It’s been bugging me that I can’t remember much about this story. Basically, a huge, planet sized space travelling alien landed on Earth, about the comparative size of a worm on an apple. It was so huge it affected the climate, and even the Earth’s orbit. It moved about occasionally causing huge devastation, and then disappeared as quickly as it came. obviously leaving complete devastation behind.
“Heresies of the Huge God” by Brian Aldiss which originally appeared in Galaxy, August 1966.
That sounds about right - thanks! 