What does it mean for Voyager 1 to be one light-day from the Sun?

Published 2026-11-02 · About 2 min

NASA forecasts that Voyager 1 will be one light-day from the Sun on November 18, 2026. That means the spacecraft’s distance from the Sun will equal the distance light travels in one day.[1]

What is a light-day?

A light-day is a unit of distance, much like a light-year. It uses the distance light travels in one day; for this milestone, NASA measures from the Sun to Voyager 1.[1]

Voyager 1’s milestone at a glance

The unit: the distance light travels in one day.
The measurement: from the Sun to Voyager 1.
NASA’s forecast: November 18, 2026.

The Sun-to-Voyager distance is not the same measurement as the distance from Earth to Voyager.

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When is Voyager 1 expected to reach the milestone?

NASA’s October 30, 2026 article forecasts the milestone for November 18, 2026, 49 years after Voyager 1’s launch.[1]

What is travelling with Voyager?

Voyager 1 and its twin, Voyager 2, each carry a Golden Record with greetings, music, images and other sounds from Earth. Each record includes spoken greetings in 55 languages and 116 images.[1]