# The farthest thing people have ever made is a day away, even for light

Its signal needs about a day to reach Earth. On 18 November 2026, at 10:16 in Britain, the distance reaches one full light-day. The golden record aboard carries greetings in 55 languages.

Example for 17 October 2026, 12:00 universal time: Voyager 1 was 25,816,167,337 kilometres from Earth, and the signal received then had left the craft 23 hours and 55 minutes earlier. The distance reaches one light-day on 18 November 2026, at 10:16 in Britain.

## How far light goes in a day

Light covers 299,792 kilometres every second, and radio waves travel just as fast. Picture a flash leaving Earth this moment and follow its sphere as it grows: the clock in the corner of the picture counts the time since it left.

It passes the Moon after 1.2 seconds. It needs 8 minutes and 15 seconds to reach the Sun, 11 minutes and 49 seconds for Mars and 45 minutes and 32 seconds for Jupiter, with the planets where they are today.

Neptune, the farthest planet, is 4 hours and 2 minutes away. Beyond it, the sphere passes through the region where the Sun’s wind of particles gives way to the gas between the stars. Voyager 2 is out there, 20 hours and 3 minutes away.

Only after 23 hours and 58 minutes does it reach Voyager 1. Nothing else people have made is as far away.

## Why it gets closer to Earth from January to April

Voyager 1 never turns back. It moves away from the Sun at 16.9 km a second, in an almost straight line towards the constellation Ophiuchus.

Earth, though, goes round the Sun at nearly 30 kilometres a second. For about three months a year, from around 21 January to 24 April, its path leads partly towards the craft, and Earth gains on it faster than Voyager 1 pulls away. The distance shrinks: in 2027, by 40.7 million kilometres.

For the rest of the year Earth no longer gains on it, and the distance grows again, by much more than it fell. In JPL’s prediction the light-day line is crossed only once: the dips of later years never bring the craft back inside it.

## Five craft that will never come back

Five spacecraft are travelling fast enough to escape the Sun’s pull: Pioneer 10 and Pioneer 11, launched in 1972 and 1973, the two Voyagers of 1977, and New Horizons, which flew past Pluto in 2015. The lines are the paths they have flown, from JPL’s tables, against the real sky.

Each heads for a different part of the sky: Voyager 1 for Ophiuchus, Voyager 2 for Pavo, Pioneer 10 for Taurus, Pioneer 11 for Aquila and New Horizons for Sagittarius. The two Pioneers fell silent long ago: Pioneer 11 in 1995, Pioneer 10 in 2003.

Voyager 1 leads, and none of the others catches up with it before 2100. On 1 January 2100, where JPL’s prediction for the two Voyagers ends, Voyager 1 will be 431.1 astronomical units from the Sun and Voyager 2 376.1. JPL’s tables for the other three stop in 2050; carried on along the same orbits, Pioneer 10 reaches about 322.0, Pioneer 11 about 285.5 and New Horizons about 266.7.

## Where it will be, long after it falls silent

The page follows Voyager 1 to 1 January 2100, as far as JPL’s prediction goes. The line of two light-days from Earth falls in October 2075.

Its transmitter will fall silent long before that: NASA says the two Voyagers could stay within reach of its antennas until about 2036, if their power holds. That electrical power comes from the heat of decaying plutonium and falls by about four watts a year, and the instruments are being switched off one after another to save what is left. Its path can still be worked out after the transmitter goes quiet, from the last orbit measured: the positions on this page are a prediction from that orbit, not a reading of its signal.

NASA’s estimate, published in 2026: about 300 years to the inner edge of the Oort cloud, and possibly 30,000 more to cross it.

Example worked out for 2 November 2026, 12:00 universal time.

## Send it a signal

A radio signal travels at the speed of light. Press the button and follow it: in a little over a second it has gone as far as the Moon is, in about four hours as far as Neptune, and to reach Voyager 1 it needs almost a whole day.

## The tour that was never made

*Pasadena, 1965*

In the mid-1960s someone at the Jet Propulsion Laboratory noticed that Jupiter, Saturn, Uranus and Neptune would each come round to the right place in turn towards the end of the following decade. A craft sent to Jupiter could be thrown by the planet's gravity on to Saturn, from there to Uranus and onward to Neptune, burning almost no fuel along the way. Gary Flandro described the opportunity in a report printed at the laboratory on 31 October 1965.

