Tuesday, December 9, 2014

Have astronauts photographed your city at night?

Back in July, I blogged about a new portal that helps you find photos of cities at night, and three related citizen science projects. I have some astounding news about the project that I just needed to share!

Citizen scientists have completed the initial classification of over 130,000 images in the Dark Skies of ISS project. This projects sorts images taken at night on the international space station as to whether the picture contains either stars, cities, the astronauts, etc, and how sharp the image is. To avoid errors, each image was categorized by multiple participants, so that's probably over half a million classifications in less than half a year!

In the Lost at Night project, citizens apply their lay knowledge of local and international geography to identify which cities are in specific photographs. Every photo is again categorized multiple times, and this has resulted in the discovery of almost 2,500 images of cities that researchers like me didn't know existed. Images from cities like San Jose (shown below), and also from places less well known to Americans and Europeans, like Chennai, Inda, or Da Nang, Vietnam.

San Jose from the International Space Station.
High resolution image available from NASA.

The citiesatnight team has released a preliminary set of these photos within a Google interface so that you can easily check if your city has been photographed. Please bear in mind that this is not a final product. If you find a city that has been misclassified, they would appreciate it if you would report it to them. Believe it or not, that link contains only the cities classified by citizen scientists. The Atlas of images put together by professional scientists and enthusiasts is actually smaller in terms of number of images, and I explained the best way to use it in July.

Finally, the citiesatnight team has also released seven examples of images that were georeferenced by volunteers. In the Night Cities project, participants match locations on the image with locations on Google Maps, allowing the photos to be overlaid on top of a map. A total of 128 cities have already been georeferenced.

Manhattan at night, georeferenced by citizen scientists at citiesatnight.org

The citiesatnight project has been an astonishing citizen science success story. The project was put together almost entirely through volunteer time, as far as I know it hasn't received any government financing. The International Dark-Sky Association recognized its leader Alejandro Sanchez de Miguel with an award this fall. If you know of other ways in which the project could be recognized, please nominate it!

Note to journalists and researchers: citiesatnight asks that you cite this paper if you use the images in your work.

Full disclosure: Alejandro is a close friend of mine. I played a limited role in the project, mainly by providing some minor advice and lots of encouragement.

Monday, December 8, 2014

Greenhouses at night

Last week I posted some photos showing examples of trees that seemed to be affected by the light from nearby street lamps. There hasn't been much research into what effect (if any) street light has on trees. But when it comes to higher light levels, we do know that plants respond to the light, and use it to grow.

Some greenhouses use artificial light to extend the growing time of plants beyond what is possible with local sunlight. When greenhouses don't bother to capture and redirect scattered light back towards the plants, this can have a really profound effect on the night sky. The image below was taken by my Dutch colleague Kamiel Spoelstra:

Skyglow from greenhouse by Kamiel Spoelstra is licensed under
a Creative Commons Attribution 4.0 International License.

Of the places where accurate measurements of sky brightness have been reported, the brightest skies I know of are near greenhouses in the Netherlands. When you look at satellite images of the Earth at night from the new VIIRS DNB instrument, greenhouses are "blindingly" obvious, because they are tens or even hundreds of times brighter than city centers. This is part of the reason the Netherlands appears so bright - it has a lot of greenhouses!

Northwestern Europe at night by VIIRS

My colleague Florian Tornow took the next two photos from a window on a recent flight to the Netherlands. The first shows a large area of greenhouses:

Greenhouse complex by Florian Tornow is licensed under
a Creative Commons Attribution 4.0 International License.

The second shows how bright they can be compared to the surroundings:

Lit greenhouses at night by Florian Tornow is licensed under
a Creative Commons Attribution 4.0 International License.

In some areas, greenhouse lights only turn on after midnight, because the glow from the greenhouses disturbs the nearby residents. I have heard that newly built greenhouses in the Netherlands are required to keep their artificial light in-house. With better design, instead of emitting light into the atmosphere the light can be redirected towards the plants, saving energy and reducing the impact on the nearby nighttime environment.

Update (December 10): After seeing this post, @RICE_MM shared the photo below on twitter, which was produced by Remi Boucher. It shows how a single greenhouse complex near the small town of Anson in Maine produces light roughly comparable to that of the whole city of Sherbrooke, Quebec (population ~150,000). The image also shows the area of the Mont-Mégantic International Dark-Sky Reserve.

Greenhouse and Sherbrooke by Remi Boucher.
Image and Data processing by NOAA's National Geophysical Data Center.

@RICE_MM also shared this post showing the change in the area from 2010 to 2012:

Wednesday, December 3, 2014

Artificial light and trees

(Updated January 11, and January 16, 2015, and July 1, 2016)

Luciano Massetti, a colleague of mine from the Loss of the Night Network, recently took a series of photos in Florence that show trees near street lamps who's leaves still haven't fallen off:

LAN leaves 2 by Luciano Massetti is licensed under
a Creative Commons Attribution 4.0 International License.

LAN leaves 10 by Luciano Massetti is licensed under
a Creative Commons Attribution 4.0 International License.

LAN leaves 15 by Luciano Massetti is licensed under
a Creative Commons Attribution 4.0 International License.

LAN leaves 22 by Luciano Massetti is licensed under
a Creative Commons Attribution 4.0 International License.

LAN leaves 28 by Luciano Massetti is licensed under
a Creative Commons Attribution 4.0 International License.

