Voyager 1 is about to be one light-day from Earth.
How long light takes to reach it right now.
When that clock hits 24:00:00, Voyager 1 is a full day of light from home, a first for anything we've built. It launched in 1977 and it hasn't stopped.
- Clock hits 24:00:00 in
- —
- Pulling away from Earth at
- —
Ping Voyager.
Hit send and a ping leaves at the speed of light, the fastest anything can go. It passes the Moon in about a second. It still won't reach Voyager until tomorrow.
Log scale: each step to the right is ten times farther than the last. Showing right now.
Your pings show up here, with the exact moment each one reaches Voyager. The ping is pretend. The timing is real.
Everyone's pings show up as small dots on the line.
Pings are anonymous. The counter keeps how many were sent each hour and nothing else. Your note never leaves this device.
Who's listening.
Everything Voyager sends home lands in NASA's Deep Space Network: three dish complexes spread about a third of the way around the world from each other, so one of them can always see deep space as Earth turns. This is what they're doing right now.
Checking the dishes…
Live from NASA's DSN Now feed, checked every minute.
The wobble.
Voyager 1 flies outward at a steady 17 km/s, but the distance to it doesn't grow evenly. Earth circles the Sun at 30 km/s, swinging toward Voyager for half the year and away for the other half. From late January to late April, Earth closes in faster than Voyager flies off, and the gap actually shrinks. It's also why the light-day lands in November: right now Earth is swinging away, adding to the gap.
Drag Earth around its orbit, or focus it and use the arrow keys.
Loading the trajectory…
49 years of lag.
Every mile Voyager covers adds to the wait for anything sent to it. Scroll through the trip and watch the delay grow from about a second to a full day.
Signal delay, Sept 5, 1977
1.29 seconds
Sept 5, 1977
Liftoff from Florida. By the next morning it's as far away as the Moon.
Signal delay: 1.29 seconds
Dec 15, 1977
Passes its twin. Voyager 2 launched 16 days earlier but took the slower road.
Signal delay: 6m 51s
Mar 5, 1979
Jupiter. Its cameras catch volcanoes erupting on the moon Io, the first active ones ever seen beyond Earth.
Signal delay: 37m 45s
Nov 12, 1980
Saturn, and a close pass by its moon Titan that bends Voyager north, out of the flat plane the planets orbit in. It never comes back.
Signal delay: 1h 24m 47s
Feb 14, 1990
It turns around for one last look and photographs Earth from 6 billion km: a pale blue dot. Then the cameras are switched off for good.
Signal delay: 5h 36m 37s
Feb 17, 1998
Passes Pioneer 10 to become the most distant thing people have ever made. It still is.
Signal delay: 9h 38m 44s
Dec 16, 2004
Crosses the termination shock, where the solar wind drops from supersonic to subsonic.
Signal delay: 13h 08m 35s
Aug 25, 2012
Leaves the Sun's bubble entirely. The first human-made object in interstellar space.
Signal delay: 16h 49m 50s
Nov 28, 2017
Fires a set of thrusters that hadn't been used in 37 years. They work.
Signal delay: 19h 34m 23s
Nov 14, 2023
Starts sending gibberish. One memory chip in a 1970s computer has failed.
Signal delay: 22h 30m 34s
Apr 20, 2024
Back. Engineers moved its code around the dead chip from 15 billion miles away, waiting about 45 hours for every answer.
Signal delay: 22h 32m 36s
Nov 18, 2026
One light-day. Nothing we've built has been this far from home.
Signal delay: 24h 00m 00s
Nov 2035
Voyager 2 reaches one light-day. Voyager 1 is past 28 light-hours by then, if its power holds out.
Signal delay: 28h 25m 38s
About 40,000 years from now
It drifts within 1.7 light-years of a star called Gliese 445. A hello from Earth would take over two years to reach it.
Signal delay: about 2.3 years
How we know
NASA puts the moment at Wednesday, Nov 18, 2026, 10:16:07 UTC (2:16:07 a.m. Pacific). The numbers here come from JPL Horizons, the Jet Propulsion Laboratory's public trajectory service: Voyager 1's position measured from Earth's center, sampled daily and interpolated in your browser. That data crosses one light-day 3 ms before NASA's time.
A light-day is how far light goes in 24 hours: 25,902,068,371 km. But Voyager keeps moving while light is in flight, about 1.46 million km per day, so “one light-day away” has three fair answers.
- Nov 17, 18:24 UTC
- After this, a command sent from Earth needs more than a day to catch it.
- Nov 18, 10:16:07 UTC
- Earth and Voyager are exactly one light-day apart. NASA's moment, and this page's.
- Nov 19, 02:17 UTC
- After this, light reaching Earth left Voyager more than a day earlier.
- Title
- One Light-Day
- Subject
- Voyager 1, JPL target −31
- Drawn by
- Kevin van der Poll
- Data
- JPL Horizons, NASA
- Scale
- Not to scale. Nothing would fit.
- Photo
- NASA/JPL-Caltech/KSC
An independent project. Not affiliated with NASA or JPL.