For the first time in humanity’s long history, a man-made object will soon be a full light-day away from our home planet.
Space, as they say, is huge, and man-made objects are slow. The record for the fastest speed ever set by a human was set by Apollo 10 in 1969, and has not been broken since. The fastest human space flight is 39,937.7 kilometers per hour (24,816.1 mph), and at that speed, it would take 3,730 hours to travel just 1 astronomical unit (AU), the distance between Earth and the Sun.
At about 155 days, this is (for example) an unacceptable travel time to the Sun. And while it takes you 155 days to get to wherever you are, light and communication from Earth will reach you in about 8 minutes and 20 seconds, which really shows how great it is to be massless.
But we’ll get a real reminder of the vast distances and incredible speed of light in late 2026, when Voyager 1 becomes the first man-made object to reach within a light-day of Earth.
This spacecraft was launched in 1977 and has been traveling since then. At the time of writing, it is approximately 169.5 AU from Earth, becoming the first spacecraft to go beyond the heliosphere, cross the heliopause, and enter interstellar space. In its current state, signals from Earth take 23 hours, 29 minutes and 27 seconds to reach the spacecraft. At the current speed of about 61,198 kilometers per hour (38,027 mph), it would still take more than a year to cover that light-distance distance for a full 24 hours.
When it reaches 25.9 billion kilometers (16 billion miles) from Earth, a journey that will take about 50 years, it will finally be the distance light can travel in a day.
According to calculations by Dr. Alfredo Carpinetti, resident astronomer at IFLScience, using data from NASA’s Eyes on the Solar System, this will occur on November 13, 2026. After this date, the probe will not fall within 24 light-hours of Earth again, despite Voyager’s distance from Earth changing as it orbits the Sun.
After that, it will continue on its course guided by NASA until its power is exhausted, possibly in the early 2030s. But its journey will not end yet. First, it will leave the Solar System, passing through the Oort cloud, before making at least one close encounter with another star, Gliese 445, in the near future.
“The distant Oort Cloud marks the gravitational edge of the Solar System in a vast field of undiscovered objects,” NASA explains of the Oort Cloud, first envisioned by Dutch astronomer Jan Oort in 1950. Passing by the Sun only on rare occasions, possibly when a distant passing star or galaxy is tidally disturbed, there is speculation of other large planets in the region that may disturb comets around them, but none have yet been discovered.
At the lower limit of estimates, the Oort Cloud may originate around 1,000 AU from the Sun. If the Oort cloud starts here, Voyager could reach it in just a few centuries. However, given the sheer scale of the cloud, it will remain there for thousands of years.
“Most of interstellar space is actually inside our solar system,” NASA explains. “It will take about 300 years for Voyager 1 to reach the inner edge of the Oort Cloud and possibly about 30,000 years to fly beyond it.”
Assuming the Voyager probes pass through the cloud unscathed (a likely outcome, given that space is not the asteroid-dodging exercise science-fiction would have us believe), they could remain relatively safe for many, many years beyond that.
For a long time, Voyager will not be near any celestial bodies, drifting through the universe on its own, away from sources of heat and light. But in 40,000 years, it will get a brief close encounter with another star, coming closer to it than its home.
“It took 35 years to reach interstellar space, but Voyager 1 will take 40,000 years to get closer to the star AC +79 3888 than to our sun,” NASA said. “Alpha Centauri is the closest star to us at the moment, but because stars are rotating, Voyager 1 will actually get to within 1.7 light years of AC +79 3888 (aka Gliese 445) in 40,000 years.”
A paper examining future stellar flybys of probes on escape velocities from the Solar System puts this figure at more than 44,000 years. Gliese 445 is an M-type main sequence star with about one third the mass of our Sun. Currently, it is about 17,000 light years away from Earth, but when Voyager encounters it, it will be about 3.5 light years away. This would not be the spacecraft’s last encounter with another star.
“Statistically, a spacecraft will encounter stars within a given distance at approximately the same rate as the Sun, according to Buller-Jones et al. […] The study reports that there is an estimate of one star within 1 pc every 50 km, with more distant encounters difficult to predict due to uncertainty in the data. [million years]”Since spacecraft are not leaving the galaxy, it is inevitable that spacecraft will pass very close to some stars on long time scales.”
Nevertheless, astronomically the team was able to predict Voyager’s closest approach in the near future. They found that the spacecraft will encounter the main sequence star TYC 3135-52-1 in approximately 303,000 years. At this point, it will be about 0.965 light-years away from the star, so still quite wide. Looking at the data, it’s unlikely that Voyager 1 will be captured by a star any time soon, and will continue roaming the universe with only golden records for company.
“The time scale of a spacecraft colliding with a star is of the order of 1020 years,” the team concluded, “so the spacecraft has a long future ahead of it.”
An earlier version of this article was published June 2025,