The September 2025 sky: eclipses, oppositions and comets

September 2025 promises to be rich in captivating astronomical events. Between eclipses, planetary oppositions and comet flybys, night-sky enthusiasts will have many opportunities to observe remarkable phenomena.

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Total Lunar Eclipse on September 7, 2025

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On September 7, a total lunar eclipse will coincide with the Harvest Moon. This phenomenon will be widely visible from the eastern hemisphere, notably in Africa, Europe, Asia and Oceania. In Metropolitan France, the eclipse will be partially visible at Moonrise. The key times in Coordinated Universal Time (UTC) are as follows:

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• \nPenumbral entry : 15:28
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• \nUmbra entry : 16:27
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• \nStart of totality : 17:31
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• \nMaximum of the eclipse : 18:12
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• \nEnd of totality : 18:53
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• \nUmbra exit : 19:57
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• \nPenumbral exit : 20:55
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During the total phase, the Moon will take on a reddish hue, often called the \"Blood Moon\", due to the scattering of sunlight by the Earth's atmosphere. Observing this phenomenon is eye-safe and requires no special equipment.

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Partial Solar Eclipse on September 21, 2025

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On September 21, a partial solar eclipse will coincide with the autumn equinox. This event will be visible mainly from New Zealand and Antarctica, with solar occultation ranging between 58% and 73% depending on the region. In New Zealand, the eclipse will occur at sunrise, offering a striking view of a crescent Sun on the horizon.

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It is essential to remember that direct observation of the Sun, even partially eclipsed, can cause serious eye damage. It is therefore imperative to use certified glasses or filters to observe this phenomenon safely.

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Saturn Opposition

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In September 2025, Saturn will be in opposition, i.e., aligned with the Earth and the Sun. This configuration will make the planet particularly bright and visible all night. Saturn's rings will be well oriented, providing an ideal opportunity to observe it with binoculars or a telescope.

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Minor meteor showers

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Several minor meteor showers will be active in September:

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• \nAurigids : peak around September 1, with a low hourly rate. The meteors appear to originate from the Boötes constellation.
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• \nEpsilon Perseids : peak around September 9, also with a low hourly rate. The radiant lies in the Perseus constellation.
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• \nDiurnal Sextantids : active late September, these meteors are difficult to observe due to daytime activity.
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Although these showers are less intense than others, they still offer opportunities for observation, especially in dark and clear skies.

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Visible comets

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Two comets will attract attention in September:

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• \nInterstellar Comet 3I/ATLAS : discovered in July 2025, this interstellar comet will be visible until September before hiding behind the Sun.
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• \nComet C/2025 K1 (ATLAS) : it could reach magnitude 5 in early October, making its observation possible with the naked eye under a dark sky.
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Autumn Equinox

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September 22, 2025 will mark the autumn equinox, the moment when the length of day equals that of night. It is also the official start of autumn in the northern hemisphere.

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Constellations to observe

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The longer September nights offer an excellent opportunity to observe constellations such as Pegasus, Andromeda and the Autumn Triangle. These asterisms are especially visible early in the night.

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All in all, September 2025 promises to be a month rich in astronomical events. Whether you are an experienced observer or a beginner, don't hesitate to look up at the sky and enjoy these celestial spectacles.