We've all been there at some point. You're walking in a dark space at night, alone, maybe to your car in a parking lot. And a kind of fear seizes you. You can't see very well around you, so you don't know if there is someone waiting in the shadows. You get to where you're going as fast as you can, unlock your car door, get in and lock the door behind you. For a moment, you feel safe again.

My friend and colleague Nancy Clanton, a lighting designer based in Colorado, explains how the situation is even more acute for women. She told me about an incident once, some years ago, when she was in an unfamiliar city to attend a lighting conference. She had to walk alone at night along a dark stretch of road between the convention center and her hotel. Even with all her knowledge about lighting and darkness, she still felt uneasy being out there by herself.

She saw two people, both silhouettes, approaching. Like many people in the same situation, Nancy had to make a quick decision. Were they two threatening men? An innocuous couple? Something else? In her mind, at that moment, was born the idea of "lighting for reassurance". With a small amount of well placed light, she could have made a quick friend-or-foe determination. And if circumstances required, she could have made a quick exit. It would have changed the situation in a fundamental way.

There are many reasons that people use artificial light at night. For example, we light sidewalks and pathways to help people orient and find their way from Point A to Point B. We light roadways and "conflict zones" where different kinds of traffic come together, because we know that doing so saves lives. We like to add nighttime amenity to outdoor spaces, making them more inviting for activities like commerce. But we also liked it because many people believe that light at night deters or even prevents the incidence of crime.

Does outdoor lighting yield any real, positive influence on nighttime safety and security? Does it reduce criminal behavior? "The influence of outdoor light at night on crime is mixed," writes DarkSky International in its most recent annual report Artificial Light at Night: State of the Science 2024. "Some of the same studies that looked at lighting and traffic/pedestrian safety also considered nighttime crime incidence. Certain studies reported crime reduction when lighting is added to outdoor spaces. Others find either a negative effect, no effect, or mixed results."

​Whatever the ways in which lighting and crime interact, it's not like the effect of administering a drug to a person. That is, there is no sense that a dose X of the medicine always produces effect Y in the individual.

Crime and lighting seem to have a very context-dependent relationship. There are very many of what researchers call "confounding variables". These are influences unrelated to the study subject that might produce some kind of effect in the system. Without careful control of these variables, the researcher can draw an incorrect conclusion on the basis of observing the intended effect.

To continue the medical analogy, drug researchers try to remove differences among people in patient study samples. These include age, gender, geographic, location, and other factors that might produce a result that mimics what the drug should do. Failure to deal with these "confounders" means that one can be fooled into believing there is an effect from a drug that is in fact, unrelated to its mechanism of action.

It is also very difficult to carry out high-quality, well-controlled studies. Designing reliable (and replicable) lighting studies is challenging. There is not much research funding for this. Sometimes the sources of research funding are questionable. Researchers worry they may want to see some sort of pre-defined result from studies they support.

And there are instances where experimental design is just bad. For example, a 2019 study conducted in New York City housing projects claimed a strong relationship between high levels of light and decreased crime. The study looked at the effect of placing intense light sources on portable towers outside housing buildings and tracking changes in the incidence of crime in the immediate environment around them.

​To the surprise of few, crime dropped. But that's what happens when you treat people like criminals and light up their homes like they were prison yards: you get unreliable results.

What underlies concerns about outdoor lighting, public safety and crime is the unspoken element of fear. It is a powerful and underestimated motivator of human behavior. Our evolutionary heritage has given us limited abilities to see at night. As diurnal animals are active during the day, it made night a dangerous place for our early human ancestors.

Although we tend to think of fear of the dark as something that particularly afflicts children, many people as adults feel a deep-seated sense of terror toward dark places at night. How much we know about a place determines our sense of ease (or unease) about it. Because we are so dependent on our sense of sight, it's easy to feel that we lose control when we cannot see what is happening around us.

Psychologists have long understood that these influences have tremendous power in shaping our perception of the world. In recent years, social scientists have begun investigating what they call "feelings of safety". That is, they try to measure the degree to which people feel safe or unsafe in different situations that may involve danger.

