How Could we Light our Cities and Still See the Night Sky?

The night sky is a part of humanity’s natural heritage. Gazing up at the heavens is a unifying act, performed by almost every human that’s ever lived. Haven’t you looked up at the night sky and felt it ignite your sense of wonder?

But you can’t see much night sky in a modern city. And the majority of humans live in cities now. How can we regain our heritage? Can quiet contemplation make a comeback?

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Light Pollution is Making it Harder for Animals to Find Their Way at Night

Ah, the majestic dung beetle. The pinnacle of evolution. In all seriousness, these little critters are incredibly sophisticated navigators who have, for millennia, used the night sky to guide them about their business. But light pollution is making their lives more difficult by limiting their ability to navigate by the stars. Other nocturnal creatures, including some birds and moths, may be facing similar challenges.

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The Streetlights in an Entire County Were Swapped to LEDs. Light Pollution got Worse

“The best laid plans of mice and men often go awry” – this famous paraphrase of Scottish poet Robert Burns sometimes sums up human ingenuity.  That is exactly what happened when a county in Washington State decided to replace all of its county-owned streetlights with LEDs at least partially in an effort to combat light pollution.  New research shows that they actually made the light pollution worse.

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Astronomers Measure the Background Brightness of the Night sky Across the World. Canary Islands are the Darkest in the Survey

Being able to look up at a clear, dark sky is becoming more and more rare in the rich world.  Authors, artists, and even scientists have started to express concern about what our lack of daily exposure to a dark night time sky might mean for our psyche and our sense of place in the universe.  Now a team has collected photometric data at 44 sites around the world in an attempt to quantify how dark the night sky actually is at different places on the globe. So where was the darkest place surveyed?  The Canary Islands.

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Most light pollution isn’t coming from streetlights

Light pollution is the arch nemesis of astronomy, spoiling both the enjoyment of the night sky and the professional study of our universe. For years we’ve assumed that streetlights are the main culprit behind light pollution, but a recent study has shown that streetlights contribute no more than 20% of all the pollution, and if we want to solve this vexing astronomical problem, we have to think harder.

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Astronomers Have Some Serious Concerns About Starlink and Other Satellite Constellations

Picture the space around Earth filled with tens of thousands of communications satellites. That scenario is slowly coming into being, and it has astronomers concerned. Now a group of astronomers have written a paper outlining their detailed concerns, and how all of these satellites could have a severe, negative impact on ground-based astronomy.

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Here Comes the Next Satellite Constellation. OneWeb Launches 34 Satellites on Thursday

SpaceX has been garnering all the headlines when it comes to satellite constellations. Their Starlink system will eventually have thousands of tiny satellites working together to provide internet access, though only 242 of them have been deployed so far. But now another company is getting on the action: OneWeb.

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Oops, low energy LEDs are increasing light pollution

When it comes to technology and the environment, it often seems like it’s “one step forward, two steps back.” Basically, sometimes the new and innovative technologies that are intended correct for one set of problems inevitably lead to new ones. This appears to be the case with the transition to solid-state lighting technology, aka. the “lighting revolution”.

Basically, as nations transition from traditional lights to the energy-saving Light-Emitting Diodes (LEDs), there is the potential for a rebound effect. According to an international study led by Christopher Kyba from the GFZ German Research Center for Geoscience, the widespread use of LED lights could mean more usage and more light pollution, thus counter-acting their economic and environmental benefits.

The study, titled “Artificially Lit Surface of Earth at Night Increasing in Radiance and Extent“, recently appeared in the journal Science Advances. Led by Christopher C. M. Kyba, the team also included members from the Leibniz Institute of Freshwater Ecology and Inland Fisheries, the Instituto de Astrofísica de Andalucía (CSIS), the Complutense University of Madrid, the University of Colorado, the University of Exeter, and the National Oceanic and Atmospheric Administration (NOAA).

Photograph of Calgary, Alberta, Canada, taken from the International Space Station on Nov. 27th, 2015. Credit: NASA’s Earth Observatory/Kyba, GFZ

To put it simply, the cost-saving effects of LED lights make them attractive from a consumer standpoint. From an environmental standpoint, they are also attractive because they reduce our carbon footprint. Unfortunately, as more people are using them for residential, commercial and industrial purposes, overall energy consumption appears to be going up instead of down, leading to an increased environmental impact.

For the sake of their study, the team relied on satellite radiometer data calibrated for nightlights collected by the Visible/Infrared Imager Radiometer Suite (VIIRS), an instrument on the NOAA’s Suomi-NPP satellite that has been monitoring Earth since October of 2011. After examining data obtained between 2012 and 2016, the team noted a discernible increase in power consumption associated with LED use. As they explain in their study:

“[F]rom 2012 to 2016, Earth’s artificially lit outdoor area grew by 2.2% per year, with a total radiance growth of 1.8% per year. Continuously lit areas brightened at a rate of 2.2% per year. Large differences in national growth rates were observed, with lighting remaining stable or decreasing in only a few countries.”

