Voyager 1 will reach one light-day from Earth in 2026. Here’s what that means

An artist's concept shows Voyager 1 entering interstellar space, or the space between stars. NASA/JPL-Caltech

Voyager 1, NASA’s deep-space probe, could soon become the first spacecraft to reach a historic milestone. In November 2026, the probe will be one light-day from Earth.

Launched in 1977, Voyager 1 is the farthest spacecraft from our planet, currently exploring interstellar space 15.8 billion miles away.

The term light-day refers to the distance at which it will take 24 hours for a signal or command traveling at the speed of light to reach the spacecraft from Earth, said Suzy Dodd, Voyager project manager at NASA’s Jet Propulsion Laboratory. One light-day is equivalent to 16 billion miles (26 billion kilometers).

So if Voyager’s team is asking the spacecraft to do something onc