NASA’s Voyager 1 is nearing a historic distance from Earth. The Voyager 1 light-day milestone will come on 18 November 2026, according to NASA. At that point, the probe will sit about 25.9 billion km away. So, a radio signal will take a full day to reach it. Notably, no human-made object has ever travelled so far.
What Is One Light-Day?
A light-day is the distance light covers in one day. Light travels about 3 lakh km every second. Hence, one light-day equals about 25.9 billion km, or 173 astronomical units. In other words, Voyager 1 will be 173 times farther than the Sun is from Earth.
A 49-Year Journey
NASA launched Voyager 1 on 5 September 1977. Later, it flew past Jupiter and Saturn. Then, in 2012, it crossed the heliopause into interstellar space. It will take 49 years, 2 months and 11 days to reach one light-day. Meanwhile, its twin Voyager 2 trails about 3.2 billion km behind.
The Pale Blue Dot Image
On 14 February 1990, Voyager 1 turned its camera back towards home. It captured Earth as a tiny speck from about 6 billion km away. Later, astronomer Carl Sagan called it the “Pale Blue Dot”. Today, the image still reminds people how small Earth is in space.
Latest Update
As of early October 2026, Voyager 1 was about 25.72 billion km from Earth. Also, NASA keeps switching off instruments to save the probe’s falling power. In April 2026, it turned off the Low-Energy Charged Particle instrument. Even so, both Voyager probes still talk to Earth. Meanwhile, NASA expects Voyager 2 to reach one light-day only in November 2035.
Voyager 1 Light-Day: Key Facts for Revision
- Milestone date: 18 November 2026 (NASA estimate)
- Distance: About 25.9 billion km (173 AU)
- Launch: 5 September 1977
- Interstellar space: Entered in 2012
- Pale Blue Dot: Taken on 14 February 1990
- Power source: Plutonium-238 radioisotope generators
Why the Voyager 1 Light-Day Matters for UPSC and UKPSC
Notably, space science questions often test distance units and deep-space missions. So, remember the milestone date, the light-day distance and the 1977 launch. Also, link Voyager 1 with the heliopause and interstellar space. For official updates, also visit NASA. Next, for a related story, read about NASA’s Artemis II mission.
So, are you preparing for the UKPSC Upper PCS 2026 prelims? Then join our UKPSC 2026 Prelims Test Series for regular practice.