According to the scientists, the "ethical time horizon" – marking the period we ought to care about, but probably won't – lies 1,000 years in the future.
On a horizon marked by unknowable points of decline — questions of when, where, how things would break down — my departure time stood out for its simplicity.
The ship survived, but Budington never seriously tried to rescue his people: as Parry puts it, "One day's cursory scan of the horizon marked the sum total of all attempts to locate the men separated from the ship during the storm".
The Milky Way appears as a ghostly glow of distant stars rising vertically from the east-southeast horizon, marked by the bright stars Sirius and Procyon.
The range of brown peaks on the western horizon marked the beginning of a sandy wasteland that stretches from here all the way to Morocco's Atlantic coast.
A yawning gap in the record follows, until the fifth millennium BC, when horizon-marking megaliths appeared, erected to track or echo the passage of the sun through the sky.
The most important of those are the Transvaal basin on the Kaapvaal craton that contains economically important iron ore deposits; the Congo basin; and the West African basin, with its thick late Proterozoic sediments including a prominent tillite horizon that marks a major glaciation event at the end of the Precambrian.
The New Horizons probe marks humanity's first trip to the mysterious planet, and while the first pictures it takes are expected to reveal little more than bright dots, the images will be invaluable for scientists waiting on the ground.
BBC2's Horizon programme, marking its 50th birthday this year, will kick off a month-long poll on Thursday asking viewers which issue the prize, developed and run by Nesta, the UK's innovation foundation, should aim to tackle.
The extraordinary images of the former ninth planet and its large moon, Charon, beamed 4 bn miles back to Earth from the New Horizons spacecraft, marks the climax of a mission that has been quietly underway for nearly a decade.