At this year's Artificial Light at Night conference, Jonathan Bennie of Exeter University's Environmen and Sustainability Institute presented some intriguing data about a potential relationship between artificial light exposure and how early tree buds burst into leaves and how late leaves fall. His work, and related research by my IGB colleague Sibylle Schroer, isn't published yet, but it's starting to look like people's anecdotal observations that trees near street lamps behave differently isn't just a case of confirmation bias, it's a real phenomenon.

At this stage, there's very little information about which tree species are typically affected, or which types of lights have the strongest effect. Dr. Bennie is interested in pursuing this further, so if you've observed trees under lamps that are behaving differently than adjacent unlit trees, and if you are able to tell him the type of tree and type of lamp (e.g. high pressure sodium or LED), he'd like to hear from you. Photos of the effect are also useful, of course! You can find his contact information here.

If you liked this post, you might want to read the next one, which is about artificial light escaping from greenhouses at night. As always, if you have a photo related to artificial light that you'd like to share with the world, please send it to me along with your permission to publish it on the blog under a Creative Commons Attribution 4.0 International License as part of the "view from your app" photo series.

Update 1: took these photos of a silver birch during the day and the night, so that you can see that it's the illuminated areas where the leaves are staying longer than they otherwise would.



Update 2: Stephen Rawlings took this time series of a brightly floodlit tree, showing how the leaves closest to the floodlight were the last to fall:

floodlit tree by Stephen Rawlings is licensed under
a Creative Commons Attribution 4.0 International License.

Update 3: A new paper shows that light is associated with a one week earlier budburst date in some species, and that this probably isn't an urban heat island effect (read it open access here). John Bennie has also published an open access paper about the potential effects of light on plants.

Tuesday, December 2, 2014

This Christmas, help every star shine a bit brighter

December 2 is Giving Tuesday, and the IDA board of directors has pledged to match the first $5,000 donations that come in today. I wanted to take a moment to encourage you to consider making a donation.

The International Dark-Sky Association (IDA) works together with communities, institutions, parks, and lighting designers to improve lighting worldwide. The IDA does this in a number of ways:
  • The IDA helps parks and communities preserve the resource of a natural night sky through its International Dark-Sky places program.
  • The Fixture Seal of Approval program makes it easy for communities to find lights that shine light where it is needed, and not into the sky.
  • In partnership with the Illuminating Engineering Society, the IDA developed a Model Lighting Ordinance that communities can adopt to regulate lighting.
  • Through partnerships with companies like Lowes, the IDA helps homeowners choose lamps that satisfy security needs while minimizing waste light and energy consumption.
  • The IDA honors individuals who have made outstanding contributions to the protection of the night sky.
  • The IDA helps educate everyone about the consequences of poorly designed lighting through education and outreach programs, such as this planetarium show.
The IDA is largely a member-funded organization, and it needs your help to continue this work. The best way for you to help is to become a member, but you can also help out by making a one-time donation. A donation in another person's name is a great stocking stuffer!

Better lighting doesn't only help keep the stars in the sky, it can also improve visibility and is more efficient. That means lower electricity bills for cities (lower taxes!), and reduced need for electricity production in the night (when solar plants can't operate). Bringing back the stars is a win for everyone!



Full disclosure: I am a member of the IDA board of directors. That means I'm literally asking you to take my money today!

Monday, December 1, 2014

Data not yet appearing on GLOBE at Night maps

We haven't yet updated the scripts that process Loss of the Night app data for the new data format that is produced by the new version of the app. Because of this, your observations might not appear on the GLOBE at Night map. You can check if your data was sent on the "User Data" page under "My Measurements". If it says "successfully sent", then we should have your data.

I will try to remember to post when we have new scripts up and running to generate the points for the map. Sorry for the inconvenience!

Tuesday, November 18, 2014

An example of user data with the new version of the app

I've been browsing the incoming Loss of the Night app data, and I wanted to share the details of a recently submitted observation.

One of the things that we changed in the new version of the Loss of the Night app (iOS, Android) was to give users more options to describe what stars look like. The original app had three options: visible, not visible, and unsure. In the new version*, we now ask users to distinguish whether the star is "clearly" or "barely" visible, and added a new option, "visible only with averted vision".

If you've used the app outside, you've probably noticed that sometimes you can't see a star when you look directly at it, but when you look off to the side it appears. This is because the very center of your eye is packed with color sensing cones for vision in daytime, rather than the rods we use to see at night. The cones aren't sensitive enough to see the star, but if you look just off to the side, your eye has enough rods to let you see it.

The plot below shows the observations that project contributor Matt Sidor took using the app on the outscirts of Davis, California a few nights ago. The filled in blue circles are stars that are clearly visible, the black stars are stars that were barely visible, filled in red circles were visible only with averted vision, and empty red circles were stars that were invisible.


Matt did a fantastic job! With 14 stars, he had almost perfect separation between the stars that he could see directly and the stars that he couldn't. The new classifications give us more information than was available in the old version, and should lead to more accurate estimations of the sky brightness.

The other thing the image shows is how the app now focuses much more carefully on stars close to the limiting magnitude. Compare the stars Matt was asked to see with older data from the original app version below:

The older version of the app was much less aggressive about testing stars near the limiting magnitude. We expect that by staying closer to the limit, user observations will be more accurate. When an observer makes a mistake (it happens!), the range over which the app tests grows in response. When you finish your observation, the app will let you know how accurate your measurement was. If you use the app over time, you can see if your accuracy improves as you get more practice!

