Before we had ISON or Siding Spring, there was comet Holmes, which blazed past Earth back in November of 2007. Given its close proximity — passing by from a distance of just 2 AU — anyone handy with a telescope was able to see and study its anatomy. For those of us who weren’t that lucky, it was still bright enough to be seen without one.
The comet was initially discovered by Edwin Holmes all the way back in November, 1892. Much later, the comet experienced a massive outburst that gave it a total visual magnitude of 4 (easily bright enough to be discernible with the naked eye). During this outburst, Comet Holmes increased in brightness by a factor of about half a million, rivaling M31 (our distant neighbor, the Andromeda galaxy) in brightness. This outburst occurred just as it was passing within the constellation of Perseus. It has been said that Comet Holmes temporarily became the largest object in our solar system; with the diameter of its coma exceeding the diameter of the Sun for a short window of time.
See a larger image here.