Not everyone has an eye for graphic design, so if you can't see the that the resemblance is more than just "a circle as part of their logo", that's understandable.
If you need a tool to help, take a look at the google image search for "lonely planet". Their image matching algorithm thinks planet's logo is related to lonely planet's.
https://www.google.com/search?q=lonely+planet&tbm=isch