|Copyright: Subhash Ranjan (sranjan)
|Date Taken: 2015-02-10|
|Camera: Nikon D800|
|Photo Version: Original Version|
|Date Submitted: 2015-02-11 7:31|
|[Note Guidelines] Photographer's Note|
|These days I am trying to explore the technical potential of my newly acquired camera...I have started shooting sunrise & sunsets whenever possible. To my surprise, I found two small spots between 1 O'Clock & 2'O Clock positions of Sun yesterday. Later I came to know their actual meaning and have posted the photo for your appreciation.|
Sunspots are temporary phenomena on the photosphere of the Sun that appear visibly as dark spots compared to surrounding regions. They correspond to concentrations of magnetic field that inhibit convection and result in reduced surface temperature compared to the surrounding photosphere. Sunspots usually appear as pairs, with each spot having the opposite magnetic polarity of the other.
Although they are at temperatures of roughly 3,000–4,500 K (2,700–4,200 °C), the contrast with the surrounding material at about 5,780 K (5,500 °C) leaves them clearly visible as dark spots, as the luminous intensity of a heated black body (closely approximated by the photosphere) is proportional to the fourth power of its temperature. If the sunspot were isolated from the surrounding photosphere it would be brighter than the Moon. Sunspots expand and contract as they move across the surface of the Sun and can be as small as 16 kilometers (10 mi) and as large as 160,000 kilometers (100,000 mi) in diameter, making the larger ones visible from Earth without the aid of a telescope. They may also travel at relative speeds ("proper motions") of a few hundred meters per second when they first emerge onto the solar photosphere.
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