One of the joys of reading science fiction is the chance to visit faraway worlds. While many faraway places simply offer up locales that mimic what we can find already here on Earth—Dune, I'm looking at you—it's the worlds that are vastly different from our own that crank up the Wow Factor.

This week let's take a look at some of the cool worlds that science fiction has to offer.

Read the last SF Signal and discover new sci-fi and fantasy books for February.

Artificial Worlds

When you read "faraway worlds" do you think exclusively of alien planets? It turns out that many of the worlds seen in science fiction do not occur naturally and are not planets at all—they are worlds constructed by humans or aliens. For example, Ashes of Candesce, the new book in Karl Schroeder's wondrous Virga series, takes place in Virga, a giant air-filled balloon 3,000 kilometers in diameter whose major artificial light source is the "sun" named Candesce. Its human inhabitants live within cylindrical dwellings that are spun up to create their own artificial gravity and strung together to form nations. It's an amazing, grand-scale concept that really plays with the ideas of up and down.

Artificial worlds often play with shape, one of the most famous being Larry Niven's Ringworld. Just like it sounds, the Ringworld is a massive, ring-shaped world that's a million miles wide and has a diameter equal to Earth's orbit around the sun. Its inhabitants live on the inside of the ring, which spins around to simulate gravity. Night and day are simulated by "shadow squares" that orbit the sun, which sits in the ring's center. To help imagine the scale, if you stood on Ringworld it would look much like any ordinary planet, except that (if you were facing "spinward") the land would slope upward, and you would see in the distance a huge arch extending toward the sky, bending way over your head (the top of it would be blocked by the sun), and coming back down behind you. How's that for a cool world?

Science fiction has given us other cool-shaped artificial worlds as well. Arthur C. Clarke, in his classic book Rendezvous with Rama, presented a planet-sized alien ship. Rama is a perfect cylinder, 12 miles in diameter and 34 miles long in which the interior is inhabitable. Eric Brown's Helix serves up not one, but thousands of planets that are strung together along a helix formation around its single sun. Another popular artificial world is called a Dyson Sphere, a giant spherical construct where inhabitants live on the interior surface. Dyson spheres play significant roles in Gene Wolfe's Book of the Long Sun series and, more recently, Hex by Allen Steele. 

Natural Planets

Man-made (or alien-made) worlds are fine, but there are naturally occurring sf worlds that elicit just as much sense of wonder. In Hal Clement's classic sf novel Mission of Gravity, the planet Mesklin is a believable M&M-shaped planet where gravity varies from 3g (three times Earth's gravity) at the equatorial "Rim" up to 700g at the poles. In these harsh conditions, human explorers attempt to communicate with foot-long, caterpillar-like creatures with pincers. Physics takes a righthand turn in the unique, mind-bending universe of Greg Egan's Clockwork Rocket. Here, light travels at different speeds, its creation generates energy, and plants make food by emitting their own light.

Sometimes planets are more than they appear to be. John Varley's Gaean trilogy (comprised of Titan, Wizard and Demon) concerns a discovered satellite of Saturn that turns out to be an alien being. In 1961, Stanislaw Lem wrote Solaris, whose titular ocean-covered world holds a few surprises—the ocean is actually a sentient organism, the exploration of which by humans is harmful to it. Speaking of sentience, the planet Petaybee in Powers That Be, the first book in the young adult sf series by Anne McCaffrey and Elizabeth Ann Scarborough, is just awakening to sentience itself.

All these worlds—whether artificial or natural—are the stuff of wonder that provide unique and interesting story backdrops. And all they are really waiting for is for you to come along and explore it.