As Europe's Rosetta spacecraft closes in on comet 67P/Churyumov-Gerasimenko, the ancient icy body is beginning to warm up, causing a cloud of dust and gas to form around its nucleus.
New images from Rosetta's camera show 67P's coma already spans more than 800 miles, or about 1,300 kilometer, in length, scientists said Thursday.
"67P is beginning to look like a real comet," Rosetta scientist Holger Sierks, with Germany's Max Planck Institute for Solar System Research, said in a statement.
Rosetta and the comet are about 395 million miles, or 635 million kilometers, from the sun. Its closest approach to the sun will be in August 2015.
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The newly released images were taken in late April when Rosetta was about 1.2 million miles, or 2 million kilometers, from its target. Rosetta is due to reach 67P in August.
Unlike previous probes, Rosetta will not fly past its target, but instead will put itself into orbit around the comet for detailed studies.
Rosetta also carries a secondary spacecraft called Philae, which is due to land on the comet's body in November. Philae is outfitted with 10 science instruments to tackle a wide range of studies, including a search for organic molecules.