Light reaching now left Voyager 1 23:54:48.3 ago, from 25,808,647,052 km away.
Choose the place the light reaches.
It reaches 24:00:00.0 at 02:17:27 UTC on Thursday 19 November 2026.
Computed when this page was built, 13:36 UTC on Thursday 15 October 2026.
Offline. Working from the copy of JPL's trajectory on this device.
Every CrossingEvery Crossing
The second it happens, for your own place
Voyager 1 crosses one light-day once. Every year the distance shrinks for about three months, but in 2027 the shrinking stops 25,127,602 km short of falling back, and through 2099 it never does.
- Goldstone, California (DSS-14)02:18:44 UTC, 19 November18:18:44 PST, Wednesday 18 November+77 s
- Canberra, Australia (DSS-43)02:20:10 UTC, 19 November13:20:10 AEDT, Thursday 19 November+163 s
- Madrid, Spain (DSS-63)02:14:54 UTC, 19 November03:14:54 CET, Thursday 19 November−153 s
- the centre of the Earth02:17:27 UTC, 19 November0 s
NASA's announced moment: 10:16:07 UTC, 18 November 2026 (2:16:07 a.m. PST). Ours, from the centre of the Earth: 02:17:27 UTC, 19 November 2026. Difference: 57,680 s.
The 16 h 1 min 20 s are a difference of definition, not of arithmetic. NASA's moment is when the distance, measured at one instant, equals a light-day; solved that way from the same trajectory, this page gets 10:16:07 UTC, a difference of −0.004 s. But the light reaching the Earth at that instant left Voyager 1 when it was 1,457,720 km closer, and took 23:59:55.1. The light that takes a full day arrives 57,680 s later.
Send a Message
When your words would reach it, and the reply
Nothing leaves this page: there is no server to send it to. The page times the trip from your place, solving where Voyager 1 will be when the words catch up with it.
The Breathing Year
Why the distance shrinks for months every year
Every year from about 20 January to 24 April, the Earth runs toward Voyager 1 faster than Voyager 1 runs from the Sun, and for 94 days the distance shrinks, by 40.7 million km. The rest of the year the Earth runs away too, and the distance grows by much more.
The Whole Mission
From launch in 1977 to the prediction's end
Launched on 5 September 1977, Voyager 1 passed Jupiter in 1979 and Saturn in 1980, and has climbed almost straight since. The curve to the left of 1992 is fitted to radio tracking; to the right, JPL's 2022 refit carries it forward to 2099.
Save the Poster
The whole mission on one sheet, with your crossing marked to the second and the receipt line beneath: 18 × 24 in at true size with the type as outlines and a 100 mm check bar, or 5400 × 7200 pixels for a 300 dpi print.
The Working
JPL's trajectory, solved again in your browser
What a light-day is
A light-day is the distance light covers in one day: 86,400 seconds at 299,792.458 km a second, which is 25,902,068,371.2 km, or 173.1446 AU (one AU is the mean distance from the Earth to the Sun, 149,597,870.7 km). Radio travels at the speed of light, so at one light-day every command to Voyager 1 takes a day to arrive and every answer takes another day to come back.
Which light
The number on the first screen is the light-time of the light reaching you now: how long ago it left Voyager 1. JPL's tables and the Deep Space Network count it this way. A message sent now has to chase the spacecraft, so it takes 9.7 s longer. NASA's figure takes the distance at one instant, which sits between the two. So the three cross 24 hours at three different moments: a message sent from the centre of the Earth after 18:24:45 UTC on Tuesday 17 November 2026 takes more than a day; NASA's distance reaches a light-day at 10:16:07 UTC on 18 November 2026; and the light reaching the centre of the Earth has taken a full day from 02:17:27 UTC on Thursday 19 November 2026.
Why the distance shrinks
Voyager 1 moves away at 16.9 km a second, toward the constellation Ophiuchus. The Earth circles the Sun at 30.1 km a second. For part of each year the Earth's path points toward Voyager 1, and the Earth gains on it faster than the spacecraft pulls away: the distance shrinks. A crossing can therefore happen more than once: a first crossing, a fall back under, and a crossing for good. The data shows one, because the 2027 shrinking ends short of a light-day.
Why your place moves the moment
In November the distance grows by 25.1 km every second. Your place on the Earth can be up to one Earth radius, 6,371 km, nearer to Voyager 1 than the centre of the Earth or farther from it, and as the Earth turns that changes through the day. So the crossing moves by up to 253 s, about 4 minutes, from place to place. This page puts your place on the WGS84 ellipsoid, turns it with the Earth to the instant (Greenwich apparent sidereal time, with Meeus's precession and nutation), and solves the light-time from there.
Where the numbers come from
JPL Horizons, the solar system ephemeris service of NASA/JPL-Caltech Solar System Dynamics: Voyager 1's light-time from the centre of the Earth every hour from 2026 to 2028, its range every day from 1977 to 2099, and the positions and velocities of Voyager 1 and the Earth from the solar system's centre of mass, every day from 2026 to 2028. The page interpolates between rows with cubic curves and solves the light-time equation itself. The receipts check each step against Horizons at instants the page never saw.
| Receipt | Worst | Tolerance |
|---|---|---|
| NASA's moment, solved NASA's way (distance at one instant) | 0.004 s | 300 s |
| The light-time crossing against NASA's moment (expected to fail: a different definition) | 57,680 s | 300 s |
| Hourly cubic against Horizons at 30 random minutes | 0.641 km | 1 km |
| Light-time solved from the vectors against Horizons | under 1 µs | 0.01 s |
| A message's arrival against Horizons, seen from Voyager 1 | under 0.1 ms | 0.5 s |
| The crossing at Goldstone, Canberra and Madrid against Horizons | 0.01 s | 5 s |
| Daily vectors against Horizons' hourly ones | 77 m | 1 km |
What it cannot know
- Where Voyager 1 really is to the kilometre. Two-way tracking ended in 1992; JPL refitted that old tracking in 2022 and carried the trajectory forward. Every distance here is that prediction, and the kilometres on the first screen are the prediction's, not a measurement's.
- The next leap second. The page assumes none before 2029, as JPL Horizons does. One would move every UTC time here by a second.
- Anything after 31 December 2028 to the second. The hourly table ends there; the whole-mission curve runs to 2099 at five-day steps.
- Your device's clock. The number ticks from it; a clock that runs fast shows the crossing early.