* I'd like to acknowledge this recent paper by Andrew Crumey as the inspiration for us to move from 3 possible classifications to 5. In case you don't have access, a preprint is also available.

Monday, November 10, 2014

New version of the Loss of the Night app is released!

The updated version of the Loss of the Night app is now available for iOS and Android!


The app lets citizen scientists like you measure how bright the night sky is, by seeing which stars you are able to see. The more faint stars you can see, the more natural your sky is. Your results are then shared with the GLOBE at Night project, and will be used to track how the night sky is changing in response to widespread adoption of LED lights.

What's in the new version?
  • Improved feedback: We fit your data and tell you the estimated naked eye limiting magnitude, approximately how many stars are in your sky, and how consistent your observations were:

  • Smoother behavior: Phones that had problems with an unstable star field should now be fixed.
  • More customization: You can change font sizes and switch the screen brightness between a city/country mode. Pinch zooming will replace the zoom buttons.
  • Better night mode: Removal of gray backgrounds and replacing orange with red in many places.
  • Improved measurement technique: new options to tell us if the star is clearly or barely visible, or if you can only see it with averted vision
  • Better set of stars used: So the app is quicker and easier to use, and more accurate
  • Expanded language support: To Czech, Hebrew, Slovak, and Turkish
  • News about our project: Links to these blog posts on the news page
  • Calculation of next possible observing time: If the moon is up, the app will figure out when the next good (evening) observing time is for your location, and let you put it in your calendar
  • Feedback button: So you can tell us what we should do next! 
  • Faster GPS convergence

Thanks to everyone who gave us feedback on how to improve the app, to the translators, and to everyone who has used the app and provided us with data. This new version couldn't exist without you!

Now, we need your help once again to spread word about the app, because the project will only be a success if there are thousands of people taking data worldwide. So please post news about it on social media, tell your friends about the app, and give it a good rating in the app and play stores to help make it more visible!

If you'd like some more information, you can read our press release. Step-by-step guides for using the app are available for iOS and Android.

Sunday, November 9, 2014

A step by step guide to using the Loss of the Night app for iOS

This is a step by step guide to using the Loss of the Night app for iOS (v1.0.4). If anything is unclear, let me know in the comments and I will revise the instructions.
Instructions for Android
Infos auf Deutsch 

Requirements:


iPhone (some iPads can also be used)
A location with a light polluted sky.
A friend to accompany you while you are doing observations.
The ability to see at both near and far distances without removing glasses.
Your phone case must not have a magnetic clasp.

Before you start:


The Loss of the Night app is meant to be used outside at night. For safety's sake, inspect the area where you plan to do your observation during the day, and make sure that it has level ground where you can move around safety.

People using mobile phones are less aware of their surroundings, so you should never use the app alone outdoors at night! Always take a friend to watch out for potential hazards while you are using the app. These could include tripping hazards, vehicles, dangerous weather, and crime. If for some reason it's not safe to do an observation, put down your phone and leave the area immediately!

Installing the app:


To install the app, do a search in the app store for "Loss of the Night". Alternatively, type this address in your browser: http://tinyurl.com/vdn-ios

Or by scanning this QR code:

qr code 

Running the app:


When you first open the app it will display the privacy policies and terms and conditions. To go further, you will need to read the conditions and then click "Accept Privacy Policy", then "Start Application".

When you click "accept" you are brought to a screen with information about light pollution. Click "next" to go on.

Next comes a screen titled "USE". We would appreciate it if you would register and tell us something about your vision and your observing experience. Click "Register Now" or just "Continue as a guest".

If you choose to register, tell us your approximate age by clicking on the word "Age" and then scrolling to the correct age range. Click elsewhere on the screen to select the age. Next, click to tell us whether you wear glasses, and how much stargazing experience you have. We also ask you to provide a username and your email. If you provide your email, we will send you a thank you email within about a month of your observation. In extremely rare cases we contact a user if we have questions about their data. When you have finished entering your information, click the ⧁ button to go to the main menu.

Making an observation


To start an observation from the main menu, click "start observing stars".  The screen will show you an indication asking you to tip your phone into landscape mode. At this point, the app will only work properly if you're outside, as it needs to get a GPS signal. This can sometimes take up to a few minutes.

If it is still twilight or if the moon is in the sky, the app will give you a message that it's not "dark enough". The moon prevents measurements from being made for about two weeks at a time, so if this is the case, the app allows you to add a note to your calendar when the next observing period at your location starts. (Click "Measure anyway" if you'd like to test out the app.)

(At this point, in locations with a lot of magnetic material or electric cables around, your phone may give you a warning that your compass has a problem. You can try to calibrate it by moving your phone in a figure 8, or turning it around all three axes. It this doesn't work, then there is either a problem with your location or your phone's compass. You can opt to measure anyway, but the stars displayed on the phone will likely be shifted compared to the ones in the sky.)

Next, you are asked to input the current weather conditions. Click the relevant symbol (or symbols), and then "Continue".

Star search

The app will now try to direct you to one of the brightest stars in the sky. Turn your body in a circle and watch how the arrow changes direction. Tilt your arm down so that your app is pointed toward the ground, and it will show you the stars that are under the Earth. Tilt your arm up to the sky, and it should show you the stars that are currently in the sky. It is very important that while looking at the stars in the sky you keep the phone's screen oriented perpendicular to your body!


