Comet Hartley 2 was photographed, which will be reached in November by the Epoxy spacecraft (formerly Deep Impact)

The image was taken by the WISE Infrared Space Telescope. When the spacecraft approaches, the comet will be only 0.15 astronomical units from Earth

This deep-space visitor, seen by NASA's WISE 2 space telescope in infrared, is Comet Hartley 2, the target of NASA's Epoxy mission.

The comet, known as 103P/Hartley was discovered fairly recently, in 1986 by Malcolm Hartley from Australia. It must have originated in an icy orbit close to that of Jupiter, before something caused it to be pushed towards the Sun. The comet orbits the Sun every 6.46 years - and it reaches the closest point to the Sun, the perihelion, on October 28, 2011. Epoxy will use the Deep Impact spacecraft, which is already in deep space, and will reach it on November 4.

The Wise observatory helps Epoxy to gather a better understanding of the comet's behavior over time. The image taken on May 10, 2010 provided the most comprehensive view of the comet's dust tail - a strip of particles that the comet leaves behind on its journey through the inner solar system. The size of this path seen in the image behind the comet is 1.8 million kilometers.

Wise's infrared vision also made it possible to study the size range of the particles left behind, as well as in the comet's tail, seen here as a hazy patch to the right of the comet, in line with the particle trail. Infra-human observations are also useful for measuring the comet's nucleus and its rate of revolution around itself.

Comet Hartley 2 is about 1.2 kilometers in diameter and was 2.3 AU from the Sun when the image was taken. When Epoxy reaches the comet on November 4, it will be 1.1 AU from the Sun and only 0.15 AU from Earth (about 22.5 million km).

The hazy background of the image is noise, mainly due to dust within the solar system. Stars cannot be seen because they were removed during image processing from multiple images combined for this look. The infrared wavelengths 4.6, 12 and 22 microns are colored blue, green and red respectively.

For information on the NASA website