A thin crescent covers Jupiter on 8 September for North America and northeast Asia

On 8 September the waning crescent Moon passes in front of Jupiter. The Moon is about 7 to 9 percent illuminated and stands 31 degrees west of the Sun. Jupiter shines at about magnitude -1.8 with a disk 32 arcseconds across. The Moon needs a little more than one minute to cover that disk.

The visibility map splits by light. Northeastern Asia sees the occultation in early dawn. Eastern Russia, Canada, most of the United States, the Caribbean and Greenland lie inside the footprint. Alaska and western Canada catch it in the late morning sky. Eastern Canada and the eastern United States have the harder job: the pair is up after sunrise, and Jupiter has to be pulled out of a bright daytime field with binoculars or a small telescope next to the slim lit limb.

This is the last convenient dress rehearsal before a better North American occultation on 6 October, when the event falls under darker circumstances for the contiguous United States. September's pass is still worth the effort because Jupiter is bright enough that a carefully aimed pair of binoculars can hold it against blue sky once the observer has the Moon as a finder.

Before dawn on the same morning the geometry is kinder. The crescent and Jupiter rise about three hours before the Sun. Regulus, the brightest star in Leo, sits below the pair. On 7 September the slightly fatter crescent had already stood above Pollux in Gemini with Mars in the same eastern sky. After the Jupiter event the Moon thins further and, on 9 September, occults Regulus as a 2 percent crescent on the way to new Moon on 11 September.

An occultation is a timing tool as well as a spectacle. The disappearance and reappearance of Jupiter's limb against the lunar mountains last seconds. Observers who record those contacts to a fraction of a second add a line to a dataset that still refines the Moon's position. For most people the value is simpler. A planet that usually sits in a dark field is, for one minute, clipped by a rock 384,000 kilometres away.

Daytime attempts need a stable mount and a low-magnification eyepiece first, then more power once Jupiter is found. Polarising filters and a hooded screen help. The risk is losing the planet in glare and sweeping into the Sun. The 31-degree elongation is enough to keep the Sun out of a normal finder's field if the observer starts on the Moon and never pans toward the bright side of the sky.

New Moon follows on 11 September. The next bright planetary occultation in the same sequence is Venus on 14 September in the evening sky, under a different map. Jupiter returns behind the Moon on 6 October for observers who miss the daytime 8 September pass or who want the disk to vanish in a darker field.

The practical instruction is short. Find the crescent first. Jupiter is the steady point next to it. If the sky is still dark, watch the planet wink out along the dark lunar limb. If the Sun is up, treat it as a binocular object and accept that the minute of cover will look like a pause rather than a blackout.