astronauts take baths and use restrooms in space? (viewed 121574 times)
  53. Can we feel the Earth spin? (viewed 120998 times)
  54. Do stars move in the sky? (viewed 117641 times)
  55. Can I buy a star? (viewed 112574 times)
  56. Does your weight change between the poles and the equator? (viewed 111403 times)
  57. Will the sun go supernova in six years and destroy Earth (as seen on Yahoo)? (viewed 110730 times)
  58. What are the advantages and disadvantages of using a telescope in space? (viewed 109229 times)
  59. What is a nova? (viewed 108000 times)
  60. What is the hottest time of day? (viewed 107903 times)
  61. Are there telescopes that can see the flag and lunar rover on the Moon? (viewed 107346 times)
  62. How do stars move in the Galaxy? (viewed 106643 times)
  63. How are light and heavy elements formed? (viewed 106492 times)
  64. Why do all the planets orbit in the same plane? (viewed 105487 times)
  65. Will the magnetic field of the Earth reverse its direction in the future? Will this cause problems? (viewed 105245 times)
  66. Does the Sun have a scientific name? (viewed 104750 times)
  67. What happens when galaxies collide? (viewed 104677 times)
  68. When is the next comet due to arrive? (viewed 104278 times)
  69. What was there before the Big Bang and what is there outside of our universe? (viewed 103786 times)
  70. What is the size of the Solar System? (viewed 103623 times)
  71. Why hasn't NASA gone back to the moon? (viewed 102520 times)
  72. How do rockets work? (viewed 102376 times)
  73. Why do planets have elliptical orbits? (viewed 102158 times)
  74. Who first measured the speed of light? (viewed 102043 times)
  75. What would happen if an impact caused Earth to stop rotating? (viewed 101972 times)
  76. How long does a solar eclipse last? (viewed 101932 times)
  77. How much money do astronomers make? (viewed 101122 times)
  78. How many constellations are there? (viewed 99748 times)
  79. What will happen to life on Earth when the Sun becomes a red giant? (viewed 99189 times)
  80. Do black holes die? If so how? (viewed 99077 times)
  81. What elements make up the Sun? (viewed 98581 times)
  82. How do you calculate the lifetime of the Sun? (viewed 98324 times)
  83. Does the Sun move around the Milky Way? (viewed 97507 times)
  84. Does the Sun rotate? (viewed 97324 times)
  85. What is the observational difference between a star and a planet? (viewed 95831 times)
  86. What is the physical difference between a star and a planet? (viewed 95131 times)
  87. What is the significance of the Tropic of Cancer, Tropic of Capricorn, Arctic Circle and Antarctic Circle? (viewed 94035 times)
  88. Does evolution contradict the second law of thermodynamics? (viewed 93104 times)
  89. What is apparent magnitude? (viewed 92248 times)
  90. What's the difference between astronomy and astrology? (viewed 92151 times)
  91. What do astronauts do all day in the International Space Station? (viewed 90267 times)
  92. Which planet is most similar to Earth? (viewed 89801 times)
  93. If Mars is only about 35-60 million miles away at close approach, why does it take 6-8 months to get there? (viewed 88448 times)
  94. How critical is the Earth-Sun distance in maintaining our average temperatures on Earth? (viewed 88442 times)
  95. Does gravity vary across the surface of the Earth? (viewed 87880 times)
  96. How many meteorites hit Earth each year? (viewed 87127 times)
  97. How do astronomers use math in their jobs? (viewed 86067 times)
  98. Have astronomers discovered Earth's second moon? (viewed 86001 times)
  99. Why are stars and planets round? (viewed 85753 times)
  100. Why do different stars appear with seasons? (viewed 85437 times)
  101. What are constellations used for? (viewed 85149 times)
  102. Is there a proof that Earth moves? (viewed 85074 times)
  103. What would happen if the gravity on Earth was suddenly turned off? (viewed 84724 times)
  104. Where did the Universe come from? (viewed 84278 times)
  105. What would happen if an asteroid 10 kilometers across hit the Earth? (viewed 84080 times)
  106. Does the Sun orbit the Earth as well as the Earth orbiting the Sun? (viewed 83950 times)
  107. Why is the Moon so bright? (viewed 83696 times)
  108. Why is the Universe flat and not spherical? (viewed 83275 times)
  109. What makes the wind? (viewed 82531 times)
  110. What is a singularity? (viewed 82316 times)
  111. Where does the name "Milky Way" come from? (viewed 79904 times)
  112. Why does the Earth tilt back and forward once a year? (viewed 79381 times)
  113. What kind of schooling is necessary to become an astronomer? (viewed 79283 times)
  114. How can a star burn with no oxygen? (viewed 79177 times)
  115. What would happen if Earth had more than one moon? (viewed 78996 times)
  116. What are RA and DEC? (viewed 78632 times)
  117. Considering the motion of the Earth, the solar system, and the galaxy, how fast am I moving while lying in bed asleep? (viewed 77818 times)
  118. What kind of rock is the moon made of? (viewed 76735 times)
  119. Why isn't the sky bright at night if the universe has so many stars? (viewed 75701 times)
  120. Did astronauts really go to the Moon, or is it a hoax? (viewed 75114 times)
  121. Why aren't there any green stars? (viewed 74400 times)
  122. Since Earth is spinning, why do we land in the same place when we jump or fall? (viewed 74297 times)
  123. How are galaxies formed? (viewed 74158 times)
  124. How many stars are born and die each day? (viewed 73244 times)
  125. What is the difference between a "star" and a "sun"? (viewed 72422 times)
  126. Who has landed on the moon? (viewed 72341 times)
  127. How are black holes made? Could one be made close to us? (viewed 72197 times)
  128. Will the Sun become a black hole one day? (viewed 71472 times)
  129. What would happen if a supermassive black hole came close to the Earth? (viewed 71325 times)
  130. What is the density of a black hole? (viewed 70654 times)
  131. What are the requirements for being a planet? (viewed 70022 times)
  132. What would you see from inside a black hole? (viewed 69449 times)
  133. Do most astronomers believe in God based on the available scientific evidence? (viewed 68160 times)
  134. Can you fire a gun on the Moon? (viewed 67788 times)
  135. Can moons have moons? (viewed 67595 times)
  136. How do astronomers measure the brightness of stars? (viewed 67470 times)
  137. How do rockets move in space? (viewed 67151 times)
  138. What happens to a substance if its speed is more than the speed of light? (viewed 67020 times)
  139. Why can't you see stars during the day? (viewed 66994 times)
  140. How often does the Sun pass through a spiral arm in the Milky Way? (viewed 66917 times)
  141. What are some of the effects of solar flares on Earth? (viewed 66646 times)
  142. Why is the moon in a different place every night? (viewed 66323 times)
  143. How do we weigh objects in space? (viewed 66266 times)
  144. How can the Universe expand faster than the speed of light during inflation? (viewed 66199 times)
  145. Is it possible to measure the temperature of the Sun? (viewed 66016 times)
  146. How is astronomy impacted by trigonometry? (viewed 65703 times)
  147. How do we know the mass of the Earth and the Moon? (viewed 65539 times)
  148. When the Sun converts mass to energy, do the orbits of the planets change? (viewed 65309 times)
  149. How does the Sun compare to other stars? (viewed 65159 times)
