Portal:Astronomy/Events/September 2017
| 5 September | Neptune at opposition |
| 6 September, 04:35 | Moon occults Neptune |
| 6 September, 07:03 | Full moon |
| 12 September, 10:18 | Mercury at greatest western elongation |
| 13 September, 16:05 | Moon at perigee |
| 18 September, 00:55 | Moon occults Venus |
| 18 September, 19:42 | Moon occults Mars |
| 18 September, 23:21 | Moon occults Mercury |
| 20 September, 05:30 | New moon |
| 22 September, 20:02 | Earth southward equinox |
| 27 September, 06:51 | Moon at apogee |