Comet Hartley 2 is a small comet, with a diameter of about 1.5 km, and with an orbital period of 6.46 years. It was discovered by Malcolm Hartley in 1986 in Australia. The Deep Impact spacecraft will flyby Hartley 2 on November 4, 2010, having previously visited comet 9P/Tempel in 2005. At its closest approach, the spacecraft will be 700 kilometers away from the comet. Right now it is visible through binoculars and small telescopes. It may brighten enough to be seen with the visible eye in the near future.

The comet will be closest to Earth on October 20, 2010. On October 28, 2010 the comet will reach its closest approach to the sun. The next time that we should see is Hartley 2 is around April, 2017.

Hubble Space Telescope observations of comet 103P/Hartley 2, taken on September 25, are helping in the planning for a November 4 flyby of the comet by NASA’s Deep Impact eXtended Investigation (DIXI) spacecraft.

Analysis of the new Hubble data shows that the nucleus has a diameter of approximately 0.93 miles (1.5 km), which is consistent with previous estimates.

The comet is in a highly active state, as it approaches the Sun. The Hubble data show that the coma is remarkably uniform, with no evidence for the types of outgassing jets seen from most “Jupiter Family” comets, of which Hartley 2 is a member.

After the break is an image of Hartley 2 from the WISE space telescope.

via Hubble Probes Comet 103P/Hartley 2 in Preparation for DIXI flyby.