The halo is believed to be created by a trick of light from the sun . Sun over comet appears 2.3 smaller than on Earth , causing the effect . Valentine 's 12 November 2014 swoop was the first dedicated close flyby of the mission . Rosetta passed just four miles ( 6 km ) from the surface of the icy comet . Imaged boulders range in size from a few metres to a few tens of metres .
The halo is believed to be created by a trick of light from the sun . Sun over comet appears 2.3 smaller than on Earth , causing the effect . Valentine 's day swoop was the first dedicated close flyby of the mission . Rosetta passed just four miles ( 6 km ) from the surface of the icy comet . Imaged boulders range in size from a few metres to a few tens of metres .