About every eleven years somewhere deep in the Sun a special prosess occurs, and a few .
years latter the visible surface becomes marked with black spots which are called sunspots. .
No one knows exactly how the process works, but we do know that sunspots are produced .
by strong magnetic fields that are created in the interior. Sunspots and their magnetic effects .
are among the most fascinating features on the Sun. In spite of the fact that we do not really .
know what makes sunspots erupt from the interior, there is much that we do know about .
them. Sunspots have been studied longer than any other feature of the Sun.
Sunspots were known long before the invention of the telescope, because they often .
grow to sufficient size to be visible to the naked eye. Sunspot appearances are recorded .
throughout history, dating back to Theopharastus, a pupil of Aristotle, in the fourth century .
B.C. Chinese astronomers also recorded the appearance of naked-eye sunspots, and have left .
a lot of written records about their observations. At the time of the invention of the telescope, .
their existence was well known, but they were not believed to be the part of the Sun itself.
In 1610 Gallileo did a great amount of research on the origin of the sunspots. In the .
August of 1610, he turned his new telescope to the Sun to study sunspots by observing their .
repeated transits across the sun. Gallileo found that the spots were carried from east to west .
across the surface of the Sun over a period of about 13 days, becoming smaller and smaller .
and then dissapearing behind the Sun for the equal amount of time and then reappearing .
again at the east side of the Sun. This discovery implied that the sunspots were part of the .
solar surface. For some reason, Gallileo did not publish his discovery right away. Perhaps he .
knew that the world would not warmly receive a report proving that Sun was constantly .
changing, contrary to the Aristotle's teachings.