Now search for the star the app is asking you to look for. Turn your body until the arrow points straight up, and then raise your arms until you see a star with a crosshair on it. When you find the star, the circle will expand to fill most of the screen and three buttons will appear at the bottom of the screen.


Your job is to decide whether the star the app pointed you to is visible to your naked eye or not. If you can see the star, then click "Star is visible" on the bottom right. The app will then ask if it's "clearly visible" (very obvious and easy to see) or "barely visible" (you can see it while looking at it directly, but just barely).

If you cannot see the very first star, there may be something wrong with your phone. The app always starts with one of the very brightest stars in the sky, which should be visible even inside of large cities. The most likely problem is that your compass is not working properly. If your phone is in a carrying case that has a magnetic clasp, you will need to take the phone out of its case and then recalibrate the compass (quit the app, and then start it again).

If the stars appear to be bouncing around a lot, you may be in a location with strong electromagnetic fields (e.g. near overhead or buried power lines). It's best to try to use the app in a grassy area, like a park. Finally, it's possible that the compass or GPS from your phone is not working properly, and if this is the case the app will not work on your phone.

Continuing your observation


Each time you find a star, the app will ask you if it's visible or not. If you can't see the star for some reason, click on "Not visible or unsure". You will then be brought to a menu that gives you five options for why you can't see the star. Choose the option that is most appropriate:


If you can see the star only when you don't look directly at it, or if is only visible some of the time, then choose "Visible only with averted vision". If you're not sure which star we're asking for, or if for some reason you find it too hard to tell whether the star is there or not, choose "I'm not sure if it's there or not".

Once you have made a decision on a total of 8 stars, the app will pop up a message that says "8 stars reached". You will have the option to quit, "Register" (if you haven't done so already), or "3 more stars". We would really appreciate it when you observe a few additional stars, because observing more stars improves the accuracy of your measurement.

If you click "3 more stars" the app will ask you again when you reach 11, 14, and 17 stars. After that, if you want to continue, it won't interrupt you anymore, and you can click the "back" button whenever you are ready to end your observation. When you end your observation, the data is automatically sent to a server hosted by the GLOBE at Night project if your phone has an Internet connection. If you have a data plan, this should happen immediately, otherwise, it will be transferred the next time you have a WiFi connection.


When you finish your measurement, the app will let you know how faint the faintest visible star in your sky is (naked eye limiting magnitude), and approximately how many stars are visible in your sky. For reference, in places without light pollution, it's possible to see many thousands of stars. The app will also let you know how consistent your measurements were. The more you use the app, the better you will get at making accurate, consistent observations!

Accessing your data


The app stores the results of your observations on your phone. In the main menu, click on "User data" and then "My measurements". A screen will come up showing the dates that you did observations, and the results. If you click on an observation, then the app will show you the names and magnitudes of the stars that you looked for, and what your decision was (stars with smaller magnitudes are brighter.)

Personal settings


The "User data" menu allows you to change some of the app settings. You can toggle the display of star and constellation names, and choose whether some screens display on start up. You can also increase the size of stars and fonts (this might help if you are farsighted). If you find that the screen is too bright during your star observations, click "Make screen darker" and see if it helps.

Additional information:


As the year goes on, different stars appear in the night sky over your head. If you enjoy using the app, feel free to use it as often as you like!

The app contains a lot of information about light pollution that you might find interesting. You can access this information by clicking on "Project information" in the main menu.

You can also switch between "Day mode" and "Night mode" in the main menu. Please use the Night mode when making observations, because it is designed to have less of an effect on your night vision.

If you have a Sky Quality Meter, you can submit data taken with the device as well. From the main menu, click "Submit data from SQM" and then use the scroll wheels to enter the SQM value.

More information about the Loss of the Night app project is available on our blog.

If you'd like to read a paper that demonstrates the scientific value of citizen observations of naked eye star visibility, you can access it for free here.

The app is available in 15 languages, and automatically uses the language that your device is set to.

Thank you!


Thank you for taking part in this project! Your data will help us understand how the brightness of the night sky is changing around the world. Because we are interested in understanding long-term changes, the most valuable data are observations taken at the same place year after year.

Wednesday, November 5, 2014

A step by step guide to using the Loss of the Night app on Android

This is an old version of the instructions for using the Loss of the Night app for Android. New instructions for version 2.1.7 are available here.


Loss of the Night app expanding to 15 languages!

The updated version of the Loss of the Night app is going to come out very soon. In addition to lots of new features, we've added support for Czech, Hebrew, Slovak, and Turkish.

We would like to recognize our volunteer translators for their considerable donation of time to this project:



Arabic: Amr Al-Omari
Catalan: Salvador Ribas
Chinese: Yongguang Zhang
Czech - Milada Moudrá, Michal Bareš
French: Olivier Domingue, Johanne Roby, Martin Aubé, and Romain Clément
German: Annette Krop-Benesch
Hebrew - Roni Segoly
Italian: Andrea Giacomelli
Japanese: Nobuaki Ochi
Polish: Ania Wisniewska
Romanian: Catalin Daniel Galatanu
Slovak - Jaroslav Merc, Peter Begeni, Pavol Rapavý
Spanish: Salvador Ribas
Turkish - Nail Köker

Thanks to all of you for helping make this a truly international project!

If you are interested in helping us expand the app to include your language, please send me an email.

