A recently discovered comet is surprising skywatchers by becoming brighter than predictions had first suggested and can now be seen with the unaided eye during the next few weeks.
Comet McNaught, officially catalogued as C/2009 R1, was discovered by Australian astronomer Robert McNaught last September using the using the 0.5-meter Uppsala Schmidt telescope and a CCD camera. It's the 51st comet that bears McNaught's name.
Although initially an extremely faint object, enough observations of the newfound comet were made to allow Brian Marsden of the Smithsonian Astrophysical Observatory in Cambridge, Mass., to calculate an orbit.
Comet McNaught is expected to pass closest to the sun (perihelion) on July 2, at a distance of 37 million miles (60 million km). This sky map shows where to look in order to spot the comet in the morning sky.
The comet is visible now for people with dark skies away from urban and suburban lighting. By mid-June it may be an easy skywatching target for most people.
Comets brighten when the get nearer to the sun, because solar radiation boils icy particles and dust off the comet's nucleus. A cloud of material called a head, or coma, and sometimes a tail form. It's all illuminated by reflected sunlight.
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." [Great Comet McNaught photos.]
Comet brightens rapidly
As comet McNaught approached the sun, amateur and professional astronomers worldwide watched with interest as it slowly increased in brightness.
When April began, the comet was estimated at magnitude +12. That's still about 250 times dimmer than the faintest star that one might see without any optical aid. But the comet started brightening more rapidly in the days and weeks that followed and it's now bright enough to be glimpsed with the naked eye in a dark clear sky.
The most recent "reliable" observation was made by Alexandre Amorim of Florianopolis,Brazil who saw the comet on June 6 using 10x50 binoculars and estimated the magnitude as +5.5. That's about as bright as the faintest star in the bowl of the Little Dipper (on this scale, smaller numbers represent brighter objects).
In the coming days, the comet is expected to continue to brighten as it gets closer to the sun.
When and where to see it
If you want to get a view of the comet, you'll have to get up early in the morning. Set your alarm clock for at least two hours before sunrise. For most people that will mean around 3:30 a.m. local time. 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.
The comet will pass to the south of the second magnitude star, Mirfak around June 14. Both star and comet will be 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).
Don't expect anything spectacular just yet, however.
The comet should appear as a dim and diffuse, circular patch of light. Binoculars or a small telescope will help to bring it out better; you might even make out a faint greenish color.
From the head of the comet, a narrow tail of gas extends. John Bortle, a well known comet observer, likens McNaught's appearance as resembling an "apple on a stick."
"From the few rough magnitude estimates I have seen posted, it would appear that the comet is perhaps a magnitude brighter than had been anticipated, but whether this trend will continue is, as usual, anybody's guess," Bortle said.
Getting Lower ... and Harder to See
After June 15, Comet McNaught will rapidly slide lower toward the north-northeast horizon, passing very close to the brilliant star Capella in the constellation Auriga around June 22 and a few mornings later very near to the second magnitude star Menkalinan.
By then, McNaught will be visible – albeit with some difficulty – both in the evening sky for a short while just after sunset very low above the north-northwest horizon and in the morning sky just before sunrise very low above the north-northeast horizon.
Comets are very unpredictable, but some astronomers say Comet McNaught might reach magnitude +2 by the end of June. If so, it won't rival the brightest stars in the sky, but it should be easy to spot and readily identifiable as a comet.
SPACE.com will provide updates on this new comet as conditions change.
- Gallery: The Great Comet McNaught: Part 1, Part 2
- The Best Comets of All Time
- Astrophotography Telescopes for Beginners
Joe Rao serves as an instructor and guest lecturer at New York's Hayden Planetarium. He writes about astronomy for The New York Times and other publications, and he is also an on-camera meteorologist for News 12 Westchester, New York.