The Luxembourg night sky in September

The Pleiades are an open cluster of young, blue stars about 440 light-years away in the constellation Taurus. Known since ancient times across many cultures, they are easily visible to the naked eye, even from the city.

At roughly 100-million-years-old, the Pleiades are still a relatively young cluster, loosely held together by gravity. In the distant future, the stars are expected to slowly drift apart, blending into the wider population of the Milky Way.

Across many cultures, the Pleiades had both practical and symbolic roles: they marked seasonal change, often tied to agriculture, and their September pre-dawn visibility signalled preparations for autumn.

They are also central to many stories spanning millennia. In Greek mythology, they were the Seven Sisters (Maia, Electra, Taygete, Alcyone, Celaeno, Sterope, and Merope), daughters of the Titan Atlas and the sea-nymph Pleione. According to legend, the hunter Orion became infatuated with them and pursued them relentlessly across the Earth. To protect the sisters, Zeus placed them in the sky, where Orion still appears to follow, his constellation rising behind theirs.

In Japan they are 'Subaru', meaning "to unite", later adopted by the car manufacturer as its logo, which features a stylised version of the cluster. For the Māori of New Zealand they are 'Matariki', whose appearance heralds the new year.

From Luxembourg, the Pleiades rise in the northeast around midnight in early September and climb higher as the night progresses. By about 1am they are well placed and easy to pick out even under city lights. To locate them, find the bright orange star Aldebaran in Taurus, then shift your gaze slightly to the right to spot the tight cluster.

To the naked eye, most observers can spot six or seven stars forming a small, curved pattern that resembles a question mark. Binoculars reveal several dozen more crowded together, and long-exposure photography shows the faint blue reflection nebulae created as starlight scatters off surrounding interstellar dust.

Main events in September

7 September – Full Moon and total lunar eclipse

At moonrise, totality is already underway. Maximum phase is at 8.11pm and totality ends at 8.52pm, with the penumbral shade fading by 10.55pm. The Moon is extremely low in the east-southeast at first, so pick a site with an unobstructed horizon.

21 September – Saturn at opposition

Save this date, as on this night the ringed planet is at its brightest and largest for 2025. Saturn will be opposite the Sun and visible all night among the stars of Pisces, reaching its highest point around midnight. The rings are near edge-on this year, so their tilt is modest in small telescopes.

22 September – Autumn equinox

The equinox falls around 20.19pm. From that point, nights lengthen quickly, bringing longer, darker observing windows through autumn.

Visible planets

Saturn

Visible all night throughout the month and highest around midnight in Pisces. A small telescope shows the ring system while with a little more aperture you can pick out Titan and several other moons.

Jupiter

A pre-dawn target in Gemini, rising in the early hours and best before sunrise when it's higher and the air is steadier. Binoculars show the four Galilean moons while a small telescope reveals the main cloud bands and, when it's on the disc, the Great Red Spot.

Venus

Our sister planet shines bright before sunrise as the Morning Star. On 19 September, the Moon occults Venus in daylight for parts of Europe - an event for experienced observers only, with strict solar-safety precautions.

In the early evening, the Summer Triangle (Vega, Deneb, and Altair) still dominates, with Cygnus, Lyra, and Aquila well placed. As night advances, the autumn sky takes over: Pegasus climbs (look for the Great Square), Andromeda brings the Andromeda Galaxy (M31) into view, and Pisces stretches across the eastern sky with its fainter stars becoming easier to trace as darkness deepens.

September's sky is a handover: summer patterns slide west, Saturn peaks, and the Pleiades return to late-night view. Track these shifts and you'll have a clear read on the season and a solid plan for the richer, longer nights to come.

At a glance – Luxembourg sky in September 2025

Best time to observe

Pleiades from late night (around midnight) into pre-dawn. Saturn visible all night near its 21 September opposition. Jupiter best before dawn.

Main events

7 September – Full Moon & total lunar eclipse (visible from Luxembourg after moonrise)
21 September – Saturn at opposition in Pisces
22 September – September equinox, 8.19pm
 
Constellations

Summer Triangle still overhead in the evening.
Autumn constellations Pegasus and Andromeda rising.
The Pleiades climbing from the northeast from late night into pre-dawn.