NASA's Hubble Space Telescope spied comet C/2012 S1 ISON earlier this month, around 621 million km away from the sun (or slightly closer than Jupiter).
Sounds like a staggering distance, but the comet -- discovered last year -- is about to get way, way closer.
By late November, Comet ISON will pass by the sun at a way-too-close-for-comfort distance of just 1.1 million kilometres.
To put that into perspective: Blazing planet Mercury only ever gets around 46 million km away from the star at the heart of our solar system.
By the time it gets that close, it will be bright enough to be seen with the naked eye, or at least its tail might, until sometime in January 2014.
That's IF it survives passing that close to the sun, which is not guaranteed.
As it is, NASA says the comet's nucleus is only around five kilometres across, but its coma (that dusty "head" in the picture) is around 1.2 times the width of Australia, and its tail extends 90,000 km.