Venus

Venus (or Sol II) was the inhabited second planet of the Sol system.

History
Hugh Campbell wrote a story called "Venusian Chronicles" for the January 1953 issue of Incredible Tales magazine. In 2254, Venus was seen on a map depicting the inner Sol system. This map was scanned by the Talosians. 

Three years later, Venus was seen on a chart depicting the Sol system. This map was scanned by Nomad. 

In 2364, when the USS Enterprise (NCC-1701-D) crew was infected with polywater intoxication, an officer serving in the shuttlebay delivered an inappropriate limerick over the comm to other crewmembers. ("There was a young woman from Venus whose body was shaped like a...") Hearing this, Lieutenant Commander Data began to repeat the limerick, but was cut off by Captain Picard before completing it. 

In the late 24th century, Venus had a number of terraforming stations on its surface. 

During his early career, Chakotay spent a couple of months on Venus to learn how to pilot a shuttle in atmospheric storms. After he had finished his training, he spent a semester learning to dodge asteroids in the asteroid belt. 

In an alternate timeline, Miles O'Brien, while still in the 24th century, noted that the terraforming stations on Venus were gone, following the creation of an alternate timeline created when Benjamin Sisko, Jadzia Dax, and Julian Bashir disrupted history after transporting to the 21st century.