The Diamond Moon and Other Astronomical Events to See in September 2026
September will bring a close encounter between Venus and Spica, the Moon passing near the Pleiades, a modest meteor shower, Venus at its brightest, the equinox, Neptune at opposition, and the Harvest Moon.
After August's rich sky show, which featured two eclipses and the peak of the Perseid meteor shower, September still has plenty to offer for stargazers, even if some events are less well known.
The month opens on September 1 and 2 with a chance to see Venus near Spica, the brightest star in the constellation Virgo. Both objects will be visible to the naked eye. Venus will shine as a brilliant white dot, while Spica will appear as a much fainter bluish point. They will be about 1.5 degrees apart, which translates to roughly three full-moon widths between them.
On the night of September 3, the Moon will be close to the Pleiades, one of the most famous star clusters in the sky. The pair will be separated by about 1.1 degrees, and the Moon will be around 59% illuminated. The Pleiades, also known as the Seven Sisters or M45, are located in Taurus and contain hundreds of young stars, though only six or seven are typically visible without binoculars. The Moon's proximity will make them easier to spot, as they will look like small diamonds beside it. Another similar encounter will happen on September 30, with the two objects just one degree apart.
A modest meteor shower, the Epsilon Perseids, will peak on September 9 and 10, producing up to eight meteors per hour. While fewer than August's Perseids, this shower has an advantage: its peak occurs only two days before the new moon, ensuring dark skies. Viewing conditions should be especially good from the Northern Hemisphere, and observers are advised to find a location free from light pollution.
Venus will reach its brightest point of the year on September 22, with an apparent magnitude of about -4.8. For comparison, the full moon is -12.7, and Sirius, the brightest star in the night sky, is only -1.46. Look for Venus after sunset near the western horizon; the best views will be from the Southern Hemisphere.
The September equinox takes place on September 23, when the Sun crosses the equator moving south. This marks the astronomical beginning of autumn in the Northern Hemisphere and spring in the Southern Hemisphere.
On September 26, Neptune will reach opposition, meaning Earth will be roughly between the Sun and Neptune. This puts Neptune at one of its closest distances to Earth for the year and visible for much of the night. The planet is too faint for the naked eye, so a telescope is required. It will appear as a tiny bluish disk in the constellation Pisces.
The month ends with the Harvest Moon on September 26. This is the traditional name for the full moon closest to the September equinox. It does not mean the Moon changes color or size; rather, the name is linked to the harvest season in the Northern Hemisphere.
Whether you have a telescope or just your eyes, September offers several chances to enjoy the night sky.
