Voyager 1 will be one light-day from Earth on Nov. 18, the first spacecraft ever that far

Voyager 1, launched in 1977, will become the first human-made object to travel one light-day from Earth early on Wednesday, Nov. 18, according to NASA's mission countdown.  The moment falls at 2:16 a.m. Pacific time, when the probe will be 16.09 billion miles away.

A light-day is the distance light, or a radio signal, crosses in 24 hours:  about 16.1 billion miles.  Sunlight reaches Earth in about 8 minutes, and reaches Neptune, the farthest planet, in about 4 hours.  So a command sent from Earth that morning will take a full day to arrive, and the answer another day.  "You send your message and then you go home and you wait two days before you finally get a response," said Suzanne Dodd, Voyager project manager at NASA's Jet Propulsion Laboratory in Pasadena.

Nothing changes for the spacecraft when it crosses the line.  The milestone is about scale:  Voyager 1 has been moving at about 38,000 mph for 49 years, two months and 11 days to get there.  From that distance, by our arithmetic, the sun would look like an extremely bright star, roughly 14 times brighter than our full moon, and give about 1/30,000 of the sunlight Earth gets.

What Voyager 1 is, and what still works

Voyager 1 is a car-size probe that flew past Jupiter in 1979 and Saturn in 1980, then headed out of the solar system.  In August 2012 it became the first spacecraft to cross the heliopause, the edge of the bubble of particles blown out by the sun, into interstellar space.  It runs on plutonium-powered generators that lose about 4 watts a year.  To save power, engineers shut off its low-energy particle detector in April, leaving two working science instruments, which measure plasma waves and magnetic fields.  In September they swapped three heaters and similar devices for lower-power ones, a fix the team expects will keep those instruments going past summer 2027.

It has also had a scare.  On Oct. 18 and 19, NASA's Deep Space Network could not hear the probe; its signal returned Oct. 20.  One set of thrusters had shut off and backups took over, and engineers are still investigating why.  "We are also at a point in the mission where we have to expect the unexpected," said Kareem Badaruddin, the mission manager.

Can you see it?

No.  Voyager 1 is far too faint for any telescope to see.  It lies in the direction of the constellation Ophiuchus, low in the western sky after sunset this month.  Its twin, Voyager 2, will not reach one light-day until November 2035.

Source:  NASA Science, "NASA's Voyager 1 Conserves Power, Resolves Brief Communications Pause" (Oct. 29, 2026), "NASA Shuts Off Instrument on Voyager 1 to Keep Spacecraft Operating" (April 17, 2026), "Voyager 1: What Is a Light-Day?", Voyager mission and Voyager 1 pages, "November's Night Sky Notes: Light-Day Away" (Oct. 30, 2026) and "What's Up: November 2026."  Drafted by AI for San Jose using NASA source material.  NASA did not write or review this story.