Barnard's star is a star indeed. A member of the second closest star system to the Sun at 6 light years (1.84 parsecs) away, it pops up all over twentieth-century science fiction, from classic comics to Asimov.

Dutch-American astronomer Peter van de Kamp made the first modern claim to have spotted an exoplanet there in 1963, having studied the star since 1938. He thought that he had discovered wobbles in the position of Barnard that indicated a Jupiter-class planet in orbit around it. In 1969, van de Kamp revised his findings, positing two planets — one slightly bigger than Jupiter and one slightly smaller. But it wasn't long before other astronomers challenged the claims, suggesting that van de Kamp's 'discovery' was merely an artefact of upgrade work at his observatory.

Since van de Kamp's time, the Barnard 'system' has been a staple of sci-fi, from short stories and novels, to films and television series. In Douglas Adams' The Hitchhiker's Guide to the Galaxy series and Arthur C. Clarke's The Garden of Rama (Bantam, 1991), it is a way station for interstellar travellers. Michael Moorcock uses an imagined planet orbiting the star as the site of a refugee camp for humans fleeing social breakdown on Earth. For Isaac Asimov, a Barnard-system planet is home to invertebrate marine animals. In a series of comic-book strips in the 1970s, Will Eisner sited humankind's first contact with an extraterrestrial civilization on a planet in the system. And in the short-lived Battlestar Galactica spin-off series Galactica 1980, the dastardly Cylons are believed to be hiding there.

Recently, the status of this sci-fi staple itself wobbled. In August, a survey by a team of eight astronomers, led by Jieun Choi of the University of California, Berkeley, and covering 25 years' worth of measurements, concluded that Barnard's star does not have any planets — Earth-size or otherwise.

Two months later, astronomers had better news for the sci-fi cognoscenti. On 17 October, Xavier Dumusque at the University of Geneva in Switzerland and his team reported in Nature that Alpha Centauri B, a member of our closest star system, just 4.3 light years away, has an Earth-sized planet orbiting — albeit with a tight, sun-hugging 'year' of just 3.236 days, far from the presumed habitable zone (X. Dumusque et al. Nature 491, 207–211; 2012).

Potential effects of a tight orbit include volcanism caused by strong gravitational tides and fierce stellar winds, as imagined here for the exoplanet Gliese 876d. Credit: INGA NIELSEN

This was sure to resonate with readers of Stansilaw Lem, Robert Silverberg, Philip K. Dick and, again, Asimov and Clarke, who all made use of the Alpha Centauri system in their fiction. It also appeared in the television series Buck Rogers in the 25th Century, Doctor Who and Star Trek. Indeed, Zefram Cochrane, the Star Trek character who 'invented' the warp drive, lived there.

A probe would take 28,000 years to get to Alpha Centauri. We have to get more realistic.

So what do these two scientific developments mean for science fiction? Kim Stanley Robinson, author of the bestselling Mars Trilogy, takes a radical view. He suggests that we get over the idea of interstellar travel altogether: a probe would take 28,000 years to get to Alpha Centauri. “We can't go fast enough to get to any of these places,” he says.

Barnard's star was once “the place for nearby space”, Robinson says, as his novel Icehenge (Ace, 1984) — in which characters build a starship headed for it — attests. Now that researchers have identified some 840 exoplanets, and NASA's three-year-old Kepler space telescope has spotted 2,320 candidate planets, “there may never again be a single default destination”, Robinson continues.

In his recent book 2312, which imagines humanity three centuries from now, spread across terraformed planets, asteroids and moons in our own Solar System, Robinson writes frankly about the galactic hinterland we inhabit. “The stars exist beyond human time, beyond human reach,” says the narrator. “We live in the little pearl of warmth surrounding our star; outside it lies a vastness beyond comprehension. The solar system is our one and only home.”

Of the idea that we are destined to go to the stars and inhabit, if not the whole Universe, maybe the whole galaxy, Robinson cautions “it's a fantasy, of power, transcendence and a kind of species immortality. We have to get more realistic.”