Currently located beyond the orbit of Jupiter, Comet ISON is heading for a very close encounter with the sun next year. In November 2013, it will pass less than 0.012 Astronomical Units (Wikipedia) (1.8 million kilometers) from the center of the Sun, 1.2 million kilometers from the solar surface. The fierce heating it experiences in that approach could turn the comet into a bright naked-eye object.
NOTE: This visualization was revised in March 2013 to fix an ephemeris error. Other enhancements were included in the revision. Also fixed an error where perihelion distance was mistakenly labeled as distance from solar surface.