

Better yet, use borg to back up. Managing your own tars is a burden. Borg does duduplication, encryption, compression, and incrementals. It’s as easy to use as rsync but it’s a proper backup tool, rather than a syncing tool.
Not the only option, but it’s open source, and a lot of hosts support it directly. Also works great for local backups to external media. Check out Vorta if you want a GUI.
Alien meaning “external”.
Electrical interference can come from all kinds of places, near and far. I guess technically you might get interference from other planets but I don’t think that’s what they meant. :) Solar flares are a possibility, though.