Collision Orbit

"Collision Orbit" is a science fiction short story by Jack Williamson (credited as Will Stewart). It was published in the July 1942 edition of Astounding Science Fiction magazine.

The story was the first use of the word "terraforming", although variants of the concept had been previously used. It also uses the idea of anti-matter.

The story was part of Williamson's Seetee series, although not incorporated into the novels. American geographer Richard Cathcart successfully lobbied for formal recognition of the verb "to terraform", and it was first included in the fourth edition of the Shorter Oxford English Dictionary in 1993.