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Today in History: Eris Discovered: New Dwarf Planet Unveiled

1/5/2026

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Summary

Story summary

On January 5, 2005, astronomers discovered the dwarf planet Eris using the Samuel Oschin telescope at Palomar Observatory. Eris, the second-largest known dwarf planet, is located in the scattered disk and has a diameter of approximately 2,326 kilometers. This discovery contributed to the reclassification of celestial bodies in our Solar System.

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Story summary

On January 5, 2005, astronomers discovered the dwarf planet Eris using the Samuel Oschin telescope at Palomar Observatory. Eris, the second-largest known dwarf planet, is located in the scattered disk and has a diameter of approximately 2,326 kilometers. This discovery contributed to the reclassification of celestial bodies in our Solar System.