The Mighty Thor, which will be written by Fraction alongside previous series artist Olivier Copiel, is due to launch this April.
"Galactus comes to eat Asgard because there's something incredible that Thor has harvested out of the World Tree," Fraction explained to the publisher's official site. "Asgard vs. Galactus! Thor vs. The Silver Surfer! What's not to be psyched about?"
The writer also revealed that fans can expect serious repercussions for the end of his current Thor story arc 'The World Eaters', which ends this March.
"When the dust settles, not everyone goes home," he said. "The entire status quo of Asgard has changed."
The Mighty Thor will see Thor and Sif travel into the nexus of nine worlds. Fraction has promised that Thor will be facing off against a number of "god-scaled threats".
Following Fraction's move to the new series, Kieron Gillen will take over as writer on Thor, which is to be retitled Journey Into Mystery.
The Mighty Thor #1 launches in April.