1. What are the surface gravitational accelerations for the planets?
2. What are the atmospheric constituents of the outer planets?
3. How do astronomers weigh the planets?
4. Can a planet ever explode?
5. Can moons have moons?
6. How are planetary magnetic fields produced?
7. Are all planets round?
8. Does any moon in our solar system also have a moon?
9. How much energy do the planets each get from the Sun compared to the Earth?
10. How many moons and rings do Jupiter, Saturn and Neptune have?
11. Do planets produce eddys behind them in the solar wind?
12. Which planet is hottest, Venus or Mercury?
13. What are the climates like on the inner planets?
14. Why are the atmospheres of Venus, Earth and Mars so different?
15. How were the masses for the Sun and Jupiter determined?
16. How is the mass of a planet determined?
17. What size defines a planet,comet,asteroid or moon?
18. What are moons made of?
19. How bright would it be to stand on the surfaces of each of the planets?
20. How many stars have contributed to producing the heavy elements in our solar system?
21. Photos of the outer planets show them in vivid colors, but the Sun is so far away, aren't they in fact almost invisible if you were there?
22. Why do Venus, Uranus and Pluto have retrograde rotation?
23. Where are the highest winds in the solar system found?
24. In which direction do planets rotate?
25. How do you calculate the period of a planet from its speed and distance from the Sun?
26. What are the diameters and masses of each planet in the solar system?
27. What are the three largest moons in the solar system?
28. How do astronomers estimate the ages for the planets?
29. What are the element abundances for the solar system, Earth and Moon?
30. Do all the bodies in the solar system rotate like the planets and the Sun?
31. Is our solar system typical?
32. How many moons do each of the planets have in our solar system?
33. Are a lot of important issues in exobiology coming together these days?
34. Can you estimate the temperature of a planet by its color?
35. Which planet is the hottest: Jupiter or Mars?
36. What are the mean surface temperatures of the planets?
37. If the atmospheres of several planets contain methane, does that mean that they smell bad?
38. Are the atmospheres of the planets potentially explosive?
39. Why are the other planets lacking water?
40. Why doesn't every planet have a ring?
41. What are the masses of the satellites of Mars?
42. How is the information about the properties of planets deduced?
43. Which planets have mountains on them?
44. Do planetary orbits rotate?
45. Where do planetary rings come from?
46. Do the giant planets have similar internal structure?
47. Do the giant planets like Jupiter have solid surfaces?
48. How is the 0 degree meridian defined on other planets?
49. Where do the planetary moons come from?
50. Why don't Mercury and Venus have moons?
51. Do all planets have North and South poles?
52. What is the name of the valley on Venus that is the lowest point known?
53. Is there any truth to the hypothesis that Pluto is a comet not a true planet?
54. Why do the rings of the planets orbit around the equators rather than the poles of the planets?
55. Why are planets round and not some other shape?
56. Why do planets rotate?

1. Is there any evidence for chaotic motion in the solar system?
2. Does the solar system have a barycenter?
3. How elliptical are the orbits of the planets?
4. Could you explain what Kepler's Laws are all about in a simple way?
5. At what times are the planets closest and farthest from the Sun?
6. Do planets get hotter and colder as they orbit the Sun?
7. Do planetary moons also travel on elliptical orbits?
8. Why do planets move along elliptical paths and not circular orbits?
9. If planets travel in elliptical orbits with the Sun at one focus, what happens at the other focus?
10. Will other planets ever collide with the Earth?
11. What are the speeds of the planets in their orbits?
12. What is the oblatness of the Sun, and how much does it contribute to the precession of Mercury's perihelion?
13. How can the plane of the solar system be 'tilted' when there is no up or down in space?
14. What is the Ecliptic?
15. How fast does light travel from the Sun to each of the planets?
16. What is the relationship between the plane of the solar system and the plane of the Milky Way?
17. Is our solar system moving in orbit around another star?
18. What is the inclination of the Earth's orbit to the angular momentum plane of the solar system determined by the spinning Sun?
19. Do planets share the same 'second focus' in their elliptical orbits?
20. What happens at the 'second focus' of elliptical planetary orbits?
21. How do you deduce from Newton's Law of Gravity that planets move in elliptical orbits?
22. What is the farthest and nearest distances between the Earth and the planets Jupiter and Saturn?
23. Why don't planets move faster when they are closer to the Sun?
24. Why are planet orbits elliptical and not circular?

1. Have any new planets been discovered in our solar system?
2. Have any new asteroids or other objects been found outside the orbit of Neptune?
3. Was there a planet recently discovered in our solar system?
4. Was a gas ball between Jupiter and Saturn discovered in the 1980's?
5. Why isn't there more 'junk' inside the orbit of the Earth from failed moons of Venus and Mercury?
6. Are there really 9 planets in our solar system?
7. Why is the asteroid belt considered a planet that never formed, rather than one that broke up?
8. Have astronomers discovered other bodies orbiting the Earth or Moon?
9. If the orbits of Neptune and Pluto intersect, will they ever collide?
10. Can you tell me about the new planet discovered between the orbits of Mars and Jupiter?
11. Was there ever a planet between the orbits of Mars and Jupiter?

