This is another area where the comparison becomes complicated.
It would be tempting to say that sodium was automatically better for the night sky because it was orange.
The reality is more complicated.
The U.S. Department of Energy has examined the potential effects of converting high-pressure sodium lighting to broader-spectrum LED lighting on sky glow. The spectral characteristics of the new light source can affect the contribution to sky glow, but the overall result also depends on factors such as light output and how much light is directed upward.
In other words, colour is only part of the equation.
A badly designed lighting system can create unnecessary glare and light pollution regardless of the technology.
A well-designed LED system can use optics to direct light more precisely toward the areas that actually need illumination.
The Department of Energy notes that reducing total light output, eliminating uplight and using controls to dim lighting during low-use periods can all help address sky-glow concerns.
This is one of the hidden advantages of LEDs.
They can be controlled.
Wildlife adds another layer to the debate
Artificial light at night can affect wildlife, particularly nocturnal species.
The spectrum, intensity and timing of artificial light can all matter.
That is why some modern street-lighting policies increasingly consider environmental zones and warmer colour temperatures.
It does not mean that every warm LED is automatically harmless to wildlife.
Nor does it mean that every white LED is automatically damaging.
The actual environmental impact depends on the lighting design, intensity, spectrum, location and duration.
But warmer LEDs can be part of a strategy for reducing some of the potential effects associated with artificial lighting.
Dorset Council's policy specifically cites ecological and dark-sky considerations when explaining its move toward lower colour temperatures.
That is an important development because it demonstrates how street lighting has evolved from simply asking, "How bright should this road be?" to asking, "How should this environment be illuminated?"
The case for keeping some old lights
Despite the advantages of LED technology, there are situations where preserving older lighting can make sense.
Historic streets are an obvious example.
Street lighting is part of the visual character of a place, just like buildings, paving, signs and street furniture.
Historic England has highlighted the importance of street lighting in shaping the character of public spaces and notes that successful lighting schemes should take account of pedestrians, cyclists, architecture and the surrounding environment.
Cambridge provides an interesting historical example.
The city's Richardson Candle lamps were designed in the 1950s specifically to complement the historic character of the city centre. Historic England notes that the lamps became accepted as part of Cambridge's historic streetscape and that many survived despite pressure to replace them with more efficient modern systems.
That illustrates an important principle.
A street light is not always just a piece of electrical equipment.
Sometimes it is part of the identity of a place.
But nostalgia should not hide the weaknesses of sodium
It is easy to romanticise the past.
The old orange glow can look beautiful in photographs.
But living with older technology involved compromises.
Traditional lamps could consume considerably more electricity than modern LED systems.
They generally required more maintenance.
Their light distribution was less flexible.
Low-pressure sodium lighting provided extremely poor colour rendering.
And older systems did not offer the same level of digital control available with modern LED networks.
Local authorities have documented these practical differences repeatedly.
Suffolk's LED programme, for example, reports lower energy use, longer expected lifetimes, lower maintenance requirements and the ability to dim lighting through central management.
So the nostalgia is understandable.
But nostalgia is not the same thing as evidence that the older technology was technically superior.
And LEDs are not perfect either
The opposite mistake would be to assume that every LED installation is automatically good.
It isn't.