The unbalanced orbit of a so-called “zombie planet” in a dusty star system has astronomers struggling to explain the exoplanet’s behavior. New observations of the planet Fomalhaut b by the Hubble Space Telescope revealed the oddball orbit, which has wild extremes between its closest and farthest points from the parent star and appears to cross through a vast minefield of dusty debris.

Among the several theories to explain Fomalhaut b’s extreme orbit is the possibility that the exoplanet had an encounter with another planet, a yet-to-be discovered neighbor. The cosmic close encounter could have gravitationally ejected Fomalhaut b into its current orbit, scientists said.