Europe's Rosetta spacecraft was orbiting only 16 miles away from Churyumov-Gerasimenko when it captured this mosaic of images showing jet activity at the neck of the comet. These jets are the product of ice sublimating and gases escaping from the comet's nucleus through cracks and pores on the surface.

As comets travel closer to the sun, the dust-laden plumes of vaporizing ice are pushed back by the pressure of sunlight, forming the iconic dust tails. Comets usually develop a second tail — the ion tail — when solar radiation excites the gas particles, causing them to glow.


Expect to see more pyrotechnics in August 2015, when Churyumov-Gerasimenko reaches its closest point to the Sun, at a distance of roughly 114 million miles.

Image: ESA/Rosetta/NAVCAM.