19P/Borrelly

The comet Borrelly ( official name 19P/Borrelly ) is a short- period comet, which has been investigated on 22 September 2001 through the NASA space probe Deep Space 1.

Discovery

The comet was discovered on 28 December 1904 by Alphonse Louis Nicolas Borrelly in the constellation Cetus. Soon after, the comet was recognized as short-period, and his return for 1911 predicted correctly.

Orbit

Borrelly is running on an elliptical orbit around the sun, whose point closest to the Sun ( perihelion ) lies just inside the orbit of Mars. The sonnenfernste point ( aphelion ) is located just outside the orbit of the planet Jupiter, which marks him as a short-period comets of the Jupiter family.

Space probe Deep Space 1

On 22 September 2001 the NASA spacecraft Deep Space 1 flew in 2200 km distance to the comet over. Could be Borrelly was the fourth comet Giacobini - Zinner by Halley and Grigg - Skjellerup, which was explored by a space probe, and the second (after Halley ) in which images of the core to the earth transmitted. This showed in the pictures as an elongated structure with a size of about 8 × 4 × 4 km. The density of the core is only 0.49 g / cm ³. Its surface is the darkest in the previously known solar system: The albedo is on average 0.03, making it as dark as black toner powder. Some particularly black spots even have only a remission value of 0.007, are known to have hardly appropriate minerals.