Voyager 1 to reach one light-day on 18 November

Voyager 1 will cross the one-light-day mark, 16.1 billion miles from the Sun, on 18 November 2026, 49 years after its launch, NASA said in its November Night Sky Notes, titled “Light-Day Away”.

Voyager 1: The cover of the Golden Record carried by both Voyager spacecraft — The cover of the Golden Record carried by both Voyager spacecraft Photo: NASA/JPL-Caltech (public domain).

What one light-day means for Voyager 1

A light-day is the distance light travels in one day, so a radio signal from Voyager 1 will take about a day to reach Earth. NASA notes that a light-minute, like a light-year, is a measure of distance, not time. At the time the article was written, NASA’s Deep Space Network antenna in Canberra tracked Voyager 1 at 25.80 billion km, or just over 16 billion miles. Earth communicates with both Voyager spacecraft and tracks them through the Deep Space Network. Voyager 1 and Voyager 2 crossed the heliopause, the boundary where the Sun’s solar wind meets the interstellar medium, in August 2012 and November 2018 respectively. A NASA graphic in the article shows both probes outside the heliosphere, the protective bubble created by the Sun that extends well past the orbit of Pluto.

Key Facts

Spacecraft: Voyager 1 (launched 1977)
Milestone: one light-day from the Sun
Date: 18 November 2026
Distance: 16.1 billion miles
Heliopause crossings: Voyager 1 in 2012, Voyager 2 in 2018

The Grand Tour and the Golden Record

NASA launched the twin spacecraft in 1977 to take advantage of a once-every-175-year alignment of Jupiter, Saturn, Uranus and Neptune. Using six gravity assists between them, the “Grand Tour” gave close-up views of the gas and ice giants and several moons. The probes went separate ways at Saturn in the 1980s: Voyager 2 went on to Uranus and Neptune, while Voyager 1 took one more portrait of the solar system, including a final image of Earth as a “pale blue dot”. Each spacecraft carries the Golden Record, a 12-inch phonograph record with spoken greetings in 55 languages, 27 music tracks, 116 images and other sounds from Earth. NASA said the mission revealed details about all four giant planets, using each planet’s gravity to send the spacecraft on to the next destination.

How the Golden Record was protected

NASA said each record has an outer cover etched with the Sun’s location relative to 14 pulsars, along with instructions on how to play it. The record used copper and gold plating, and the cover used aluminium, to protect the information from space radiation. The cover was electroplated with an ultra-pure sample of uranium-238, which has a half-life of 4.468 billion years. NASA says Voyager set the stage for later orbiter missions such as Galileo to Jupiter and Cassini to Saturn, and both spacecraft still return science from the far reaches of the solar system. NASA’s Night Sky Network also offers classroom activities on gravity assists and on measuring a “light minute”.

Why It Matters: No human-made object has gone this far; the milestone shows how long a signal from deep space takes to reach Earth.

Source: NASA: November's Night Sky Notes: Light-Day Away · NASA Voyager mission · NASA JPL Voyager