In November 2026, for the first time in human history, an object made by people will be one light-day from Earth. That object is Voyager 1.
A light-day is the distance light travels in 24 hours. For Voyager 1 to reach it took 49 years of flight at 17 km/s. A radio signal from the probe will take one full day to reach the Deep Space Network.
| Voyager 1 | Voyager 2 | |
|---|---|---|
| Launch | Sep 5, 1977 | Aug 20, 1977 |
| Distance (Aug 2026) | 172.59 AU | 143.47 AU |
| Solar escape velocity | Yes (Jun 1980) | Yes (Aug 1985) |
| Heliopause crossing | Aug 2012 (121 AU) | Nov 2018 (119 AU) |
| Planets visited | Jupiter, Saturn | Jupiter, Saturn, Uranus, Neptune |
| RTG life expectancy | ~2036 | ~2034 |
| One light-day | Nov 2026 | ~2036 |
A light-day is a unit that lives mostly in astronomy textbooks — the distance light travels in one day. The Earth-Moon distance is 1.3 light-seconds. The Sun is 8.3 light-minutes away. Pluto is 5.5 light-hours out.
Voyager 1 at one light-day means the entire solar system — including the Oort cloud — fits inside a sphere you could communicate across in one day. Beyond that is interstellar space measured in years, not hours.
The Golden Record, designed to last a billion years, is heading toward the constellation Ophiuchus. It will pass within 1.6 light-years of Gliese 445 in about 40,000 years.
By the time Voyager 1's RTG finally dies (engineering data expected through ~2036), the probe will be about 200 AU from Earth — already 15% of the way through the Oort cloud, which will take another 300 years to cross entirely.