It is important to know that feelings of safety are independent of whether people are actually safe. There are many instances in which people feel unsafe about a situation but the evidence shows that there was no actual danger.

There are ways in which feelings of safety can increase in dark places at night that lead people to accept lower light levels. This relates to a sense in which people feel trapped by their surroundings. They are looking for the exits, so to speak, in case danger suddenly emerges. Research shows that lower light levels are less acceptable to most people in any situation where they feel trapped. If there are clear opportunities to escape if needed, the acceptability of lower light levels begins to rise. Other work shows that most people prefer somewhat higher levels of outdoor light at night. Most prefer light that is cooler than warmer in color appearance.

​But the value of this extra light diminishes very quickly as light intensities increase. The relationship between feelings of safety and light intensity appears to be logarithmic. What that means is that as light levels increase, the amount of an increase necessary to produce some certain amount of increase in feelings of safety becomes larger.

​The biggest increases in feelings of safety happen in moving from situations where there is no light to those in which there is a very small amount of light. To raise feelings of safety by again as much requires increasing the light intensity by much more, often more than a factor of ten.

​The increase in feelings of safety flattens out at highlight levels. We don't quite understand why. One theory is that high intensity lighting makes people feel insecure by promoting the sense that they are on display. Bright lighting can create deep, dark shadows between objects that obscure those spaces. A person moving through an outdoor space at night may not be able to tell whether there is a threat hiding in those shadows.

​The glare from very intense lighting sources also has a disabling effect on the viewer. Glare causes the pupil of the eye to contract, which reduces the depth of field of vision. It conveys a distinct disadvantage to the viewer. And it's the same "prison yard lighting" effect in the New York study mentioned earlier.

That's where "lighting for reassurance" comes in. It's an outdoor lighting ethic still new in the design community. While traditional design holds that more is better, lighting for reassurance asserts that better is better. Often that's less light chosen with a strategy in mind. The goal is to improve outdoor visibility at night and help users of spaces discern where threats might be.

​In particular, it makes use of the incredible properties of human vision, even at low light intensities, to see very small changes in contrast. It ensures that all potential safety hazards are clearly indicated. It also means not going overboard with lighting levels to the point that it becomes a disability for the viewer.

It also makes outdoor spaces at night more inviting to other users of those spaces. People generally tend to feel more unsafe when they are alone in such places at night. As more people fill outdoor squares, streets and other places, they begin to feel more safe in the presence of a crowd. This couples with the popularity of using outdoor light at night for aesthetic purposes. This can include lighting of building façades, statues and monuments, and other landscape features to enhance the sense of nighttime placemaking. And it avoids creating glare to the greatest practical extent.

The task is now to communicate this to more lighting designers. They don't usually learn it either in their formal education or as part of their praxis. We also have to change how lighting designers and engineers think about the concepts of minimum and maximum lighting levels. Right now, lighting standards generally tend to indicate only minimum lighting levels for various lighting applications. This is a belief, not always supported by evidence, that only certain minimum values are "safe". But it is often not clear why those values are "safe" while other values are not.

​It also does not take into account the idea that lighting can be too bright in some cases. That can create its own security problems. Organizations that make outdoor lighting standards are just beginning to embrace the notion that along with recommended minimum lighting values should come corresponding maximum values. The right lighting levels would make Goldilocks herself feel safe at night because they're neither too low or too high. They're just right.

What can we learn from all this? For one thing, many people experience fear of nighttime darkness, and that fear is visceral. We shouldn't tell them that they are wrong to feel fear because we have data that somehow show that their fears are unfounded.

It's also the case that feelings of safety are very powerful. We should recognize this and leverage that fact in outdoor lighting design. Furthermore, the human eye is an underrated detector of faint light at night. That said, lighting design often does not fully exploit its amazing properties. Instead, and as lighting has become much cheaper than ever to consume, design has pushed light levels very high.

The result is that the way we do lighting design now often does more harm than good, even though its practitioners clearly want to do good. What we can do for them is to help them put in place better design through lighting for reassurance. It combines the best of what scientists tell us about lighting with the power of psychology.

