Lighting the way to darker skies

Dr Joseph Caruana

As the sun sets and the sky darkens, a black velvety curtain adorned with flecks of twinkling lights is drawn across the heavens, and a milky white band of fuzzy glow stretches majestically overhead. Unfortunately, this experience is nowadays denied to us thanks to artificial lighting. The sky is often left awash in a cold, jarring glow, making Malta one of only five countries whose citizens are denied the possibility of observing the Milky Way from their home.

A few select coastal sites remain where we can see the Milky Way. But even those are under continuous threat. In 2002 the Malta Environment and Planning Authority designated a number of sites in Gozo and Comino as Dark Sky Heritage Areas, stating that ‘reflective signs shall be employed to guide driving at night, whilst the installation of lighting which is not related to aerial or maritime navigation, shall be strongly discouraged.’ Since then, light pollution has still been increasing and is seriously impinging upon these areas.

To some, the ability to appreciate and study the night sky might be less of a priority, but light pollution affects our lives in many more ways. Our night-time environment is fast becoming a vista of blindingly cold light, and we need to act now to reverse this. Badly designed lighting can result in glare, which is especially dangerous while driving. Light trespassing into people’s homes creates a myriad of problems, ranging from mild discomfort to serious sleep disruption. Studies have linked bright LED lighting with adverse health effects, as it can interfere with our circadian (daily) rhythm. Light pollution also disturbs wildlife. For example, conserving colonies of birds that make their home at the cliffs of Dwejra, like Scopoli’s Shearwater and Yelkouan Shearwater, depends heavily on our efforts to curb light pollution.

The solution is not as drastic as switching off all our lights, but adopting full cutoff lighting in streets to illuminate the ground without spilling light everywhere else.

Luckily, light pollution is a reversible problem. Authorities can choose to bring about positive change, sometimes requiring little effort. Do we really need our public monuments, churches, building facades, and playing fields to be illuminated all night long, oftentimes with skyward-pointing floodlighting? When planning new lights for a road or a public space, should we not consider the impact the proposed lighting will have on the surrounding community and environment?

Conservation of our natural environment is not diametrically opposed to human activity and business interests. Other countries have long recognised the night sky’s potential for eco-tourism.

The Department of Physics (Faculty of Science, University of Malta [UM]) and Institute of Space Sciences and Astronomy (UM) are currently embarking on a new study of our islands’ night sky’s brightness. Interested parties, authorities, and non-governmental organisations alike are most welcome and encouraged to get in touch. It is only through awareness, dedication, and proper coordination that we can help ensure that future generations can still enjoy the peaceful beauty of the Maltese night sky.

Further reading: Falchi et al., ‘The new world atlas of artificial night sky brightness’, Science Advances, vol. 2, no. 6, 2016, e1600377

Author: Dr Joseph Caruana

Understanding gravity to understand the universe

For a primate species clinging to a speck of dust in an incomprehensibly vast universe, curiosity has seen humans discover a great deal about how it all works. However, there are still mysteries that the cosmos is reluctant to relinquish, one of which is gravity. The most accurate theory describing gravitational attraction is general relativity, developed by Albert Einstein in 1915. Unlike Isaac Newton, Einstein did not describe gravity as a force, but rather a manifestation of the curvature of spacetime, thought of as a stretchable and squeezable fabric that is distorted by matter. However, his theory does not fully explain phenomena such as the accelerating expansion of the Universe and inconsistent orbital speeds of stars within galaxies.

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Extreme stars unlock gravitational secrets

Our understanding of gravity has changed over the years and will likely continue to as researchers arm themselves with new ideas tested by increasingly sophisticated technology. Dr Jackson Levi Said, Mark Pace, and Filippos Nachmias (University of Malta [UoM]) tell THINK more about their mission to unlock gravity’s secrets from neutron stars.

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The Universe is Strange and Beautiful

Super dense stars shooting jets of radiation, black holes swallowing up stars, supernovae, and unexplained bursts of gamma rays. These are all examples of a ‘transient event’, an incident that lasts at most a few days. They are amongst the most powerful and mysterious phenomena in the universe, but from Earth they appear as ‘blips’ on our telescopes, making them very difficult to study.

Byron Magri (from the Astronomy, Astrophysics and Cosmology Research Programme (AACRP) and supervised by Dr Kris Zarb Adami) is shedding light on how to detect these fleeting wonders. His work is focused on fast transients that only last a few seconds.

Earth-based radio telescopes (aka antennae) are as big as they can get. The problem is that astronomers need bigger telescopes to produce higher resolution images to reveal finer details about these objects and find new discoveries. The solution is to use arrays of smaller radio antennae that are linked together. Interferometry is used to combine the data.

The technique uses enormous computing power to measure the radio waves phase delays being gathered by the individual antennae. Interferometry then overlaps and superimposes them to produce a stronger signal and an image with a much higher resolution.

For this technique to work, it must carry out all the calculations as the event is happening. The computer algorithm interpreting the data must also filter out all the noise due to the Earth’s atmosphere. To top it all off, the transient events need to be singled out.

To meet these challenges Magri used GPUs (Graphic Processing Units), which are usually used by hardcore gamers to power the most advanced graphics. The design of GPUs lends itself well to heavy numerical processing. Magri wrote an algorithm that acts as an inferometer on a GPU and he is testing it on data from the BEST-2 radio telescope array in Medicina, Italy.

Developing these algorithms is important to make future arrays larger. The next generation interferometer, the Square Kilometer Array, will have hundreds of antennae, meaning that information extraction will need to be extremely efficient and rapid. These algorithms are a keystone to maximise the potential of a €1.5 billion telescope to find more amazing phenomena in our universe.


This research was performed as part of an M.Phil. (Melit.) in Physics at the Faculty of Science. For more about Malta’s role in the Square Kilometre Array see pg. 14, Issue 02 of  Think magazine (


Malta is involved in the creation of the largest telescope ever built, the Square Kilometre Array. The telescope will be composed of 10 million antennas, process petaflops of data per day, and cost 1.5 billion euros. When built the array will peer deep into space to see how the first stars were born and attempt to solve the riddle of our origin. Words by Dr Kris Zarb Adami and Dr John Abela.

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