noun
artificial planet; man-made planet
A celestial body constructed by humans, distinct from natural planets. Used in astronomy and science fiction contexts.
人工惑星の建設はまだSFの域を出ない。
Building an artificial planet is still in the realm of science fiction.
人工衛星 is an artificial satellite, much smaller and orbiting a planet, while 人工惑星 is a planet-sized artificial body.
Compound of 人工 (artificial) and 惑星 (planet).