This data is not consistent with energy reductions on a global scale, but rather an increase in light pollution. The increase corresponded to increases in the Gross Domestic Product (GDP) of the fastest-growing developing nations. Moreover, it was also found to be happening in developed nations. In all cases, increased power consumption and light pollution has natural consequences for plants, animals, and human well-being.

As Kevin Gaston – a professor from the Environment and Sustainability Institute at the University of Exeter and a co-author on the study – explained in a University of Exeter press release:

“The great hope was that LED lighting would lead to lower energy usage, but what we’re seeing is those savings being used for increased lighting. We’re not just seeing this in developing countries, but also in developed countries. For example, Britain is getting brighter. You now struggle to find anywhere in Europe with a natural night sky – without that sky glow we’re all familiar with.”

The team also compared the VIIRS data to photographs taken from the International Space Station (ISS) which showed that the Suomi-NPP satellite sometimes record a dimming of some cities. This is due to the fact that the sensor can’t pick up light at wavelengths below 500 nanometers (nm) – i.e. blue light. When cities replace orange lamps with white LEDs, they emit more radiation below 500 nm.

The effect of this is that cities that are at the same brightness or have experienced an increase in brightness may actually appear dimmer. In other words, even in cases where satellites are detecting less radiation coming from the surface, Earth’s night-time brightness is actually increasing. But before anyone gets to thinking that it’s all bad news, there is a ray of light (no pun!) to be found in this research.

In previous studies, Kyba has shown that light emissions per capita in the US are 3 to 5 times higher than that in Germany. As he indicated, this could be seen as a sign that prosperity and conservative light use can coexist:

“Other studies and the experience of cities like Tucson, Arizona, show that well designed LED lamps allow a two-third or more decrease of light emission without any noticeable effect for human perception. There is a potential for the solid state lighting revolution to save energy and reduce light pollution, but only if we don’t spend the savings on new light”.

Reducing humanity’s impact on Earth’s natural environment is challenging work; and in the end, many of the technologies we depend upon to reduce our footprint can have the opposite effect. However, if there’s one thing that can prevent this from continually happening, it’s research that helps us to identifies our bad habits (and fix them!)

Further Reading: Eureka Alert!, University of Exeter, Science Advances

Stunning Astrophotos Reveal the Importance of Dark Skies

The World at Night’s (TWAN) annual Earth & Sky photography contest showcases the stunning beauty of the night sky while highlighting the challenges of keeping our skies free from light pollution. TWAN has now announced the winners of this year’s contest, and the winning photos are simply breathtaking. This year’s theme of “Dark Skies Importance,” were judged in two categories: “Beauty Of The Night Sky” and “Against The Lights,” said Babak Tafreshi, the founder and director of TWAN,” and the winners were selected from submissions by photographers in about 45 countries.”

The selected images were judged to be those most effective in impressing the public on both how important and delicate the starry sky is as an affecting part of our nature, and also how bad the problem of light pollution has become.

Tafreshi added that “the amazing number of eye-catching entries from across the world tells how public attention to night sky is growing as well as interest to sky photography and we are very pleased if TWAN has a role on this increasing awareness.”

The overall contest winner and first prize in the Beauty Of The Night Sky category is our lead image, taken by Stephane Vetter of France, for his March 2013 panoramic photo “Sky Above Godafoss” of aurora and the Milky Way over the “Waterfall of the Gods” in Iceland.

See more winners and more information about the contest below:

The first prize in Against The Lights category goes to Andreas Max Böckle of Austria for his photo “Under the Hood” taken from overlooking the city of Salzburg in a moonlit night:

Stars over Salzburg, Austria by Andreas Max Böckle, the first winner in Against the Lights category in TWAN 2013 Earth & Sky Photo Contest.
Stars over Salzburg, Austria by Andreas Max Böckle, the first winner in Against the Lights category in TWAN 2013 Earth & Sky Photo Contest.

David Malin, one of the judges and a world-known pioneer in scientific astrophotography said, “The 685 entries the judges examined (more than twice than the 2012 judged images) represent some of the best TWAN-style photographs ever gathered together in one place… I feel privileged to have seen so many beautiful images in such a short time!”

Click on the images here to see larger versions. You can see all the winners (and the great prizes they won) at the TWAN website, and this video highlights the winning photos:

‘Crossed Destinies,’ the Milky Way of Reunion Island, Indian Ocean by Luc Perro from France is the 2nd place winner in the Beauty of the Night Sky category in the TWAN 2013 Earth & Sky Photo contest.
‘Crossed Destinies,’ the Milky Way of Reunion Island, Indian Ocean by Luc Perro from France is the 2nd place winner in the Beauty of the Night Sky category in the TWAN 2013 Earth & Sky Photo contest.