113 FAQs about the Sun (The Astronomy Cafe)

Facts about the Sun , Solar Ephemeris Calculator

Current satellite images

Today's Space Weather , Real Time Monitor , Real-time ACE solar wind data

Solar Storms and Human Impacts

Naming the Sun:

  1. What are the mythological names of the two sundogs?
  2. When we travel to the stars, will the Sun get a more accurate name?
  3. Why didn't Johann Bayer give a name to the Sun like 'Alpha-Prime' or something?
  4. Does our Sun have a technical name?
  5. Why is the Sun named the 'Sun'?
  6. Where did the legend about Ra the Sun god start?

 

Basic Properties and Physics, Evolution

  1. How old is the Sun?
  2. How does the solar wind work?
  3. How is the solar magnetic field generated?
  4. What is the evidence from the SOHO spacecraft that demonstrates solar particle outflows in the solar wind?
  5. How is the outward stream of electrons and charged particles from the sun detected by the Ulysses spacecraft?
  6. How can I convince children in 3rd grade that the Sun is the center of the solar system?
  7. What was the Solar Maximum Mission?
  8. Does the Sun revolve around the Milky Way or does it just stay put?
  9. Does the solar wind affect spacecraft the way it does the tails of comets?
  10. How do astronomers measure the temperature of the Sun without going there?
  11. If the solar wind can't rearrange the dust on the Moon, why does it blast dust from comets?
  12. If gamma rays are produced in the Sun's core and are invisible to the eye, where does sunlight come from?
  13. Can H-alpha images of the Sun be affected by terrestrial clouds?
  14. What is the rate of mass loss by the Sun from the solar wind?
  15. What is the kinematic viscosity and plasma resistivity of the Sun?
  16. How bright would the Sun be from the distance of Sirius?
  17. Have astronomers determined exactly how the Sun will change in the next 10 billion years?
  18. Does water exist on the Sun?
  19. Can the Sun ever die and be reborn like a Phoenix?
  20. Why doesn't the Sun just collapse into a white dwarf?
  21. Will the Sun blow up before it gets to Hercules at 70,000 kilometers/sec?
  22. Why doesn't the Sun run out of energy?
  23. What will become of the Sun after the red giant phase?
  24. In terms of a name, what distinguishes our 'Sun' from other suns in space?
  25. If there are no sounds in space, how do we know the Sun roars?
  26. Why can't you measure the distance to the Sun using parallax?
  27. How much mass does the Sun convert to energy each hour?
  28. How much energy does the Sun produce in one hour?
  29. When the Sun becomes a black dwarf, what state of matter will it be in?
  30. If the Sun causes the solar wind, why is its speed faster by Uranus than near the Sun itself?
  31. What would happen if the Sun had a temperature of 3000 or 10000 K instead?
  32. Why is the solar corona visible only during a solar eclipse, and not with a sun filter?
  33. How large is the Sun's core?
  34. What is the chemical composition of the solar photosphere?
  35. How thick is the solar corona?
  36. Is the Sun actually very dark at its center, rather than blindingly light?
  37. Is the loss of mass by the Sun sufficient to change the orbits of the planets?
  38. Why is the corona of the Sun not visible exactly at total eclipse?
  39. Why is the Sun hotter on the outside than the inside?
  40. Will the Sun soon be passing through a dust cloud?
  41. Is the Sun shrinking in size?
  42. What would happen if the Sun vanished just after sunset?
  43. Does the Sun give off smoke?
  44. When is the Sun predicted to go nova?
  45. How hot would the Sun be at different distances in the solar system?
  46. Is the Sun rotating, or does it always show the same side towards the Earth?
  47. How hot is the Sun?
  48. If the Sun appears yellow in a blue sky, why doesn't that mean that the Sun is actually green?
  49. Why is the Sun yellow?
  50. Why doesn't the Sun blow up?
  51. Is our Sun considered to be a young or old star?
  52. Does the Sun have a south pole?
  53. How bright is the Sun?
  54. How large is the Sun compared to the earth?
  55. Does the Sun have a rotational axis?
  56. Why is the Sun's chromosphere and corona hotter than the inner layers?
  57. If the Sun is made of hydrogen and helium, why can't we see through it?
  58. Does the Sun rotate?
  59. Why are sunspots dark?
  60. Can aircraft be protected against the Sun's harmful electro-magnetic rays?

Solar Activity and Sunspots

  1. Is there a safe, inexpensive way to view Sunspots?
  2. Is sunspot activity seasonal and are we now in a 'high' season?
  3. Where can I get sunspot numbers since 1985?
  4. Is there a correlation between sunspot activity and the weather?
  5. What is a solar flare, and are they harmful to humans?
  6. Can you say anything about the April, 1997 solar storm?
  7. Can you say anything about the largest sunspots seen in 1840?
  8. Could you get me the Zurich sunspot numbers since 1985?
  9. When will the next sunspot cycle start?
  10. Is the Sun a variable star?
  11. How do you measure changes in the Sun's magnetic field?
  12. In January 1997, the Sun 'hiccuped'. Did this damage any satellites or the Shuttle?
  13. Why do sunspots vary in an 11 year cycle?
  14. Where can I get the yearly sun spot numbers from 1700 to the present?
  15. Why are sun spot numbers correlated with average lake level?
  16. Do the planets affect the sunspot cycle?
  17. Will the April, 1997 solar storm affect Comet Hale-Bopp?
  18. Was there an explosion on the Sun in January, 1997 that will affect the weather?
  19. Could a massive solar flare light up the Moon and Jupiter, but still not destroy the Earth?
  20. What is the period of the Sun's magnetic variation?

Rising/Setting, Orbit, Calendar etc

  1. What is the speed of the Sun and the size of it's orbit?
  2. Can you calculate the time and date of the winter solstice from the year and location on the Earth?
  3. Why don't Venus and Mercury transit the Sun every year?
  4. Is there a simple way to determine the exact time of the Vernal Equinox?
  5. Can you explain why the latest sunrise and sunsets don't happen at the Winter Solstice, but happen on December 7 and January 4?
  6. On what dates does the Sun pass through the constellations along the Ecliptic?
  7. At what latitude do you see the earliest sunset in December and the latest in January?
  8. Does the Sun never set in Antarctica?
  9. If the Sun rises and sets every day, why do people say it is in a particular constellation?
  10. Why do the sunrise and sunset times change at different rates during the December equinox?
  11. What is the exact time of sunset from San Juan on August 21, 1997?
  12. Does the summer solstice sunrise occur north of due east?
  13. What is the distance to the Sun from the Earth in miles?
  14. If you were standing between the equator and the Tropic of Cancer at the summer solstice at noon, why wouldn't the Sun be south of your east-west line?
  15. Can you calculate the declination of the Sun and the real-mean time difference from the current date?
  16. At what latitudes north and south does the Sun reach each year?
  17. What is the equation of time?
  18. Why doesn't the Sun set in the same place every day?
  19. Does the Sun set in the same place every day?
  20. Why do we loose and gain sunlight unevenly during the year with respect to the sunrise and sunset time?
  21. Why does the latest sunrise occur more than a week after the winter solstice in December?

Miscellaneous

  1. What causes the green flash seen in the setting Sun?
  2. Could you send a space probe directly INTO the Sun, and what would it tell you that us useful?
  3. Does the Sun have any moons?
  4. What is a solar conjunction?
  5. Is there any absolute proof that the Sun is not a member of a binary star system?
  6. Does Stoneheng tell the Sun's position in the sky as it appears today, or 3800 years ago? There is a difference isn't there?

RETURN to the Question and Answer Index.