Comet Thatcher was discovered on Apr. 5, 1861 by A. E. Thatcher.
It takes 415.5 years for comet C/1861 G1 Thatcher to orbit the sun once. Comet Thatcher last reached perihelion (closest approach to the sun) in 1861. Comet Thatcher is a long period comet. Long period comets have orbital periods of 200 years or more.
When comets come around the sun, the dust they emit gradually spreads into a dusty trail around their orbits. Every year the Earth passes through these debris trails, which allows the bits to collide with our atmosphere where they disintegrate to create fiery and colorful streaks in the sky.
The pieces of space debris that interact with our atmosphere to create the Lyrid meteor shower originate from comet Thatcher. This annual meteor shower takes place each April. The Lyrids are one of the oldest known meteor showers: they have been observed for 2,700 years. (The first recorded sighting of a Lyrid meteor shower goes back to 687 BC by the Chinese.)
How Comet C/1861 G1 (Thatcher) Got Its Name
Comets are usually named for their discoverer(s) or for the name of the observatory/telescope used in the discovery. Since A. E. Thatcher discovered this comet it is named for him. The letter "C" indicates that comet Thatcher is a long period comet and is not expected to return to the inner solar system in less than 200 years. 1861 stands for the year of discovery. The "G" indicates the first half of April and "1" means Thatcher was the first comet discovered in that half-month period.