Get out your binoculars or telescope and set your alarm clock for at least two hours before sunrise, and if you're in an area without much light pollution and mountains don't get in your way you'll get to see a rare treat low in the northeastern sky.
Comet McNaught (formally designated C/2009 R1) will be gracing the morning sky through the end of June. It was visible to the naked eye as a fuzzy blob this morning, June 15, 2010) in dark sky areas, but with a little optical help you should have no trouble spotting it.
The comet is currently moving through the constellation of Perseus, the Hero, which at that early hour will be low in the northeast part of the sky.
This will not be the biggest or brightest comet to approach earth, but it has two very special things to recommend it: It's head is a lovely emerald green color, and because its orbit is hyperbolic this is the first and probably only time it will ever be seen from earth. A once in a lifetime event, and you have the opportunity to experience it!
Right now you'll find it to the south of the second magnitude star, Mirfak. Both star and comet are about 20-degrees above the northeast horizon (10-degrees is roughly equal to the width of your clenched fist held at arm's length; so the comet will be about "two fists" up from the horizon). (If you can spot the lovely little Pleiades contellation low in the sky, look up and to your left to find Mirfak and the comet.)(Click here for a sky map that will help you locate it.)
For the rest of June, Comet McNaught is expected to continue brightening, but it will also be dropping lower into morning twilight. Although it will remain a binocular object for most of the next two weeks, there is still some uncertainty as to how bright it will get (some speculate that it may become as bright as the stars in the Big Dipper-- but maybe not). Also, it will draw closer to the northeastern horizon, and harder to see, as each day passes, so a clear view of the horizon will be necessary. By June 20 it will have an altitude of about 15 degrees (one and a half "fists") on June 20, and about 5 degrees on June 25.
By around June 25 the comet will be barely and briefly visible both in the evening sky very low above the north-northwest horizon just after sunset, and in the morning sky just before sunrise, very low above the north-northeast horizon.
By the way, this recently discovered comet, McNaught C/2009 R1, should not be confused with another dazzling comet to bear McNaught's name – C/2006 P1 McNaught – which also put on a show for skywatchers in 2007 that was so stunning it earned the moniker "Great Comet of 2007."