Space Topics: Asteroids and Comets
The Year in Pictures: 2007
McNaught by McNaught
Credit: R. H. McNaught, Siding Spring Observatory |
The arcing, striated dust tail of comet C/2006 (McNaught) blazes across
the star-studded Australian sky in a photo
captured at the desert location of Siding Spring Observatory by the comet’s discoverer, Robert McNaught.
Comet McNaught entered Earth’s skies in the Northern Hemisphere,
just bright enough to be seen in daylight. Then, for a few days, it was
invisible to Earth observers as it passed
through its perihelion and a close encounter with the Sun.
The perilous passage ignited a burst of cometary activity: tons of dust
and gas erupted from the comet’s tiny nucleus and, pushed into slightly
more distant orbits by solar radiation pressure, began to trail out behind.
As McNaught receded from the Sun, it
became visible to Southern Hemisphere observers as the brightest comet seen for 40 years.
McNaught’s tail was broken up into more than a dozen striations by
a process that is still not well understood but probably has to do with discrete
episodes of cometary activity causing more dust to be released at some times
than at others. Each night, the comet’s tail expanded until it occupied
nearly 30 degrees of the sky. By the end of February, however, the comet
had faded from view, on a return trip to the outer reaches of the solar system,
never to return. |
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