A Comet at Midsummer Dawn

If you’re up before sunrise on a clear night over the next two weeks, you’ll get a chance to see a comet ambling across the midsummer sky.  It won’t be a dazzler, but it’s not everyday you see a visitor from the deep reaches of the solar system.  And like many comets, this one may be unpredictable and brighten unexpectedly, putting on a good show for early risers at mid month.

The comet was discovered in September 2009 by the Australian astronomer Robert McNaught at the Siding Springs Observatory in New South Wales.  By convention, this comet is named after McNaught.  It’s official name is C/2009 R1 (McNaught), or just Comet McNaught.

*** Recommended by One-Minute Astronomer ***

The ideal binoculars for summer stargazing.  Big 50 mm lenses give bright pinpoint images of stars, while the 7.5 degree field of view gives sweeping images of comets, bright nebulae, and the Milky Way.  Waterproof metal housing and nitrogen-purged optical path to prevent fogging.  Perfect for grab-and-go astronomy.  Click here to learn more…

* * * * *

This is not the first Comet McNaught.  While most astronomers are lucky to discover one new comet in their career, Robert McNaught has bagged 54 and counting.  His most famous comet was also called Comet McNaught, and was also known as the “Great Comet of 2007”.  It delighted stargazers in the southern hemisphere in early 2007.  McNaught works as part of a NASA survey team which scans the sky for hazardous near-Earth objects, so his work gives him opportunity to see new comets and uncatalogued asteroids as they approach the inner solar system.  This comet poses no danger to Earth.

Like all comets, McNaught is an icy remnant of the formation of the solar system.  It likely comes from the Oort Cloud, a spherical congregation of perhaps a trillion comets and which may stretch a quarter way to the nearest star.  Small perturbations by a passing star or by the gas giants of our solar system sometimes nudge a comet out of the Oort cloud, beginning its long trip towards the Sun.  This Comet McNaught appears to be in an open hyperbolic orbit, which means this is its first and probably last visit to the inner solar system.

This comet is expected to be fairly dim, though you will be able to see it in a small telescope or decent pair of binoculars.  But you never know with comets… their brightness is hard to predict.  So there’s a chance it will brighten enough to see with your unaided eye in dark sky.

The map below shows you where to find the comet.

The path of Comet C/2009 R1 (McNaught) through mid June (click to enlarge)

At 4 a.m. or so, look east-northeast about two fist-widths below the W-shaped constellation Cassiopeia.  You’ll see a line of bright stars descending diagonally to the northern horizon.  These are Mirach and Almaak (in Andromeda), Mirphak (in Perseus), and Capella (in Auriga).  The comet follows the line of these stars over the first few weeks of the month.

From June 1-7, it hovers below the imaginary line connecting Mirach and Almaak.  From June 13-15, it lies a few degrees below Mirphak: this is likely the best time to see it, since the Moon won’t be around to brighten the sky.  In binoculars or a small telescope, the comet will look fuzzy and extended and quite unlike the sharp point-like stars.

Like most comets, McNaught will get brighter as it gets closer to the sun towards the end of the month.  But that means it’s harder to see.  After June 15, it appears to sink about one degree lower in the sky each day and approaches bright Capella near sunrise.  At month’s end, the comet swings behind the sun, then reappears in the southern sky briefly before it fades from view.

Here’s an image of Comet McNaught taken through a telescope and astrocamera.

Unlike McNaught’s bright comet of 2007, which put on the best show for southern hemisphere stargazers, this modest comet will be best seen in the northern sky.