  150. What are the "dog days of summer"? (viewed 65066 times)
  151. What would happen if you took off your helmet in space? (viewed 64631 times)
  152. How does the Moon stay "suspended" in the air? (viewed 63798 times)
  153. How do you measure a planet's mass? (viewed 63782 times)
  154. Why do stars change colour when they twinkle? (viewed 63739 times)
  155. What kinds of jobs do astronomers do? (viewed 63714 times)
  156. Does the Mediterranean sea have tides? (viewed 63238 times)
  157. How are elements heavier than iron formed? (viewed 62957 times)
  158. What are black holes made of? (viewed 62390 times)
  159. What causes seasons? (viewed 62221 times)
  160. When can I see the Moon through the hole in the Pantheon? (viewed 61837 times)
  161. If the universe is infinite does that mean there is an infinite number of "me"s? (viewed 61779 times)
  162. What is the evidence supporting the nebula theory of Solar System formation? (viewed 61689 times)
  163. Does quantum entanglement imply faster than light communication? (viewed 61589 times)
  164. Why doesn't the earliest sunset occur on the shortest day of the year? (viewed 61023 times)
  165. Why do we not have eclipses every month? (viewed 60897 times)
  166. How did the stars get named? (viewed 60838 times)
  167. How did asteroids form and what is the difference between an asteroid and a comet? (viewed 60381 times)
  168. How fast is the Universe expanding? (viewed 60329 times)
  169. Where does the name "Moon" come from? (viewed 60168 times)
  170. What's the best college for astronomy? (viewed 60070 times)
  171. Why doesn't the length of each day change much around the solstices? (viewed 59857 times)
  172. Why do planets not twinkle? (viewed 59603 times)
  173. What are Altitude and Azimuth? (viewed 59444 times)
  174. What would happen to us if the sun went out for an hour? (viewed 59371 times)
  175. Traveling at light speed, how long would it take to get to the nearest galaxy? (viewed 59200 times)
  176. How do you measure the mass of a star? (viewed 59115 times)
  177. How long would it take the Earth to fall into the Sun? (viewed 59114 times)
  178. Where did the matter in the universe come from? (viewed 58824 times)
  179. What is the mass of the Universe? (viewed 58554 times)
  180. Are there stars outside of galaxies? (viewed 58545 times)
  181. Where, in relation to the entire universe, is the Milky Way located? (viewed 57630 times)
  182. How does light pollution affect astronomers? (viewed 57577 times)
  183. Does the Moon rotate? (viewed 57523 times)
  184. Could there be life in the galaxies nearest to the Milky Way? (viewed 57124 times)
  185. How can I calculate the position or path of the Sun for a given time and location? (viewed 56606 times)
  186. Why does the Earth have only one moon? (viewed 56453 times)
  187. Why does the Sun's apparent path through the sky change throughout the year? (viewed 55842 times)
  188. Can any galaxies be seen with the naked eye? (viewed 55720 times)
  189. What is the shape of the universe? (viewed 55250 times)
  190. What's the difference between dark matter and dark energy? (viewed 55243 times)
  191. What is the largest structure in the universe? (viewed 55084 times)
  192. How does the parachute in a model rocket work? (viewed 54532 times)
  193. What is the origin of spiral structure in galaxies? (viewed 54440 times)
  194. Where are stars born? (viewed 54247 times)
  195. How long does the supernova stage of a star last? (viewed 53767 times)
  196. How close was the Moon to the Earth when it formed? (viewed 53750 times)
  197. Are names given to black holes? (viewed 53666 times)
  198. How does astronomy benefit humankind? (viewed 53595 times)
  199. What makes up most of the Universe? (viewed 53498 times)
  200. What is the size of a black hole? (viewed 53092 times)
  201. Can you see satellites? (viewed 53025 times)
  202. How do astronauts use math in their jobs? (viewed 52734 times)
  203. What is a star's "spectrum"? (viewed 52734 times)
  204. Why isn't the summer solstice the hottest day of the year? (viewed 52699 times)
  205. Which constellation does our Sun belong to? (viewed 52059 times)
  206. How do you calculate the azimuth and altitude of an object? (viewed 51824 times)
  207. How do we measure the size of the Moon and of the Sun? (viewed 51718 times)
  208. Are aliens or UFOs real? (viewed 51603 times)
  209. What can we learn from the color of a star? (viewed 51591 times)
  210. Why do we see stars? (viewed 51028 times)
  211. How can I find the distance to the Sun on any given day? (viewed 50897 times)
  212. How can I measure the distance of a star? (viewed 50727 times)
  213. What are some astronomy science fair projects? (viewed 50723 times)
  214. Why is looking out into space the same as looking back in time? (viewed 50711 times)
  215. What other careers involve Astronomy besides Astronomer? (viewed 50545 times)
  216. Is the speed of light constant? (viewed 50282 times)
  217. If gravity is a "curvature of space" rather than a force, why do a ball and bullet follow different paths? (viewed 50266 times)
  218. What happens to a bullet fired on the moon? (viewed 50260 times)
  219. Is the Moon seen as a crescent (and not a "boat") all over the world? Is the same phase of the moon visible from the Northern and Southern hemispheres? (viewed 49671 times)
  220. Are there any asteroids on a collision course with Earth? (viewed 49518 times)
  221. How long has there been water on Earth? (viewed 49470 times)
  222. Is time travel possible? (viewed 49437 times)
  223. Who discovered each planet? (viewed 49127 times)
  224. Which hemisphere has the best view of the Milky Way? (viewed 49053 times)
  225. How do the astronauts communicate in space if sound cannot travel in a vacuum? (viewed 49035 times)
  226. If the Earth's rotation period is less than 24 hours, why don't our clocks fall out of sync with the Sun? (viewed 48673 times)
  227. What would happen if the Moon fell out of its orbit around Earth? (viewed 48635 times)
  228. Why does the Moon look big on the horizon? (viewed 48369 times)
  229. Why is the sky blue and not blue & purple? (viewed 48270 times)
  230. Would your weight change as you go underground? (viewed 48142 times)
  231. Can we look back far enough in time to see the Big Bang? (viewed 47916 times)
  232. Why is it difficult to understand the expansion of the universe? (viewed 47588 times)
  233. Are meteorites hot or cold when they hit Earth? (viewed 47521 times)
  234. What is a graviton? (viewed 47219 times)
  235. What do a galaxy's colors mean? Are they its true colors? (viewed 47081 times)
  236. If light has no mass, then what draws it into a black hole? (viewed 46949 times)
  237. Why is twilight short near the equator? (viewed 46921 times)
  238. What is the difference between nutation and precession of the Earth? (viewed 46832 times)
  239. Are the planes of solar systems aligned with the plane of the Galaxy? (viewed 46237 times)
  240. How is the time of sunrise calculated? (viewed 46012 times)
  241. What's the difference between astronomy and astrophysics? (viewed 45850 times)
  242. What skills do astronomers need? (viewed 45788 times)
  243. Where did all the water in the universe come from? (viewed 45692 times)
  244. What do I need to do to become an astronomer? (viewed 45392 times)
  245. Do dead stars still shine? (viewed 45254 times)
  246. Where is the nearest black hole? (viewed 44762 times)
