Variable Star is a 2006 science fiction novel by American author Spider Robinson, based on the surviving seven pages of an eight-page 1955 novel outline by the late Robert A. Heinlein († 1988).

It describes the coming of age of a young musician who signs on to the crew of a starship as a way of escaping from a failed romance.

Eighteen-year-old aspiring musician and composer Joel Johnston, a Ganymedean on Earth for his education, falls in love with fellow college student Jinny Hamilton.

Joel learns that Conrad has already mapped out his future; he is to be groomed for a role in the family business and to produce children to continue the dynasty.

The ship is headed to a distant star on a 20-year voyage to establish a colony, one of several scattered dozens of light-years from Earth.

Only one experimental ship exists, capable of carrying ten people; aboard are several Conrads, including the domineering Richard, Jinny, her husband, and Evelyn, who has aged faster than Joel because of time dilation.

Joel eventually realizes that Conrad is lying; he only contacted the Sheffield to obtain needed supplies and has no intention of returning.

SFF World felt it was written as though Heinlein himself were alive today, as it includes modern cultural references such as The Simpsons, but also noted some missteps, such as a section which reads, Loving Zog’s Farms was another profound connection, one that went back in time almost as far as music.

[3] Sci-Fi Dimensions was more enthusiastic, saying, "Variable Star is both a worthy continuation of the Heinlein legacy and a darn fine Spider Robinson novel to boot.