| 1 September | Alpha Aurigids meteor shower |
| 3 September, 05:54 | Mercury at greatest western elongation (18.07º)(diameter = 7.3") |
| 3 September, 15:11 | Mercury in ascending node |
| 4 September, 17:39 | First quarter moon (diameter = 31.8') |
| 5 September, 07:34 | Moon in ascending node (furthest south (- 23.1))(diameter = 31.6') |
| 8 September, 06:48 | Mercury at perihelion (Perihermion)(diameter = 6.3") |
| 10 September, 11:42 | Comet Elenin at perihelion (distance = 0.4824 AU (72,170,000 km; 44,840,000 mi)) |
| 11 September, 16:20 | Moon greatest latitude north (4º 56') |
| 12 September, 08:24 | Venus heliacal rising east |
| 12 September, 09:27 | Full moon (diameter = 29.6') |
| 13 September, 14:28 | Mars northward equinox (Northern Autumn / Southern Spring) |
| 16 September | 1 Ceres at opposition |
| 16 September, 06:13 | Moon at apogee (406 065 km)(diameter = 29.4') |
| 16 September, 15:27 | Moon in conjunction with Jupiter |
| 16 September, 18:20 | Pluto at direct motion with Sun |
| 16 September, 11:59 | Pluto stationary in R.A. |
| 17 September, 07:53 | Mercury heliacal setting west |
| 18 September, 12:07 | Mercury greatest helio latitude north |
| 19 September, 19:38 | Moon in descending node (furthest north (22.9))(diameter = 30.2') |
| 20 September, 13:39 | Last quarter moon (diameter = 30.5') |
| 23 September, 09:05 | Earth southward equinox |
| 23 September, 06:24 | Moon in conjunction with Mars |
| 25 September, 16:23 | Moon greatest latitude south (4º 57') |
| 26 September, 00:15 | Uranus at opposition (diameter = 3.7") |
| 26 September, 12:52 | Saturn heliacal rising east |
| 27 September, 11:09 | New moon (diameter = 33.4') |
| 27 September, 09:07 | Moon in conjunction with Mercury |
| 28 September, 00:57 | Moon at perigee (357 566 km)(diameter = 33.4') with only 14 hours separating New Moon and perigee, expect unusually high tides. |
| 28 September | Pluto at eastern quadrature (diameter = 0.1") |
| 28 September, 09:36 | Moon in conjunction with Saturn |
| 28 September, 09:34 | Pluto in square with Sun |
| 28 September, 20:18 | Mercury at superior conjunction (diameter = 4.8")(1º21' N of Sun) |
| 30 September, 11:06 | Venus in conjunction with Saturn (Angle distance = 1°24' south of Saturn)(Elongation to sun = 11.8° East) |