  247. How do gravitons escape black holes to tell the universe about their gravity? (viewed 44477 times)
  248. Do supermassive black holes cause galaxy rotation? (viewed 44372 times)
  249. Why do the size and brightness of the full moon change? (viewed 44227 times)
  250. Will we get sucked into the black hole at the center of the Milky Way? (viewed 44190 times)
  251. What is a wormhole? (viewed 44038 times)
  252. How are black holes discovered? (viewed 43891 times)
  253. How do we know what other planets (and stars, galaxies, etc.) are made of? (viewed 43792 times)
  254. Why can't we see Venus at night when it is an inner planet? (viewed 43739 times)
  255. Can I calculate the size of the Universe by converting light years to kilometres? (viewed 43686 times)
  256. How do galaxies collide in an expanding universe? (viewed 43500 times)
  257. The Moon slows the Earth's rotation, but how fast was it spinning billions of years ago? (viewed 43223 times)
  258. Is the Earth slowly getting larger? (viewed 42992 times)
  259. Why are there stars? (viewed 42959 times)
  260. Why does the Sun appear larger on the horizon than overhead? (viewed 42902 times)
  261. Why does Barnard 68 appear dark? (viewed 42881 times)
  262. Can we find the place where the Big Bang happened? (viewed 42380 times)
  263. What is the biggest crater recorded on Earth? (viewed 41839 times)
  264. Was the Sun made in a supernova? (viewed 41639 times)
  265. How much longer will the Earth last? (viewed 41042 times)
  266. Why are most months 30 or 31 days long? (viewed 40920 times)
  267. Are Kuiper Belt Objects asteroids? Are large Kuiper Belt Objects planets? (viewed 40859 times)
  268. Why does the location of sunrise change? (viewed 40828 times)
  269. Can I buy land on the Moon? (viewed 40819 times)
  270. Has there been an experiment that measured speed faster than the speed of light in vacuum? (viewed 40791 times)
  271. Could the Universe have expanded faster than the speed of light at the Big Bang? (viewed 40647 times)
  272. Why doesn't dark matter fall into a black hole? (viewed 40581 times)
  273. Are there eclipses on other planets? (viewed 40552 times)
  274. Is the Moon hollow? (viewed 40515 times)
  275. Is there a "South Star"? (viewed 40478 times)
  276. What happens when two black holes get too close? (viewed 40335 times)
  277. What is the best way to see the Milky Way? (viewed 40316 times)
  278. What's the biggest meteorite? (viewed 40296 times)
  279. How would the weather on Earth be different if it were a cube? (viewed 40235 times)
  280. What happens to spacetime inside a black hole? (viewed 40084 times)
  281. What is time dilation? (viewed 40034 times)
  282. Why does the Earth only see one side of the Moon? (viewed 39965 times)
  283. What is the difference between the "Doppler" redshift and the "gravitational" or "cosmological" redshift? (viewed 39939 times)
  284. What color would Mars be if you were standing on it? (viewed 39805 times)
  285. Why don't people walk upside-down on the bottom of the Earth? (viewed 39797 times)
  286. What is the most distant known galaxy? (viewed 39723 times)
  287. Did life originate on Earth, or did it come from somewhere else? (viewed 39692 times)
  288. How does Astronomy involve Chemistry? (viewed 39545 times)
  289. How can two moons of Saturn share the same orbit? (viewed 39198 times)
  290. How long could life on Earth survive if the Sun stopped shining? (viewed 38887 times)
  291. How much can the location of sunset differ from due West? (viewed 38815 times)
  292. How long would it take for a mini-black hole to eat the Earth? (viewed 38701 times)
  293. What are the names of the three stars in Orion's belt? (viewed 38667 times)
  294. Can terrestrial planets have rings? (viewed 38657 times)
  295. How many Astronauts have been in space? (viewed 38446 times)
  296. Could someone travel the universe in his or her own lifetime? (viewed 38323 times)
  297. Why do pictures of distant galaxies have higher resolution than those of nearby planets? (viewed 38252 times)
  298. What if the Earth rotated twice as fast? (viewed 38204 times)
  299. What are "blue stragglers" in globular clusters? (viewed 37791 times)
  300. What is the typical size of a visible shooting star? (viewed 37716 times)
  301. Does Mt. Everest cast a shadow on the moon? (viewed 37667 times)
  302. Why do people draw stars with five points? (viewed 37606 times)
  303. If a white dwarf is a "dead" star, why is it so hot? (viewed 37404 times)
  304. Is it possible to see the full Moon and the Sun simultaneously in high northern latitudes when the Sun doesn't set? (viewed 37234 times)
  305. Is the Great Wall the largest galaxy cluster? (viewed 37220 times)
  306. How do we know that nuclear fusion is still going on in the Sun? (viewed 37146 times)
  307. How does night and day work? (viewed 37140 times)
  308. What is the speed of gravity? (viewed 37072 times)
  309. What can I use for fuel in my homemade rocket? (viewed 36943 times)
  310. How do we feel heat? (viewed 36931 times)
  311. Can a person go into a black hole and come out alive? (viewed 36868 times)
  312. How big is the universe? (viewed 36854 times)
  313. How fast does the Earth go at perihelion and aphelion? (viewed 36840 times)
  314. Can the acceleration of the Universe be analogous to apparent acceleration in a airplane? (viewed 36770 times)
  315. Where is the supernova remnant that led to our solar system? (viewed 36680 times)
  316. What is Earthrise over the Moon? (viewed 36653 times)
  317. What is a dimension? (viewed 36594 times)
  318. Can I communicate faster than light? (viewed 36564 times)
  319. Where do planetary rings come from, and what are they made of? (viewed 36425 times)
  320. On which days can I see the Moon in the evening / morning and why is this so? (viewed 36298 times)
  321. Can you see the future as you fall into a black hole? (viewed 36268 times)
  322. What is the approximate GPA needed in High School in Math and Science to be an astronomer? (viewed 36112 times)
  323. Why are Saturn's rings flat? (viewed 36032 times)
  324. Is there really a 10th planet? (viewed 35985 times)
  325. Does the Sun have an iron surface? (viewed 35877 times)
  326. Why is sea water salty, and not lake water? (viewed 35784 times)
  327. What would happen to the Earth if an asteroid hit the Moon? (viewed 35774 times)
  328. Are all stars the same? (viewed 35769 times)
  329. How many stars can I see? (viewed 35739 times)
  330. Why can we see the sun's image before sunrise and after sunset? (viewed 35686 times)
  331. How do I tell which planet is which? (viewed 35669 times)
  332. Does the Coriolis force determine which way my toilet drains? Does it affect black holes? (viewed 35555 times)
  333. How do we determine the age of the universe? (viewed 35522 times)
  334. Who (and when) discovered that the earth's axis is on a 23 degree tilt? (viewed 35487 times)
  335. What companies or businesses can astronomers work for? (viewed 35441 times)
  336. Do you think it's possible to maintain life on other planets? (viewed 35437 times)
  337. Do the Sun's or Earth's magnetic field reverse? (viewed 35233 times)
  338. Is the Sun always up for exactly 12 hours at the equator? (viewed 34994 times)
  339. Is there a beginning and an end to a galaxy's life? (viewed 34946 times)
  340. If the universe is 15 billion years old, how can it be larger than 15 billion light years across? (viewed 34898 times)
