NASA’s NEOWISE telescope spotted Comet C/2013 A1 Siding Spring shortly before it is expected to fly by Mars in the fall of this year. In this composite image encompassing four frames, the comet can be seen in multiple positions as it traverses through space relative to the stars in the background.  At the time that these pictures were taken, Comet Siding Spring was approximately 175 million miles (1.88 astronomical units) from the Sun.

This picture of comet Siding Spring also provides a view of the radio galaxy Fornax A (NGC1316) near the upper right corner.