401.

September equinox Day and night have equal length, marking the beginning of autumn in the northern hemisphere and spring in the southern hemisphere. Sat, 22 Sep 2018 at 21:48 EDT (2,107 days ago) in Virgo

402.

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. Fri, 21 Sep 2018 at 20:56 EDT (2,108 days ago) in Capricornus

403.

Mercury at superior solar conjunction Mercury passes around the far side of the Sun. Thu, 20 Sep 2018 at 22:01 EDT (2,109 days ago) in Virgo

404.

Conjunction of the Moon and Mars The Moon and Mars share the same right ascension, at a separation of 4°46'. Thu, 20 Sep 2018 at 02:40 EDT (2,109 days ago) in Capricornus

405.

Close approach of the Moon and Mars The Moon and Mars pass close to each other. Thu, 20 Sep 2018 at 01:19 EDT (2,109 days ago) in Capricornus

406.

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. Wed, 19 Sep 2018 at 20:53 EDT (2,110 days ago) in Capricornus

407.

Asteroid 30 Urania at opposition Asteroid 30 Urania makes closest approach to the Earth. Wed, 19 Sep 2018 at 07:58 EDT (2,110 days ago) in Pisces

408.

Close approach of the Moon and Saturn The Moon and Saturn pass close to each other. Mon, 17 Sep 2018 at 12:43 EDT (2,112 days ago) in Sagittarius

409.

Conjunction of the Moon and Saturn The Moon and Saturn share the same right ascension, at a separation of 2°03'. Mon, 17 Sep 2018 at 12:29 EDT (2,112 days ago) in Sagittarius

410.

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. Sun, 16 Sep 2018 at 19:15 EDT (2,113 days ago) in Ophiuchus

411.

Mars at perihelion Mars passes its orbit's closest point to the Sun. Sun, 16 Sep 2018 at 08:53 EDT (2,113 days ago) in Capricornus

412.

Close approach of the Moon and Jupiter The Moon and Jupiter pass close to each other. Fri, 14 Sep 2018 at 00:43 EDT (2,115 days ago) in Libra

413.

Conjunction of the Moon and Jupiter The Moon and Jupiter share the same right ascension, at a separation of 4°22'. Thu, 13 Sep 2018 at 22:19 EDT (2,116 days ago) in Libra

414.

Comet 21P/Giacobini-Zinner passes perihelion Comet 21P/Giacobini-Zinner makes its closest approach to the Sun. Thu, 13 Sep 2018 (2,116 days ago) in Auriga

415.

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. Tue, 11 Sep 2018 at 22:12 EDT (2,118 days ago) in Virgo

416.

New Moon The Moon disappears into the Sun's glare for a few days. Sun, 09 Sep 2018 at 14:02 EDT (2,120 days ago) in Leo

417.

September ε-Perseid meteor shower 2018 The September ε-Perseid meteor shower reaches its peak. Sun, 09 Sep 2018 (2,120 days ago) in Perseus

418.

The Moon at perigee The Moon makes its monthly closest approach to the Earth, making it appear fractionally larger than at other times of the month. Fri, 07 Sep 2018 at 21:19 EDT (2,122 days ago) in Leo

419.

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. Fri, 07 Sep 2018 at 14:18 EDT (2,122 days ago) in Aquarius

420.

Close approach of the Moon and M44 The Moon and M44 pass close to each other. Thu, 06 Sep 2018 at 22:26 EDT (2,123 days ago) in Cancer