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Today in History: William Lassell discovers Triton, Neptune's largest moon

10/10/2025

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Summary

Story summary

On October 10, 1846, English astronomer William Lassell discovered Triton, the largest moon of Neptune, just 17 days after Neptune's own discovery. Triton is unique for its retrograde orbit and thin atmosphere, believed to have originated as a dwarf planet from the Kuiper belt before being captured by Neptune's gravity.

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Story summary

On October 10, 1846, English astronomer William Lassell discovered Triton, the largest moon of Neptune, just 17 days after Neptune's own discovery. Triton is unique for its retrograde orbit and thin atmosphere, believed to have originated as a dwarf planet from the Kuiper belt before being captured by Neptune's gravity.