The Odin satellite observes water in comet 103P/Hartley 2

1 November 2010

The Comet Hartley 2 orbits the Sun with a period of 6.5 years. This year, it passed closest to the Sun on 28 October at 1.059 AU (Astronomical Unit= distance Sun-Earth=150 millions km) and on 20 October, it was only at 0.121 AU from the Earth! An international team, with astronomers from Paris Observatory, took this opportunity to observe the fundamental line of water at 557 GHz with the satellite Odin. The comet produces 180 to 300kg of water per second, and this production varies in time, certainly in phase with the rotation of the comet’s nucleus.

Figure 1: A map of water in comet Hartley 2, observed by Odin on 29 october 2010. © Swedish Space Corporation/Centre national d’études spatiales/Observatoire de Paris.

Figure 2: The evolution of the production of water in comet Hartley 2, as observed with Odin. © Swedish Space Corporation/Centre national d’études spatiales/Observatoire de Paris. Click on the image to enlarge it

Reference International Astronomical Union electronic telegram No. 2524. Contact Nicolas Biver (Observatoire de Paris, LESIA et CNRS) Jacques Crovisier (Observatoire de Paris, LESIA et CNRS)