Mercury's comet-like appearance spotted by satellites looking at the Sun
Scientists from Boston University's Centre for Space Physics reported today that NASA satellites designed to view the escaping atmosphere of the Sun have also recorded evidence of escaping gas from the planet Mercury. The STEREO mission has two satellites placed in the same orbit around the Sun that the Earth has, but at locations ahead and behind it. This configuration offers multi-directional views of the electrons and ions that make up the escaping solar wind. On occasion, the planet Mercury appears in the field of view of one or both satellites. In addition to its appearance as a bright disk of reflected sunlight, a 'tail' of emission can be seen in some of the images. Announcing this new method of observing Mercury and trying to understand the nature of the gases that might make up this tail feature were the topics presented at the European Planetary Science Congress meeting in...