This was originally written for the University of Birmingham Astronomical Society's website, http;//www.astrosoc.org.uk
Quick Info:
Discovered by: Don Machholz
Official name: Comet C/2004 Q2 (Machholz)
When: August 27, 2004
Where: Southern California, USA
What with: 6-inch, f/8 reflector Criterion Dynascope, from 1968 it cost $200! This is a reflecting telescope and was one of the favourite telescopes in use at that time.
Orbital Period: 120,000 Earth Years (approx)!
Orbital Size: 2419 AU (astronomical unit - distance between the Earth and Sun)
Mass: 7.37^10+14 kg (Earth's is over 1 000 000 000 times greater!)
What does it look like:

by Jimmy Westlake from Colorado

by Mike Holloway

by Jimmy Westlake from Colorado
Just by doing a quick search on google.co.uk will reveal even more wonderful photos of this object.
Background on the discovery:
Machholz has spent more than 7,000 hours searching for comets since 1975. It took him 1,457 hours since his previous discovery. The comet was at 22 degrees south declination at discovery. So it is very strange that southern hemisphere observers did not see it first since it was better placed for observations by them.
So far Don Machholz has discovered 10 comets. More information can be found about the discovery on the discoverers web entry at: http://ephemeris.sjaa.net/0410/b.html
How can I observe it?
Well as I write this the comet is "naked eye" visible (i.e. you do not need a telescope or binoculars) and so by looking in the southern sky about 20 degrees about the horizon at 10 o'clock should reveal it.
Not enough info? OK, below is a sky chart which show the comets position in relation to some of the more obvious constellations (Orion is one of them) over the next few weeks.
The comet will get brighter and brighter over the coming month and so will be easier to see in early January. At this point it is expected to reach a brightness of 3rd magnitude (the brightest stars are magnitude -1 and so the scale decreases with increasing brightness, the Sun is about -26.8).
Oh you need to find a relatively dark spot. Preferable not in an urban area - this is hard to do. You should be able to see it through the haze of the city especially as it gets brighter in early January.
If you have a small pair of binoculars around then you view will be increased dramatically. You might even be able to make out the tail when it is brighter with the eye but it is doubtful. With binoculars you will get a nice view of the tale and through a telescope it will look wonderful.
Position in the sky?
The comet will be well placed for Northern Hemisphere observers when at its best in January, a naked-eye object (possibly up to 3rd magnitude) from suburban and most urban skies. It is currently 5th magnitude.
It will loop north, gradually accelerating in December as it passing from Eridanus into Taurus. Into January it will get brighter. On the night of January 6-7, it will be just 2.5 degrees from the Pleiades (M45, the seven sisters). At this point it is predicted to be about 3rd magnitude. During January it will move from Taurus through Perseus into Cassiopeia.
It will pass 0.35 AU from the Earth in early January, and reach perihelion (the point nearest the sun in the orbit of a planet or other celestial body) on January 24 at 1.20 AU from the Sun. It will be nearly opposite the Sun at that point making it easily observable.
Around March 10, the comet will pass within 5 degrees of Polaris (the North Star) and will be below 6th magnitude and thus not visible by naked eye observers.
Sky Chart:
Position of comet (click for larger):
All sky chart (click for larger; for December):
More information?
An introduction to comets:
http://www.solarviews.com/eng/comet.htm
Comet Observation Homepage:
http://encke.jpl.nasa.gov/
BBC Introduction to comets:
http://www.bbc.co.uk/science/space/solarsystem/comets/index.shtml
Society for Popular Astronomy: (useful for general observing)
http://www.popastro.com/
Federation of Astronomical Societies (find you local astronomy group):
http://www.fedastro.org.uk
BAA Comet Section:
http://www.ast.cam.ac.uk/~jds/
More advanced finder charts:
http://www.shopplaza.nl/astro/comets/comets.htm
Heavens-above.com (excellent and user friendly charts):
http://www.heavens-above.com