Monday, November 3, 2014

There's a (weak) meteor shower during November's observing period

This month the observing period for the Loss of the Night app runs from about November 10 to November 27*. That means that this year's Leonid meteor shower on the night of November 17 will be visible at the same time that you can do app observations. The Leonid shower isn't expected to be particularly dramatic this year, but since the Leonids are known for producing particularly bright meteors that can be easily seen inside of cities, it might be worthwhile to go out if you have clear skies on the 17th.

Leonid Meteor
A Leonid meteor during the 2009 shower

* exact dates depend on where you live, and what time of night you want to observe.

Sunday, October 26, 2014

Photos from our light over Linz, Austria

Tonight we did a measurement flight over the cities of Linz and Wels in Austria. The goal is to make a mosaic image of these ares of Land Oberöstereich, in order to understand the region's waste light emission. We have done something very similar for Berlin.

I wanted to share a few photos from tonight's flight:













The project is a research collaboration between Freie Universität Berlin, Universität Wien, and Land Oberöstereich. The flight costs were paid for by Land Oberöstereich.

Friday, October 24, 2014

Hesitations on the 2014 Nobel Prize in Physics and its negative impact on human health – was this the aim of Nobel Prize?

This guest post was written by my colleague, Professor Abraham Haim, from The Israeli Center for Interdisciplinary Research in Chronobiology, University of Haifa. Professor Haim is also the vice chair of the Loss of the Night Network (LoNNe). The views presented here are his own. My comments regarding the Nobel decision are available here.


Recently the 2014 Nobel Prize in Physics was given jointly to Isamu Akasaki, Hiroshi Amano and Shuji Nakamura "for the invention of efficient blue light-emitting diodes which has enabled bright and energy-saving white light sources".  This is of course a huge scientific achievement and they should be congratulated for receiving this prestigious prize. Many of us in the scientific community would be delighted with being awarded the Nobel Prize and I am sure that when we carry out research, somewhere in our mind we think that maybe the results could bring us closer to this desired prize.  However, this recent award raises more fundamental questions about how the negative impacts of such research should be acknowledged and the difficulties created when such prizes disproportionately raise public awareness about their positive applications.
To the best of my knowledge the Nobel Prize foundation was established in response to the concerns of Alfred Nobel, that his inventions (notably explosives) had inevitably let to large-scale loss of life through diverse military applications.  The spirit of the prizes was therefore to reward research that supported global peace, health and other benefits related to human wellbeing. What is irritating in the decision of the committee awarding the prize to the three distinguished physical scientists is the apparent lack of awareness that LED lamps deliver energy saving at the sake of our environment and health. Exposure to blue light from LEDs has a high health risk well known in environmental literature, and scientists are looking for ways to eliminate this wavelength emission from LED bulbs. A question to be asked in regards to the committee decision is: Shouldn’t the members of such a distinguished group pay attention to environmental and health problems arising from the invention? In the case of light pollution, many of the leaders of the high profile campaign for dark skies come from the discipline of astrophysics, as in Western Europe and North America it’s difficult to observe stars. LED illumination is increasing the problem due to its intensity and the aggressive way it penetrates our lives. The potential negative medical impacts such has epigenetic modification would be recognized only after ten years or more, if I am correct. So far we have demonstrated that blue LED can suppress melatonin production and among the known sources of illumination this is the most efficient one. The neuro-hormone melatonin produced in the pineal gland during the dark phase of the 24h cycle is a “jack of all traits”, but is particularly important for our sleep, it is also an efficient anti-oxidant and anti cancer agent in regards to breast and prostate cancer. In June 2012 the American medical Association passed a resolution that light at night is a source of pollution; were the distinguish committee members not aware of this resolution?     
In our modern lifestyle most of the new electronic devices we use include LED in their screens or operation light indicator and many of these find their way into the bedrooms of young people who are exposed to this illumination during their sleep, when they need to be in the dark to produce the neuro-hormone melatonin. Looking directly to the source of LED illumination may also destroy our retina as indicated by results of studies carried out on this topic, which showed that LED illumination can result in death of retinal cells. LED technology as a source of illumination in public spaces is under discussion where those with an environmental approach would argue that we need more research in regards to smart use of this technology. Awarding a Nobel Prize at this stage is a mistake, as the unintended consequences of LED lighting are only starting to emerge. The information given here is mainly intended to help make the public aware of the danger of using LED illumination, yet there is a basic awareness of this issue within the scientific community, which should have been considered by the prize committee.  It cannot be said that “we did not know”.  I feel like the child from the story by Hans Christian Andersen, who did not pretend to admire the “new clothes of the king” and shouted “The king is naked”.                  
As has happened with past awards there is a strong risk that the integrity of the Nobel Prize may be undermined, when the large-scale negative impacts of LED lamps are realised.  In fact, surely the origin of the Nobel Prize itself points to the argument that researchers and inventors should not only seek to develop new technologies, but also to address their weaknesses and to avoid unintended consequences for society.   

Wednesday, October 22, 2014

Your chance to see Berlin at night from the air

I've flown over Berlin at night many times as part of our research campaigns to understand the light emission of the city. It's a very cool experience, and for a short time, it's open to everyone.



During the celebration of the 25th anniversary of the fall of the Berlin Wall, Air Berlin is operating a special flight over the city. In addition to the many historic and modern landmarks visible from the air, thousands of lit balloons will mark the former path of the wall through the city.

I suspect that the balloon display will be more moving from the ground than from the air. But I think this is a great opportunity, and I can highly recommend the experience to anyone who loves Berlin!

