With the release of Season 9 Season of Dawn a number of planets have had Obelisks added to them, which tie into the Sundial on Mercury.
Donating your Polarized Fractaline will rank up an Obelisk unlocking extra benefits.
What is the maximum rank for an Obelisk?
There is a Triumph to get 40 ranks
Increase the Resonance Rank of any obelisks.
..and I have seen bonuses for Rank 11, so it doesn't cap out at 10. With 4 Obelisks x 10 Ranks for the 40 Global Resonance Triumph.
Do they just keep ranking up as long as you have seasonal currency?