A milestone in the history of human space exploration will occur in November 2026, when NASA’s Voyager 1 becomes the first human-made object to reach a distance of one light-day from Earth. This achievement comes nearly five decades after its launch and highlights the vastness of interstellar space and the enduring reach of robotic exploration.
Launched in 1977, Voyager 1 has steadily traveled outward from Earth for almost 50 years, surpassing all other spacecraft in terms of distance. It has already crossed the heliosphere and entered interstellar space, and is now on track to reach 25.9 billion kilometers—approximately 16 billion miles—from Earth, the equivalent of a light-day.
The implications of this distance are substantial. A light-day represents how far light travels in 24 hours, offering a new perspective on the scale of the universe and the limits of human-made machines. The upcoming milestone also draws attention to the probe’s technological resilience and the scope of long-term scientific missions in deep space.
Traveling Beyond the Heliosphere Into Interstellar Space
Voyager 1 was launched with the mission of studying the outer Solar System, but it has long since passed those objectives. According to IFLScience, the spacecraft is currently located around 166 astronomical units (AU) from Earth. One AU equals the average distance between the Earth and the Sun, approximately 149.6 million kilometers.
The spacecraft has already crossed the heliopause—the boundary where the solar wind slows and the interstellar medium begins—entering interstellar space in 2012. This position places it outside the influence of the solar wind but still within the gravitational pull of the Sun. At this distance, radio signals from Earth take more than 23 hours to reach the probe.
A Historic Distance Reached at Constant Speed
The probe is traveling at a speed of approximately 61,195 kilometers per hour, or 38,025 miles per hour. Despite this high velocity, it has taken nearly five decades for Voyager 1 to reach its current location. According to data cited by IFLScience, the spacecraft will hit the one light-day mark from Earth on November 15, 2026.
This specific point represents a distance that light—traveling at 299,792 kilometers per second—covers in 24 hours. It is a symbolic but significant threshold that demonstrates both the spacecraft’s endurance and the slow but continuous progress of human-made objects through space.
A Vast Solar System With No Clear Boundary
While Voyager 1 has exited the heliosphere, it has not necessarily left the Solar System in a definitive sense. According to NASA, there is ongoing debate among astronomers about where exactly the Solar System ends. Some argue that it lies beyond the Oort cloud, a theoretical shell of icy bodies far past Pluto and the planets, where the Sun’s gravitational influence wanes.
The agency notes that a more distant boundary might be halfway to Proxima Centauri, the nearest known star beyond the Sun. At its current speed, Voyager 1 would take nearly 40,000 years to reach that point, covering a distance of about two light-years.