Tuesday, October 14, 2014

GLOBE at Night observing period begins tonight

Once again the moon has gotten out of the way in the evening, and it's possible to observe skyglow via GLOBE at Night, the Dark Sky Meter app, or the Loss of the Night app. This early evening moon free period runs until October 23.

Friday, October 10, 2014

Moon phase calendar for 2015

Loss of the Night app user Andrew Cool from Australia has once again produced his very cool calendar of the phases of the moon in 2015:


You can download his original images in high and low resolution on his SkippySky website.


If this is your first-ever visit to the blog, welcome! The blog is about a citizen science app called "Loss of the Night". We need your help to understand how changes in street lighting technology are changing the night sky. You can read our introduction to the blog here, and instructions on how to use the app here.

There's lots more to see, including:
You can see bring up our entire photo series via this link, and all of our posts about the moon here. Thanks for visiting!

Thursday, October 9, 2014

Last night's lunar eclipse, viewed from space

Each night, an instrument called VIIRS DNB takes visible band images of the entire Earth. When the moon is up, it's really easy to see the patterns of the clouds, and when the moon is set you can basically only see the artificial light from cities. But what happens when you have a lunar eclipse? This:

2014/10/08 lunar eclipse viewed by VIIRS DNB by Christopher Kyba & NOAA
is licensed under a Creative Commons Attribution 4.0 International License.
Based on a work at http://ngdc.noaa.gov/eog/viirs/download_ut_mos.html.
Image and Data processing by NOAA's National Geophysical Data Center.

As the Earth's shadow darkened the face of the moon, there was progressively less light for DNB to be able to see land, clouds, and sea. As a result, with each pass of the satellite the image gets darker. The satellite takes about an hour and a half to go around the Earth, so the effect lasts over 2-3 passes. Since we don't have a geostationary satellite capable of imaging the Earth in moonlight, it's not yet possible to produce an video, like this one of a solar eclipse.

For the next several days, you can access the full (giant) resolution image from NOAA. You can get an in-between resolution image from my personal webpage.

If you'd like to see images of hurricanes imaged by VIIRS DNB with moonlight, follow @DanLindsey77 on twitter:

Note for new visitors: This blog is about the Loss of the Night citizen science app, which lets regular people measure how bright the sky is by looking at stars. The goal of the app is to track how the brightness of the sky changes as LED lighting is implemented worldwide. The app is free, and can be downloaded for Android phones. An iPhone version is in development and will come out soon.

Tuesday, October 7, 2014

The promise and the peril of LED lighting

Wonderful news for Isamu Akasaki, Hiroshi Amano, and Shuji Nakamura, who won the physics Nobel Prize today "for the invention of efficient blue light-emitting diodes which has enabled bright and energy-saving white light sources"!

When used for outdoor lighting, white LEDs (which are built out of blue LEDs) have two incredibly useful properties. First, they can be directed more carefully than the older gas discharge tube lamps, and that means that with good design it's possible to put light on a walkway and the surrounding areas without shining lights up into the sky, into people's bedroom windows, and without glaring down the street. Second, they can be turned on and off and dimmed instantaneously. This means that dusk-till-dawn lighting can become a thing of the past, and in the future city lighting will hopefully be delivered on-demand, rather than left burning on every street all night long.

 It's possible to imagine a future in which driverless cars run without headlamps (the car itself can be dimly lit to make it visible), pedestrian and cyclist lights provide more uniform lighting at greatly reduced light levels, and the sky above even large cities once again glitters with thousands of stars.

But unfortunately, this future won't come about simply thanks to the genius of the physicists honored today. It will take the combined efforts of hundreds of thousands of other lighting innovators: engineers, designers, city planners, and perhaps most importantly, lawmakers. The problem is that without careful design and planning, high efficiency LEDs can end up looking like this during the night:

Exposure set to match street level
Exposure set to image the screen

At the corner of one of the busiest pedestrian crossings in Berlin (Kurfürstendamm and Joachimstraße), drivers turning right through a crosswalk are blinded by an LED screen that's left running at daytime appropriate levels during the night!

Due to the remarkable compactness of LEDs, the glowing area of the lamps themselves are far brighter than many older style lamps. This, combined with their greater component of blue light can make them far more glaring, a problem that disturbs both drivers and pedestrians alike on many poorly lit LED streets.

Interesting architectural lighting can be accomplished using highly efficient 1 Watt LEDs. But if it's poorly designed, it blind visitors to the city coming out of a train station into an unfamiliar surrounding, such as this problematic area just outside of the Alexanderplatz station in Berlin:

Exposure adjusted to street levels

Exposure auto-set by camera

In the coming decade, LED lighting is going to entirely change the way we light both indoor and outdoor spaces, and for that we should most certainly thank today's prizewinners. But will we actually save energy - or just waste extra light? And will we have a more pleasant living environment? The answers to these questions will depend mainly on their implementation.

Note for new visitors: This blog is about the Loss of the Night citizen science app, which lets regular people measure how bright the sky is by looking at stars. The goal of the app is to track how the brightness of the sky changes as LED lighting is implemented worldwide. The app is free, and can be downloaded for Android phones. An iPhone version is in development and will come out soon.