  341. How can I find my age on another planet? (viewed 34565 times)
  342. Is Andromeda part of the Milky Way? Where can I find them in the sky? (viewed 34410 times)
  343. How do we know the Milky Way is a spiral galaxy? (viewed 34243 times)
  344. Why do clocks turn in the opposite direction from the Earth and Moon? (viewed 34190 times)
  345. How do we define distance in an expanding universe? (viewed 34189 times)
  346. Why have star signs shifted by one constellation? (viewed 34118 times)
  347. What was that really big falling star that I saw? (viewed 34115 times)
  348. How can the universe be "flat"? We're 3D! (viewed 33763 times)
  349. How are photons created and destroyed? (viewed 33704 times)
  350. When we look back to the Big Bang, why don't we see the universe as a tiny speck of matter? (viewed 33451 times)
  351. How does the brightness of a star depend on its distance from us? (viewed 33419 times)
  352. Why do humans want to go in space? (viewed 33352 times)
  353. Who came up with the name "black hole"? (viewed 33351 times)
  354. Is the Earth at the centre of the Universe? (viewed 33326 times)
  355. What would happen if two stars collided? (viewed 33315 times)
  356. Why don't astronomers use everyday units to measure distances (what is an AU or a pc)? (viewed 33277 times)
  357. What is the pattern to the distances between each planet and the sun? (viewed 33276 times)
  358. How can we estimate the number of Earth-like planets in the Galaxy? (viewed 33187 times)
  359. What is the significance of the second focus of elliptical orbits of planets in our Solar System? (viewed 33149 times)
  360. Is there a simple formula to calculate solar eclipse timings from any position on Earth? (viewed 33141 times)
  361. How do astronauts communicate with their families from space? (viewed 33088 times)
  362. Can a lunar and a solar eclipse happen in the same month? When will this happen next? (viewed 33038 times)
  363. How are planets detected around other stars? (viewed 33021 times)
  364. Are Earth and the Moon "twin planets"? (viewed 32904 times)
  365. How is it that we see farther out in space (farther back in time) than in the past? (viewed 32846 times)
  366. Will the Moon be invisible in 500 million years? (viewed 32832 times)
  367. Which American colleges teach astronomy? (viewed 32665 times)
  368. Will we ever stop having solar eclipses because of the moon's motion away from the Earth? (viewed 32633 times)
  369. How dangerous are the asteroids? (viewed 32631 times)
  370. Why is our solar system so different from all the others we've found? (viewed 32498 times)
  371. Can we colonize other planets? (viewed 32439 times)
  372. Why are there blue shifted galaxies? (viewed 32383 times)
  373. Why is Uranus tipped on its side? (viewed 32220 times)
  374. What kind of eyepieces do I need to look at planets? (viewed 32152 times)
  375. How do I become both an astronaut and an astronomer? (viewed 31779 times)
  376. How can I calculate distances between stars? (viewed 31714 times)
  377. What are quasars made of? (viewed 31666 times)
  378. Why doesn't gravity change the speed of light? (viewed 31411 times)
  379. Why do constellations look the same after several years even though all the stars are moving? (viewed 31227 times)
  380. Is it possible to count the stars? (viewed 31203 times)
  381. Is time travel possible using merging black holes? (viewed 31181 times)
  382. Why do astronauts in space need to exercise? (viewed 31053 times)
  383. Why are there no craters on Earth? Did all the meteorites miss us? (viewed 31014 times)
  384. How do sunrise and sunset times change with altitude? (viewed 31006 times)
  385. What is happening just around the black hole in the center of the Milky Way? (viewed 30950 times)
  386. Is the gravitational force exerted by the Earth on the Moon equal to the centripetal force acting on the Moon? (viewed 30868 times)
  387. What is dark matter? (viewed 30793 times)
  388. How hot is each one of the layers of the sun? (viewed 30665 times)
  389. Did the speed of light change over the history of the universe? (viewed 30617 times)
  390. How can we distinguish a star's "real" color from the change in color that we observe due to the star's motion? (viewed 30607 times)
  391. Can we see dead stars with the naked eye? (viewed 30582 times)
  392. How big a change in the Earth's orbit would be required to destroy all life? (viewed 30561 times)
  393. How do we measure distances to other stars? (viewed 30401 times)
  394. Can superheavy elements (such as Z=116 or 118) be formed in a supernova? Can we observe them? (viewed 30362 times)
  395. Is it true that the Sun burns off a billion tons of gas every 5 seconds? (viewed 30351 times)
  396. Are time machines possible? (viewed 30313 times)
  397. What happens when an antimatter black hole collides with a matter blackhole? (viewed 30275 times)
  398. Is the universe really like an expanding balloon? (viewed 30217 times)
  399. How do I make a scale model of the Solar System? (viewed 30132 times)
  400. How many moles of stars are in the known universe? (viewed 29854 times)
  401. Is there any limitation to what a black hole can "suck" in? (viewed 29659 times)
  402. Can you describe a day on the job as an astronomer? (viewed 29461 times)
  403. How are galaxy distances inferred from their recessional velocities? (viewed 29443 times)
  404. What's that dark spot on the Sun? (viewed 29276 times)
  405. What is the farthest in space that we have gone? (viewed 29066 times)
  406. How can we tell what the interiors of planets are like? (viewed 29007 times)
  407. How can I tell if the rock I found is a meteorite? (viewed 29006 times)
  408. What are the closest and/or brightest stars? (viewed 28914 times)
  409. What happens when you change the mass of a White Dwarf or Neutron Star? (viewed 28908 times)
  410. How can we know that there are other galaxies if we cannot leave ours? (viewed 28853 times)
  411. Could an astronaut or satellite fall into a black hole that we didn't know about? (viewed 28706 times)
  412. Can astronauts produce water in space? (viewed 28660 times)
  413. Will the seasons change due to precession? (viewed 28636 times)
  414. What are the facts about the Star of Bethlehem? (viewed 28619 times)
  415. Did I see the Aurora Borealis as a child? (viewed 28600 times)
  416. Is the Local Group expanding along with the entire Universe? (viewed 28588 times)
  417. Don't tachyons travel faster than light? (viewed 28557 times)
  418. Why is the time between two successive full moons different from the lunar synodic month? (viewed 28529 times)
  419. Why do most moons orbit their planets at the equator? (viewed 28525 times)
  420. Do astronomers believe in astrology? (viewed 28520 times)
  421. Aren't jobs in astronomy scarce? (viewed 28425 times)
  422. What are the atmospheres of Mars and Pluto like? (viewed 28417 times)
  423. How long does it take the Big Dipper to move in the sky? (viewed 28410 times)
  424. How was the starting point for the Julian Date system chosen? (viewed 28373 times)
  425. Why does the SETI project search for radio signals? (viewed 28345 times)
  426. What do "homogeneity" and "isotropy" mean? (viewed 28285 times)
  427. Has anyone made a map of the Milky Way? (viewed 28213 times)
  428. When are there 5 Sundays in February? (viewed 28207 times)
  429. Why do we study black holes? (viewed 28144 times)
