Voyager 1 is Nearly One Light Day From Earth

As it hurtles out of our solar system never to return, at 38,200 mph (61,500 kmh), the deep space probe Voyager 1 is about to clock up another cosmic milestone.

Voyager 1 | NASA

The veteran probe launched in 1977 to make a flyby of Jupiter and Saturn before heading out on a one-way trajectory into interstellar space. Despite the occasional glitch and only being designed to last for 5 years, Voyager 1 is now almost 50 years old and still flying through the incredibly cold, radiation-saturated depths of space at the edge of the solar system.

Remarkably, it still continues to function and NASA is determined that it will continue to do so until its nuclear power source finally gives out in the next year or so.

Already the farthest object that mankind has ever communicated with, Voyager 1 is headed for yet another cosmic milestone. In late 2026, it will become the first spacecraft to travel so far that a radio signal from Earth takes 24 hours, or one light day, to reach it.

Functioning or not, Voyager 1 will continue moving farther and farther from Earth. As it does so, the time light takes - which, as you know, travels at 186,000 miles per second (299,388 km/s) - to reach it stretches out as well. According to NASA, the probe is about 15.7 billion miles (25.3 billion km) from Earth, with a one-way message taking 23 hours, 32 minutes and 35 seconds to reach its destination.

But in around a year, (currently estimated to fall on 15 November 2026), Voyager 1 will be 16.1 billion miles (25.9 billion km) from Earth, crossing the line where a signal from it will take 24 hours to reach us. Namely, one light day.

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The Fastest Ever Human-Made Object: If you could somehow hitch a ride on the NASA Parker Solar Probe, you could travel from Los Angeles to London in approximately 49 seconds.