110 FAQs about Asteroids, Meteors and Comets (The Astronomy Cafe )

Basic Facts: NASA/NSSDC Fact Sheet, Near Earth Orbit Asteroids,Comets

Orbits and Discoveries: IAU Minor Planet Center , Trans-Neptunian Bodies

Pictures: Galileo Pictures,NEAR Pictures,Comet Images,Hubble Space Telescope

Impact Hazards and Extinctions: NASA/Ames Research Center

 Back to the Astronomy Cafe - 365 of the most popular questions since 1996. Over 1 million page requests!

Beginner:

  1. How big do comets get?
  2. Where on the web can I find out about comets?
  3. Do comets have random orbits or do they follow the ecliptic plane too?
  4. Where in the Milky Way do comets captured in the Oort Cloud originate?
  5. When astronomers say there are trillions of comets beyond the orbit of Pluto, are they still considered a part of our solar system?
  6. Can a comet be larger than the Sun?
  7. Where can I get a list of all the known naked-eye comets?
  8. What is the difference between the Kuiper Cloud and the Oort Cloud?
  9. How fast do comets move?
  10. Where do short-period comets come from?
  11. What is a comet?
  12. Why don't comets get captured by planets when they come close?
  13. How are comets formed?
  14. Is it true the Earth passes through the tail of Halley's Comet in 1910?
  15. How fast do the nuclei of comets rotate?
  16. What is the difference between an asteroid, a comet and a meteorite?
  17. How do you name a comet?
  18. How fast do comets move?
  19. Can you 'simulate' a comets nucleus in the laboratory?
  20. What is the brightest comet ever seen from the earth?
  21. Is it a conspiracy that no major observatories have photographed Hale-Bopp since October 1996?
  22. What would the surface of Hale-Bopp look like up close?
  23. Will Earth pass through the tail of Comet Hale-Bopp?
  24. Could you say something about the 1997 comet Hale-Bopp?
  25. How many times in Earth's history has Halleys Comet appeared?
  26. Was anything peculiar seen in the tail of Comet Hyakutake?
  27. I saw a bright comet in 1959-1962. Any ideas which one it might have been?
  28. What is the name of the spectacular comet seen in the mid 1970's?
  29. When was the last time we had two bright comets in the same year?
  30. Can you say anything about comet P/Wild 2?
  31. Has anything weird been seen near Comet Hale-Bopp in the last week?
  32. Have other comets been seen that are bigger than Hale-Bopp?
  33. Where can I get more information about Comet Hale-Bopp?
  34. Did Mark Twain (1835-1910) really get born and die during the apparitions of Halley's Comet?
  35. When will Halley's comet return?
  36. Why do some comets emit gas and dust even when they are far from the Sun?
  37. Will Comet Swift-Tuttle collide with the Earth in 4000 AD?
  38. What two comets were visible around 729 AD?
  39. What can you tell me about Comet Arend-Roland?
  40. Can you tell me something about Comet Myrkos?
  41. What comets were visible to the naked eye in the late 1950's?
  42. Will the asteroid 1981 Midas collide with the Earth in the 22nd century?
  43. Is the Pentagon planning to shoot down an asteroid soon?
  44. How do you tell if a rock is a meteorite?
  45. When is the best time for viewing the Geminids this year?
  46. If I were to see a fireball in the sky, who should I report it to?
  47. Do any meteorites come from outside the solar system?
  48. Has anyone ever been hit by a meteor?
  49. How big are the particles we call 'Shooting Stars'?
  50. Why do some meteors produce smoke trails and others not?
  51. If I hear a sonic boom soon after seeing a fireball, how close could it have impacted to where I was standing?
  52. How do meteorites form in space?
  53. If meteors burn up in the Earth's atmosphere, where do they keep coming from?
  54. Is a meteor an exploding piece from a supernova?
  55. Which meteor shower is called the 'Tears of St. Lawrence' and why?
  56. How old is the Murchison Meteorite?
  57. How many meteors enter the Earth's atmosphere every day?
  58. What are fireballs and bolides, and how often can you see them?
  59. What does an impact created from a small meteor look like?
  60. What is the difference between an asteroid and a meteorite?
  61. Did the Earth almost get hit by an asteroid on March 23, 1989?
  62. Could Comet Shoemaker-Levy 9 have done more damage to Jupiter if Jupiter had been solid?
  63. Where exactly did the Tunguska Impact occur in 1909?
  64. What would the Cretaceous Impactor have looked like from the ground?
  65. Did the Yukatan Impact really kill the dinosaurs, and when will the next one happen?
  66. What would a scale model of the closest comet passes to the Earth look like?
  67. Which comet has come closest to the Earth?
  68. What happens to a meteor when it hits the ground?
  69. I found an object with a metal detector that looks like a meteorite but is non magnetic. What are the chances?
  70. Is the Earth about to crash into the asteroid belt?
  71. Will a rogue comet or asteroid hit Earth in the next 50 years?
  72. Could an asteroid strike the Earth with little warning?
  73. How much notice would we get from a asteroid like the one that hit Earth 65 million years ago?
  74. Will Halley's Comet ever strike the Earth?
  75. Could a laser beam be used to deflect an asteroid or comet?
  76. What would happen if a large object hit the Earth?
  77. How should a near Earth asteroid be deflected?
  78. How could we protect the Earth against a deadly comet impact?
  79. If a comet was about to strike a heavily populated area, would the authorities try to hush it up to avoid panic?
  80. Will Comet temple-Tuttle hit the Earth on November 11, 2097 and 2396?
  81. Will and asteroid or a comet collide with the Earth in the next 50 years?
  82. What are most asteroids made from?
  83. What ever became of the December 1997 Greenland Fireball?
  84. What would the world do if we knew an asteroid would hit tomorrow?
  85. What would you do if there was a one week warning of an impending asteroid impact?
  86. What building blocks for life could have come from asteroid impacts?
  87. What is the latest about the object that struck Greenland in December, 1997?
  88. Can the impact of a large comet or asteroid change the tilt of a planets rotation axis?
  89. Where can I get information on the 1996-7 Long Island Fireball?
  90. How much actual mass is in the tail of a comet?
  91. Have asteroids hit any of the 50 states in the United States?
  92. Are meteorites worth anything?

Intermediate:

  1. Why do some comets have two tails?
  2. How are comet masses determined?
  3. Why don't the ices in comets just sublimate away?
  4. Why are comets sometimes fainter their first time around the Sun than in subsequent passes?
  5. Why was Halley's Comet so disappointing in 1986?
  6. How do astronomers know that Comet Hyakutake has been around the Sun before?
  7. How did asteroid Ida end up with a companion moonlet?
  8. Can an asteroid have an atmosphere?
  9. Can you build an electronic meteor detector?
  10. How far apart can two people be and still see the same meteor shower?
  11. Is a program for spotting near Earth asteroids and comets really necessary?
  12. How rapidly does dust accumulate on the surface of the Moon?
  13. Can a gigantic comets magnetism cause the Earth's poles to shift?
  14. Could a comet impact on Jupiter trigger thermonuclear fusion in its atmosphere?
  15. Could a laser beam be used to deflect an asteroid or comet?
  16. How are comets and meteors different?
  17. Why isn't the government doing more to protect us from deadly meteor impacts?
  18. What are the odds of the Earth being hit by an asteroid?

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