1. How was the solar system formed? (Part I)
2. How are planets formed?
3. How was the solar system formed? (Part II)
4. How old are the Sun, Moon and Earth?
5. Why do the planets orbit the Sun in the same plane?
6. What is the relationship between star formation in nebulae, and planet formation?
7. Why were the terrestrial and gaseous planets formed so differently?
8. How is it that the Sun and the planets formed from the same gas cloud if their chemical compositions are so different?

1. How often do planetary alignments occur?
2. Why don't planetary alignments affect the Earth?
3. When will Mercury or Venus pass in front of the Sun?
4. When was the last time a 'May 5, 2000' conjunction occurred?
5. An MIT astronomer predicts tidal effects due to the upcoming alignment of the planets on MAy, 2000. Is this true?
6. Will there be any pretty conjunctions of Venus or a bright planet in the next year or so?
7. During the last 25 years, when were Mars and Earth closest?
8. Exactly when did the planetary conjunctions between 7-8 B.C. happen?
9. Did the universe somehow align itself on March 9, 1920?
10. Will there be any significant planetary alignments marking the year 2000 AD?
11. Will there be a planetary alignment on May 5, 2000 that will devastate the world?
12. When is the next alignment coming involving the planets out to Saturn?
13. When will the February, 1997 conjunction of Venus and Jupiter occur as seen from California?
14. Can the gravitational pulls of the planets in conjunction cause earthquakes?
15. Is there any truth to the statement that there will be a planetary alignment on May 5, 2000?
16. The 'Millenium' TV program claims that terrible things will happen on May 5, 2000. Is this true?
17. How do you calculate simple alignments between the Earth and Venus?
18. When will the planets line up?
19. When will Saturn and Mars be about the same brightness in 1997?
20. Were all 8 planets in the daytime sky on 23 August 1946 from San Antonio, Texas?
21. Was there a planetary conjunction on 12/27/1986?
22. Is it true that Venus, Mars and Jupiter will be very close together in the sky in the year 2015?
23. Will there or will there not be a planetary alignment on May 5, 2000?
24. Where did the idea come from that something bad was going to happen on May 5, 2000?
25. Do the Moon, Venus and Orion ever come into alignment?
26. Have planets ever been observed to eclipse one another in the sky?
27. Will there be global flooding caused by upcoming planetary conjunctions?
28. When will all the planets be in conjunction as viewed from the Earth or the Sun?
29. What happens when many of the planets line up or are in conjunction?
30. What was the 'harmonious conjunction' that happened back in 1987?
31. Will there be any interesting conjunctions in December, 1997?
32. Will there be a dramatic planetary alignment in February, 1997?
33. Will all the planets and the Moon align in the next 10 years?
34. What is synodic time?
35. What is the bright planet near the Moon on July 29th, 1996?
36. During the last five years, how often was Venus a morning and an evening star?
37. Can you explain the apparent motion of Venus as seen from Earth?
38. What is the most distant planet you can see with the naked eye?
39. Are there going to be any interesting planetary alignments in the year 2000?
40. What is the most spectacular planetary conjunction in the past or the future?
41. How do you find planets in the sky?
42. Is it possible for all the planets to line up in the solar system, and what would happen?
43. When can both Mercury and Saturn be seen, and where?
44. Was there or will there be a conjunction of Jupiter and Saturn on September 2 or December 5?
45. Can you define conjunction and opposition?

1. Have any spectacular phenomena ever been seen in the solar system in recent history?
2. Which planets played an important role in ancient civilizations?
3. What is the largest volcano in the solar system?
4. Is there a nemonic for remembering the ordering of the planets in the solar system?
5. Where can I find color pictures of solar system objects on the WWW?
6. Why do astronomers not agree on the magnitude of planets between european and american values?
7. Would you see stars in the daytime on the Moon and Mars?
8. If a person was 7 weeks old on Pluto, how old would they be on Earth?
9. If Jupiter had become a star, what would the solar system look like?
10. If you swapped the Moon and Mercury, what would be the repercussions?
11. If Venus and Earth had been swapped at birth, would Venus now have life instead of Earth?
12. What is your favorite planet other than the Earth?
13. If you could terraform a satellite around Jupiter or Saturn, which would you choose?
14. How do you locate the ecliptic plane in the sky?
15. What planets never show retrograde motion in the sky?
16. Is there a video tour of the solar system assembled from Voyager data?
17. Why did the Ancients arrange the planets as Moon, Mercury, Venus, Sun,etc and not Moon, Venus, Mercury, Sun,etc?
18. How well determined are the harmonics to Jupiter's gravitational field?
19. On Earth, altitudes are measured relative to sea level. What 'sea level' is used on Venus and the other planets?
20. Could life start on another planet in this solar system?
21. Does there exist life on other planets in our solar system?
22. How much of the mapable area of the solar system has in fact been mapped?
23. Why are the names of the planets capitalized but not the Sun's name?
24. If the Sun were one meter across, what would be the relative sizes of the planets and their orbits?
25. If the Sun were to be taken away, how would the orbit of the earth change?
26. Where can I get software to show the scale of the solar system and the Milky Way?
27. Were can I get software to produce an ephemeris?
28. Where did the symbol for the Earth originate?
29. Can you terraform a planet to make it like the Earth?
30. How fast do you have to go to get to outer space?

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