​Together, we can make outdoor spaces at night that are truly more safe while also helping people in them feel safer. If we overcome the fear that now leads to demand for brighter outdoor spaces, we'll increase support for measures that gradually draw down light pollution. To do so would be a win for all involved: for people, for the environment, and for the night sky.

On Wednesday, 6th November, the world awoke to the news that former U.S. President Donald Trump won election for the second time. The 2024 campaign was long and bruising, but the win was definitive. On 20th January 2025, Trump will take office as the 47th President of the United States. Changes are of course coming to many aspects of American governance. And some people are wondering what this means for efforts to advance the cause of dark skies in the United States.

As 2024 draws to a close, it's worth considering what the new year may bring. Here we must set aside politics and leave this year's campaign in the past. Instead, in this post we focus on the relevant policies of the first Trump Administration and what little we know about relevant plans for the second.

​The way the U.S. government manages federally owned lands has much to do with landscape-scale preservation of dark skies. Despite lacking a Congressional mandate, all the major land-management agencies take part. But they also oversee various activities on those lands that can yield light pollution. And there is a complex interplay between federal, state and local government in terms of activities next to public lands. The good news is that the land managers have largely embraced dark skies as an important conservation goal.

The world is in a precarious position at the moment. Our planet is experiencing a climate crisis. Scientists expect that its effects will become more plain in coming decades. In previous posts here, we explored how outdoor lighting and light pollution interact with environmental concerns. That includes topics such as climate change, corporate social responsibility, and the "Rights Of Nature".

The laws in many countries mandate the use of outdoor lighting because it serves the public interest. Lighting has demonstrated safety benefits and saves lives. But when lighting becomes excessive, light pollution can cause its own problems. As the world transitions to renewable energy, this can create new challenges. This post explores concerns on both sides of the issue and asks whether competing interests can be balanced in reasonable and effective ways.

Artificial light at night (ALAN) has several connections to environmental concerns. For one, lighting consumes electrical power. That has a significant climate impact via the burning of fossil fuels. Also, ALAN exerts pressure on species already experiencing environmental stress. That stress comes not only from climate change, but also from sources like habitat and biodiversity loss. Energy-efficient lighting like LED seems at first like a solution the first problem. But it can also contribute to making the second problem worse.

Its lower cost of operation has led to rapid adoption of LED technology in the past two decades. With this has come overconsumption of outdoor ALAN. Outdoor lighting is now perceived to be cheap and free of environmental consequences. There is evidence to suggest that had led to the installation of a lot of new and unnecessary lighting. It may have also eliminated any overall environmental benefit from the transition to LED. And it means more light in the nighttime environment, yielding further ecological stress.

In concept, the simplest solution to the climate crisis is to reduce humanity's energy consumption. But our recent history suggests that we're not going to do that. Instead, economists expect energy demand to grow coming years and decades. If so, the next-best approach is to 'decarbonize' the global energy generation portfolio. That requires finding sources of energy that aren't limited to an exhaustible fuel supply.

"Renewable" energy sources like solar, wind and geothermal harness the power of forces of nature. These forces are at work around us all the time, their energy is "free" and it yields no polluting byproducts.  We have used some, like the wind, to power our transportation for thousand of years. Yet until recently, we couldn't move that energy from where we captured it to where we wanted to use it.
Making the best use of renewables now involves constructing both facilities to collect the energy and the infrastructure needed to move it. For this reason, people who live in areas near renewable projects often oppose their construction. Often there are real concerns about the environmental impact of these facilities. When faced with the task of evaluating applications to allow them, governments have to make difficult choices. Sometimes they conclude that the benefits involved outweigh any adverse local impact. Those impacts can include light pollution.

There are certain "speciality" lighting applications that must evaluated in their own contexts. Lighting for specific public safety applications is among those applications. Wind farms, whether built on land or in bodies of water, are a particular concern.  Wind turbines are obstacles for both pilots and sailors in both daytime and nighttime. That's true whether they're in active operation or not. Countries have set rules for lighting windmills at night to reduce the chance of accidents. These rules often supersede other concerns in environmental impact assessments.

