T'Khut

T'Khut, or The Watcher, was the third planet in the Vulcan-system, and shared a tidally locked co-orbit with Vulcan around a common center of gravity orbiting the star 40 Eridani A - Vulcan and T'Khut were only 149,895.3579 kilometers apart. It was home to extensive mining settlements and was the site of the first off-world colony for the Vulcans.

T'Khut was a Class G, and had one moon, T'Rukhemai (the 'Eye of the Watcher'). The Watcher was known by a variety of names depending on when it was in the Vulcan year; these included, T'Rukh, T'Kuht, T'Khul and Valdena. Because Vulcan and T'Khut were tidally locked, T'Khut was only visible from one side of Vulcan, including filling the sky above Vulcan's Forge. The planet went through a full set of phases every day and filled thirty degrees of the sky when at full phase, reflecting forty times as much light as Earth's moon Luna.