Roseville Stargazing & Astronomy Report

Key Sky Quality Metrics

SQM (mag/arcsec²)

18.25

Bortle class

Class 8 (Class 8)

Darkness Quotient

25%

Dataset

March 2026

City sky

Roseville: The Practical Verdict

Roseville is a fast-growing suburban city in northern California, part of the greater Sacramento area and known for its broad spread of residential districts, retail development and commuter character.

The city generally experiences High Light Pollution, with a Darkness Quotient of 25% — making it brighter than many smaller inland towns, though not quite as overwhelmed as the largest urban cores.

For practical observing from within the city, the most realistic targets are the Moon, planets, double stars and the brightest open clusters. A few showpiece objects such as Orion Nebula and the brightest globular clusters can still be attempted, but faint galaxies, dim nebulae and the Milky Way are largely washed out by the urban glow.

Meaningfully darker skies are not close at hand, and a proper improvement takes a fairly substantial drive. The nearest reasonable step up is about 85 kilometres to the north-north-west, near Near Butte County, California, where conditions reach Bortle 4.

The map shows Roseville embedded in a broad, intense pool of urban light, with the brightest colours concentrated across the built-up core and blending into the larger metropolitan glow nearby. Rather than an isolated bright patch, the city sits within a connected band of illumination, so the sky brightness spreads well beyond the immediate centre.

The strongest darkening appears away from the main urban mass, especially towards the north, north-east and east, where the colours transition from yellow and green into blue, grey and eventually near-black. By contrast, the south and south-west remain tied to a much larger luminous zone, suggesting that those horizons stay heavily affected by distant city glow even after leaving Roseville itself.

There are also smaller bright islands scattered across the wider map, showing that outlying settlements interrupt the darker countryside in several directions. Even so, the overall pattern makes it clear that the cleaner escape routes are generally away from the densest urban corridor, with the most promising darker regions lying inland and to the north-eastern half of the compass.

How the sky looks overhead

Looking straight up from Roseville, the sky remains strongly affected by urban lighting. With an overhead reading of 18.25 SQM, the zenith sits in a bright city-sky regime where the background never becomes truly dark.

That usually means the familiar brighter constellations are still easy enough to trace, but the sky lacks richness and depth. Many of the fainter stars that normally fill in patterns are missing, and the Milky Way is generally lost from view.

For casual observing this is still enough for the Moon, planets and a handful of standout objects. For deep-sky work, though, the overhead brightness quickly becomes the main limiting factor.

• Near Modoc County, California

  Direction

  SE

  Distance (km)

  275

  SQM

  21.45

  Bortle

  3

  Milky Way visible, broadband DSO imaging

• Near Lake County, California

  Direction

  W

  Distance (km)

  119.7

  SQM

  21.18

  Bortle

  4

  Bright nebulae, galaxies, narrowband imaging

• Near Butte County, California

  Direction

  NNW

  Distance (km)

  86

  SQM

  21.04

  Bortle

  4

  Bright nebulae, galaxies, narrowband imaging

Historical Light Pollution Trends

Roseville's long-term trend is fairly steady, but it points in the wrong direction for stargazers. The average reading across the record is 18.38 SQM, while the latest figure is 18.25 SQM, which is also the dimmest result in the series.

Since 2012, the change has been modest rather than dramatic, slipping from 18.48 SQM to 18.25 SQM across 76 datasets. That suggests a slow brightening of the night sky over time, consistent with gradual urban growth rather than a sudden shift.

In practical terms, observers in Roseville are dealing with a sky that has become a little more washed out over the years. The difference is not huge night-to-night, but over the long run it makes faint targets progressively harder to pick out from the city.