Why the sky goes out

The Sun is about four hundred times wider than the Moon and about four hundred times further away, so the two discs match almost exactly in our sky. When a new Moon crosses precisely between Earth and Sun, its inner shadow, the umbra, touches the ground as a moving spot at most a few hundred kilometres wide. Stand inside that spot and the Sun goes out; stand a little outside it and you get a partial eclipse and no darkness at all. That knife edge is why path maps matter.

Magnitude is the fraction of the Sun's diameter the Moon covers. Above 1, the Moon more than covers it, and the margin buys time in darkness. Gibraltar's 1.022 at maximum is a comfortable totality of 4 minutes 28 seconds; the global maximum for this eclipse, in Egypt, runs over six, which makes 2 August 2027 one of the longest total eclipses of this century anywhere.

Somewhere on Earth sees a total eclipse every year or two, but the umbra's track is so narrow that any single town waits centuries for its turn on average. The Moon's orbit is tilted about five degrees to Earth's, so most new Moons pass above or below the Sun; only when the alignments coincide does the shadow touch down, and where it touches is different every time. Gibraltar's turn happens to be 2 August 2027, mid-morning, in the clearest month on this coast.

On 12 August 2026, a year before the main event, a total eclipse crosses northern Spain, and Gibraltar sees it as a deep partial: magnitude 0.938 at 20:39 local time, with the Sun only six degrees above the horizon. A nearly-swallowed Sun setting over the Strait is a serious sight in its own right, and a live rehearsal for glasses, spots and cameras. It needs a clear view low to the west-north-west; timeanddate's records make that evening's cloud odds worse than the main day's, at 28% of years since 2000.