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In the night sky: Orion
In the night sky: Orion

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4.2.6 Comets

An image of Halley’s Comet.
Figure 18 Halley’s comet. Image taken at the Kitt Peak National Observatory near Tucson, Ariz. on 7 May 2004.

Comets are clumps of dust and organic material bound together by ice, with an irregular shape and up to a few kilometres across.

An image of Halley’s Comet.
Figure 19 The irregular shape of Halley’s comet. The ‘potato shaped’ nucleus of the comet measures roughly 15 kilometers across.

When the European Space Agency’s Giotto mission photographed Halley’s comet in 1985, it was the first time that the irregular shape of a cometary nucleus had been observed.

An image of Comet 67P/Churyumov-Gerasimenko.
Figure 20 Comet 67P/Churyumov-Gerasimenko.

In March 2004, the European Space Agency (ESA) launched the Rosetta spacecraft, with the goal of meeting up with comet Churyumov-Gerasimenko (named after its discoverers) in July 2014, flying alongside it for 18 months. This included dropping a lander (Philae) onto the comet’s surface which happened in November 2014.

Find out more about the Philae lander in the next section.