A tiny new moon has been discovered around the planet Neptune, the first new moon to be discovered around Neptune in a decade. The moon was discovered by Mark Showalter of the SETI Institute while poring over some data from the Hubble Space Telescope.
For now the moon has the drab name S/2004 N1, and its size is estimated by scientists as about 20 kilometers. This new moon orbits between two much larger moons, named Proteus and Larissa, with sizes of about 400 and 200 kilometers respectively.
Scientists think that the existence of a moon this small in this orbit is surprising. It seems surprising that a moon this small could have avoided both of two different fates which would have eliminated it from its current position: (1) the fate of falling into the much larger nearby moon Proteus because of gravitational attraction; (2) the fate of being struck by an asteroid early in the formation of the solar system, when asteroids were flying around much more commonly.
Referring to the early solar system and the newly discovered Neptune moon, a New Scientist article says, “In the post-Triton chaos, such a small rock should have been swept up to become part of Proteus, or broken up by interloping asteroids sometime after the system settled down.” So the existence of the new moon is something of a riddle.
Now as long as we have a cosmic mystery, I think we are entitled to think outside of the box, and ask: is it possible that the new moon of Saturn may be a recent arrival to the solar system – perhaps a spaceship from another star?
This question is not quite as outrageous as it may seem at first. If the new moon were, say, 1000 kilometers in width, then it would be pretty ridiculous to suggest even a remote possibility that it came from another star.
However, a size of twenty kilometers (about 12 miles) is actually within the size range imagined by scientists for one type of interstellar spacecraft: an artificial world spaceship, originally called the Bernal Sphere.
The Bernal Sphere was originally conceived in 1929 by John Desmond Bernal as a mobile artificial world which could travel from one star to another. In a web page on the Bernal Sphere, the British Interplanetary Society lists a size of 16 kilometers as its proposed size, and mentions it having a population of 20,000 people. Such a traveling artificial world could be created by hollowing out an asteroid, or it could be constructed from materials created from asteroids or lunar materials.
A Bernal Sphere (which could also be a cylinder) might create artificial gravity for its inhabitants by simply rotating, thereby creating artificial gravity through centrifugal force. Such a spaceship would not be designed to travel from one star to another in a single lifetime. It would instead be designed to reach another star after a long slow journey lasting many generations.
The same web page mentions some work done by Bond and Martin to create detailed engineering specs for a cylindrical artificial world spaceship similar to a Bernal Sphere. Below are pictures of the spaceships they designed. In their design, the radius of these rotating cylinders is 5 kilometers, meaning the total length of the proposed spaceships is some 250 kilometers.
Credit: Adrian Mann/British Interplanetary Society
In light of such plans, it can be said that there is nothing unreasonable about the idea that aliens might have created an artificial world spaceship of 20 kilometers, and parked it in orbit somewhere in the solar system. But is it conceivable that some alien civilization might have had the technology to do such a thing?
The universe is about 13 billion years old, and astronomers say that intelligent life could have evolved on other planets millions or even billions of years ago. When scientists imagine what a civilization could do if it were millions of years more advanced than ours, they imagine astonishing engineering feats such as the dismantling of planets or the construction of spheres surrounding an entire star (Dyson spheres). Compared to such possibilities, the creation of a traveling world spacecraft of 20 kilometers is a relatively modest task.
In short, the creation of a traveling world spaceship of about 20 kilometers in size is something that would be similar to what Earth scientists have already envisioned doing, and we have reason to suspect that many alien civilizations might be capable of undertaking such a task (and also tasks that are vastly more difficult).
So is it possible, then, that S/2004 N1 (the newly discovered moon of Neptune) is an alien spaceship, a traveling world spacecraft that originated in another solar system? Yes, it is possible. But it is not likely. Even though the existence of a moon of this size in this orbit is surprising to scientists, one would need more basis for suspicion before drawing any extraordinary conclusion about the moon.
But I suggest that this moon may be worthy of further investigation, to rule out the possibility of an artificial origin.