It is the moon.

Enel thinks that the infinite earth (moon) is God's place. After being defeated by Luffy, he drove his Ark proverb to the infinite land. (1) Enel easily defeated the pirates in the ongoing "Moon Relics Excavation Plan" on the infinite earth, stumbled upon Hualuka, once the hometown of the empty islanders, met four small robots who wanted to avenge Dr. Zkimi and came to the infinite earth, and then led the Enel army to dominate the infinite earth. (Note: ① Serialized on the cover of One Piece comics, the ninth bomb "Enel's Space War")