Comet ISON Viewing GuideComet ISON is visible through binoculars and it is set to get even brighter over the coming weeks as it makes its approach to the Sun.
As Comet C/2012 S1 ISON approaches the Sun, water-ice in the comet's nucleus will sublimate which means that it will instantly turn from a solid to a gas, without melting into a liquid. When this happens we will have a better indication of just how spectacular comet ISON will become later in the year.
During October comet ISON and Mars follow an almost perpendicular path across the evening sky, at the beginning of the month, Comet ISON will be just under 2° from Mars. Comet ISON will be around magnitude 11 so you'll need a telescope to view it.
On the 15th of October, Comet ISON and Mars pass the bright star Regulus and will form a very close conjunction with Regulus at the bottom, Mars will be 1° above it and Comet ISON 1° above Mars. By this time ISON should be around magnitude 8.2 and visible in modest binoculars.
Towards the end of the month, ISON approaches the Sun on its first pass into the inner Solar System and joins the regular visitor comet 2P/Encke. On the 27th of October, Comet Encke passes the magnitude 2.1 star Denebola by 3.5" and at the end of the month, ISON and Encke will be around 20° apart.
How To View Comet ISON
The most important requirement for any successful comet viewing is a completely dark, clear, unobstructed horizon. Darkness is essential if you plan to get a good view of the tail.
On 11 November the Comet ISON will cross the orbit of Venus, and by 20 November it will be so close to the Sun that it will be almost sunrise before its head clears the horizon, so viewing it at all at this time might be challenging, demanding crystal-clear skies. By the end of the month, it should be easily seen in the eastern sky before dawn and we might just see the tail sticking up from beyond the horizon before the Sun comes up.
Comet ISON will put on its best display throughout November and December and its coma will look like a tiny ball of light set within a milky glow. From the solid part of the comet, the tiny icy nucleus is hidden within the coma, and the tail (or tails!) will arc across several degrees of the sky.
Comet ISON is roughly heading towards the centre of our Solar System and it will pass within 1.2 million miles of the Sun's surface on 28th November when it reaches perihelion (the point when it's at its closest to the Sun) before being whipped around to head back roughly in the direction it came.
As ISON makes its outbound journey, it will pass over the northern hemisphere of Earth at a distance of around 40,000,000 miles on 26th December.
If ISON lives up to the hype, you could expect to see the Comet with the unaided eye anywhere between the middle of November and the middle of January 2014.
