Comets are huge bodies of ice and rock moving towards the Sun from the remote parts of the Solarsystem.
Due to gravitational impacts from planets, some of these are being pulled out of their position and captured by the Suns gravitation.
As they approach the Sun, the increased radiation make the ice evaporate and flush out from the comets core.
Some observed comets:
Panstarrs
C/2007 N3 Lulin
8P-Tuttle
17P/Holmes
C/2007 E2 Lovejoy
C/2006 M4 Swan
73P/Schwassmann Wachmann 3
C/2006 A1 Pojmanski
C/2004 Q2 Machholz
C/2004 F4 Bradfield
C/2002 V1 NEAT
C/2002 X5 Kudo-Fujikawa
C/2002 F1 Utsunomiya
C/2002 C1 Ikeya-Zhang
C/2000 LINEAR
C/1995 O1 Hale Bopp
C/1996 B2 Hyakutake
Comet Panstarrs, on 18.March 2013. Canon 200mm f/2.0L IS, Canon 7D.
Comet Panstarrs, on 21.March 2013. Canon 200mm f/2.0L IS, Canon 7D
Comet Panstarrs, on 2.April 2013. Canon 200mm f/2.0L IS, Canon 7D
Comet Panstarrs, on 4.April 2013. Canon 200mm f/2.0L IS, Canon 7D
Comet C/2007 N3 Lulin, on 28.February 2009. 8x60sec. Canon 5D on Vixen R200SS, f/4, 800ISO".
Comet C/2007 N3 Lulin, on 28.February 2009. 8x180sec. Canon 5D, 70-200mm f/2.8L IS at f/4. 800ISO.
Comet 8P-Tuttle, on 15.Desember 2007. 5x120sec. Canon 20D on Televue 4".
Comet 17P-Holmes, on 04.November 2007. 10x300sec + 10x 120sec + 10x 10sec. Canon 20D on Televue 4".