Rotating Question Curious About Astronomy? Ask an Astronomer

Previously answered questions by Dave Rothstein

(in order of times viewed)

  1. What is the universe expanding into?
  2. Is the universe expanding faster than the speed of light?
  3. How can we see the Milky Way if we are inside it?
  4. Why isn't the sky bright at night if the universe has so many stars?
  5. Does your weight change between the poles and the equator?
  6. Can we feel the Earth spin?
  7. What is the physical difference between a star and a planet?
  8. Why hasn't NASA gone back to the moon?
  9. Does evolution contradict the second law of thermodynamics?
  10. How do you calculate the lifetime of the Sun?
  11. What is the observational difference between a star and a planet?
  12. What would happen if the gravity on Earth was suddenly turned off?
  13. Does gravity vary across the surface of the Earth?
  14. How long does a solar eclipse last?
  15. What is apparent magnitude?
  16. How do astronomers use math in their jobs?
  17. Why is the moon in a different place every night?
  18. What is the density of a black hole?
  19. What happens to a substance if its speed is more than the speed of light?
  20. Do most astronomers believe in God based on the available scientific evidence?
  21. When the Sun converts mass to energy, do the orbits of the planets change?
  22. How long would it take the Earth to fall into the Sun?
  23. Why doesn't the length of each day change much around the solstices?
  24. What can we learn from the color of a star?
  25. How does astronomy benefit humankind?
  26. Could there be life in the galaxies nearest to the Milky Way?
  27. If gravity is a "curvature of space" rather than a force, why do a ball and bullet follow different paths?
  28. What is a star's "spectrum"?
  29. How do astronauts use math in their jobs?
  30. What is the difference between the "Doppler" redshift and the "gravitational" or "cosmological" redshift?
  31. Why do clocks turn in the opposite direction from the Earth and Moon?
  32. How do we know that nuclear fusion is still going on in the Sun?
  33. How do we define distance in an expanding universe?
  34. What are "blue stragglers" in globular clusters?
  35. Can you see the future as you fall into a black hole?
  36. What companies or businesses can astronomers work for?
  37. How does the brightness of a star depend on its distance from us?
  38. Will we ever stop having solar eclipses because of the moon's motion away from the Earth?
  39. How do astronauts communicate with their families from space?
  40. When we look back to the Big Bang, why don't we see the universe as a tiny speck of matter?
  41. Will the Moon be invisible in 500 million years?
  42. Is the universe really like an expanding balloon?
  43. Do we see the same stars from above and below the equator?
  44. Why do astronauts in space need to exercise?
  45. How can we distinguish a star's "real" color from the change in color that we observe due to the star's motion?
  46. What is the farthest in space that we have gone?
  47. What does the term "visible universe" mean?
  48. How can we see galaxies if their stars are so faint?
  49. How close does a supernova need to be to damage the Earth's environment?
  50. What happened to all the black holes that were around in the early universe?
  51. What process would bring about a quark star?
  52. How long do supernova remnants last?
  53. How can we compare dark matter and dark energy?
  54. Would extraterrestrial civilizations know that there is life on Earth?
  55. Could there have been multiple Big Bangs at different places in the universe?
  56. Could dark energy come from matter anti-matter pairs forming spontaneously and then annihilating?
  57. Why do spacecraft need heat shields coming back to Earth but not leaving?
  58. Why are accretion disks flat?
  59. Have astronomers observed any phenomena that could be produced by extraterrestrial civilizations?
  60. Can gravitational lensing from intervening galaxies cause the observed ripples in the Cosmic Microwave Background?
  61. Why do some eclipses take longer than others?
  62. How can we understand the meaning of large numbers like "a million million?"
  63. Is light of different colors affected differently by gravity?
  64. Why aren't accretion disks around giant stars as hot as accretion disks around black holes?
  65. When measuring the expansion of the universe, do astronomers consider that they're seeing how galaxies moved long ago, not today?
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