The penultimate post on invisibility in fiction in my attempt to blog 30 days in a row! I’ve got more stories to blog after that, but this will probably be the end of my continuous run.

So we’ve technically already had one story about an actual “Invisible World,” but Ed Earl Repp’s story clearly didn’t go far enough — the world itself wasn’t invisible, it just had an atmosphere that guided light around it, acting like a cloaking device. But what if the entire planet, and everything on it, were perfectly invisible? That’s the story in Thorne Lee’s “Ghost Planet,” which appeared in the June 1943 issue of Startling Stories:

When the President of the United Planets is kidnapped and taken away in a rocketship, Captain Elko Van-Darcy takes off in pursuit, along with fellow pilot Armand Rambeau and the President’s daughter Nora Reed. They are baffled at first when their quarry seems to be flying into empty space, but soon realize — when they crash into it — that the craft has flown to an invisible planet! They are swiftly captured by the invisible aliens of this world, and must figure out how to free themselves and rescue the President before all of them are killed!

That’s about all the synopsis I need to give of the story, because there isn’t a whole lot to it — there are evil aliens, a damsel in distress, a brave and clever hero, and a turncoat who betrays them at an unexpected moment. All of these are standard fare in pulp science fiction stories.

The invisibility mechanism is somewhat clever, however, and worth mentioning. Van-Darcy and Rambeau stumble across the secret when they fall asleep with their heads in the sunlight — and their heads turn invisible!

To begin with, Van-Darcy explains the invisibility using the now very familiar “everything is ultraviolet in color” explanation that first was used by Ambrose Bierce in “The Damned Thing.”

“Just because almost everything on the Earth is in a visible color, we take it for granted that everything in the universe is colored similarly. But why couldn’t there be a planet with a peculiar color pattern of its own—a pattern different from any other planet?

“Suppose the very substance of the planet, and the very flesh of its people, are ultra-violet in color ! Suppose every tree and every building, even the very clothing they wear, is some shade of ultra-violet!

Incidentally, it’s worth noting why, in reality, it is just not possible to have something be “some shade of ultra-violet” — the answer is “chemistry.” The absorption of light by atoms is dictated by the allowed energy levels of electrons around the nucleus. These energy levels correspond to frequencies of light that stretch over the visible and ultraviolet parts of the spectrum, and this is true for all atoms. This picture is a bit oversimplified, because the structure of a material — the way its atoms are arranged — also plays a role in the absorption spectrum, but overall the absorption of light is strongly influence by fundamental atomic structure. There simply aren’t any materials which do not absorb visible light to some degree.

But in a science fiction story, this is fine! But why did the heads of our heroes disappear when exposed to sunlight?

Van rubbed his invisible head, dubiously. “Well,” he said, “it must be something about the atmosphere of the planet which filters only through certain colors. On Earth when you’re sunburned, you turn red and then brown. On this planet when you’re sunburned, you turn ultra-violet.”

This is a very silly idea, but a very charming one! The sunburn in this world makes one turn an invisible color!

Van-Darcy also realizes that he can make himself sensitive to ultra-violet by staring at the sun for an extended period of time on this world (don’t stare at the sun in real life, ever). He does so, and can then see his invisible captors. This gives him an advantage, and he presses this advantage once he realizes that there is a specific visible color of light that the invisible creatures can’t see themselves!

This is another invisibility story that isn’t a particularly compelling story, but carries some fun ideas about invisibility that made it fun to read!