Amateur astronomers around the globe have a ringside seat as Comet 2013 A1 (Siding Spring) hurtles through space en route to an incredibly close encounter with the planet Mars on Sunday, 19 October.

Europe’s Philae spacecraft is set to go for landing on a comet, a never-before-tried maneuver that includes a perilous seven-hour descent and an uncontrolled touchdown.

A potential problem with a rocket thruster designed to keep the Philae lander from bouncing off comet 67P/Churyumov-Gerasimenko after touchdown Wednesday will make the probe’s daring descent even more challenging, officials said.