Herschel/HIFI image and spectrum of Comet 103P/Hartley 2
This Herschel/HIFI image and water emission spectrum of Comet 103P/Hartley 2 was taken on 30 October 2010 when the comet was at a distance of 19.5 million km from the Herschel Space Observatory.
The HIFI instrument is able to detect weak spectral lines not previously observed in short-period comets, and to obtain high spatial resolution imaging of water emission from the comet's nucleus. The spectrum portrays the 557 GHz emission from water molecules in the comet. By analyzing the spectrum scientist are able to derive a water production rate of 230 kg per second.
The image is 1.5' by 3' and the Sun symbol and arrow indicate the projected direction towards the Sun.