Yentral

Yentral, also known as Hantramore IV, was a planet in the Left Wing of the galaxy. It is not inhabited, but it was discovered by humans in the year -1.

Pre-discovery
Before it was discovered by humans, Yentral was supposedly an ocean planet, but it oceans eventually froze over.

Post-discovery
After it was discovered by humans and some research was done about the planet, they discovered that its orbit was perfectly in sync with its day system - 300 Yentrallan days was equal to one full orbit round its sun. Because of this, a Yentrallan year began to be used as the galactic standard definition of a year.

Yentral is protected under the Historic Protection Act, preventing it from being inhabited, attacked or destroyed.