  430. Was I hit by a meteorite? (viewed 28134 times)
  431. Wouldn't the Big Bang theory be considered a hypothesis and not a theory? (viewed 28121 times)
  432. How do we know if the universe will keep expanding forever? (viewed 28076 times)
  433. How are galaxies named? (viewed 28015 times)
  434. What does the term "visible universe" mean? (viewed 27874 times)
  435. What colors are visible through an amateur telescope? (viewed 27833 times)
  436. How can geometry be different in space? (viewed 27787 times)
  437. Does the Milky Way spin counter-clockwise? If so, do all spiral galaxies spin in this direction and why? (viewed 27652 times)
  438. Why can't a plane fly slowly and let the Earth pass underneath? (viewed 27578 times)
  439. Could you tell me about the life cycle of galaxies? (viewed 27488 times)
  440. Why are the compositions of comets and asteroids different? (viewed 27439 times)
  441. Can you use an infinite line of reflectors to send light to the edge of the Universe? (viewed 27405 times)
  442. Do you believe in UFOs? (viewed 27364 times)
  443. Will winter and summer constellations change due to abnormal warmth or cold on Earth? (viewed 27273 times)
  444. How do asteroids, meteors and comets disappear? (viewed 27270 times)
  445. How much time do astronomers spend looking through telescopes? (viewed 27153 times)
  446. How will the two black holes that are going to collide affect Earth? (viewed 27139 times)
  447. Have there been other Big Bangs before? (viewed 27049 times)
  448. How can we see galaxies if their stars are so faint? (viewed 26907 times)
  449. What's the best thing about being an astronomer? (viewed 26901 times)
  450. Can life exist on the recently discovered extrasolar planets? (viewed 26897 times)
  451. Do we see the same stars from above and below the equator? (viewed 26778 times)
  452. How do astronomers measure the radius of a star? (viewed 26714 times)
  453. How close do you have to come to the Earth to be influenced by its gravity? (viewed 26713 times)
  454. Is the Milky Way a collision of two galaxies? (viewed 26613 times)
  455. How do I explain to my children why the Moon has phases? (viewed 26557 times)
  456. How are galaxies and solar systems similar? (viewed 26544 times)
  457. Is there a project I can do on black holes? (viewed 26534 times)
  458. Can two lunar eclipses occur in the same month? (viewed 26526 times)
  459. How can we measure distances to more stars? (viewed 26506 times)
  460. Could you escape from a black hole if you were able to go faster than the speed of light? (viewed 26370 times)
  461. Why do so many of the world's UFO sightings happen in America? (viewed 26304 times)
  462. Is infinite temperature possible? (viewed 26268 times)
  463. How do scientists slow light down? (viewed 26252 times)
  464. Do we know everything about the Sun? (viewed 26245 times)
  465. How close does a supernova need to be to damage the Earth's environment? (viewed 26114 times)
  466. Do the magnitudes and colors of stars ever change? (viewed 26024 times)
  467. Can one star orbit another? (viewed 25998 times)
  468. Can "tired light theory" explain the observed redshifts of galaxies? (viewed 25929 times)
  469. How far does a galaxy extend? (viewed 25833 times)
  470. Is it worthwhile to continue the search for extraterrestrial life? (viewed 25786 times)
  471. How do I polar align my telescope? (viewed 25754 times)
  472. What supernova created the Crab nebula? (viewed 25741 times)
  473. Is there such a thing as hyperspace? (viewed 25701 times)
  474. Can double stars have planets? (viewed 25663 times)
  475. What happens to the material that has been sucked into a black hole? (viewed 25633 times)
  476. What type of energy does a black hole have? (viewed 25581 times)
  477. What is the origin of the stellar classification system "OBAFGKM"? (viewed 25578 times)
  478. What causes gamma ray bursts? (viewed 25572 times)
  479. Do asteroids hit the sun? (viewed 25564 times)
  480. What will happen to the Milky Way in the future? (viewed 25512 times)
  481. What is the farthest Northern Latitude in which the Magellanic Clouds can be seen? (viewed 25503 times)
  482. Why do the explosions of Type Ia supernovae have a more predictable spectrum than those of regular Type II supernovae? (viewed 25496 times)
  483. Can astronauts play musical instruments in space? (viewed 25461 times)
  484. What is sidereal time? (viewed 25419 times)
  485. Which way does the sun travel in the southern hemisphere? (viewed 25371 times)
  486. How will a change in the speed of light affect the evolution of the Universe? (viewed 25316 times)
  487. How do we know what parameters to use when simulating the collision of the Milky Way and Andromeda? (viewed 25134 times)
  488. Is there oxygen in the atmospheres of other planets? (viewed 25109 times)
  489. What's the object I saw that moved across the sky and then got very bright? (viewed 25071 times)
  490. What is "nothing", from a scientific point of view? (viewed 24998 times)
  491. How do we know that sunspots are associated with the Sun's magnetic field? (viewed 24990 times)
  492. Why did the Pioneer and Voyager take only 2 years to reach Jupiter, while Galileo and Cassini took more than 5 years? (viewed 24966 times)
  493. How different would the night sky have looked in 40,000 B.C.? (viewed 24919 times)
  494. What is a Cepheid variable? (viewed 24898 times)
  495. Why do we assume that the universe is homogeneous? (viewed 24850 times)
  496. Are there any dark stars or dark galaxies made of dark matter? (viewed 24842 times)
  497. Was Stonehenge built to mark solar phenomena? (viewed 24789 times)
  498. Is there sound coming from the Sun? (viewed 24787 times)
  499. What calculations go into predicting eclipses? (viewed 24732 times)
  500. Is there a list of the sizes of different kinds of stars? (viewed 24697 times)
  501. Why is the shadow on the Moon the shape it is? (viewed 24684 times)
  502. When unmanned spacecraft accelerate in space, what causes them to slow down? (viewed 24651 times)
  503. What is a Dyson Sphere? (viewed 24647 times)
  504. What's so exciting about the new planet around 55 Cancri? (viewed 24626 times)
  505. What process would bring about a quark star? (viewed 24615 times)
  506. Have gravitational waves been proven to exist? (viewed 24532 times)
  507. Did a giant impact cause the Dark Ages? (viewed 24527 times)
  508. What is the difference between homogeneity and isotropy? (viewed 24513 times)
  509. Which part of the sky did the famous 'wow' signal originate from? (viewed 24497 times)
  510. If we invented special suits could we ever go to the sun? (viewed 24483 times)
  511. When did people discover that the Sun is a star? (viewed 24457 times)
  512. How many sunspots can the Sun have at once? (viewed 24418 times)
  513. Can I see a quasar? (viewed 24392 times)
  514. Are planetary nebulae the result of supernovae? (viewed 24388 times)
  515. Can I see details on Venus? (viewed 24339 times)
  516. How are asteroid compositions and classifications determined? (viewed 24289 times)
  517. Can any comparison be made between spiral galaxies and hurricanes? (viewed 24262 times)
  518. What is our galaxy's halo made of, and how was it formed? (viewed 24247 times)
  519. Why are there active volcanos on Io? (viewed 24214 times)
  520. Is there any possibility that the Solar System or the Universe is in a black hole? (viewed 24137 times)
