86 FAQs about the Moon (The Astronomy Cafe)

 

Basic Facts: NASA/NSSDC Fact Sheet, Links

Missions: Prospector,Ranger,Orbiter,Surveyor,Apollo,Clementine

Calculators: Apogee and Perigee

Pictures: NASA Archive

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

Beginner:

  1. Is the rotation speed of the Earth slowing down?
  2. What do we now know about the patches of ice on the Moon?
  3. Is the Moon moving away from the Earth?
  4. Have gold, silver or diamonds been found on the Moon?
  5. Were there ever lakes on the Moon?
  6. How long is a day on the Moon?
  7. How hot is the Moon?
  8. Is the brightness of the Half Moon really 1/9 the Full Moon?
  9. Why do we only see one side of the Moon?
  10. Can you buy land on the Moon?
  11. If I stood on the Moon, would I see the Earth?
  12. Is there such a thing as Moon germs?
  13. How is it possible for ice to exist on the Moon without sublimating away?
  14. Does our Moon have a technical name?
  15. When we see the Moon in the daytime in North America, do chinese observers see it at night time?
  16. How fast does the Moon rotate and revolve?
  17. Have any new craters been seen in the 100 years of lunar photographs taken from Earth?
  18. Has anyone used a powerful telescope to look at the old Apollo landing sites?
  19. Is it true that the Moon is moving away from the Earth?
  20. Will the Earth always appear in the same location in the sky as seen from the Moon?
  21. How high can you jump on the Moon?
  22. Why is the lunar month exactly equal to the human female menstrual cycle?
  23. At what depth do moonquakes occur?
  24. Why does the Moon rise 50 minutes later each day?
  25. How many pounds of Moon rocks were brought back to earth?
  26. Why is it that you can see the Moon in the daytime during some time of the month, but not at other times?
  27. Can sound travel through the thin atmosphere of the Moon?
  28. Are there any active volcanoes on the Moon?
  29. Has anyone ever seen a crater form on the Moon?
  30. What are the dark spots on the Moon?
  31. What is the physiological process behind the Moon Illusion?
  32. What is the brightest star that can ever be occulted by the Moon?
  33. Which way does the Moon go around the Earth?
  34. Is there a place on the Earth where you will never see the Moon?
  35. Where is the barycenter of the Earth-Moon system located?
  36. Does the Moon have an atmosphere?
  37. What is the biggest and smallest crater on the Moon?
  38. What is the exact orbital period of the Moon?
  39. What direction does the Moon travel in the sky from day to day?
  40. What is the distance to the Moon?
  41. How often are planets occulted by the Moon?
  42. There was a large ring around the Moon one night. What was it?
  43. What is the history behind the Man in the Moon?
  44. Why does the Moon seem to be in different parts of the sky every time I look?
  45. Can we see the back side of the Moon?
  46. What is the term for the point between Earth and Moon where the gravitational forces are equal?
  47. What is it about the lunar surface that makes it so bright from the Earth?
  48. Will we ever go back to the Moon?
  49. In what direction does the Moon move in the sky relative to the stars?
  50. What is the Moon's speed per day relative to the stars?
  51. How many layers make up the Moon's mass?
  52. How is it possible to see the Moon in the daytime?
  53. Has the Moon ever rotated faster than it does now?
  54. Does the Earth go through a complete cycle of phases from the Moon?
  55. Are the rocks on the moon like the ones on earth?
  56. When is the next occultation of the star Aldebaran by the Moon?
  57. Does the Moon have magnetic poles too?
  58. Why is the lunar month longer than the sidereal month?
  59. Is the Moon visible from Barrow Alaska in the summer?
  60. Without a Moon, what would the Earth be like?
  61. Has ice really been detected on the Moon?
  62. Why do some craters have rays and others not?
  63. By how much does the Moon's apparent diameter in the sky change?

Intermediate

  1. Why does the Moon move on a circular orbit?
  2. Is there an archive of lunar perigee and apogee distances for the future?
  3. How do astronomers know that the center of gravity of the Moon is 2 kilometers away from its geometric center?
  4. How will gamma rays be used to detect water ice on the Moon?
  5. Why aren't lunar craters as deep as their diameters would lead you to expect?
  6. If the Earth's rotation were reversed, what would happen to the Moon?
  7. What would happen if the Moon suddenly left orbit around the Earth?
  8. What effect did the Moon have on the Earth during the first few billion years?
  9. How far away from the Earth was the Moon first formed?
  10. Is there an approximate way to calculate the distance to the Moon for any given day?
  11. How many minerals are known to exist on the Moon?
  12. Why do some lunar craters like Tycho and Copernicus have rays?
  13. How was the Moon formed?
  14. Why does the Moon seem bigger on the horizon than high up in the sky?
  15. The Earth- Moon system is almost a double planet. What would have happened if Earth had no Moon?
  16. Creationists say that the lunar crust is thin which means the moon was formed recently. Is this true scientifically?
  17. Who owns the Moon for commercialization purposes?

Advanced

  1. Why does the gravity of the Earth and Moon balance at 40,000 miles from the Moon?
  2. What would happen to the Moon if the Earth changed its mass by 1/2 or 1/4?
  3. Can other moons in the solar system get synched with their planets rotation?
  4. For part of its orbit, the Moon is close to the Sun. Why doesn't the Moon escape the Earth then?
  5. Could you explain what causes the Moon's synchronous rotation?

RETURN to the Question and Answer Index.