These travelling masses of ice and dust galloping throughout the universe are believed to have shaped the course of life
on this planet. As a result of comet-hunting, many deep-sky objects including nebulae and galaxies have been discovered
with perhaps the most obvious collection being the 109 (or 110) DSO's attributed to Charles Messier. With over 1000 comets
now having been catalogued and approximately 200 having been established as being periodic, historical records suggest
comets to have been observed and documented as far back as 240 BC (Comet Halley by the Chinese).
Comets are appealing to amateurs for a variety of reasons: they lead to incredible photographs thanks to their glowing and colourful tails extending millions of kilometers as they approach the sun and the ice and various frozen gases in the nucleus begin to vaporize; they are the precursors of meteor showers as remnants left behind on prior visits are encountered by our planet while we orbit the sun; and they represent an active adventure and form the basis of a "culture" (comet hunters) based on the discovery of new comets during the early dawn hours on the eastern horizon or just after sunset on the western horizon.
Note: Comet C/2009 P1 (Garradd) illustrated below while passing through the constellation of Pegasus and within the immediate vicinity of the globular cluster M15 was discovered on Aug 13, 2009 by Siding Spring Observatory astronomer Gordon J. Garradd on four plates and was estimated to be between magnitude 17.5 to 17.7 at the time. Continuous monitoring has revealed a continuous brightening of the nucleus and which is now expected to reach mag 7.1 by the end of February, 2012. Perihelion has been estimated to be Dec 23, 2011 at a distance of 1.55 AU while perigee is believed to be on March 5, 2012 at 1.27 AU.
For an ephemeris and orbital elements on this hyperbolic comet from Harvard's Minor Planet Center, click here. For a simulation of the comet including various orbital elements and physical parameters, click here.
C/2009 P1 (Garradd)
Gordon J. Garradd
Aug 13, 2009
RA / Dec:
21h 46m 15s /
11° 15' 34"
237.4 million km
July 29, 2011
02:00 - 04:25 UT+3
AP 305/f3.8 Riccardi-Honders
AP 1200GTO GEM
SBIG LRGB filters
1.36" / pixel