Comet Siding Spring and MarsA unique composite image of comet Siding Spring as it made its never-before-seen close passage of a comet by Mars.Credits: NASA, ESA, PSI, JHU/APL, STScI/AURA Download Share Tags Hubble Space TelescopeImage CreditNASA, ESA, PSI, JHU/APL, STScI/AURASize1024x754px