The principle underlying these rules is that certain safety concerns cannot be mitigated. As a necessary condition of permitting wind farms, they are seen as acceptable risks. These considerations have led governments to deny permission to build some projects. In other cases, the perceived benefits are too important not to permit renewable energy projects.

Neighbors often oppose wind projects on aesthetic grounds. Their concerns about property values are often labeled NIMBYism ("Not In My Backyard"). Yet there are also real concerns about the environmental impact of this lighting. Renewables projects are often built in remote locations. These are often ecologically sensitive places. Windmills can be hazardous to birds, for example, and in particular at night for migratory species. Very large wind projects involving hundreds or thousands of turbines could light up the night sky. This may happen even when the lighting employed is the smallest amount allowed by law.

So what is the real impact, and should we worry about it? Until recently there were essentially no scientific results to inform the debate. Salvador Bará (Universidade de Santiago de Compostela, Spain) and Raul Lima (Politécnico do Porto and the University of Coimbra, Portugal) just published the first significant work on this topic. They made a simple model of the visual impact of individual wind turbine lights. They used this model to compare their expected brightness to that of astronomical sources like bright stars and planets. It takes into account real-world influences like attenuation of light by the Earth's atmosphere .

Bará and Lima found that windmill lights can be very bright at short distances. Up to 4 kilometers away, medium-intensity turbine lights can exceed the apparent brightness of the planet Venus. After the Sun and Moon, it is often the brightest natural object in the night sky. At 10 km away, the lights can still be brighter than the brightest stars. They can remain visible to the unaided eye to distances as far as almost 40 km. The authors concluded that "the visual range of wind farms at nighttime may be significantly larger than at daytime, a factor that should be taken into account in environmental impact assessments".

​So far this does not address the environmental effects of these lights. The researchers also looked at the amount of illumination on the ground that the lights can cause. Except at very close range, the intensity is low. As a benchmark, the authors used the expected light intensity on the ground from a starry night sky in the absence of the Moon. They found that even the brightest beacon lights on turbines yield these conditions out to distances of only a few hundred meters. Within 5 km the intensity is almost completely negligible. That said, it could still be harmful to wildlife very close to the windmills, whether on land or at sea.

What about the night sky? "Skyglow, in absolute terms, should not be very intense far away from the poles," Bará tells us. "The luminous intensity of the standard lamps used here at nighttime is 2000 candela, and this would make less than about 24,000 lumens per beacon, something like a couple of streetlights." Of course, if designers packed turbines into wind farms, the collective effect might be detrimental to the night sky.

​In a paper published last year, Bará and colleagues considered the effect of skyglow immediately near streetlights. They found that the contribution to skyglow from an isolated, single street light is small and localized close to the light. Small wind farms may thus have little impact on the night sky in their surroundings. But that's less likely as installations grow larger.

What can be done about all this? Clearly there is a climate need to shift energy production away from fossil fuels and toward renewables. Almost one-third of global electricity production now comes from renewables. That percentage is steadily increasing. Certain flavors of renewable energy, like solar, don't need facility lighting at night. But they're not suitable for every condition or situation. For example, electricity generated from solar cells drops to zero at night. To reduce uncertainties, experts recommend diversifying investments in types of renewables. This ensures that no one technology dominates in an area.

To the extent that wind energy is a good option in many parts of the world, there remains the question of where to put it. The social unacceptability of wind farms near populated places is unlikely to change. That leaves locations that may be especially sensitive from an ecological perspective. At the same time, transportation safety concerns will persist and even grow.

Technology may be able to help. For example, some wind farms are now equipped with Aircraft Detection Lighting Systems (ADLS). These systems sense the approach of aircraft within a predefined volume of space around and above wind farms by using low-powered radar. When an aircraft enters a predefined detection zone, the ADLS switches on bright lighting to make windmills visible to the pilot. Once the aircraft exits the detection zone, ADLS turns off the lighting automatically. ADLS can improve situational awareness of obstructions like windmills even in challenging weather. It is sometimes deployed in conjunction with Enhanced Vision Systems (EVS) equipment. EVS combines views from infrared and visible-light cameras to help pilots see through fog, snow, and other low-visibility conditions.

