Milky Way only visible from 13% of Malta

The Milky Way is only visible in 12.8% of the entire surface area of the Maltese island, a study on light pollution based on scientific measurements shows.

The Milky Way is the galaxy that contains our Solar System, with the name describing the galaxy’s appearance from Earth: a hazy band of light seen in the night sky formed from stars that cannot be individually distinguished by the naked eye.

Before the advent of night-time lighting in the early 20th centuries, the Milky Way was a familiar sky feature for everyone.

When light from street-lamps, homes and illuminations is thrown up into the sky it bounces off particles and moisture droplets in the atmosphere and is scattered, resulting in artificial “sky glow” – one of the key factors contributing to light pollution. In this way spectacles like the Milky Way are obscured from view.

A global atlas of light pollution published three years ago had found that the Milky Way was no longer visible to more than one third of the world’s population. 60% of Europeans and almost 80% of North Americans cannot see the glowing band of our galaxy because of the effects of artificial lighting.

But the problem is even worse in Malta.

The study shows that 87% of the area of the Maltese Islands is affected by light pollution, with the percentage rising to 96% when Gozo is excluded.

In Malta, the worst affected town is Birkirkara, while in Gozo, Victoria and Għajnsielem are the two brightest zones. The least affected site in Malta is Rdum tal-Vigarju (cliffs off Baħrija, limits of Rabat), whereas in Gozo, the darkest region is Ta’ Ħarrux (off Dwejra).

The prevailing level of night sky brightness over the archipelago is also impinging upon Dark Sky Heritage Areas (DSHAs) in coastal zones in Gozo, which are specifically designated to allow the appreciation of the night sky and offer nocturnal animals a respite from artificial lighting.

One major mitigation measure suggested by the study is the proper regulation of outdoor lighting through the use of properly designed lighting fixtures that direct their light downward, and the adoption of luminaires that emit a warmer colour, which results in less scattering of light. In technical terms, these desirable fixtures are said to have a correlated colour temperature (CCT) less than 3000 K.

The study also identified the main permanent culprits of light pollution to be public monuments, churches, shops, showrooms, billboards, public squares, and playgrounds, all of which could employ smart lighting and be subject to specific curfews.

Existing road lighting in Gozo also utilises lighting fixtures that emit light with a CCT larger than 3000 K, with the same type of luminaires now being introduced in Malta. “We have found evidence that recently-installed, badly-implemented road lighting has resulted in excessive night sky brightening,” the study said.

Specifically, the study refers to LED fixtures containing excessive blue rich luminaries, installed along the 1.4km Mellieha bypass between 2018 and 2019, which had a considerable negative impact.

Furthermore, the study proposes the establishment of a perimeter and buffer zone that would help conserve DSHAs. A new Dark Sky Heritage Area is also proposed for Malta at Rdum Majjiesa (near the Majjistral Nature & History Park) and the area stretching between Rdum tal-Vigarju and Miġra l-Ferħa.

The landmark report, which includes the first ever map of the night sky brightness for the Maltese islands, was prepared by a team of scientists led by astrophysicist Joseph Caruana from the Department of Physics and the Institute of Space Sciences and Astronomy (ISSA) of the University of Malta.