From Halopedia, the Halo wiki
At least 4
The Ealen system is a stellar system situated in close proximity to humanity's Outer Colonies. The star system is home to at least four planets, including Ealen IV. The system was colonized by the Covenant during the Human-Covenant War due to how close it is to the human colonies. After the war, a peace conference between the Sangheili and Jiralhanae was to be held on Ealen IV, but it was interrupted by Covenant mercenaries led by Vata 'Gajat.