Sol – Our Sun

The Sun has a magnetic field that varies across the surface of the Sun. The magnetic field also varies in time and location. As and when the magnetic field increases drastically, at certain spots, a dark patch known as “Sunspots” appear to be visible in photosphere and correspond to concentrations of magnetic field which restrict the movement of heat from convection zone causing the area to be  colder than the surrounding area in photosphere. This colder region is called sunspots.

Sunspots appear in pairs of opposite magnetic polarity. The sunspots can last from a few days to a few months. Bigger spots move slower while smaller spots move faster across the disk of Sun. Indicating intense magnetic activity, sunspots sometimes followed by more different activities immediate next being prominence.

“Prominence” is a large, bright, gaseous feature extending outward from the Sun’s surface, often in a look shape. Prominences are anchored to the Sun’s surface in the photosphere and extends outwards into Sun’s corona. Prominence and Solar corona are both composed of plasma which is not visible to human eye. But prominence contains plasma at much lower temperature than that of corona and hence is much brighter than that of solar corona. Plasma or prominence can not be seen through normal telescopes and only specialised telescopes can be used to see it. Prominences can form over timescales of about a day and may stay for several weeks. Prominence can be a loop as high as few hundred of kilometres to lakhs of kilometres. The plasma in prominence loop flows along a tangled and twisted structure of magnetic fields generated by the Sun’s internal dynamo. Sometime these loops break apart and may give rise to Solar Flares.

Solar Flares are suffer flash of increased brightness on Sun usually observed near its surface and in close proximity to a sunspot group. Flares are closely associated with the ejection of plasmas and particles through the Sun’s corona into outer space; flares also copiously emit radio waves. If the ejection is in the direction of Art, particles associated with this disturbance can penetrate into the upper atmosphere and cause bright auroras and may even disrupt long range radio communication. It usually takes days for the solar plasma ejecta to reach Earth. Even the most powerful flares are barely detectable in the “Total Solar Irradiance”, Powerful flares are often but not always accompanied by a CME.

CMEs or Coronal Mass Ejectionis a significant release of plasma and accompanying magnetic field from the Solar Corona. They often follow solar flares and are normally present during a solar prominence eruption. The plasma is released into the solar wind, and can be observed in coronagraphy imagery. CMEs often originate from active regions on the Sun’s surface such as groupings of sunspots associated with frequent flares.