It was the best of times, it was the worst of times. Thus wrote Charles Dickens at the start of A Tale of Two Cities, before running through a sequence of superlatives and concluding it to be “a time like any other”. Its salient feature was that it was the day on which Dickens wanted to begin his tale.

The same could be said of our decision to publish, in this week's Nature, a moment-by-moment account of one day in the world of science (see page 1040; or for greater detail our website). The day is 21 June, the summer solstice. It is the longest day; it is the shortest day. It is the most ancient day (marked by humankind with its earliest megaliths) and the most recent day (give or take the subsequent seven). But it is, in the end, a day like any other.

And therein lies the wonder. It is an ordinary day filled with extraordinary goings-on. It is easy for scientists working on their own projects to forget the breadth, complexity and intricacy of the overarching project of which they are part, the project of understanding the world and its contents. Concentrating on one day, from the seas off Singapore and Svalbard to the mountains of Madagascar and the ice-cap of Antarctica, from glimpses of the farthest galaxies to the afterglow of a strangely close gamma-ray burst, is a way of celebrating that quest for knowledge in a day's worth of arbitrary details.

And in every detail there is a human story. People finish projects and begin them (although most are in the middle, as most things are, most of the time). People receive good news — that a vaccine has been approved — and bad — in the unexpected shortcomings of a diagnostic test. Children learn ancient knowledge (how to measure the circumference of the Earth) and modern know-how (how to race a toy car powered by a fuel cell). People offer small kindnesses and share global enthusiasms.

But what we are celebrating here is not just on an individual scale. It is on the scale of the planet. By taking the whole world as its subject, science pulls the world together, whether by cloning rare forest oxen or assessing the vulnerability of arctic algae to ultraviolet light, by mapping undersea currents or comparing infinitesimally precise measurements made continents apart to sense the expansion and contraction of space.

Science, perhaps more than any other human endeavour, stretches around and through the Earth. It reaches places where commercial activity is banned, such as the South Pole, and where politics are meaningless, such as the night sky, aglow with the faint passage of cosmic rays. It penetrates into minds deciding between breakfast cereals on supermarket shelves and pools the whole world's exhalations — animal, vegetable and internally combusted mineral — into a single measurement of the state of the atmosphere on a mid-ocean mountaintop.

While nature never fails to inspire, the process of understanding it can sometimes efface itself. Yet the process is wonderful and remarkable, and last Wednesday, many of you played a part in it. It was a day, like any other — and thus worthy of celebration.