The name "Forbidden City" is a translation of the Chinese name "Zijin Cheng" (). The name "Zijin Cheng" was used for the first time in 1576. Another English name for Zijin Cheng is "Forbidden Palace". The word "Zi" means "purple" in Chinese. It means the North Star. This is because in ancient China it was called the "Ziwei" Star. In Chinese astrology the North Star was the home of the Celestial Emperor. Because the Forbidden City was the home of the emperor on Earth, the Chinese thought that it was Earth's equivalent of the "Ziwei" Star. "Jin" means "Forbidden" in Chinese. This was because no one was allowed to go in or out of the palace without the emperor's permission. "Cheng" means city.