Vulkanoid

Vulkanoid refers to a hypothetical type of planet that orbits extremely close to its star, much closer than Mercury orbits our Sun. These planets are theorized to be tidally locked, meaning one side perpetually faces the star while the other remains in eternal darkness. The intense stellar radiation and heat on the star-facing side would likely make it uninhabitable, potentially a molten or vaporized landscape. In contrast, the dark side could be extremely cold.

The concept of vulkanoids arises from attempts to explain the existence of a hypothesized "ring of Vulcanoids" within the orbit of Mercury. While no such ring has been directly observed, the theoretical vulkanoids are considered a possible explanation for discrepancies in Mercury's orbit and for phenomena like unexplained occultations of stars by Mercury. The extreme proximity to the Sun poses significant challenges for their detection and survival. Any such planets would experience immense tidal forces and radiation bombardment.

Despite the theoretical nature, the search for vulkanoids continues. Missions like the BepiColombo spacecraft, a joint project between the European Space Agency and the Japan Aerospace Exploration Agency, are designed to study Mercury and its environment in detail, which could potentially provide evidence for or against the existence of vulkanoids. Their discovery would offer valuable insights into planetary formation and evolution under extreme stellar conditions.