CREATING A MODEL OF THE SUN'S MAGNETIC FIELDS
| The image to the left is an image of the Sun from April 12, 1997 showing a view of the Sun in the extreme ultraviolet wavelengths. This image was captured by the SOHO/EIT instrument at the He II emission line at 304 Å. Notice the bright areas in the upper right quadrant and in the lower right quadrant.|
He II is the ionized form of helium observed when one electron has been removed from neutral helium, in this case by heat in the Sun.
|The bright areas from the EIT image above can be viewed in this image of the Sun called a magnetogram, captured by SOHO/MDI. This image indicates strength of magnetic fields. This type of image shows areas of intense magnetic activity as paired areas of dark and light. This pairing represents the poles of a magnetic field extending into the corona from below.|
|This image of the Sun was taken at roughly the same time using wavelengths of light in the extreme ultraviolet using the EIT instrument on the SOHO spacecraft. Notice again, the bright areas in the upper right quadrant and in the lower right quadrant.|
These three images, two produced in the ultraviolet, using EIT, and one using MDI, show areas of intense activity. The image to the left has been recorded using the emission spectrum of Fe XII at 195 Å.
Fe XII is the ion resulting from the removal of eleven (11) electrons from neutral iron by the heat of the Sun.
As in the image viewed in He II above, the image is in false color. The actual color is beyond the range of human perception, being found outside the range of visible light in the electromagnetic spectrum.
|To solar scientists, the orientation of east and west is reversed when viewing the Sun. This result is achieved when orienting yourself by lying on the ground with your head pointing towards north.|
| An observation that has been made of the Sun is that sunspots are areas of intense magnetic activity. When measured by instruments such as the Michelson Doppler Imager (MDI) found on the SOHO spacecraft, these areas have been found to be composed of two parts corresponding to the poles of a magnetic field- north and south.|
Sunspots have been observed to have bipolar areas that appear to run along the lines of latitude of the surface. On the Sun's northern hemisphere, the paired areas have been measured to have the northern (+) magnetic pole on the western edge of the pair and the southern (-) magnetic pole on the eastern edge.
|Using imagery generated from the magnetic polarity data received from SOHO/MDI instrument, it has been observed that the northern polar area (+) of a sunspot appears darker than the southern polar area. The orientation of northern and southern regions is exchanged in the Southern Hemisphere of the Sun, with the northern pole (+) on the eastern side of a sunspot and the southern pole (-) on the western end.|
Interestingly, the Sun's south magnetic pole is presently viewed at the norhtern geographic pole when viewed from earth, but that will change over the next solar cycle.
|TRIVIA- The Earth's geographic North Pole is actually the magnetic South Pole. When using a compass, the needle end designated "N" points toward the geographic north pole, but we know that opposites attract and that the "N" directional arrow is actually pointing towards the magnetic "S" pole. (but convention prevails)|
Connections to National Standards: