Quote:
Originally Posted by Macro Mouse
The part about "clearing its path" was added only to prevent our solar system planet tally from reaching into the dozens. It's not applicable to other systems for many reasons. For one, we have no way of knowing whether extrasolar objects have cleared their region or not. Furthermore, it's not based on size...so a Ceres-sized object that has cleared its orbit would be a planet but a region of Earth-sized objects would remain dwarf planets. Such scenarios, which are very feasible, really make the definition useless. Location should not matter at all.
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Ironically, there's evidence in the Beta Pictaurus and Epsilon Eridani accretion disks seeming to indicate a large object is in the process. Both have rather impressive, and fairly stable, gaps in the debris field. Nothing confirmed, but strong strong suspicion of a planet.