Segment of Time was a time measurement used by people who left Earth on the Ark. The reign of Nero, the Trojan War and wars involving the Daleks were said to be part of the First Segment of Time. (TV: The Ark) The First Doctor was said to look like an inhabitant of the First Segment of Time. (PROSE: Tarnished Image) During the 58th Segment of Time, the planet Metralubit was discovered by human settlers. (PROSE: The Well-Mannered War) The Master stole from a Farquazi time cruiser during the 300th Segment of Time. (PROSE: The Quantum Archangel)