Gaea, the goddess of the Earth, is the mother of both Thor and Atum. Thor's older half-brother, Atum, received various characteristics from their mother. Thor's father, Odin, desired a son who could comprehend and endure life on Earth, and this was a feature he got from his mother. However, Atum is not the same as Thor. Atum is the physical manifestation of the earth's ecosystem, making him more powerful than Thor. They don't have much of a connection. However, there was an encounter with Atum in the Marvel Universe when he took the guise of Demogorge. Atum is far more powerful than Thor.