Stars, planets, and moon phases this month.

Earth and the Sun

September, aside from historical events, is associated with children and students returning to school, and in the sky, it is above all a period of balance between the length of day and night. The nights are already getting longer and are often cloudless, making them perfect for astronomical observations. We’ll be able to observe a few interesting phenomena in the September sky. To do this, let’s try to find time and places away from city lights so that, even for a moment, we can gaze at the starry sky and admire the Milky Way—even with the naked eye—as it stretches across the entire sky, from the northern to the southern horizon.

We enjoyed this year’s summer as much as possible, while the Sun, in its journey along the ecliptic, steadily moved toward the celestial equator, causing its declination—that is, its altitude above the equator—to decrease, and consequently, the days to grow shorter and shorter. This year, on September 23 at 2:06 a.m., the Sun will reach the celestial equator, after which it will ‘move’ from the northern hemisphere of the sky to the southern, thereby marking the beginning of astronomical autumn in our region.

In Kraków, on September 1, Sun rises at 5:55 a.m. and sets at 7:23 p.m., while on September 30, it rises at 6:39 a.m. and sets at 6:20 p.m.; this means that over this month, the day in Lesser Poland will be 107 minutes shorter! However, the phenomenon of refraction in the Earth’s atmosphere causes us to see all objects in the sky slightly higher than they actually are, so the observable alignment of day and night will not be visible until around September 25.

The Moon

Dark, nearly moonless nights, ideal for astronomical observations, will occur during the second and third weeks of September. The Moon will begin this month moving toward the Last Quarter, which will occur on September 4 at 9:51 a.m.; the New Moon will be on September 11 at 5:27 a.m.; the First Quarter on September 18 at 10:44 p.m.; and the Full Moon on September 26 at 6:49 p.m.

The Moon will reach its perigee (closest to Earth) on September 6 at 10:00 p.m., and at apogee (farthest from us) on September 19 at 5:00 a.m. This month, Moon will approach Mars on September 6, Jupiter on September 8, and Venus on September 14, but these events will not be visible from our location.

Planets

Mercury can be observed very low on the western horizon from the first week of September through the end of October. Venus, on the other hand, acts as the Evening Star, setting lower and lower each night—after the Sun. Mars is currently in the constellation Taurus and will move into Gemini by the end of the month. We can observe it during the second half of the night. In the latter half of the night, in Cancer, we can also spot Jupiter with its magnificent cluster of Galilean moons.

In Pisces, gaseous Saturn strides across the sky with its largest moon, Titan, which we can admire using a small telescope. Since it will be in opposition to the Sun on October 4, we can observe it all night long. Uranus will be visible after midnight in Taurus, while Neptune remains visible all night in Pisces, even though you’ll need at least a small telescope to observe them.

Evening sky as seen on September 15, 2026, from Kraków (Stellarium).

Adam Michalec, Elżbieta Kuligowska