  521. What equipment do I need for astrophotography? (viewed 24098 times)
  522. Does Cerenkov radiation travel faster than light? (viewed 24065 times)
  523. How is it proved that the Universe is expanding? (viewed 24017 times)
  524. Can a human give birth in space? (viewed 23988 times)
  525. How big was the Sun when it first "fired up"? (viewed 23927 times)
  526. What happened to all the black holes that were around in the early universe? (viewed 23870 times)
  527. Why are there more maria on the near side of the Moon? (viewed 23834 times)
  528. If clocks run slow in a gravitational field, how can we know the true age of the Solar System and Universe? (viewed 23793 times)
  529. How can we compare dark matter and dark energy? (viewed 23789 times)
  530. Could we send a space mission to a comet? (viewed 23764 times)
  531. What caused Shoemaker-Levy 9 to split up? (viewed 23755 times)
  532. Could we be seeing dead stars? (viewed 23701 times)
  533. Why are telescopes kept in cold conditions? (viewed 23683 times)
  534. Why do photos of space taken from space never show any stars? (viewed 23648 times)
  535. How are sunspots formed? (viewed 23581 times)
  536. If the Universe was infinitely dense at the Big Bang, why didn't time stand still? (viewed 23575 times)
  537. How long do supernova remnants last? (viewed 23535 times)
  538. How do solar flares affect airline pilots? (viewed 23507 times)
  539. Would the biggest airplanes cause tsunamis if they crashed? (viewed 23467 times)
  540. Why doesn't light from distant galaxies reach us instantaneously? (viewed 23459 times)
  541. How many comets are currently orbiting our sun? (viewed 23379 times)
  542. As the universe expands, why don't galaxies get stretched out? (viewed 23377 times)
  543. What happened to the girl who named Pluto? (viewed 23358 times)
  544. Why is the Hubble Space Telescope in space? (viewed 23346 times)
  545. Could a different theory of gravity explain the dark matter mystery? (viewed 23301 times)
  546. How does the Earth compare in size to the entire universe at the present epoch? (viewed 23270 times)
  547. How do we know that superclusters are the largest structures in the universe? (viewed 23236 times)
  548. Can you tell time by the Big Dipper? (viewed 23188 times)
  549. Why doesn't NASA build rotating spacecraft to simulate gravity? (viewed 23182 times)
  550. How powerful are quasars? (viewed 23097 times)
  551. Can you give me advice on buying a telescope? (viewed 23086 times)
  552. Would extraterrestrial civilizations know that there is life on Earth? (viewed 23045 times)
  553. Can I build an instrument to measure the size of the Sun and of the Moon? (viewed 22912 times)
  554. Where does the kinetic energy of infalling bodies come from? (viewed 22887 times)
  555. How is the Cepheid yardstick validated? (viewed 22876 times)
  556. Did I really hear a meteor? (viewed 22828 times)
  557. Can supernovae hinder the formation of life in galaxies? (viewed 22803 times)
  558. What would happen if there was a collision between two white dwarfs? (viewed 22775 times)
  559. Are there any new craters on the moon? (viewed 22730 times)
  560. Do unmanned spacecraft like Voyager travel in straight lines? (viewed 22729 times)
  561. Why are stars of different masses? (viewed 22707 times)
  562. How do planets capture satellites? (viewed 22665 times)
  563. Did time go slower just after the Big Bang? (viewed 22628 times)
  564. Why is it important to study meteorites? (viewed 22625 times)
  565. How big is the Hubble Ultra Deep Field image? (viewed 22612 times)
  566. Do galaxies orbit around anything? (viewed 22599 times)
  567. Do similar laws of physics throughout the Universe imply that all life must be like life on Earth? (viewed 22591 times)
  568. What kind of instruments are used to detect extrasolar planets? (viewed 22582 times)
  569. How do I become an astronomical artist? (viewed 22520 times)
  570. Why are telescopes located in remote places? (viewed 22507 times)
  571. Could there have been multiple Big Bangs at different places in the universe? (viewed 22308 times)
  572. How can I contribute to science as an amateur astronomer? (viewed 22266 times)
  573. Are the properties of extrasolar planets known? (viewed 22214 times)
  574. Are the asteroids the remains of a planet which broke apart? (viewed 22206 times)
  575. Do the Earth's magnetic poles ever change places? (viewed 22205 times)
  576. What kind of telescope should I use for astrophotography? (viewed 22203 times)
  577. How could galaxies have gotten so far away in only 15 billion years? (viewed 22167 times)
  578. How are astronomy and poetry linked? (viewed 22148 times)
  579. Does the Moon look different in the northern and southern hemispheres? (viewed 22142 times)
  580. Why is NASA shutting down the Hubble Space Telescope? (viewed 22126 times)
  581. How can you tell if a crescent moon is preceding or following a new-moon phase? (viewed 22121 times)
  582. Can I listen to the SETI@home radio signal? (viewed 22120 times)
  583. Does the Sun have any heavy elements? (viewed 22086 times)
  584. Could dark energy come from matter anti-matter pairs forming spontaneously and then annihilating? (viewed 22083 times)
  585. What would happen if a human were exposed to space without wearing a spacesuit? (viewed 22024 times)
  586. What month was it when Odysseus saw Orion in 1000BC? (viewed 21983 times)
  587. Will we discover an 11th planet? What would it be called? (viewed 21975 times)
  588. Can the theory of formation of the solar system explain all the observables? (viewed 21955 times)
  589. How do unmanned space probes avoid running into things? (viewed 21813 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 21768 times)
  591. What class of spiral galaxy is the Milky Way? (viewed 21767 times)
  592. Why can't relative velocities add up to more than the speed of light? (viewed 21764 times)
  593. Why does one side of Mars look more catastrophic than the other? (viewed 21707 times)
  594. Why does the apparent density of galaxies drop off at larger distances? (viewed 21639 times)
  595. What makes a satellite geosyncronise itself with Earth's orbit? (viewed 21620 times)
  596. Would a planet near the galactic center have a brighter night sky? (viewed 21596 times)
  597. What is the solar cycle? (viewed 21536 times)
  598. Is it possible for amateurs to do optical interferometry? (viewed 21380 times)
  599. Can other terrestrial moons be (or have been) stable? (viewed 21297 times)
  600. Can a black hole come back to the visual universe through a "little bang"? (viewed 21271 times)
  601. How are supernovae discovered? (viewed 21271 times)
  602. How do astronomers observe the Sun's interior? (viewed 21269 times)
  603. Why was the Platonic year named after Plato? (viewed 21239 times)
  604. Do stars' orbits in galaxies obey Kepler's Laws? (viewed 21213 times)
  605. Could we send a manned mission to the outer planets? (viewed 21152 times)
  606. What would the Big Crunch look like to an observer on Earth? (viewed 21139 times)
  607. Where was the water in the big bang? (viewed 21121 times)
  608. Does inflation allow for an infinite number of universes? (viewed 21114 times)
  609. Could our position in the universe affect our perceptions of the expansion? (viewed 21089 times)
  610. What is meant by "stopping down a telescope"? (viewed 20980 times)
  611. Why doesn't the hydrogen on Jupiter explode? (viewed 20896 times)
