San Anselmo, CA — light pollution & stargazing
San Anselmo, California has a light-pollution rating of about Bortle 5 — a suburban sky (fair — suburban) — measured from VIIRS 2024 satellite night-lights at 7.6 nW/cm²/sr at the town center. Only faint traces of the Milky Way survive, and only near the zenith on the clearest nights. The Andromeda Galaxy is a challenge with the naked eye; a telescope still shows plenty. The nearest genuinely darker skies are around Tamalpais-Homestead Valley, CA (about 7 mi away, Bortle 4). Tonight's Moon phase, cloud cover, and aurora odds load live below, computed in your browser. This is a satellite upward-radiance proxy for planning, not a survey-grade sky-brightness measurement.
Stargazing in San Anselmo tonight
- Estimated Bortle class
- 5 of 9
- VIIRS radiance (town center)
- 7.6 nW/cm²/sr
- Naked-eye limiting mag.
- 5.6–6.0
- Milky Way
- faint, only near the zenith
Suburban sky. A satellite upward-radiance proxy for planning — not a survey-grade sky-brightness reading.
What you can see from San Anselmo
Only faint traces of the Milky Way survive, and only near the zenith on the clearest nights. The Andromeda Galaxy is a challenge with the naked eye; a telescope still shows plenty.
Darker skies within reach
The nearest town in each darker class — your ladder from San Anselmo's sky toward truly dark skies.
| Town | State | Bortle | Sky | Drive |
|---|---|---|---|---|
| Tamalpais-Homestead Valley | CA | 4 | Rural / suburban transition | 7 mi |
Frequently asked questions
- Can you see the Milky Way from San Anselmo, CA?
- Barely. At about Bortle 5 the Milky Way is faint and only shows near the zenith on the clearest, moonless nights. For a clear view, head toward Tamalpais-Homestead Valley, CA (~7 mi).
- How dark is the sky in San Anselmo?
- San Anselmo rates a suburban sky — about Bortle 5, with a naked-eye limiting magnitude around 5.6–6.0. That comes from a VIIRS satellite night-lights reading of 7.6 nW/cm²/sr at the town center. It is a satellite proxy for planning, not a survey-grade measurement.
- Where is the nearest dark sky to San Anselmo?
- The nearest town with genuinely darker skies is Tamalpais-Homestead Valley, CA — about 7 mi away at roughly Bortle 4. See the "darker skies within reach" list on this page for more options.
- Can I see the aurora from San Anselmo tonight?
- It depends on tonight's space weather. The live panel on this page reads the current NOAA aurora forecast for your latitude, along with cloud cover and the Moon — most U.S. locations only see aurora during strong geomagnetic storms.
The darkness rating is measured from VIIRS satellite night-lights at the town center and is a proxy for planning, not a survey-grade sky-brightness measurement — and the darkest skies are usually a short drive out of any town. Tonight's Moon, cloud, and aurora figures are live third-party forecasts that can change. See the methodology for sources and limits.
More in California
See every town's darkness rating in California, learn to read the Bortle scale, or check tonight's Moon phase.