Monday, September 29, 2014

Announcing the "International Nights of Skyglow Observation" in 2015

In many areas of the world, the Milky Way is no longer visible, due to waste light emitted from cities. This "skyglow" represents a great deal of lost energy, and is in a large part due to poorly designed or incorrectly installed light fixtures. For the last century, skyglow has increased dramatically year after year, but with the development of new lighting technologies and laws regulating light emission, it seems possible that skyglow could actually be reduced in the future - without turning all the lights off. Because skyglow may be having important effects on ecology, scientists want to track how it is changing. One of the best ways to do this is through citizen science.

While it is possible to take citizen science data about skyglow all year round, such data is easiest for scientists to analyze if it is taken in a burst around the same time each year.  Therefore, two "International Nights of Skyglow Observation" are being established as a part of the International Year of Light. Citizen scientists from around the world will measure how bright the night sky is, and report their data either through the web (GLOBE at Night) or via their smartphone with the Loss of the Night (Android/iOS) or Dark Sky Meter (iOS) apps.

In addition, we expect that in several cities, "Flashmob for Science" events will be organized, where tens or hundreds of people come together to make observations at the exact same time and place. This will help us understand how measurements vary with different observers (and different phones).

The dates for 2015 are March 14 and September 12.

This could be you next year in March and September next year!

 If you want to hold a Flashmob for Science in your city, please read our guidelines for holding the event, and then get in touch with me.

To make the event a success, we need as many people to know about it as possible!  Please pass the dates and this link on to anyone you think might be interested (e.g. teachers, amateur astronomers, or jorunalists).

(Click here to see all posts on this blog related to the International Nights of Skyglow Observation)

Update October 17: DaNel Hogan points out that if you want to truly get into the spirit of Pi-day, then you should make your observation at 9:26 pm (i.e. 3/14/15 9:26)!


Thursday, September 18, 2014

Star trails in Australia

One of the original testers* of the Loss of the Night app recently created this cool photo of star trails far from city lights in the Outback of Australia:

South Celestial Pole Star Trail by Andrew Cool is licensed
under a Creative Commons Attribution 4.0 International License.

Andrew says that there was a great amount of green airglow visible on the night he made the photos. The image was originally published by the Planetary Society.


*I was very grateful for Andrew's help in testing the app in the Southern Hemisphere. It turned out that the first version we gave him to test asked him to look for the stars that were currently up in the sky... over Germany! So Andrew was left staring at his boots instead of up into the sky.

Monday, September 15, 2014

Moon free observing period has started

The 9th period of GLOBE at Night's 2014 campaign begins tonight, and that means that Loss of the Night app observations are possible again as well. The current observation period lasts until September 24 (and several days later for our app, if you're willing to stay up until the moon sets).

Tuesday, September 9, 2014

Can you see colors and read text under (full) moonlight? Yes!

If you look around the web for the answer to this question, you'll find a lot of conflicting information. A number of seemingly authoritative sources declare flat out that colors cannot be seen under moonlight, because the eye's cone cells are not active. The same sites also often mention that normal sized printed text cannot be read in moonlight, because the central fovea is packed with cones that won't be active. Both of these claims are false.

Since this is something that's really easy to test, there's no reason for this misconception to persist. All you have to do is wait for a night with a full moon, find a place outside that doesn't have any direct lamp light (e.g. a park), take something colorful with you (e.g. a children's book), and see if you can recognize the colors or not.

I did it last night, with Mr. Forgetful:



I found out the answer right away: I was able to distinguish the red hat and blue body not as different shades, but as "red" and "blue". I did have more trouble on some other pages. For example, on the page below I was pretty sure that the "grass" wasn't green, but I had no idea what color it was. When I went back inside I found out it was not actually grass, but brown dirt:


I also had no trouble at all reading the text, which is probably about 14 point font. I tried reading a text with a smaller font, and while I had a bit more difficulty, it was certainly still possible.

But please don't take my word on this! This is a science experiment that can be performed by anyone without vision impairment, so the next time there's a full moon, go out and try it yourself!


You might ask why any of this matters. It turns out that this actually came up one time in court! A witness claimed to have seen a red car under moonlight, and experts called to testify disputed the fact that such a feat was even possible. The case motivated some Australian researchers to do a controlled test. It turns out that certain colors are easier than others (red is the easiest), and the color of larger objects is easier to discern than smaller objects.

But there's another reason why it's important. The confusion online demonstrates the extent to which vision at night is poorly understood. It's almost certainly the case that lighting levels in our cities could be dramatically reduced without meaningful effects on visual performance. Doing so would save money, energy, might help people sleep better, and would bring many stars back to our urban skies. But how low can we go and still be able to see well on city streets? The world spends something close to 100 billion dollars per year on outdoor area lighting, so spending a few million to get the right answer could result in a massive payback in reduced electricity bills.

Monday, September 8, 2014

The harvest moon and lunar elevation

Tonight is the full moon, and since it's the moon closest to the autumnal equinox, it's the "Harvest Moon". I found a number of explanations of why it's called the harvest moon online (e.g. this one by Bob King), and everyone mentions the fact that for several days, the moon rises near the sunset time. The moon therefore allows people to bring in crops by moonlight, hence "harvest" moon. I'm not a historian, but I have a very strong suspicion that this is only a part of the story.
autumnal equinoxa
autumnal equinox
autumnal equinox
autumnal equinox
autumnal equinox

Moonrise over Nationalpark Müritz by Alejandro Sanchez de Miguel is licensed
under a Creative Commons Attribution 3.0 Unported License.

