Astronomical Events: September 2026

Sept. 1

Aurigid meteor shower peak
The Aurigid meteor shower reaches peak activity, producing meteors that appear to radiate from the constellation Auriga.

Sept. 3

Close approach of the Moon and M45 (Pleiades)
The Moon passes near the Pleiades star cluster in the night sky.

Sept. 4

Moon at last quarter
Half of the Moon's surface appears illuminated as it enters its last quarter phase.

Venus at aphelion
Venus reaches the farthest point from the Sun in its orbit.

Sept. 5

Lunar occultation of Beta Tauri
The Moon passes directly in front of Beta Tauri, also known as Elnath, temporarily obscuring the star from view in parts of the world.

Sept. 6

Conjunction of the Moon and Mars
Mars appears near the Moon along the same celestial longitude.

Close approach of the Moon and Mars
The Moon passes near Mars in the sky.

Moon at perigee
The Moon reaches its closest point to Earth and appears slightly larger than average.

Sept. 8

Close approach of the Moon and M44 (Beehive Cluster)
The Moon passes near the Beehive Cluster in the constellation Cancer.

Conjunction of the Moon and Jupiter
Jupiter appears near the Moon along the same celestial longitude.

Close approach of the Moon and Jupiter
The Moon passes near Jupiter in the sky.

Lunar occultation of Jupiter
The Moon passes directly in front of Jupiter, temporarily obscuring the planet from view in parts of North America and other regions.

Sept. 9

September Epsilon Perseid meteor shower peak
The September Epsilon Perseids reach peak activity, producing a modest number of meteors that appear to radiate from the constellation Perseus.

Sept. 10

Uranus enters retrograde motion
Uranus begins appearing to move westward against the background stars due to the relative motions of Earth and Uranus around the Sun.

Sept. 11

New Moon
The Moon is positioned between Earth and the Sun and is not visible in the night sky.

Sept. 12

Conjunction of the Moon and Mercury
Mercury appears near the Moon along the same celestial longitude.

Sept. 13

Moon at perihelion
The Moon reaches the point in its orbit closest to the Sun.

Sept. 14

Conjunction of the Moon and Venus
Venus appears near the Moon along the same celestial longitude.

Close approach of the Moon and Venus
The Moon passes near Venus in the sky.

Lunar occultation of Venus
The Moon passes directly in front of Venus, temporarily obscuring the planet from view in parts of Africa, Asia and Europe.

Sept. 17

Lunar occultation of Antares
The Moon passes directly in front of Antares, the bright red star in Scorpius, temporarily obscuring it from view in parts of the Southern Hemisphere.

Sept. 18

Moon at first quarter
Half of the Moon appears illuminated as it reaches first quarter.

Sept. 19

Moon at apogee
The Moon reaches its farthest point from Earth and appears slightly smaller than average.

Sept. 20

Lunar occultation of Sigma Sagittarii
The Moon passes directly in front of Sigma Sagittarii, also known as Nunki, temporarily obscuring the star from view in parts of the South Pacific.

Sept. 22

Venus at greatest brightness
Venus reaches its greatest brightness in the evening sky, making it especially prominent after sunset.

Sept. 23

September equinox
The September equinox marks the beginning of astronomical fall in the Northern Hemisphere and astronomical spring in the Southern Hemisphere. Day and night are nearly equal in length around the equinox.

Moon at aphelion
The Moon reaches the farthest point from the Sun in its orbit.

Sept. 25

NGC 55 well placed
NGC 55, a barred irregular galaxy in the constellation Sculptor, becomes favorably positioned for observation.

Sept. 26

Neptune at opposition
Neptune reaches opposition, placing it opposite the Sun in Earth's sky and making this one of the best times of the year to observe the planet.

Full Moon
September's Full Moon reaches peak illumination and remains visible for much of the night.

Sept. 27

Close approach of the Moon and Saturn
The Moon passes near Saturn in the night sky.

Mercury at aphelion
Mercury reaches the farthest point from the Sun in its orbit.

Conjunction of the Moon and Saturn
Saturn appears near the Moon along the same celestial longitude.

Daytime Sextantid meteor shower peak
The Daytime Sextantids reach peak activity. Most of the shower occurs during daylight, making its meteors difficult to observe visually.

47 Tucanae well placed
47 Tucanae, one of the brightest globular clusters in the night sky, becomes favorably positioned for observation.

Sept. 30

Asteroid 192 Nausikaa at opposition
Asteroid 192 Nausikaa reaches opposition, making it favorably positioned for observation from Earth.

Close approach of the Moon and M45 (Pleiades)
The Moon passes near the Pleiades star cluster in the night sky.

—Compiled by Mykel Del Angel