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A light year is a distance, not a time. We worked out how long it would take to travel one by train, by plane and by spacecraft, and how far India’s own missions are in light-time.
On 18 November 2026, a radio signal from Earth needs a full day to reach Voyager 1. The arithmetic of that distance explains why the mission still works, and why it cannot work for much longer.
One spacecraft has visited the seventh planet, for a few hours in 1986. Forty years on, even its basic facts are being revised, and the calendar of Uranus’s long seasons is making the case for a return.