At the end of the day, we can't have it all. So we have to make accommodations. Situations arise where even our best technology can't fully mitigate dangers associated with wind energy projects. But where to locate these facilities remains a choice. Decisions should consider ecological sensitivity in relation to the amount of traffic and the need for lighting. In other words, it's a problem of many variables that has more than one solution. Sometimes the answer is to not build the project at all.

Dark-sky advocates have long wrestled with such tradeoffs. It is often the case that the most "wildlife friendly light" is the one that is never installed to begin with. And yet, better lighting practices exist in the real world alongside complex social and political influences. Lighting for safety remains among the most complex of them all. As the climate crisis becomes more acute, we are again confronted with often difficult choices. The right balance between competing risks serves both the interests of nature and society. That balance leads in a direction toward a world that is more sustainable in all its aspects.

The Sun is the nearest star, a slow-spinning globe of plasma that powers almost all life on Earth. But it's not only a passive radiator of energy that warms our planet. Rather, it's an active and dynamic system that reaches all the way out to us across almost 150 million kilometers. As its substance reaches the Earth, complex interactions yield various effects on the planetary environment. Among those is an influence on the brightness and appearance of the night sky we're still struggling to understand. The emerging view is that "space weather" determines what the night sky looks like in the absence of light pollution. And that turns out to be important in defining what a "dark sky" is. As we approach the peak of the current solar cycle, here we dig into the ways the Sun changes our experience of night.

Nuclear reactions taking place deep in its core power the Sun. Protons fuse to make helium nuclei at temperatures approaching 15 millions of degrees. These fusion reactions release light, which takes about a million years to work its way up to the thin edges of the Sun's atmosphere. Along the way there are a lot of electrically charged particles running around. The rotation of the Sun drags the particles along. In turn, that generates a magnetic field. And that's where things get interesting.

A simple view of this magnetic field is like a simple bar magnet, with a "north pole" and a "south pole". On large scales, the field is weak; a typical refrigerator magnet is about ten times more intense. If that were true everywhere on the Sun, not much in the way of interesting phenomena would ever happen. Yet the local strength of the magnetic field can be much higher.

​The lines of the global magnetic field twist as they wrap around the interior of the Sun. Much like winding up a rubber band, the field lines strain under the tension and begin to kink. Some of these contortions emerge from the visible surface of the Sun. We see these protuberances as sunspots. Eventually the contortions burst under pressure, producing what we see as solar "flares". Coronal mass ejections (CMEs) sometimes follow flares. These events release incredible amounts of energy and hot, charged particles into space.

A few years after this process starts up, it takes about as long to quiet down again. Strong magnetic fields almost disappear at the surface, sunspots disappear, and flares end. The Sun remains quiet for some time. Then the process starts all over again. A complete cycle takes about 11 years to repeat, and we have seen it repeat with near-perfect reliability for at least four centuries.

We are now near the maximum of this cycle, the 25th such event since astronomers began counting in the 1700s. This cycle has an intensity like those over much of the past 250 years. Notable outbursts associated with CMEs have occurred in recent months. In May 2024, millions of people around the world saw auroral displays during a strong solar "storm".  Such events are likely through at least 2025.

The world recently watched the spectacle of the 2024 Olympic games. Assembling the world's best athletes once every four years sets the Games apart from many other athletic competitions. The Olympic flame extinguished, another long period commences before they meet again in another world city.
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The world astronomy community has its own version in the form of a similar gathering of greats with a long period between. The International Astronomical Union's General Assembly, held somewhere in the world every three years, is sometimes called the "Olympics of Astronomy". The events draw astronomers from all over the world for meetings where many would only ever encounter one another. Since dark skies were on the agenda at the latest edition, it's a good time to catch up here on efforts to protect astronomy for the benefit of future generations. 