  612. Why are accretion disks flat? (viewed 20862 times)
  613. Does a photon observe other photons moving past it at the speed of light? (viewed 20743 times)
  614. Did I find a rock that came from the Moon? (viewed 20696 times)
  615. Can gravitational lensing from intervening galaxies cause the observed ripples in the Cosmic Microwave Background? (viewed 20669 times)
  616. Have astronomers observed any phenomena that could be produced by extraterrestrial civilizations? (viewed 20624 times)
  617. What is the SU(3) quark model? (viewed 20583 times)
  618. Why do spacecraft need heat shields coming back to Earth but not leaving? (viewed 20541 times)
  619. How can water be chemically trapped in rocks? (viewed 20503 times)
  620. How can the Sun have such a strong gravitational field if it's made of gasses? (viewed 20486 times)
  621. What's new with the Big Bang? (viewed 20401 times)
  622. Is it possible to build a cheap device to measure declination? (viewed 20248 times)
  623. If comets are boiling away, why are there any left? (viewed 20233 times)
  624. Could photons be dark matter? (viewed 20208 times)
  625. Why do some eclipses take longer than others? (viewed 20201 times)
  626. Why can we have solar eclipses? (viewed 20197 times)
  627. Will I be able to see the shadow of the Moon streaking towards me in a total solar eclipse? (viewed 20192 times)
  628. How fast do particles travel in space? (viewed 20140 times)
  629. Why search for only Earth-like life on other planets? (viewed 20128 times)
  630. How can we find galaxies behind the Milky Way? (viewed 20080 times)
  631. Where can I find information on the moons of other planets? (viewed 20068 times)
  632. Why is pressure broadening greater in low mass stars than in high mass stars? (viewed 19910 times)
  633. How much power is contained in a beam of light? (viewed 19880 times)
  634. What would an "open geometry" for the universe look like? (viewed 19844 times)
  635. What are the boundaries of the constellations? (viewed 19809 times)
  636. Why is the Cosmic Microwave Background not absorbed by interstellar hydrogen? (viewed 19771 times)
  637. How do astronomers come up with their facts? (viewed 19749 times)
  638. Why aren't discoveries of extrasolar planets reported on the news? (viewed 19717 times)
  639. Did the Sumerians measure precession? (viewed 19672 times)
  640. How do bars form in spiral galaxies? (viewed 19641 times)
  641. What kinds of star clusters are there? (viewed 19633 times)
  642. Can HST see the Oort cloud? (viewed 19619 times)
  643. Why is the WMAP picture of the CMB an ellipse? (viewed 19596 times)
  644. Why don't astronauts sublimate in space? (viewed 19560 times)
  645. Do electrons age? (viewed 19504 times)
  646. How do photons from distant objects maintain enough energy to reach us? (viewed 19454 times)
  647. Can the Space Shuttle abort and return to Earth before reaching orbit? (viewed 19451 times)
  648. Can we make a movie of the Milky Way galaxy's rotation? (viewed 19378 times)
  649. How long is twilight on the Moon? (viewed 19282 times)
  650. Does the shuttle worry about space junk? (viewed 19194 times)
  651. Why do supernova remnants look like rings rather than spheres? (viewed 19096 times)
  652. How does melting a material reset its radioactive clock? (viewed 19092 times)
  653. How did Mars get so dusty? (viewed 19048 times)
  654. How do you classify galaxies? (viewed 18984 times)
  655. Where can I see Newton's original reflecting telescope? (viewed 18978 times)
  656. What is the best time of the year to see eclipses? (viewed 18945 times)
  657. Why doesn't SETI concentrate its observations to the nearby stars and the solar systems that we are discovering? (viewed 18880 times)
  658. Do constellations looks the same from space? (viewed 18860 times)
  659. Will the next generation telescope OWL be able to detect an Earth like extrasolar planet? (viewed 18812 times)
  660. Will astronauts ever be able to go ice-skating on Europa? (viewed 18779 times)
  661. What causes a particle to decay? (viewed 18740 times)
  662. How can we understand the meaning of large numbers like "a million million?" (viewed 18735 times)
  663. Will the Leonid meteor shower go away? (viewed 18732 times)
  664. Why don't all neutron stars become pulsars? (viewed 18714 times)
  665. How can I nominate myself for a Nobel Prize in Physics? (viewed 18702 times)
  666. How long has humanity known that we live in a galaxy similar to others in the Universe? (viewed 18690 times)
  667. Can planets collide with one another? (viewed 18679 times)
  668. Is light of different colors affected differently by gravity? (viewed 18605 times)
  669. What are collections of galaxies called? (viewed 18579 times)
  670. What are "curled" dimensions? (viewed 18564 times)
  671. What was that eclipse I saw in the sky? (viewed 18532 times)
  672. How does interferometry work? (viewed 18418 times)
  673. How do we find out about the star formation histories of galaxies? (viewed 18326 times)
  674. Does the temperature of matter increase as it is accelerated to relativistic speeds? (viewed 18294 times)
  675. How do distant galaxies differ from those nearby? (viewed 18292 times)
  676. Can astronomers observe anything when the moon is full? (viewed 18259 times)
  677. Do asteroids ever do anything good in the Solar System? (viewed 18245 times)
  678. Wouldn't the vast distances of space distort SETI signals into unintelligeble forms? (viewed 18031 times)
  679. Do we really observe the edges of galaxies at different epochs? (viewed 18023 times)
  680. Can you tell me the characteristics of W, R, N and S type stars? (viewed 18004 times)
  681. What do stellar classifications mean? (viewed 17970 times)
  682. Why is it called astronomy when all the other sciences end in -ology? (viewed 17969 times)
  683. Why will fusion wait until hydrogen is gone before starting to fuse heavier atoms? (viewed 17930 times)
  684. What kind of interference must astronomers contend with when observing? (viewed 17917 times)
  685. How are astronauts trained for weightlessness? (viewed 17863 times)
  686. What would happen if you went back in time and killed your grandmother? (viewed 17859 times)
  687. If nothing can escape a black hole, why do some black holes have jets? (viewed 17853 times)
  688. How can I watch the Perseid meteor shower? (viewed 17849 times)
  689. Are black holes spherical? (viewed 17763 times)
  690. How does the color index of a star relate to its actual color? (viewed 17720 times)
  691. Will the diameter of a cluster of galaxies change with redshift? (viewed 17603 times)
  692. Why aren't accretion disks around giant stars as hot as accretion disks around black holes? (viewed 17578 times)
  693. If the universe is "bounded" today, could it one day become "unbounded"? (viewed 17557 times)
  694. Is cosmic expansion happening on microscopic scales? (viewed 17467 times)
  695. What is the three-body problem? (viewed 17437 times)
  696. How can I find out if the new moon has been sighted? (viewed 17386 times)
  697. Do we have to worry about relativity when studying galactic objects? (viewed 17178 times)
  698. Could neutrinos be dark matter? (viewed 17001 times)
  699. What kinds of cancer research have been done in space? (viewed 16978 times)
  700. How does a star take mass from another star? (viewed 16907 times)
  701. How can you tell the difference between single and multiple extrasolar planets? (viewed 16703 times)
