Light pollution is slowly limiting our ability to see the stars, Milky Way and beyond.
The Sydney Observatory and Melbourne Observatory had been in operation from the 1860s, but the growing light pollution of the cities slowly limited their ability to do observations, with Melbourne stopping altogether in the early 1900s.
Mt Stromlo Observatory, established in 1924, was chosen for its remote location and dark skies. However, by the 50s, despite a population of only 50,000 people or so, light pollution was becoming a problem.
This led to our establishment of Siding Spring Observatory, a 7-8 hour drive north of Canberra in the Warrumbungle National Park. With the exceptionally dark skies, the glow of Sydney can be seen on the horizon - despite being nearly 450km away.
Light pollution is becoming a bigger problem, but it is not about getting rid of lights - just being better and smarter about them.
Most of light pollution is due to inefficient or unnecessary lighting, and it can quickly add up to a big problem.
Depending on the city, streetlights contribute 20-50 per cent of the light pollution. Floodlights from ovals, and mostly, lights from homes and businesses also contribute.
Buildings at night that have lights on - that is not more efficient, it is a waste of energy and source of light pollution. New apartment buildings, like in Woden, that have every single light on despite no one having moved in for weeks - is wasting energy and contributing to light pollution.
We can be smarter - and Canberra is doing just that.
The ACT government, along with light operator Omexom, have been changing and improving streetlights to provide better lighting on the ground, and reduce light spill and pollution.
New or replaced lights have highly efficient LEDs that are flat, making it brighter on the streets, and darker in the skies. Since the program started in 2019, Canberra's skies have darkened by 30 per cent.
Whether for streetlights or at home, turning or reducing off unnecessary lights is key. At 6pm when people are coming home from work or activities, we need lights on, but do we at midnight?
At home, draw curtains or blinds so light does not spill out. Even better are sensory lights - so they turn on when we needed, and of when not.
In Canberra, the same streetlights are controllable and can do adaptive lighting. The lights can change how much light is output at certain times of the night, when few are around. Tuesday at 2am - there are not many people on the roads.
Through tests we have been doing, we have dimmed streetlights to 50 per cent, but due to their efficient LED and flat angle, the lighting on the ground is still sufficient. Yet, the dimming has reduced light spill. For every 10 per cent the lights are dimmed, light pollution is reduced by 5 per cent.
And across all the streetlights in Canberra - that is 2-3 gigawatts worth of energy saved per year.
Colour of light is another way to help. Instead of choosing the bluer, cool white LED, the warmer, orange white LEDs are much better - for our eyes, our sleep and, especially, our native animals.
Simple measures and new technology can turn back to the time - to see the Milky Way - and regain the night sky.
The ACT government, Omexom and Canberra are doing just that.
- Brad Tucker is an astrophysicist and cosmologist at Mount Stromlo Observatory, and the National Centre for the Public Awareness of Science at ANU.
