The New Horizons probe snapped several images of volcanic Io and sedate Europa on the mission's closest approach to Jupiter. This composite of several images shows the relative positions of the two moons as they were moving past each other – in reality they were separated by 490,000 miles (790,000 kilometers).

Three volcanic plumes billow spaceward from Io, notably a 190 mile (300-kilometer) high plume from the Tvashtar volcano at the 11 o'clock position. Io's night side is bathed in greenish reflected light from Jupiter. By contrast, Europa's night side is dark as it faces away from Jupiter. New Horizons captured the images of Io and Europa at distances of 2.8 million miles (4.6 million kilometers) and 2.4 million miles (3.8 million kilometers).

This picture is a rare New Horizons image taken primarily for aesthetic value, instead of purely scientific reasons. The composition was suggested by space enthusiast Richard Hendricks of Austin, Texas, in response to a request on the Internet.

--JHU/APL and SPACE.com Staff

Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute