June 5, 2017 - To Know Neptune

To Know Neptune Born 205 years ago this week, Johann Gottfried Galle was a German astronomer who, in 1846, became the first person to observe Neptune and know it was a planet. Prompted by calculations made by Urbain Leverrier, and aided by Heinrich Louis d’Arrest, Galle identified the planet where Leverrier calculated it would be. Neptune, seen here in an image taken by the Voyager 2 spacecraft in 1989, is thus unique because it is the first planet whose existence was predicted before it was observed. Galle also discovered three comets, compiled a catalogue of 414 comets, and proposed a method of accurately calculating the distance to the Sun. Galle, who lived to the ripe old age of 98, was honored by having two craters named after him, one on the Moon and the other on Mars.

Image credit: NASA / JPL

Weekly Calendar

June 5-11, 2017

Holidays - Sky Events - Space History

Monday 5

Ceres in conjunction with Sun

1819: John Couch Adams born
1989: Voyager 2 begins regular observations of Neptune
1991: STS-40 Columbia launched
2002: STS-111 Endeavour launched