Hobbies And Interests
Synodic Period
A synodic period represents the time required for an object in our solar system, such as Mars, to return to the same position relative to the sun, as observed from earth. Because the earth moves around the sun, this period is slightly different than the object's sidereal period. A sidereal period represents the time required to complete one orbit around a fixed star, the sun. This period is considered to be an object's true orbital period. The earth's sidereal period is 365.26 days. Because the sun does not orbit other objects, it has no synodic or sidereal period. However, the sun does rotate about its axis every 25.38 days. While this period is 25 times that of earth, the sun's circumference is 109 times that of earth.
Sunspot Period
Galileo Galilei made the first European sunspot observations in 1610. Continuous sunspot observations were begun at the Zurich Observatory in 1849. However, it was astronomer Samuel Heinrich Schwabe who, in 1843, discovered that the sunspots adhered to a cycle. The sun experiences a time of heightened sunspot activity, called the solar maximum, and a time of minimal sunspot activity, called a solar minimum. The period of this sunspot cycle averages 11 years. This means a solar maximum occurs approximately every 11 years on the sun.
Magnetic Field Period
Similar to the earth, the sun has a magnetic field. This field reverses its polarity near the peak of sunspot activity. This means the sun's magnetic cycle has a period of 22 years, with each successive solar maximum representing a polarity reversal. Scientists attribute this cycle to the fact that the sun's outer photosphere rotates faster at the equator than at the poles. This causes magnetic currents, called Meridional flows, on the surface. These flows correlate with pairs of sunspots. The magnetic flow causes the sun's magnetic field to reverse.
Interesting Facts
From 1645 to 1715, there was an extended period of sunspot inactivity on the sun, known as the Maunder minimum. This inactivity corresponds to the climatic period on earth known as the "Little Ice Age." During this period, average global temperatures on earth noticeably decreased. The earth's magnetic field also undergoes polarity reversals, though much less frequently. On earth, reversals take place every 5,000 to 50 million years, with the last one having occurred around 740,000 years ago.