  702. What is Hot Dark Matter theory? (viewed 16598 times)
  703. Could the Universe's dark matter be made up of black holes? (viewed 16590 times)
  704. Does lunar gardening really work? (viewed 16172 times)
  705. How does libration allow us to see more than 50% of the Moon? (viewed 16150 times)
  706. How can observations of the distant universe prove that the expansion is accelerating *now*? (viewed 16072 times)
  707. Is it a coincidence that we can have total solar eclipses? Are there other planets which also have them? (viewed 16053 times)
  708. If photons have zero mass, why do they feel the effects of gravity? (viewed 15972 times)
  709. Is light blueshifted when it is gravitationally lensed? (viewed 15957 times)
  710. Do binary or triple star systems form together? (viewed 15954 times)
  711. No matter how fast the universe is expanding, shouldn't gravity eventually make it recollapse? (viewed 15896 times)
  712. When measuring the expansion of the universe, do astronomers consider that they're seeing how galaxies moved long ago, not today? (viewed 15826 times)
  713. Is the green flash real? (viewed 15748 times)
  714. What percent of the time can astronomers observe without interference from the Moon? (viewed 15710 times)
  715. What is the photoelectric effect? Why can't multiple low-frequency photons free an electron? (viewed 15693 times)
  716. How do we know the density of some extrasolar planets? (viewed 15627 times)
  717. What do meteorites tell us about life on other planets? (viewed 15607 times)
  718. Could matter-anti-matter repulsion power the expansion of the universe? (viewed 15423 times)
  719. Why is it easier to see a star if you look slightly to the side? (viewed 15382 times)
  720. How do supernovae show us that the Universe's expansion is accelerating? (viewed 15382 times)
  721. Are there any 'lonely galaxies'? (viewed 14997 times)
  722. Why doesn't the ammonia and methane in Jupiter's atmosphere sink into the core? (viewed 14988 times)
  723. If the sun went out and our atmosphere froze solid, what color would it be? (viewed 14885 times)
  724. Can we prove that the Moon isn't hollow? (viewed 14800 times)
  725. How do we detect incoming meteorites? (viewed 14679 times)
  726. What was different on Mars in the past to allow liquid water to be present? (viewed 14551 times)
  727. During close approaches, can Mars appear in our sky as large as the Moon? (viewed 14377 times)
  728. When will Hale-Bopp return? (viewed 14320 times)
  729. Why don't skydivers burn up like meteors? (viewed 14126 times)
  730. How are planets affected by the Hot Ionised Medium? (viewed 14111 times)
  731. Has anyone ever seen a star "turn on"? (viewed 13997 times)
  732. What happens to the helium formed in the sun? (viewed 13830 times)
  733. Why was Mir burnt up in the atmosphere? (viewed 13644 times)
  734. What are the largest radio wavelengths observed from radio sources in the sky? (viewed 13577 times)
  735. How can we discern different galaxies/clusters along the same line of sight? (viewed 13574 times)
  736. Can the sun rise from the west on Mars? (viewed 13380 times)
  737. How has light from 13 billion years ago not passed us by? (viewed 13282 times)
  738. Why are craters round? (viewed 13254 times)
  739. What is the relationship between the width of a star trail on a photo and the star's intensity? (viewed 13145 times)
  740. Can we harvest H & O from space to make water? (viewed 12289 times)
  741. What is between the Oort cloud and the closest star? (viewed 12172 times)
  742. Why does Titan, in spite of being smaller than Mars, have an atmosphere more dense than Earth's? (viewed 11675 times)
  743. Does weightlessness affect hunger? (viewed 11319 times)
  744. Are there solar tides? (viewed 11283 times)
  745. Could a planetary system survive if its star merged with another, or if its star went supernova? (viewed 11266 times)
  746. Do planets radiate noise? (viewed 10466 times)
  747. What time is sunrise/sunset or moonrise/moonset at my location? (viewed 10446 times)
  748. Is Earth-moon tidal friction causing global warming? (viewed 10417 times)
  749. Is the moon spherical? (viewed 10093 times)
  750. What would happen if a nuclear-powered shuttle exploded? (viewed 10085 times)
  751. Is dark energy affected by black holes? (viewed 9810 times)
  752. What happens to the Earth as the moon gets farther away and will it ever go away entirely? (viewed 9432 times)
  753. Did the Moon or planets form in a manner similar to that of Earth? (viewed 9243 times)
  754. Do more meteorites fall at low latitudes? (viewed 9128 times)
  755. Is it sensible to consider terraforming Mars? (viewed 8999 times)
  756. Why is the Moon higher in the sky in winter and lower in the summer? (viewed 8930 times)
  757. If there are infinity universes, will every thing that is possible happen? (viewed 8921 times)
  758. Will Comet Elenin (C/2010 X1) affect the Earth on its close approach in Fall 2011? (viewed 8897 times)
  759. What are the possible ends of the universe? (viewed 8860 times)
  760. Where are the protons and electrons in a Neutron Star? (viewed 8820 times)
  761. Will the Pioneer and Voyager probes ever leave the Milky Way? (viewed 8742 times)
  762. The Moon and Sun are the same apparent size in the sky. The Moon is moving away from us at 3.8 centimeters/year. Isn't it improbable that we live in an epoch in which they appear the same size in the sky? (viewed 8729 times)
  763. What color are meteors? (viewed 8427 times)
  764. Wait, I'm still confused why information can't travel faster than the speed of light. (viewed 8371 times)
  765. Where is everybody? (viewed 8234 times)
  766. Is the Moon always visible during winter on the North Pole? (viewed 8231 times)
  767. Why does Mars have a dusty atmosphere? (viewed 7595 times)
  768. If I were traveling through space, could I see distant galaxies with my own eyes? (viewed 7548 times)
  769. The naming of Mars (viewed 7537 times)
  770. Does the singularity in a black hole create a new Universe? (viewed 7408 times)
  771. Is the reddish dust of Mars biogenic? (viewed 7220 times)
  772. When will humans travel to Mars and revisit the Moon? (viewed 6816 times)
  773. Where is the Spitzer Space Telescope? (viewed 6801 times)
  774. Does the particles involved in a star's final core collapse travel faster than the speed of light? (viewed 6143 times)
  775. When is the best time to observe zodiacal light? (viewed 5869 times)
  776. How likely is it for a planet to transit its star? (viewed 5254 times)
  777. Why do astronomers use telescopes? (viewed 4856 times)
  778. What causes the aurora? (viewed 4556 times)
  779. How did a transit of Venus provide astronomers with the first measurement of the Earth-Sun distance? (viewed 4372 times)
  780. Can the Sun be closer to the Earth than any planet is to Earth? (viewed 3519 times)
  781. Can we hear sound on Titan? (viewed 3373 times)
  782. Cosmologists say the expansion of the universe is accelerating, what is driving this? (viewed 3271 times)
  783. Does the direction of the moon's crescent change through the night? (viewed 3117 times)
  784. What do all the angles in a table for a planet's orbit mean? (viewed 2862 times)
  785. How do I maximize my chances of seeing shooting stars? (viewed 2084 times)
  786. Are exoplanets real? (viewed 1851 times)
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