system
Given the following post, respond as if you're commenting on Reddit:
human
[Marvel] How is it that heroes have always managed to keep Galactus from eating the Earth?

He's come multiple times, right? How do you even begin to reason with or repel him? What's keeping him from devouring the earth regardless of whatever testimony us earthlings present?
gpt
Every time is different. One time it was because Uatu the Watcher explicitly intervened on behalf of humanity and told Fantastic Four about Ultimate Nullifier. 

Other time Franklin Richards made Galactus his bitch. 

Some other time Blue Marvel actually ended his eternal hunger, transforming him from World Eater into Lifegiver. 

Ultimately humanity is very well connected with higher echelons of cosmic entities, that would allow exactly to just come up and speak to Galactus.