Saturn with its rings nearly shut
Saturday 20 September 2025, into the small hours · Pisces
| Date | 2025-09-20/21 |
|---|---|
| Time (UTC) | 23:20 – 00:40 |
| Instrument | 200 mm f/6 Dobsonian |
| Eyepieces | 13 mm (92×), 9 mm (133×), 6 mm (200×) |
| Seeing | Antoniadi III, dropping to IV in spells |
| Transparency | 3/5, thin high cloud passing through |
| Sky | NELM about 5.6; no SQM reading (cloud) |
| Altitude | Saturn about 32° at its highest |
Opposition is tomorrow and the Moon is new, so the sky was as dark as it gets for a planet session, not that Saturn cares. The real problem from up here is height. It is just south of the equator this year, which puts it barely over 30° when it crosses the meridian, and everything I looked at tonight was through a fair depth of wobbling air.
The rings are the story this year. They went edge-on to us back in March, when Saturn was too close to the Sun to see, and they are still only a couple of degrees open. At 92× the planet looks as if someone has pushed a knitting needle through it: a bright, perfectly straight line sticking out either side of the globe, much longer than I expected, and fading to a point at each end. Without the usual broad ellipse, the globe looks smaller and oddly plain.
At 133×, in the steadier moments, a dusky equatorial belt and a darker cap around the pole on the side tipped towards us. Where the ring line crosses the disc I thought I could see a fine dark thread, but the seeing came and went too often for me to put money on it. 200× was too much for most of the session; I had perhaps five good seconds with it in fifteen minutes.
Titan was easy, well out from the planet and close to the line of the rings. Two or three much fainter moons were strung along that same line nearer in. With the rings this thin the moons all sit almost in a row, which is a nice effect. I didn’t try to name them.
Then a detour for Neptune, which is only a few degrees from Saturn this year. Starhopped from the chart in the pocket atlas, and at 133× one “star” in the right place refused to focus to a point — a tiny grey-blue disc. My first Neptune since 2019, and a far easier find with Saturn as a signpost.
Cloud thickened at 00:40 and I called it.
Next timeCome back in late November when the rings are at their thinnest again, and try to catch the shadow line in better seeing.