Voyager 1 will reach one light-day from Earth on Nov. 18

Voyager 1 will reach one light-day from Earth on Nov. 18, 2026, marking the first time a human-made object has traveled that far from our planet. A light-day expresses distance rather than time, spanning about 173.14 astronomical units, or roughly 16.1 billion miles and 25.9 billion kilometers—the distance light covers in 24 hours at about 299,792 kilometres per second. At that mark, a radio signal from Earth needs about 24 hours to reach Voyager 1, and the spacecraft’s reply takes another 24 hours, so a command and a response require roughly two days. On Nov. 18, 2026, Voyager 1 will be about 16.09 billion miles away, or 16.094 billion miles by other estimates. Sources disagree on the exact clock time of the crossing on Nov. 18, 2026. EarthSky attributes to NASA 12:16:07 a.m. CST, Jagran Josh attributes to NASA 2:16 a.m. Pacific Standard Time, and Smithsonian and HNGN give about 5:16 a.m. Eastern time. The exact times listed by different sources do not convert cleanly into one another. Voyager 1 keeps just two working science instruments: a magnetometer that measures magnetic fields, and a plasma wave subsystem that detects oscillations of charged particles. Engineers finished the Big Bang operation in September 2026, switching three devices to three lower-power alternatives at the same time to balance heat while cutting electricity use; without it, another instrument would have had to shut down as early as summer 2027. The six devices swapped in the Big Bang all help keep the spacecraft warm in space, and engineers ran the procedure on Voyager 2 first because it is closer and safer. HNGN reports output is about half of launch levels, while SciTechDaily and Gizmodo say the plutonium-238 generator costs about four watts of electrical power a year. NASA turned off Voyager 1’s Low-Energy Charged Particle instrument on April 17, 2026, after a planned roll maneuver on Feb. 27 caused an unexpected drop in power; the device had been measuring electrons, ions and cosmic rays in the interstellar medium, and NASA could still reactivate it later if power allows. The cosmic ray instrument was switched off in February 2025, and of the 10 identical science-instrument sets each Voyager carried, seven have been shut off on Voyager 1. Voyager 2, closer to Earth with more spare power, still had three working instruments as of April 2026. In mid-October 2026, NASA lost contact with Voyager 1 when the network missed its radio signal during two scheduled contacts on Oct. 18 and Oct. 19, 2026, which were 24 hours apart. The signal came back on Oct. 20, 2026, ending a 48-hour interruption even though engineers had not yet sent troubleshooting commands. At the time of the October silence, the spacecraft was roughly 16 billion miles, or 25.75 billion kilometers, from Earth, and it had already lost one of its two radio transmitters during an earlier low-power event. Engineers found that one thruster group went offline while backup thrusters activated on their own, a fault-protection response that puts the spacecraft into a safe, stable configuration while the cause is investigated. These thrusters are small rocket engines that control movement or orientation. The team has not identified what caused the switch. Kareem Badaruddin, Voyager mission manager at NASA’s Jet Propulsion Laboratory in Southern California, said: “This is the first time we’ve seen the spacecraft do something like this.” Voyager 1 launched from Cape Canaveral, Florida, on Sept. 5, 1977, and had spent more than 49 years in flight by the time of the milestone. It visited Jupiter and Saturn before heading out of the solar system, officially crossing the heliopause—the sphere of the Sun’s influence—on Aug. 25, 2012, to enter interstellar space. It is moving at roughly 38,000 miles per hour, or 61,000 kilometers per hour, through interstellar space and is headed toward the constellation Ophiuchus, up out of the solar plane. EarthSky calculates the journey at 49 years, two months and 11 days to reach the one-light-day mark. Voyager 1 passed Voyager 2 on Dec. 15, 1977, following its own later launch on a quicker path, while Voyager 2 completed a Grand Tour of Jupiter, Saturn, Uranus and Neptune. Voyager 2 entered interstellar space in November 2018 and is about two billion miles (3.2 billion kilometers) closer to Earth than Voyager 1, moving more slowly and unable ever to catch up. NASA said the twin will not hit the one-light-day mark until November 2035, nine more years away. It has been the most distant spacecraft since February 1998, when it passed Pioneer 10. The crossing is symbolic rather than an actual event, and nothing changes aboard the spacecraft or around it when the boundary is passed. The two Voyagers still phone home through NASA’s Deep Space Network, an international array of large radio antennas at three facilities around the globe. HNGN reports that the lag makes troubleshooting slow and uncertain, because engineers can only send a command and wait for the reply. Suzanne Dodd, Voyager project manager at JPL, said: “you send your message and then you go home and you wait two days.” The twin probes will reach 50 years in space in 2027, and scientists estimate their power sources will run out in 10 to 15 years, ending data transmissions. Garry Hunt, an astrophysicist on the original imaging team, warned that the probes’ signal could fade below detectability around 2035. HNGN states that after Nov. 18, the craft will stay beyond one light-day permanently because it keeps moving away at about 17 kilometers per second. NASA estimates that Voyager 1 will pass near AC+79 3888, also called Gliese 445, a star now more than 17 light-years from Earth, coming within about 1.7 light-years in roughly 40,000 years. No replacement craft is in orbit, and the two Voyagers remain the only vehicles to study interstellar space directly. Voyager 1 cannot practically be seen through a telescope: by early October, light arriving at Earth had left the craft 23 hours, 52 minutes and 30 seconds before. Readers can follow the mission through NASA’s Deep Space Network rather than trying to spot the probe visually. NASA invites the public to a Shine Bright for Voyager’s Light-Day celebration after sunset on Tuesday, Nov. 17, 2026. People can point a flashlight, phone, glow stick or other light at the sky and send V-G-R in Morse code—dot dot dot dash, dash dash dot, dot dash dot—using NASA’s automated flasher or manual instructions. Each Voyager carries a Golden Record, a 12-inch gold-plated copper disc holding greetings in 55 languages, Earth sounds, music, images and messages from world leaders as a symbolic message for any future finders. Carl Sagan said of the Golden Record: “the launching of this ‘bottle’ into the cosmic ‘ocean’ says something very hopeful about life on this planet.” The craft captured the famous Pale Blue Dot image of Earth in 1990, which inspired Carl Sagan’s book Pale Blue Dot: A Vision of the Human Future in Space. During its March 5, 1979, Jupiter flyby it discovered a faint ring and two previously unknown moons, Thebe and Metis, and at Saturn on Nov. 12, 1980, the craft found five new moons and the G-ring. Unresolved issues include identifying what caused the October silence before the next scheduled contact, determining whether the Big Bang buys the expected extra time, and deciding which instrument goes dark next.