The International Astronomical Union, or IAU, is the world's main professional body representing astronomers. Founded in the wake of the First World War, it now represents over 12,000 people in astronomy and related fields. Their professional predecessors were among the first to sound the alarm about light pollution. Astronomers made some of the first descriptions of its effects on the night sky. The earliest accounts come from the 19th century in the era of gas lighting. By the turn of the 20th century, electric light quickly became a new scourge. Astronomical observatories moved out of the capitals of Europe for more rural locations. Some viewed this as the price of progress while wondering whether the price was too high.
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The scientific study of light pollution began in the 1960s and 1970s, and again astronomers led the way. One of the first scholarly mentions of light pollution was a little over 50 years ago in the pages of the journal Science. Astronomers worked to understand the influences that had been brightening skies over observatories for decades. And they put energy into changing public policies in and around observatory sites. For instance, the city of Flagstaff, Arizona, enacted what may be the world's first outdoor lighting law in 1958. Nearby Lowell Observatory played no small part in that effort.

IAU was a little late to the party in recognizing the seriousness of light pollution. It contributed to the the Starlight Declaration of 2007, which called access to dark skies “a fundamental socio-cultural and environmental right”. At its 27th General Assembly in 2009, the IAU adopted a resolution on light pollution. It urged its members to work to reduce light pollution from the local to international levels. And in 2020-21, it helped arrange two international workshops on the subject. The events addressed the connection between light pollution and cultural heritage, "dark sky oases", astrotourism, and the bio-environment.
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The IAU has also built dark skies into its formal activities. In 1973 it set up Commission 50, dedicated to "Protection of Existing & Potential Observatory Sites". In 2018 it became Inter-Division B-C Commission B7, reflecting the duel influences of Commissions B ("Facilities, Technologies and Data Science") and C ("Education, Outreach and Heritage"). In the early 2020's IAU began to realize the threat posed to astronomy by large satellite constellations, which we previously wrote about here. In response it established the Centre for the Protection of the Dark and Quiet Sky from Satellite Constellation Interference (CPS).

As athletes were competing in Paris, astronomers from 107 countries gathered in Cape Town, South Africa, for the 2024 General Assembly. Besides dedicated sessions about light pollution and "Dark and Quiet Skies", these themes recurred in other programming during the two weeks of the General Assembly. Each of the IAU Offices (for Development, Outreach and Education) included aspects of these topics in their offerings.

CPS hosted a session early in the General Assembly dedicated to progress on the satellite issue. Richard Green, Interim CPS Director, opened the session with a summary of the status quo and developments since establishment of the Centre. Each of the four CPS "hubs", or sections, put on presentations during the daylong session. This was further supported by a poster session with a variety of results across CPS technical, policy and community engagement efforts. The session concluded with the perspectives of figures in the commercial space industry who described their actions taken by companies to reduce the impact of satellites on astronomy.

Some common themes emerged. CPS touted its achievements in encouraging the industry to find creative solutions to mitigate potential harms to the night sky. CPS leaders called for more dialog and engagement with industry as the way to get the best outcomes. Technical presentations evaluated mitigations attempted to date. And space policy experts examined possibilities for affecting change in a challenging global regulatory climate. In particular, they pointed to the gradual emergence of best management practices among industry participants. These informal or "soft" approaches may have the best chance of success.
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At the same time, other presenters took a more skeptical point of view, criticizing elements of the engagement between astronomers and the industry. They pointed out inadequate attention to the issue among many astronomers. Lively exchanges between participants pulled at all the threads involved: legal, technical, and commercial. It was clear that the players are still far from agreement on some points. It's also the case that there is much we don't know about the broader problem. That includes the "carrying capacity" of orbital space and what effects re-entering satellites will have on Earth's upper atmosphere. Yet all agree that more satellites will be in orbit in the future, and we still lack the means of ensuring the sustainable development of space. ​

Later in the General Assembly dedicated sessions on light pollution took place. Inter-Division B-C Commission B7 held a business meeting to discuss strategy in the next 'triennium', or three year period of IAU activities. Its leadership acknowledged that much of the Commission's attention focused on the satellite problem in the previous triennium. It aimed to sketch out the major pieces of a strategic plan for 2024-27. Freeform discussion among the meeting attendees followed.

