Beyond the horizon: exploration to today

Discover asked why people got in boats at all, and what happened afterwards, good and bad, to everyone involved. This layer picks the story back up and carries it all the way to today.

A scientist-captain charts the Pacific and, without quite meaning to, hands his own government a claim on other people's land. Two teams race on foot to the bottom of the world, and a continent ends up belonging to nobody, by treaty rather than by conquest. Humans leave Earth's gravity behind entirely, first briefly, then for good. And a probe, still talking to Earth after nearly fifty years, becomes the furthest a human hand has ever reached.

By now you have the tools for harder questions than Discover asked: who gets to decide what happens somewhere nobody lives, and whether "leaving people alone" is always the respectful choice, or sometimes just another decision made about them, from a distance.

Some of this goes beyond what a Class 6-7 syllabus expects, on purpose: space law, deep-sea law and Fermi estimates are not usually taught this young. The lesson plate says where.

By the late 1760s, European ships had crossed the Atlantic and rounded Africa for over two and a half centuries. The Pacific was still mostly blank on their charts, even though it had been home to skilled Polynesian navigators for thousands of years, crossing greater distances than Columbus ever attempted, in canoes, without a compass.

In 1768, the British Admiralty and the Royal Society sent Lieutenant James Cook and the ship Endeavour into that ocean. This was the first of 3 Pacific voyages Cook would go on to command. It is worth telling properly, because it shows something the earlier voyages in Discover only hinted at: a voyage can be genuinely, carefully scientific, and still end up being used for conquest.

By 1900 the map still had two blank white patches at the very top and bottom of the world. Reaching either pole meant weeks of hauling sledges across ice at temperatures that could injure exposed skin in minutes, with no way to call for help and no certainty of getting home.

People went anyway, for the same tangle of reasons you met in Discover: rivalry between nations wanting to be first, personal ambition, and real scientific measurement of a part of the planet nobody had instruments in. The race to the South Pole in 1911-12 shows all three at once, and shows how differently a race can end for the winner and the loser.

Every voyage so far in this topic stayed on one planet. The next one did not.

To leave Earth for good, a spacecraft must reach escape velocity: about 11.2 km/s, roughly 40,000 km/h, straight up. Anything slower falls back, the way a thrown ball falls back to your hand. This is not a technology limit that a better engine might one day beat; it is a consequence of Earth's gravity itself, the same force pulling every object towards the planet's centre that you meet in the Gravity topic. Go fast enough, and instead of falling back you fall past the Earth, all the way to somewhere else.

There is a place on Earth harder to reach than the Moon, in the sense that far fewer people have ever been there. It is not up. It is down, at the bottom of the Pacific Ocean.

The Challenger Deep, in the Mariana Trench, is the deepest known point in any ocean: about 10,935 m. Only a handful of crewed dives have ever reached it, because the water pressure there is enormous, more than a thousand times the pressure at the surface.

The four places in this chapter have something in common: nobody lives in most of them, or, in one case, somebody lives there and has clearly said they want to be left alone. That makes the ordinary rule, ask the people who live somewhere what they want, hard to apply.

This chapter does not give you answers. It gives you the strongest version of each side, and lets you decide what you think, and why.

Three projects, no marks attached. Pick one, or try all three over a few weekends. Each one asks you to go and find real information, not just read this lesson again.

Scientists and engineers often cannot get an exact number, so they build a Fermi estimate: a rough calculation, using numbers you can find or reasonably guess, that gets you within shouting distance of the truth. It is named after the physicist Enrico Fermi, famous for estimating things like "how many piano tuners are there in Chicago" from almost nothing.

Here is one to try yourself, using numbers you already have from this lesson.