U08a2 Measure of Solar Rotation Paper Essay Example | Topics and Well Written Essays - 1250 words

U08a2 Measure of Solar Rotation Paper - Essay Example The synodic period is the temporal interval that it takes for an object to reappear at the same point in relation to two other objects (linear nodes), e.g., when the Moon relative to the Sun as observed from Earth returns to the same illumination phase. The synodic period is the time that elapses between two successive conjunctions with the Sun-Earth line in the same linear order. The synodic period differs from the sidereal period due to the Earth's orbiting around the Sun (Wikipedia 2011). Using Sunspots in Measurement of Solar Rotation. The rotation of the sun has been measured by the motion of various features ("tracers") on the solar surface. The first and most widely used tracers are sunspots. Though sunspots had been observed since ancient times, it was only when the telescope came into use that they were observed to turn with the Sun. The English scholar Thomas Harriot was probably the first to observe sunspots telescopically as evidenced by a drawing in his notebook dated De cember 8, 1610, and the first published observations (June 1611). Johannes Fabricius had been systematically observing the spots for a few months and had noted their movement across the solar disc. This can be considered the first observational evidence of the solar rotation. Christopher Scheiner, (1630) was the first to measure the equatorial rotation rate of the Sun and noticed that the rotation at higher latitudes is slower, so he can be considered the discoverer of solar differential rotation. Each measurement gives a slightly different answer, yielding the above standard deviations (shown as +/-). St. John (1918) was perhaps the first to summarize the published solar rotation rates, and concluded that the differences in series measured in different years can hardly be attributed to personal observation or to local disturbances on the Sun, and are probably due to time variations in the rate of rotation, and Hubrecht (1915) was the first one to find that the two solar hemispheres rotate differently (The Essential Cosmic Perspective, 5th Edition, Page: 287). Sunspot Analysis: (Spotexerweb[1].pdf) (Day 1) June 22, 2011 Sunspot Latitude 15 Degrees Sunspot Longitude: 60 Degrees (Day 2) June 23, 2011 Sunspot Latitude: 15 Degrees Sunspot Longitude: 45 Degrees (Day 3) June 24, 2011 Sunspot Latitude: 15 Degrees Sunspot Longitude: 30 Degrees A AC( ( A\ Rotation of Sun Calculation: Difference in Longitude in Day 1 and Day 2: DL1: 15 (Delta Longitude) S1 = 2 days x 360 degrees 2 x 360 = 2 x 24 = 48 Degrees DL1 15 Difference in Longitude in Day 2 and Day 3: DL2: 15 (Delta Longitude) S2 = 2 days x 360 degrees 2 x 360 = 48 Degrees DL2 15 Calculation of Average (S): S = (S1 + S2) = (48 + 48) = 96 = 48 Synodic Rotation Period 2 2 2 Sidereal Period of Rotation (P): P = (S x 365.25) = (48 x 365.25) = 17532 = 42.424 Sidereal Rotation (P) (S + 365.25) (48 + 365.25 413.25 Comparison with Period of Solar Rotation for Solar Equator: Solar rotation is able to vary with latitude be cause the Sun is composed of gaseous plasma. The rate of rotation is observed to be fastest at the equator (latitude ?=0 deg), and to decrease as latitude increases. The differential rotation rate is usually described by the equation (Wikipedia 2011): Citations The Essential Cosmic Perspective, n.p. (5th Edition), Page: 287, Book Tracking Sunspots Data from SOHO, Spotexerweb[1].pdf, Web Sunspots,Wikipedia, The