27 Oct, 2018
Blog 66: Comets, Part 2
Of the comets I've seen, no two were alike, ranging from a monster that, counting its coma of particles, was the biggest thing in the solar system, to a puny streak that -- once it had dipped out of view from the northern hemisphere -- turned into a dazzling spectacle with multiple tails.
As NASA points out, comets are "dirty snowballs" that coalesced when the solar system formed about 4.6 billion years ago, mostly "ice coated with dark organic material." The agency also describes them as