Which dwarf planet, located in the scattered disc and discovered in 2005 by Mike Brown and team, was found to be slightly more massive than Pluto, triggering the IAU's planet redefinition?
Answer and explanation
Correct answer: C. Eris
- Step 1: Eris is a trans-Neptunian dwarf planet orbiting between 38 and 97 AU from the Sun with an orbital period of 558 years.
- Step 2: Possessing a moon named Dysnomia, mass calculations revealed Eris was roughly 27% more massive than Pluto, compelling the IAU to formally establish criteria for 'planet' versus 'dwarf planet' in 2006.
Answer
Eris
Why not the others: 'Makemake' Makemake is a smaller Kuiper belt dwarf planet discovered in 2005, less massive than Pluto; 'Haumea' Haumea is an elongated, rapidly rotating dwarf planet with rings in the Kuiper belt; 'Sedna' Sedna is a distant planetoid with an extremely elongated orbit, not the catalyst for the 2006 reclassification.
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