C/2012 S1, more commonly known as the comet ISON, will achieve perihelion on November 28th, 2013. At its closest, ISON will be only 724,000 miles (1,165,000 km) above the surface of the Sun.
Initially thought to have a hyperbolic orbit, ISON now appears to follow an elliptical orbit, achieving perihelion every 400,864.54 years.
So when will it be closest to Earth?
Assuming the Sun’s gravity doesn’t pull it in or tear it apart, ISON will pass us at a distance of 39.9 million miles (64,210,000 km) on December 26th of this year. However, Earth won’t cross the comet’s orbit until mid-January 2014, well after ISON has moved on.
Although unlikely as we won’t be passing through the tail, there is a chance that we may see an increase in meteor activity due to ISON’s passing.
As of November 25th, ISON is most likely to be visible to the naked eye near Mercury. It will probably be at its brightest during the close solar pass on the 28th, though scientists are not yet sure that it will survive the encounter.
In the Northern Hemisphere, the best placement for viewing will be from mid-December 2013 until early January 2014, when it will appear to pass within 2º of Polaris.
Does this mean you should make an effort to catch a glimpse? Absolutely.
After all, how often do celestial wonders come to us?