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Library of Past Questions

The Solar System

  • We no longer answer questions on this topic, to concentrate our limited resources on questions on space based astrophysics and closely related areas (see this page for more explanation).
  • Check out the resource links. These are the sites we used to point to in answering your questions.
  • Browse through the library of questions below. We may have already answered your questions.

Resources for this Topic

  1. The Nine Planets (

  2. Solar System Live (positions of the planets) (

  3. Views of the Solar System (

  4. Planetary Rings Node (

  5. Resources for Exploring the Solar System (

Library of Past Questions and Answers

    The Sun

  1. How many times would the Earth fit into the sun?

  2. Does the Sun rotate?

  3. What manages to keep the Sun so hot all of the time? Could it burn out?

  4. Is the sunspot cycle and Jupiter's orbital period related?

  5. Are there any satellites currently studying the sun?

  6. What would happen to the Earth if the Sun was at Pluto's distance?

    Planetary Motions

  1. How does the Sun just stay in one spot and how do all of the other planets stay on course/track?

  2. Why aren't the orbits of the planets circular?

  3. How can astronomers determine the Astronomical Unit (average Sun-Earth distance)?

  4. Did Venus and Earth ever swap orbits?

  5. Since Neptune and Pluto's orbits cross, will they eventually collide?

  6. Why is the orbit of Pluto so different than the other planets?

  7. How unique is the retrograde rotation of Venus?

  8. When will the next alignment of the planets be?

  9. Can an alignment of the planets affect the Earth?

  10. Do the moons of other planets have synchronous rotation?

  11. What keeps planetary rings in place?

    Solar System as a Whole

  1. When were all the planets discovered?

  2. How large is the solar system?

  3. Why are the densest planets closest to the sun?

  4. Why do some planets have more moons than others?

  5. Why aren't the gas giant planets stars?

  6. What are some substances not found on Earth, but found on other planets or comets?

  7. Can you describe two or more aspects of the solar system that are not common knowledge?

  8. Where can I find Internet information on Planet X?

  9. Will Planet X end life on Earth in 2012?

  10. What will happen to the Solar System when the Sun evolves?

  11. What can you tell me about the Nemesis Star that supposedly had a hand in the extinction of the dinosaurs?

    Individual Planets

  1. When can I best view Mercury?

  2. Who discovered Venus, and when?

  3. When are the next transits of Venus?

  4. Do you have information about the oppositions of Mars?

  5. Is there water on Mars?

  6. Does Mars have precipitation?

  7. If all of the planets are named after Roman gods, why is it that the moons of Mars (the Roman god of war) are Deimos and Phobos (the sons of the Greek God of war)?

  8. Is the 'face on Mars' really only just a hill?

  9. Is the Jupiter referred to in the New Testament the planet or the Roman god?
  10. Can you walk on Jupiter? What causes its radioactivity?

  11. How big is Jupiter's Great Red Spot?

  12. How long will the Great Red Spot on Jupiter last?

  13. What is the average thickness of Saturn's rings?

  14. Do scientists still believe that diamonds can be found at the core of Uranus?

  15. Why are Uranus' moons named after Shakespearean characters rather than something related to Uranus?

  16. Is Pluto a Planet or Not?

    Asteroids and Comets

  1. Are there pictures of the Asteroid Belt?

  2. Could the Asteroid Belt be a destroyed planet?

  3. When was the earliest known sighting of a comet?

  4. How can ice, which is a form of water and which has a finite vapor pressure, exist in the near vacuum of space?

  5. What happens if a comet is hit by a solar flare?

  6. Can you give me information about the instruments and measurements that are made of comet's tails?

    Life in Space (Solar System and Beyond)

  1. What are the remote indicators of life on Earth from space?

  2. Has evidence been found for life on Mars?

  3. What would an alien be like on Europa?

  4. Is there any other form of life out there?

  5. What are the chances of life existing outside our solar system?

  6. Where can I find information on extraterrestrial life?

  7. Could life based on an element other than carbon exist?

Imagine the Universe is a service of the High Energy Astrophysics Science Archive Research Center (HEASARC), Dr. Alan Smale (Director), within the Astrophysics Science Division (ASD) at NASA's Goddard Space Flight Center.

The Imagine Team
Acting Project Leader: Dr. Barbara Mattson
All material on this site has been created and updated between 1997-2012.

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