621.

The Moon at apogee The Moon recedes to its orbit's furthest point from the Earth, making it appear fractionally smaller than at other times of the month. Tue, 12 Sep 2023 at 11:42 EDT (309 days ago) in Leo

622.

Conjunction of the Moon and Mercury The Moon and Mercury share the same right ascension, at a separation of 5°59'. Wed, 13 Sep 2023 at 13:41 EDT (308 days ago) in Leo

623.

New Moon The Moon disappears into the Sun's glare for a few days. Thu, 14 Sep 2023 at 21:41 EDT (307 days ago) in Leo

624.

Conjunction of the Moon and Mars The Moon and Mars share the same right ascension, at a separation of 39'. Sat, 16 Sep 2023 at 15:20 EDT (305 days ago) in Virgo

625.

Comet C/2023 P1 (Nishimura) passes perihelion Comet C/2023 P1 (Nishimura) makes its closest approach to the Sun. Sun, 17 Sep 2023 (304 days ago) in Virgo

626.

The Moon at perihelion The Moon passes its orbit's closest point to the Sun, which happens each month around the time of new moon. Sun, 17 Sep 2023 at 13:19 EDT (304 days ago) in Virgo

627.

Venus at greatest brightness Venus reaches its greatest brightness in the dawn sky. Mon, 18 Sep 2023 at 08:09 EDT (303 days ago) in Cancer

628.

Neptune at opposition Neptune lies in the opposite direction to the Sun in the sky, making it optimally positioned to be observable for much of the night. Tue, 19 Sep 2023 at 07:09 EDT (302 days ago) in Pisces

629.

Lunar occultation of Antares The Moon will pass in front of Antares (Alpha Scorpii), creating a lunar occultation visible from Japan, Russia, Guam and Northern Mariana Islands. Thu, 21 Sep 2023 at 04:47 EDT (300 days ago) in Scorpius

630.

Mercury at greatest elongation west Mercury is bright and well placed in the dawn sky. Fri, 22 Sep 2023 at 07:27 EDT (299 days ago) in Leo

631.

Mercury at dichotomy Mercury reaches half phase in the dawn sky. Fri, 22 Sep 2023 at 15:26 EDT (299 days ago) in Leo

632.

Moon at First Quarter The Moon reaches first quarter phase – appearing high in the sky at sunset and setting in the west at around midnight. Fri, 22 Sep 2023 at 15:32 EDT (299 days ago) in Sagittarius

633.

September equinox Day and night have equal length, marking the beginning of autumn in the northern hemisphere and spring in the southern hemisphere. Sat, 23 Sep 2023 at 02:46 EDT (298 days ago) in Virgo

634.

Mercury at highest altitude in morning sky Mercury is bright and well placed in the dawn sky. Sat, 23 Sep 2023 (298 days ago) in Leo

635.

Mercury at perihelion Mercury passes its orbit's closest point to the Sun. Sat, 23 Sep 2023 at 14:06 EDT (298 days ago) in Leo

636.

NGC 55 is well placed NGC 55 (mag 8.2), a barred irregular galaxy in Sculptor culminates at around midnight local time. Mon, 25 Sep 2023 (296 days ago) in Sculptor

637.

Conjunction of the Moon and Saturn The Moon and Saturn share the same right ascension, at a separation of 2°38'. Tue, 26 Sep 2023 at 21:29 EDT (295 days ago) in Aquarius

638.

Close approach of the Moon and Saturn The Moon and Saturn pass close to each other. Tue, 26 Sep 2023 at 23:12 EDT (295 days ago) in Aquarius

639.

The Moon at aphelion The Moon recedes to its orbit's furthest point from the Sun, which happens each month around the time of full moon. Wed, 27 Sep 2023 at 02:44 EDT (294 days ago) in Aquarius

640.

47 Tuc is well placed The second brightest globular cluster in the sky, 47 Tuc (NGC 104; mag 4.0), in Tucana culminates at around midnight local time. Wed, 27 Sep 2023 (294 days ago) in Tucana