Galactus has always been a character I've struggled to take seriously. I like the idea of Galactus and appreciate the threat he represents to a world on his dinner menu, but the logistics of his modus operandi are to me, well, funny. Characters like Galactus--aliens, celestial beings, etc--signal mankind's tendency to imagine higher lifeforms as something like ourselves: bi-pedal, two eyes and a mouth situated on a head mounted on a torso with limbs. How would such a life form evolve in the vacuum of space?
That's why sea creatures look so alien. They've adapted to an environment so different from ours here on land that their bodies don't look or function like ours. Two arms and legs aren't very practical for surviving under water, and I imagine it would be the same in outer space.
That's why I'm inclined to look at the Ultimate version of Galactus, or even the nebulous cloud from that wretched Fantastic Four sequel, as more plausible incarnations of a being that devours entire planets for sustenance.
But this is comics, and his helmet is pimp, so who gives a shit?