THEMIS Science Frequently Asked Questions

Here are some common, and popular, questions about aurora, Earth's magnetism, and space weather. The answers are often illustrated, and are based on our very latest understanding of these complex systems and their interactions through time and space.

This archive contains the most popular questions submitted to The Astronomy Cafe since 1995, and answered by NASA astronomer Dr. Sten Odenwald. More questions about aurora, magnetism and the NASA Themis mission will be added to this page in the future as they are submitted by the teachers and students of the Themis Project.


  1. What would happen if you traveled through an aurora?
  2. Are there places on the WWW that give aurora forecasts?
  3. Are auroras seen on other planets?
  4. Can you hear an aurora?
  5. How often are aurorae seen in the continental United States?
  6. What are some of the early theories about auroras?
  7. How long have auroras been observed?
  8. Is plasma present during an aurora?
  9. Is there a monument to the Northern Lights somewhere?
  10. How much power do aurora produce and can we use it?
  11. When do auroras occur?
  12. What effects do auroras have on the Earth?
  13. How hot do auroras get?
  14. What causes auroras to have different colors?
  15. Why don't auroras happen near the equator?
  16. How do auroras affect the Earth?
  17. How much mass does the Earth gain from the solar wind?
  18. What effects do sunspots have on the Earth?
  19. How can you artificially create aurora?
  20. What does the solar activity cycle have to do with auroral activity?

Magnetic Field

  1. When the Earth's magnetic field reverses, does its rotation also switch?
  2. Where is the biggest difference between true north and magnetic north?
  3. What is the strongest magnetic field ever known?
  4. Do animals really use magnetism in any interesting way to navigate?
  5. Do magnets loose their magnetism in space when they are outside the earth's magnetosphere?
  6. What would happen if the magnetic field of the Earth suddenly changed?
  7. Is it true that the Earth's magnetosphere is expanding?
  8. Where can I get information about the Earth's magnetosphere?
  9. Is the Earth's magnetic field changing?
  10. Is the Earth about to reverse its magnetic field?
  11. Will there be a 'restructuring' of the Earth's magnetic field in the year 2013 that will end the Earth?
  12. Can you store and extract energy from a magnetic field?
  13. Does Earth's magnetic field or solar activity influence the El Nino cycle?
  14. What do we know about Earth's ancient magnetic field?
  15. Why does the magnetic pole of the Earth flip?
  16. Who discovered the reversal of the Earth's magnetic field?
  17. Does the Earth have more than two magnetic poles?
  18. Is there a relationship between Earth's rotation and its magnetic field?

Sun - Earth Connections

  1. What is the average density of solar wind particles that produce the aurora?
  2. Is there a greater risk for solar radiation when taking the polar route by jet plane?
  3. How are auroras produced?
  4. If auroras didn't exist how would the Earth be affected?
  5. Does the reversal of the Sun's magnetic field have any effect on the Earth?

Earth - Miscellaneous

  1. Where does the atmosphere end and outer space begin?
  2. Is it true that organic matter cannot pass through the van Allen radiation belts?
  3. Did the Earth gain a new van Allen radiation belt in 1998?
  4. What is the South Atlantic Anomaly?
  5. What is the ionosphere composed of?
  6. Where are the Van Allen radiation belts and are they important to life?
  7. Why does the Earth have radiation belts?

For other questions about the Sun, Earth and Cosmos, visit Dr. Sten Odenwald's "Ask the Astronomer" resource at the Astronomy Cafe (