The arrangement comes round rarely, and not on a fixed beat: the planets’ periods do not divide into one another, and a workable trajectory allows some margin. Two NASA pages say “about every 175 years”; the figure repeated everywhere else is 176. Neither page shows how its number was worked out.

The full route was cut all the same, for want of money. A craft that would last twelve years and carry the instruments needed was judged too expensive. The two Voyagers were funded for Jupiter and Saturn, and no further. More than ten thousand trajectories had been studied first.

> How many planets can a single craft visit along that line of planets?
>
> The physics allowed four. The budget paid for two. And Voyager 2 reached all four in the end, for a reason that arrives fifteen years later in this story.

## The second craft left first

*Cape Canaveral, August and September 1977*

Voyager 2 lifted off on 20 August 1977 at 14:29:44 UTC. Voyager 1 followed sixteen days later, on 5 September at 12:56:01 UTC. The numbers were not mixed up: the order was chosen.

Voyager 2 left on the long trajectory, the one that kept Uranus within reach. Voyager 1 left on a shorter and faster path, with Jupiter and Saturn on it. On 15 December 1977 it drew farther from the Sun than its twin. It became the most distant human-made object only on 17 February 1998, at 69.4 astronomical units, when it overtook the Pioneer 10 probe.

> Which of the two is farther from the Sun today?
>
> Voyager 1, by some 28 astronomical units, which is about 4.2 billion kilometres.

## Something rises from behind the edge of Io

*Pasadena, 9 March 1979*

On 5 March 1979 Voyager 1 had passed 280,000 kilometres above Jupiter’s clouds. Four days later Linda Morabito, the engineer responsible for optical navigation, was working through the pictures taken after the encounter. She was not looking for volcanoes. She was looking for stars: the pictures were used to fix exactly where the craft was, and the faint stars in the corners were the reference points.

To bring out a star of magnitude 8.3 in the lower left quadrant she stretched the contrast of the image. Io fell in the same corner. She wrote later: “It was at the moment that I displayed the lower left hand quadrant in which the 8.3 visual magnitude star was predicted to be in… that I noticed the peculiar marks to the left of Io.”

Her first explanation was the simplest one: “It looks like a satellite behind a satellite.” Her colleague Steve came to the monitor and said “Jesus, what’s that?” Had it been a whole moon, it would have been about twenty pixels across, and the tables gave no known moon anywhere near Io at that moment.

Three days before the encounter, Peale, Cassen and Reynolds had published in Science that tidal friction might have melted much of Io’s interior, and that the consequences might show in the very pictures Voyager 1 would return. They did. It was the first volcanic eruption seen anywhere beyond Earth.

> What did Morabito first think she was seeing beside Io?
>
> Another moon. In her own words, written later: “It looks like a satellite behind a satellite.”

## The trade at Titan

*Saturn, 12 November 1980*

At 23:46 UTC on 12 November 1980, Voyager 1 passed about 126,000 kilometres above Saturn’s clouds. Its real target, though, was Titan, the moon whose thick atmosphere hid its surface. The craft found that atmosphere to be ninety per cent nitrogen, with methane and more complicated hydrocarbons in it.

The Titan flyby came at a plain cost, known in advance: the trajectory bent the craft upward, out of the plane the planets move in. After Saturn, Voyager 1 could reach nowhere else. Not Uranus, not Neptune, not Pluto, though it could have been aimed there.

Voyager 2 waited behind as the fallback. Had Voyager 1 missed Titan, its twin would have been sent there instead, at the same cost. NASA puts the decision plainly: “Once Voyager 1 had successfully gathered data at Titan, Voyager 2 was allowed to go on to Uranus and Neptune.” The four-planet tour exists because the first craft did its job.

> Would you have sent Voyager 1 to Titan, knowing what it gives up?
>
> NASA sent it. The cost was real: after Saturn, Voyager 1 met no further planet. So was the gain: Titan examined, and a Voyager 2 free to go on to Uranus and Neptune.

## The last photograph, and a dot on it

*40 astronomical units, 14 February 1990*

Twelve years after departure the cameras were turned back towards the place the craft had come from. Sixty-four frames were taken, from forty astronomical units: a family portrait of the solar system with six planets in it. Mercury and Mars did not show. These were the last of the 67,000 photographs the two craft took.

