In the sci-fi film Silent Running, botanist Freeman Lowell pilots his ship, the Valley Forge, through the rings of Saturn and isolates himself from other humans for a long time. Eventually, he is found by the ship called the Berkshire. It is unclear to me how much time he spent alone. How much time is there between when he exits the rings of Saturn and when he is found?
The film's official novelisation (based on the original screenplay) indicates that the order to jettison and auto-destruct the domes was given on the 14th of November. This occurs shortly before the crew suffer their "accident" and the ship tumbles through Saturn's rings.
A clock/calendar on the wall read: 21:00 Wednesday 14 November
All at once the radio filled the room with whistling, howling static which finally gave way to a very distant-sounding voice . . . Lowell tried to tune it in, but Barker took over.
The next time we see a clock it's just before the Berkshire arrives on the 8th of April, some 5 months later.
Lowell’s laughter went on and on. It was uncontrolled and hysterical amidst his loneliness with only the companionship of the unfeeling drones. His eyes watered and his lips trembled and his laughter filled the recreation room and spilled out over the bronzed hull of Valley Forge, drifting through space under a sea of stars.
At last Lowell fled from the recreation room to the corridor and then to his room. He flopped on his cot . . .
Above his bed, on a shelf, a calendar clock read: 04:02 Tuesday 8 April.