A history of the term 'planet' for aggregators:
At some point, a couple of other sites emerged with the name “planet” as what I believe was a tongue-in-cheek reference to the “planet” gaming sites. Planet Debian is the first one I remember seeing but I have no idea if it was the first to exist. Many of these sites were built using auto-aggregation from the then-new RSS protocol. This joke ended up spreading pretty far and wide and at one point there was even a “planet planet” to keep track of all the planets2 (although it seems to have gone down sometime in 2017).