If you look with a certain kind of eye at the photos of Jupiter’s moon Io taken by the Voyager, Galileo and Cassini spacecrafts, you cringe. It is a seething wasteland.

Sulfurous, flaky yellow sands stretch across distances cracked by miles-wide gouges. Ten-thousand-foot mountains jut up like inverted chasms, and pools of lava heave from gashes in the surface like massive boils. Volcanic ash and gas shoot hundreds of feet into emptiness.

In Io’s sky, Jupiter crawls like a gargantua, a bright, vast, streaked disk eating the blackness of space, so huge it seems intent on crushing everything under it. You could actually see it up there obliterating stars, if somehow you could stand on Io’s disturbed surface. It overwhelms the sky and could outright terrify you, like the man who was fool enough to demand to see an angel’s real face.

But worse than what you can see, is what you can’t see. Except for these glimpses snatched by robot cameras of blistered yellow-orange flatness, reddish lava, puking volcanoes and fang-shaped mountains, most of what happens on Io is invisible to your eyes.

Io is twisting and writhing. Every 42 hours – the period of one Ioic day – it turns its face from Jupiter and looks out toward its sister moons Europa and Callisto and brother Ganymede, which is larger than Mercury. The tugging and jostling of their gravitation and motion, and Jupiter’s stupendous gravity, and Io’s own frantic 3 1/2-day tear around the giant planet, all wobble and squeeze Io out of round by as much as 300 feet. The surface stretches and buckles like a crushed lemon. Inside, the warping generates heat that liquefies rock. We see only the fissures that burst open like running sores.

We see Io’s volcanoes throw up gases, but don’t see them intermingle with Jupiter’s magnetosphere – a plasma of atomic particles formed from the interaction of the planet’s magnetic field with gusts of particles flowing from the sun. The plasma co-rotates with Jupiter and sets up an electric current. If Io’s inside spins the way astronomers think it does, then it too has a magnetic field that interacts with Jupiter’s, and the two planetary dynamos generate perpetual electrocution. A torus of intense radiation swarms the general vicinity of Jupiter, and Io bakes in fire unknown to human flesh.

Most of this is invisible to the cameras, and yet real enough to astronomers, who attach numbers to what little the spacecraft detects. In fact 96 percent of the material in the universe is beyond our perception, but we know it’s there by the numbers. The numbers themselves are never seen; they exist only in the mind, and only their expressions are actually visible. Those magnetic fields half a billion miles away are known to exist by equations built from measurements.

It’s almost impossible to look at pictures of Io and not see, in your mind’s eye, hell. This is an expression of an ancient psychology: What is seen, combined with what is imagined, is an equation for what is real.

No scientist or anyone I know believes Io is literally hell. But still there exists a deep intuition of suffering so intense it’s barely separable from terror, as expressed in images from Dante’s Inferno, and Buddhism’s Avici hell, and Islam’s Na’ar. Io’s pits for all the world resemble those undiscovered countries, and they are disturbing.

-dwilde@bangordailynews.net