Voyager 1 to reach one light-day from Earth on 18 November 2026: what the milestone means

NASA's Voyager 1 will become the first human-made object to reach one light-day from Earth on Wednesday 18 November 2026. NASA puts the moment at 5:16:07 a.m. EST, which The Register, reporting on 11 November 2026, gives as 10:16:07 UTC. That is 10:16 in the morning in the UK.

The spacecraft has not crossed the line yet. As this article is published on 12 November 2026, the milestone is six days away, and NASA is asking the public to mark it the evening before.

What is a light-day, and how far is it?

A light-day is the distance light travels in 24 hours. NASA's figure is 16,094,799,096 miles, or 25,902,068,356 km, which it rounds to about 16 billion miles (26 billion km).

NASA stresses that the milestone "is about distance, not time". Nothing happens to the spacecraft at that point. In its 29 October 2026 mission update, the Jet Propulsion Laboratory (JPL) said the probe will detect no change in its environment and nothing on board will change.

What does change is a round number in the mission's daily routine. JPL says a radio signal will take 24 hours to reach the probe, and the reply will take another 24 hours to come back.

Distance from Earth	Light travel time (NASA)
The Moon	1.3 seconds
The Sun	About 8 minutes 20 seconds
Neptune	About 4 hours 10 minutes
Voyager 1 on 18 November 2026	24 hours
Proxima Centauri, the nearest star	About 4.24 years

EarthSky reports that one light-day is 173.14 astronomical units, meaning 173 times the distance between the Earth and the Sun. Science News describes it as more than four times the distance from the Sun to Pluto.

How long did it take Voyager 1 to get there?

Voyager 1 launched on 5 September 1977. NASA counts the journey to one light-day as 49 years, two months and 11 days.

The probe flew past Jupiter and Saturn, and Science News notes that it overtook Pioneer 10 in 1998 to become the most distant human-built object. NASA says it entered interstellar space in August 2012.

It is still moving at nearly 38,000 mph (61,000 kph), according to NASA. EarthSky reports that in early October 2026 it was about 15.98 billion miles (25.72 billion km) away, with light from the spacecraft taking 23 hours, 52 minutes and 30 seconds to arrive.

What is NASA asking people to do on 17 November?

NASA is running a public event called Shine Bright for Voyager's Light-Day. After sunset on Tuesday 17 November 2026, it invites people to point a light at the sky and flash the letters V-G-R, the three-letter call sign NASA uses for the mission, in Morse code.

According to NASA's instructions:

• V is three dots and a dash
• G is two dashes and a dot
• R is dot, dash, dot
• Dots last less than a second and dashes about one second
• The sequence is repeated for around one minute

NASA also offers an automated flasher at go.nasa.gov/vgr that runs in a phone or tablet browser.

The gesture is symbolic. The Register points out that Voyager 1 cannot see the flashes, because its cameras were switched off decades ago after the Pale Blue Dot image was taken.

Is Voyager 1 still working?

Yes, but with a scare last month. JPL said NASA's Deep Space Network failed to detect Voyager 1's signal during two scheduled contacts, 24 hours apart, on 18 and 19 October 2026. The signal came back on 20 October and contact has been maintained since.

JPL said one group of thrusters went offline and their backups switched on. That is an automatic response known as fault protection, which puts the spacecraft into a safe, stable state and pauses normal operations. The cause is still being investigated.

"We're relieved to be back in contact with Voyager 1 and are eager to understand what happened," said Kareem Badaruddin, Voyager mission manager at JPL, in the agency's update. The Register covered the outage on 30 October 2026, and BBC Sky at Night Magazine reported the recovery on 3 November 2026.

The power problem

The larger constraint is electricity. JPL says both Voyagers lose about 4 watts of power each year as the plutonium in their generators decays.

In early September 2026, engineers switched off three devices that help keep Voyager 1 warm and replaced them with three lower-power alternatives. JPL said the swap had to happen at the same moment, and that without it another science instrument would have had to be shut down as early as summer 2027.

The mission launched with 10 science instruments. EarthSky reports that NASA turned off Voyager 1's Low-Energy Charged Particle instrument in April 2026, and that most of the instruments on the two probes are no longer working.

When will Voyager 2 reach one light-day?

Not for another nine years. NASA says Voyager 2 is on pace to reach one light-day in November 2035. EarthSky puts it about 2 billion miles (3.2 billion km) closer to Earth than its twin.

Whether it will still be in contact by then is an open question. The Register notes that Voyager 2's power margins are thin.

Analysis: why a symbolic line still matters

This section is our own analysis, based on the figures above.

The milestone is arbitrary in physical terms, as NASA itself says. It matters because it turns an unimaginable distance into something people can feel. Everyone knows how long a day is.

It also shows how small humanity's reach remains. Using NASA's numbers, one light-day is about 0.27% of a light-year. The nearest star, Proxima Centauri, is about 4.24 light-years away, which works out at roughly 1,550 light-days. At its present speed Voyager 1 would need about 17,600 years to cover a single light-year. Those are our calculations from NASA's speed and distance figures, not NASA statements.

There is a practical lesson for engineers too. A two-day wait for an answer means the spacecraft has to protect itself, which is exactly what happened in October when fault protection took over without any command from Earth. For comparison, the satellite internet covered in our Starlink Mini 2 guide works with delays measured in fractions of a second. Deep space operations are a different discipline: every instruction is a letter posted with no chance of correction for 48 hours.

Finally, the timing is tight. The October outage and the 4 watts lost each year are reminders that the hardware is close to 50 years old. The light-day mark is being reached by a spacecraft that engineers are keeping alive one power-saving step at a time.

Sources

• NASA Science: Voyager 1, what is a light-day?
• NASA Science: Shine Bright for Voyager's Light-Day
• NASA JPL: Voyager 1 conserves power, resolves brief communications pause (29 October 2026)
• The Register: NASA asks Earthlings to wave as Voyager 1 reaches a light-day away (11 November 2026)
• The Register: Voyager 1 gives controllers the silent treatment (30 October 2026)
• EarthSky: Celebrate as Voyager 1 reaches 1 light-day from Earth (10 November 2026)
• Science News: Voyager 1 is nearly one light-day from Earth (14 October 2026)
• BBC Sky at Night Magazine: NASA gets Voyager 1 back online after comms glitch (3 November 2026)