The Wanderer is a science fiction novel by American writer Fritz Leiber, published as a paperback original by Ballantine Books in 1964.

[1] The Wanderer was the first novel to win the Hugo Award without previously being published in hardcover or appearing in some form in a genre magazine.

Both the USA and the USSR have lunar bases, but the Soviets have retained their early lead by sending an expedition to Mars.

From the point of view of most of the population of the Earth, a new planet appears out of nowhere close to the Moon towards the end of a total lunar eclipse.

This is later confirmed by a man captured by a feline humanoid, and she also explains that the moon was destroyed to fuel the wandering planet.

The planet's appearance is startling - several massive patterns of purple and gold, and initially resembling the Tao symbol of human culture.

Its gravity causes mass death and destruction as it raises huge ocean waves and causes earthquakes and volcanic eruptions.

There is a man attempting a solo crossing of the Atlantic Ocean, a smuggler operating off the coast of Vietnam, two friends in England, a trio of drug addicts in New York City, and the military controllers of the USA Moon mission, deep in a bunker somewhere near Washington, D.C.

Paul Hagbolt is escorting Margo Gelhorn (and her cat, Miaow) to observe the lunar eclipse at an observatory in California.

Following on a whim a sign advertising a "flying saucer symposium", Paul and Margo fall in with a group of intellectuals, dreamers, charlatans and misfits.

A large, female telepathic feline creature, she initially mistakes Miaow as the intelligent being whose thoughts she can hear, and Paul as a "monkey".

They belong to a culture that spans the Universe, has achieved immortality, and can construct planets and traverse hyperspace.

Their flight has brought them to Earth orbit to refuel as huge amounts of matter must be converted to energy to power their hyperspace drive and their weapons: the Wanderer is running on empty.

A second planet, "The Stranger", colored a dull gray where the Wanderer is bright purple and yellow, appears and threatens battle.

Don and Paul give their testimony as to the good treatment they have seen, along with thousands of other humans appearing by some kind of holographic projection.

[4] James Nicoll has described the novel as "terrible", saying that although its premise — "hollow planets filled with catgirls who want to steal the moon" — may be "amazing or at least intriguing", the novel itself "falls well short of its potential"; he attributes its Hugo win to a weak slate of nominees, and to Leiber's "blatant and unabashed sucking up to SF fandom".