Many ideas came up: opportunities to inform the framing of national light pollution legislation; better quantifying the cost to astronomy from light pollution; and standardizing the ways we measure and report light pollution impacts on astronomy. Those involved are also struggling with the degree to which their advocacy should directly address environmental concerns.

Supporters see that strategy as one that may prompt people to care about light pollution in ways that astronomy alone won't. The IAU itself is changing. It now often looks outward and engages with society beyond the community of professional astronomers alone. To do so calls for them to avoid excluding audiences from certain spaces because astronomers are "the experts".

On the last day of the General Assembly, the IAU Executive Committee Working Group on Dark & Quiet Sky Protection convened another daylong session. The format was again a mix of presentations, posters and freely flowing discussion among participants. Nearly all agreed on the need to broaden the appeal of dark night skies and the protections from light pollution they need.

The development of astrotourism, a form of sustainable tourism oriented toward night-sky viewing, is seen as a key element in protecting more places in the world. The need for well-crafted and implemented outdoor lighting policies is acute. But several speakers also noted that people most affected by those policies should be consulted as a matter of basic democratic principles.

Lastly, the session looked beyond both our home planet and the wavelengths of light we can see with our eyes alone. The quiet part of "Dark and Quiet Skies" refers to radio frequency interference (RFI). This is the equal of light pollution in the radio part of the electromagnetic spectrum. Radio astronomers continue to suffer interference from diverse sources of artificial radio energy on the ground. But now they also find their observations under attack from above. Yet ways to focus the public's attention on RFI threats to radio astronomy remains elusive. Many people are simply unaware of the existence of radio astronomy, much less of RFI.
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Many of these threats to astronomy may play out again as humanity establishes a permanent presence in the cosmos. Plans to commercially develop the Moon, for example, are ramping up fast. Astronomers have long prized access to the Moon as the site of future telescopes with exquisite sensitivity. Such facilities could revolutionize our understanding of the universe. But they now face prospects like RFI from satellites in orbit around the Moon and damage from lunar dust kicked up by various activities. There is still a window of opportunity to protect the Moon from interference that would impact astronomy. The time remaining to protect the most vulnerable sites is running out. The IAU has established a Working Group on Astronomy on the Moon whose work is just beginning. ​

Astronomers were the vanguard in sounding the alarm about light pollution. And for good reason: it threatened the success of their enterprise. Now of course we have powerful space telescopes situated far above our planet. But we still rely on their ground-based counterparts to be the workhorses of research and discovery. And even the most remote of those facilities is under assault by light pollution.

There are many takeaways on the subject of dark (and quiet) skies from two weeks in Cape Town for this year's IAU General Assembly. It seems that many astronomers don't pay a lot of attention to the issue, if they ever did. While the dark skies sessions were well-attended, they faced competition from science sessions held on the same days and times. The General Assembly offers a jam-packed schedule that inevitably involves conflicts among parallel sessions vying for participants' attendance.

​To some astronomers we talked to, putting their attention on dark and quiet skies feels like work that they often assume someone else is (or should be) doing. They face their own struggles with inadequate research funding and an unstable labor market. That was all the more evident among attendees from developing economies that don't enjoy the comparative luxuries of their North American and European colleagues. It's not that they don't care about light pollution. But they rarely have time to think about it, much less to take action.

The satellite problem has thrown a new complication into the mix. Despite the efforts of organizations like CPS, it has even less recognition among astronomers than ground-based light pollution. Some wondered aloud why the community failed to expect the threat, which forced it to play defense from the beginning. Yet there is still hope that the IAU will lead on all these issues and to come out more forcefully in support (and defense) of astronomy and astronomers everywhere.
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We're entering an era unprecedented in the history of astronomy. The biggest telescopes ever built will soon see first light. Machines like the James Webb Space Telescope are pushing the frontiers of discovery nearly to the origin of the universe itself. Computing power is cheap, allowing us to make very sophisticated models to understand the physics of the cosmos. And yet it is all threatened by forces from beyond and above. Astronomers still hold a place of special fascination and even reverence among the public. Will they use their status to rally that public in support of their science? The outcome will determine the very future of astronomy itself.