thank you marahatna, i am not the only one here doing that am i?
no problem byrd62au, someone had to ask. thanks for that. 
we do it to express gratitude to the sun, giver of life.
108 has been a special number for yogi’s since a long time and there are many reasons,
i like this scientific reason, since the yoga of postures is called hatha yoga and hatha means sun & moon, i found it on wikipedia;
[I]the diameter of the Sun is nearly 108 times the diameter of the Earth, the distance from the Sun to the Earth is nearly 108 times the diameter of the Sun, and the average distance of the Moon from the Earth is nearly 108 times the diameter of the Moon[/I]
as i said there are many reasons, i am sure you’ll look it up.
wim