In one of the frames Earth appears as a bright speck caught in a band of light scattered by the camera’s own optics, six billion kilometres from the Sun. Nothing on it can be seen: at that distance, the laboratory writes, Earth was a crescent 0.12 of a pixel across. The photograph shows only where it was.

> How large does Earth appear in that frame?
>
> Less than one pixel. What shows is a patch of light wider than the planet, spread by the camera’s optics.

## “Greetings to everybody”, in Romanian

*Ithaca, New York, 1977*

Each of the two craft carries a thirty-centimetre gold-plated copper disc. On it are 115 images, 35 sounds of Earth, ninety minutes of music, messages from President Jimmy Carter and from the Secretary-General of the United Nations, Kurt Waldheim, and greetings in 55 languages. The English one says: “Hello from the children of planet Earth.”

The greetings were recorded within a few weeks, mostly at Cornell University, with people from the language departments and the town around it. NASA writes that the speakers were given no instructions other than that the greeting was for possible extraterrestrials and that it had to be brief.

The Romanian greeting was spoken by Sanda Huffman, then a teacher of Romanian and French at Cornell. In a 2015 interview with the Romanian daily Jurnalul she recalled that nothing had been written down beforehand: everyone said what came into their head. She chose “Salutări la toată lumea”. NASA publishes only the English translation, “Greetings to everybody”, and her recording, a little over two seconds long, can be heard on NASA’s greetings page.

A year later, in 1978, the same Sanda Huffman was one of the interpreters, with Sergiu Celac, at the White House talks between Jimmy Carter and Romania’s Nicolae Ceaușescu, as she tells it in the same interview. Carter’s message was already in space, on the same disc as her voice.

Swahili is missing from the record. The reason, given by Linda Salzman Sagan, who gathered the greetings, is that no speaker could be found in time.

> What do you think the Romanian voice on the record says?
>
> “Salutări la toată lumea”: greetings to everybody. Said with nothing written down, in a language laboratory at Cornell; on the record it lasts a little over two seconds.

## It left the Sun’s bubble. It did not leave the solar system

*At the edge of the heliosphere, 25 August 2012*

The Sun blows a wind of particles around itself which holds the matter between the stars at bay. The edge of that bubble is the heliopause. On 25 August 2012 Voyager 1 passed through it, the first craft to do so. Nearly eight years earlier, on 16 December 2004, it had crossed the termination shock, where the solar wind slows abruptly.

There is nothing to see there, and the craft no longer had a working plasma sensor. The answer came from the Sun: an eruption of March 2012 reached the spacecraft thirteen months later, and the plasma around it, NASA writes, “began to vibrate like a violin string”. On 9 April 2013 the instrument that listens to plasma waves caught it. The pitch gave the density: more than forty times what they had met at the edge of the heliosphere. Don Gurnett’s team at the University of Iowa published the result in Science on 12 September 2013; counting back, the crossing falls in August 2012.

From here the confusion starts. “Voyager 1 has left the solar system” is false by NASA’s own reckoning. Beyond the heliopause lies the Oort cloud, a shell of bodies still bound to the Sun, whose near edge is thought to sit somewhere between 2,000 and 5,000 astronomical units out. NASA writes that Voyager 1 will enter it in about 300 years and leave its far side in perhaps 30,000.

> How long until Voyager 1 enters the Oort cloud?
>
> About 300 years, according to NASA. And perhaps another 30,000 to pass its outer edge.

## The instruments go out, one at a time

*17 April 2026*

The power on board comes from the heat of decaying plutonium. At launch the three generators together gave about 470 watts. By the beginning of 1997, after nineteen and a half years, some 335 were left. Today each craft loses about four watts a year.

Of the ten sets of instruments each Voyager carries, seven had been switched off before April 2026. The order is not decided in a hurry: the science and engineering teams sat down years ago and settled what would be switched off and in what sequence.

On 27 February 2026, during a routine roll, Voyager 1’s power fell unexpectedly. On 17 April the command to shut down the low-energy charged particles experiment left for the spacecraft. The command would take some 23 hours to arrive, and the shutdown itself three hours and a quarter. A half-watt motor, the one that turns the sensor, was left running so the instrument could be switched back on if power is ever found.

Two instruments are still working on Voyager 1: the one that listens to plasma waves and the one that measures the magnetic field. In August 2026 the team completed on Voyager 2 a power-saving change it calls “the Big Bang”, swapping a group of devices all at once for less hungry ones, and plans the same operation on Voyager 1.

