Moons

Why a lunation gets its own page

A single table of every new and full moon is a useful reference and it is not a page about any of them. The interesting content of one lunation is not its timestamp — it is the degree it happens at, which planets are stationary or aspecting it that week, whether the Sun is about to change sign, how far the Moon is from the lunar nodes, and whether that last figure is small enough to make it an eclipse. All of that is specific to one instant and it is a paragraph, not a row. Giving each lunation a page is what makes room for the paragraph; the table on this index is what makes the set navigable once the paragraphs exist.

The month in a URL is a UTC month

Each of these pages is named for the calendar month its instant falls in, measured in UTC, and that occasionally disagrees with the reader. A new moon at 17:41 UTC on the thirty-first is already the first of the following month in Sydney. The URL, the heading and the structured data all stay on the UTC month, because a URL that means different things to different readers is not a URL — and the page says so in a line that appears only for readers whose own calendar disagrees. That is also the honest answer to why published lunation dates differ from source to source: most of them are naming a local day and not saying which.

What the rolling window is and is not

The site footer and the hub surface a moving subset of these pages — the month in progress and the three after it — rather than all of them, so the chrome stays a fixed size as the set grows. The subset is presentation only. Nothing is removed when it stops being surfaced, every page keeps its URL forever, and this index is where the ones outside the window are reached. The distinction matters because the opposite arrangement, where a page disappears from the site when its month passes, is common and it quietly destroys whatever the page had accumulated.

The cycle underneath the list

The interval between one new moon and the next averages a little over twenty-nine and a half days, which is why the dates walk backwards through the calendar month and why a single calendar month occasionally contains two full moons. It also means consecutive lunations of the same kind land about thirty degrees further along the zodiac each time, so a run of them traces the signs in order — and a run that stalls is worth looking at, because it usually means the boundary fell awkwardly. Each page prints the neighbouring lunations of its own kind for exactly that comparison.