I think these aren't on the manager because they are a tad on the large size. Total size on my rig is 4.3gb. Just one galaxy is over 500mb. They're currently stored on Google Drive which occasionally blocks downloads due to bandwidth limitations. And because there is no direct download link (it's a multi-step process with Google Drive), it's impossible to put them on the manager.
I suppose if someone had 5gb of spare space on a server somewhere, and unlimited bandwidth, they could be relocated.
However, you can get them from the wiki here: Povray Planets
I'm currently working on this.. should be upgrading my current hosting package to unlimited bandwidth shortly. At which point, I can host the Povray packages there.. lord knows I've done little enough with my webserver the last few years. Since I'm paying for it anyway, may as well do something useful with it.