Key Takeaways:
- William Lassell, an amateur astronomer, discovered Neptune's moon Triton on October 10, 1846, using his self-constructed 20-foot reflector telescope, a mere 17 days after Neptune's initial identification.
- This same instrument later enabled Lassell to discover Uranus's moons, Ariel and Umbriel, in 1851.
- Subsequent data from the Voyager 2 flyby revealed Triton's unique characteristics, including its status as one of the solar system's coldest objects, exhibiting active nitrogen geysers.
- The moon's surface is further distinguished by an unusual dimpled texture, visually likened to a giant cantaloupe.
On Oct. 10, 1846, William Lassell peered through his 20-foot reflector in Liverpool, England. Lassell was a self-funded amateur astronomer who had made a fortune as a brewer, and he’d built his own scope – apparently doing quite a good job of it, since through it, Lassell spotted Triton orbiting Neptune. Neptune itself had been discovered only 17 days earlier, and the moon was less than 1/10th the diameter of the planet. Lassell would go on to discover two moons of Uranus, Ariel and Umbriel, with the same telescope in 1851.
Though Triton was far too small for Lassell to see its characteristics when he discovered it, the Voyager 2 flyby would help us understand its uniqueness: It is one of the coldest objects in the solar system, yet is volcanically active and erupting in huge geysers of nitrogen. The moon also sports an unusual dimpled surface, making it appear like a giant cantaloupe.
