Follow the curve of the Plough's handle away from the bowl, keep going, and the arc lands on an orange star sitting low and steady in the west after sunset. That is Arcturus, fourth brightest in the sky, and the brightest thing in Boötes by a margin that makes the rest of the constellation look like scaffolding.

It is 36.7 light-years away, plus or minus two tenths, a figure that comes from a parallax shift of 88.83 milliarcseconds measured by Hipparcos. Convert that distance into a date and the light entering your eye tonight left the star around Christmas 1989. The error bars are narrow enough to be worth stating: mid-October 1989 at the earliest, early March 1990 at the latest. Nothing here is exact to the day, and it does not need to be.

Which is before. Before the two evenings of 29 and 30 November 1990 spent playing the lead in Caryl Churchill's Serious Money at the Bowen West Theatre in Bedford, a building since demolished and replaced with flats. The light landing on the town tonight is about eleven months older than the thing it feels like it should belong to. It left while all of that was still ahead of everyone involved.

Run the arithmetic the other way. The light that left Earth on those two nights, the streetlamps and the stage wash and whatever escaped through the windows, is now 35.78 light-years out, and it reaches Arcturus in eleven months. That is not a second coincidence. It is the same eleven months, and it could not be anything else: the amount by which the incoming light predates the evenings is exactly the amount of journey the outgoing light has left to run. Being behind and being awaited are one measurement read from either end.†

Which leaves a third parcel, and it is the one that matters. Arcturus was also shining in November 1990. Photons left its surface during those same weeks, started across the same gap, and have not arrived. They are somewhere out there this evening, closing at the only speed on offer, and they land here on exactly the day Bedford's light reaches the star, both being that one moment plus the same distance. That coincidence survives the uncertainty in a way the calendar does not. Whatever the true figure turns out to be, the two arrivals share it and stay simultaneous; it is only the date they share that can move by a season.

The timetable is unglamorous and specific. Light that left Arcturus at the start of September 1990 gets here in the middle of next May, the 1st of November arrives in mid-July, and the 30th, the second night, arrives around 11 August 2027. So for those few weeks between mid-July and mid-August the star overhead will not be a way of thinking about November 1990. It will be November 1990, delivered, thirty-seven years late and on schedule.

The inversion held at the time, too. Anyone who stepped outside the theatre on those nights and looked up was seeing Arcturus as it had been in about March 1954, while the star's actual output that week was already in flight toward an audience that did not yet exist. No two points in the sky report the same date. A single view of a single night is a staggered archaeology, every object filing from its own distance, with the word "now" doing no work at all.

The two beams passed each other around October 2008, roughly 17.9 light-years out, in a stretch of nothing with no name.

In 1933 a city built a ceremony out of this and got it slightly wrong. The Century of Progress exposition opened in Chicago on 27 May, and at 9:15 that evening the fair's floodlights came on under starlight from Arcturus, gathered by telescopes at Yerkes, Harvard, Allegheny and Illinois, dropped onto photoelectric cells and run as a thread of current down a telegraph wire to the lakefront. The Tribune's man wrote it up next morning as a beam of light which forty years ago started from the star Arcturus. Forty years was the entire point. Arcturus was reckoned to sit forty light-years out, so the beam would have departed during Chicago's previous world's fair in 1893, and the city could open its future with a signal sent by its own past.

The distance was wrong. At 36.7 light-years that beam left around 1896, three years adrift, and thousands of people stood in the dark and cheered a piece of arithmetic that did not hold. The idea is credited to Edwin Frost of Yerkes, who was by then blind, and who stood outside the Hall of Science and asked the crowd whether this was not a fitting demonstration of a century of progress. It was fitting, though not in the way he meant. A ceremony hung on light that left at the wrong time is exactly what tonight is, scaled up and sold tickets for.

The exchange is even but the bookkeeping is not. Arcturus's light arrives and is collected: you can stand outside and take delivery of December 1989 with your own eyes, and next August take delivery of November 1990. Bedford's light will arrive too, that same day, on time, and find no receiver and no flux worth the name, spread so thin across an expanding sphere that no instrument could reassemble an image from it. Both directions transmit. Only one of them is ever read.

The star is indifferent to the arrangement. It is around seven billion years old, older than the Sun, and moving fast enough at 122 kilometres a second that Halley caught it shifting in 1718 by setting its position against the one Ptolemy had written down, which is the same trick as everything above. That motion also means next summer's delivery is not an old picture of the current star. Arcturus has slid about eighty arcseconds across the sky since 1990, a little over a minute of arc, so the light will have set out from a position the star has already left.

Hauntology usually runs the other way. The past reaches you as residue, as things that outlasted their moment or as the holes where they used to be: a demolished theatre, a recording, a smell, the flats that went up on the site. This is the exception. Nothing about it survived, was kept, or was reconstructed. It has simply been in transit the whole time, and it is not behind anyone. It is inbound.

The date is in the diary now, which is the only part of this that ever needed anyone. Next summer the sky will look exactly as it does tonight, one orange star at the end of an arc, giving no indication whatever that what left in November 1990 has finally got here.

Amendment, 8 September 2026. This post was expanded on the day of publication. The original ran to the outbound half of the arithmetic only, tracing Bedford's light toward Arcturus; the inbound half, the star's own November 1990 still on its way here, was added along with the 1954 backward view and the proper-motion figure. Nothing in the first version was retracted. ↩

Sources: