The Milky Way was visible from central Paris only 100 years ago. Here’s how to get back the night sky

For more than 100,000 years since humans have been on Earth, we have looked at night and seen the stars and our celestial home, the Milky Way. Cultures around the world have stories and records covering this majestic, majestic sight.

however, Almost 3 billion people When they look up at the night sky they can no longer see the Milky Way. In turn, their connection to the universe – and the sense of deep time it represents – is severed.

Light pollution is responsible for this loss. But this is a relatively recent problem. In fact, nearly a century ago, the skies above some of the world’s largest cities were dark enough to see the Milky Way’s gas clouds and infinite points of light shining in the far reaches of the universe.

So, what happened? And what can we do to make the darkness reign again?

A long legacy of lighting

Light pollution is light or glow that shines upward in the sky.

Lights help you see the ground. But for a variety of reasons — from poor design to inefficient lighting and unnecessary lighting — light pollution can grow rapidly in an area.

Light pollution also comes from various sources.

Much of this comes from streetlights. They contribute 20% to 50% Light pollution in a city. But they are not the only evidence. Others include floodlights from ovals, billboards and lighting in our homes – inside and out.

At night, when all the lights are on inside a large building or an empty apartment building, without shades or covers, it is light pollution.

A new problem

For thousands of years, humans have made detailed observations of the Milky Way — including the dark patches that block the starlight from behind.

For example, Aboriginal and Torres Strait Islander peoples in Australia have complete records. The great celestial emu. It is formed by dark dust lanes in the Milky Way from near the Southern Cross constellation known as the Kolchak Nebula.

Almost a century ago, standing in the middle of Paris, known as the „City of Lights,” you could see classic scenes like this one in the night sky.

From the late 1880s to the 1910s, French astronomer Guillaume Bigorton He observed many galaxies from the Paris Observatory.

In 1917, He said The Milky Way can be seen from the Paris observatory in the summer, when the sun is low enough below the horizon, about the stage of marine twilight – when at sea, you can no longer see the horizon.

But it was during this period that light pollution began to become a problem in modern cities.

Melbourne Observatory Established in 1863 But it stopped doing astronomy in the early 1900s. Light pollution from Melbourne hinders astronomers’ ability to accurately observe the night sky.

In 1924, the Mount Stromlow Observatory, located outside Canberra, took over the task of observing the Milky Way. It was chosen for its remote location and dark skies.

However, by the 1950s, the Australian capital had less than 10% of its current level of light pollution, and a new dark floor was discovered as the Milky Way slowly faded away. vision The site the scientists chose was located eight hours away at the Siding Spring Laboratory.

However, even Siding Spring can now see the glow of Sydney – from 450 kilometers away.

What can be done?

By living our modern lives more intelligently, the Milky Way can be seen again from anywhere – including the heart of Sydney, Paris or Los Angeles – just as it was 100 years ago.

Safety of lighting is an important aspect. Instead of open lighting, flat lights or shielded lights that prevent upward spills are important. They direct light to the ground, not the sky.

In Canberra, the Australian Capital Territory government and lighting operator Omex are replacing streetlights – with no upward leakage, controllable lights.

By doing so, Canberra has reduced its light pollution by about 30% in just a few years, my colleagues and I report in a forthcoming paper.

It is also important to turn off or dim unnecessary lights.

Canberra is doing the same. At midnight the total brightness of street lights is reduced by up to 50%. By doing so, the city saves energy – and reduces light pollution. Our forthcoming paper finds that for every 10% dimming of streetlights, we reduce light pollution by 5%.

The color of the light is another part of the solution. Instead of using bright white LEDs and cold-colored lights, we can use warm colored lights that help our eyes, sleep cycles, native animals — and reduce light pollution.

With these simple steps, we can return to a time not too long ago when we could see the Milky Way wherever we stood on Earth.

Reclaim the night sky.