India, Nov. 3 -- NASA's Voyager 1, launched 49 years ago, is expected to reach a milestone on November 18, when it will be 16.09 billion miles (25.89 billion kilometres) from Earth, meaning it will cross the one-light-day distance mark. At that distance, light takes 24 hours to travel between Earth and the spacecraft, the equivalent of one light-day.

The farthest human-made object in space, the probe is travelling at a speed of 28,000 mph. It was also the first spacecraft to enter interstellar space in August 2012, closely followed by its twin, Voyager 2, in December 2018.

Known for taking the iconic "Pale Blue Dot" photograph of Earth, Voyager 1 would have crossed a distance of roughly 16.09 billion miles on November 18 to reach the on...