September 23 - The Discovery of Neptune

This Day in History: 23 September 2020

 

23 September 1846

174 years ago, today, the planet Neptune was discovered by German astronomer Johann Gotfried Galle at the Berlin Observatory. The planet was mathematically predicted before it was directly observed by Urbain Le Verrier. Galle's telescopic observations confirmed the existence of the major planet using Le Verrier's calculations. It was a sensational moment for 19^th century science. After it was discovered, it turned out that Neptune had been observed many times in the past but not recognised. The discovery of Neptune also led to the discovery of its moon Triton by William Lassell just seventeen days later.

Neptune, the blue and densest gas giant, has a diameter four times that of Earth, and was named after the Roman god of the sea. It is known to have eight moons, of which Triton is the largest, and a ring system containing three bright and two dimmer rings. Every 165 years, it completes an orbit of the sun, and is the farthest known Solar planet away from it. In 1989, the US spacecraft 'Voyager 2' was the first human spacecraft to visit Neptune, which spotted that the planet's southern hemisphere had a Great Dark Spot like Jupiter's Great Red Spot.

Want to find out more about the discovery of Neptune? Click here for more information, or here for more about Neptune.