> You have four watts to save. What do you switch off?
>
> The team switched off an instrument. The heating has to stay or the fuel in the lines freezes; without the transmitter the craft goes silent for good.

## One light-day, on three different days

*18 November 2026, 10:16 GMT*

A light-day is how far light travels in twenty-four hours: 25,902,068,371 kilometres. On 18 November 2026, at 10:16:07 by universal time, which is also the time in Britain, that is the straight-line distance between Earth and Voyager 1. NASA announces the very same second on California’s clock: 2:16:07 in the morning. No object made by people has ever been this far away.

At that instant nothing arriving on Earth shows it yet: the signal received at 10:16 left the craft almost a day earlier, from a closer position. The signal reaching Earth has genuinely spent twenty-four hours in flight only from 19 November, at 02:17.

Why sixteen hours later, when a day has twenty-four? In a day the craft alone puts another million and a half kilometres between itself and Earth. Were Earth to stand still, the distance would grow by exactly that much in a day, and the threshold would arrive a day later. In November, though, Earth is drawing away from the craft as well, so the distance grows by some twenty-five kilometres a second, faster than the seventeen the craft manages alone. The distance grows faster, and the threshold arrives after sixteen hours.

And there is a third date. Measured from the Sun rather than from Earth, the same line is crossed on 3 February 2027, at about 21:39. Earth travels round the Sun and moves the reckoning by up to one astronomical unit either way.

All three dates come out of the same published NASA laboratory ephemeris, used for three different quantities. Which one is “the moment” depends entirely on the question.

> Measured from where, to give 18 November 2026?
>
> From Earth, in a straight line, at that instant. Measured by the signal’s journey the moment comes on 19 November; measured from the Sun, on 3 February 2027.

## What the sources cannot say

- The full list of speakers on the record. Sanda Huffman’s name comes from her 2015 interview and from Wikipedia’s table; the 1978 book by Carl Sagan’s team, Murmurs of Earth, which prints every speaker’s name, is not freely available.
- Why “176 years” is repeated for the planets’ arrangement. Two NASA pages say 175, and neither shows how its number was worked out.
- What damaged the onboard computer’s memory in 2023. NASA suspects that a single chip has stopped working, and says plainly that whether it was struck by a particle or simply wore out cannot be told.
- How much power Voyager 1 has today. The sources give 470 watts at launch, some 335 at the beginning of 1997 and a loss of about four watts a year. The sources consulted give no figure for 2026.
- What density exactly the plasma-wave instrument measured in 2013. The laboratory’s statement gives the ratio, more than forty times, and the Science paper that gives the figures requires a subscription.

## How the numbers are worked out

The positions of Voyager 1, Voyager 2, Earth and the Sun come from JPL Horizons (for Voyager 1, the solution Voyager_1_ST+refit2022_m), requested daily to the end of 2028. The page works out the distance for every second itself, on your device, with a cubic through the four neighbouring days; between the table's days the curve is out by less than a kilometre.

Light-time is worked out in the frame of the solar system's centre of mass, with the craft at the moment the signal leaves and Earth at the moment it arrives. Worked out around the Sun instead, which itself moves round that centre, the 19 November moment would come out 21 seconds later. With this rule the page finds all three moments to the second: 10:16:07, 02:17:27 and 21:38:59, universal time.

The planets' positions are worked out from JPL's approximate orbital elements for 1800–2050. Compared with Horizons every 100 days from 1977 to 2030, they differ by at most 0.03 astronomical units, for Saturn. That is why the times to the planets are rounded to the minute.

The state of the antennas comes from NASA's public DSN Now feed, read every 30 seconds while the page is open. The stars on the chart are those down to magnitude 4.8 in the Yale Bright Star Catalogue.

The place used for tonight's sky is your approximate location, estimated by Cloudflare from your internet connection at the moment of the request; it is not kept. The time you send the signal and your birth year stay on your phone or computer only.

The Romanian greeting was listened to in the 2.3-second recording NASA publishes. An automatic transcription (Whisper) recognises Romanian and the words “la toată lumea”; it writes the first word as “Salută-i”, where the 2015 interview gives “Salutări”.

## Sources

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- JPL Horizons — Voyager 1, Voyager 2, Earth and Sun ephemerides. https://ssd.jpl.nasa.gov/horizons/app.html
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https://mariuscomper.uk/voyager-1/en/