If you think back to a memory of walking through the country on an extremely bright moonlit night, the odds are very good that you'll be thinking of a snow-covered winter landscape. Snow of course makes the landscape much brighter, but full moons are also brighter in winter because the full moon rises much higher in winter than it does in summer. (A useful way to remember this is that the full moon always does the opposite of the sun: in summer it's low in the sky, and in the winter it's high).

But it's a bit more complicated in the spring and fall. At those times, the highest elevation moons are during either the first quarter (spring), or the third quarter (fall). Now here's where I think the "harvest" moon comes in. In the days shortly before the full moon in autumn, the moon sets shortly after midnight, and the landscape isn't particularly brightly illuminated because the moon doesn't rise very high in the sky (both of which are not so useful if you want to work all night). In contrast, the moon soars high in the sky in the days immediately after the full moon in autumn.

This year in Berlin, the moon on September 6 (3 days before the full moon) reaches only 24° above the horizon. On September 12 it's 47° above, and that makes the landscape about 78% brighter (if I accounted properly for the light absorbed and scattered by the atmosphere, it would increase that number even further).

I'd love to hear from a historian whether I'm right about the nighttime harvest taking place on the days after the full moon rather than before. If you anyone knows, or can find information about this from a reliable source on the Internet, please make a post in the comments.

Thursday, August 28, 2014

15,000th observation submitted!

The Loss of the Night app project passed another milestone today, with the 15,000th observation being submitted early this morning. The observation was made by an anonymous user in New Jersey, USA under partly cloudy skies. The naked eye limiting magnitude was about 4, with 5 of 7 stars observed.

As I noted when we passed 10,000 observations, most submitted observations are not made under ideal conditions. Sometimes people test or demonstrate the app indoors, sometimes the moon is up, and very often (as in the case of observation #15,000) the sky isn't clear. But through the dedication of our participants, we are continuously building up a record of how skyglow is changing worldwide.

Now the race is on to observation #20,000. To celebrate that milestone, I will again send a holographic postcard to the registered user who makes a complete observation (7 or more stars, no moon, no twilight, no clouds) with the observation number closest to 20,000.

Tuesday, August 19, 2014

New version of the app is coming soon - we need your help this week!

An updated version of the Loss of the Night app is currently in development. The most exciting changes will include:

  • iPhone version!
  • Improved feedback: We fit your data and tell you the estimated naked eye limiting magnitude, approximately how many stars are in your sky, and how consistent your observations were.
  • Smoother behavior: Phones that had problems with an unstable star field should now be fixed.
  • More customization: You can change font sizes and switch the screen brightness between a city/country mode. Pinch zooming will replace the zoom buttons.
  • Better night mode: Removal of gray backgrounds and replacing orange with red in many places.
  • Faster GPS convergence
  • Expanded language support
  • More accurate measurement technique
  • Better set of stars used

We can still use your help with that last point!  The new version has removed stars that are so close together that it's difficult to tell which we're asking for, for example the Pleiades and Alcor. But we have also built in a new list of "easy" stars. These are stars for which you, the users, were able to make decisions on quickly and decisively. We have lots of data about bright Northern Hemisphere stars, but we've had far fewer observations of faint stars, and much less data from the Southern Hemisphere.

The final list of "easy" stars needs to be completed by Monday, so there's one week left for you to help us learn which stars are the best! If you have clear skies at some point this week, please take a moment to go outside and use the app. The more stars you observe, the better, so if you are enjoying yourself, please continue after you've reached seven stars.

This could be you this weekend!

Thank you to everyone who has used the app in the last year!
We appreciate everyone who provided valuable feedback through email or comments!
Dankeschön to our translators!

And finally, if you've told other people about the app, then we can't thank you enough! The more people that take part, the better and more accurate our results will be.


Watch for the official announcement of the new version here in the fall.

Wednesday, July 9, 2014

How to find pictures of cities at night

Update December 16, 2014: NASA has changed their website around, breaking nearly all of my links to their pages. I will update this post sometime over the Christmas break.


Astronauts have taken over a million photographs of Earth from the International Space Station. Many of them have been taken at night, like this one of Berlin:

Berlin at Night from the ISS, original image ISS035-E-17210 available here.

NASA has made all of the images freely available through its "Gateway to Astronaut Photography of the Earth". But when you've got a haystack of 1.2M photos and you just want to find the original of the one Chris Hadfield took of Calgary at Night, you could use some help to find what you're looking for.

A group of ISS photo enthusiasts and light pollution researchers have solved your problem by putting together an Atlas of nighttime images of the Earth. This post is a short note to help you use a feature of the Atlas that's not necessarily very obvious from the main page.

When you go to the main page, scroll down to "Gallery of cities at night". Here you can scroll and zoom over the Earth to find a city (like Calgary). When you click on the dot, it will pop up some information about the photo, as well as a thumbnail:


The thumbnail has a link to the photo at the NASA gateway - but if you click on it you'll notice that it's not the one that Commander Hadfield tweeted! The problem is that multiple photos of Calgary have been taken.

While the Atlas website is super for finding cities that have been imaged, it's not what you want to use if you're looking for all photos of a given city. To do that, you want to click below where it says "Original at http://www.nightcitiesiss.org."

When you click there, you will get to a google spreadsheet that looks like this:


Now click on "Table of data" near the top left, type the city you're looking for in the box at the top left, and then click "Find":


Now you can see more detailed information about the photos, including thumbnails and links to the NASA site if you scroll way over to the right. The photo that Chris Hadfield took is the top one on the list, and now you can go to the NASA site and get the link to the full resolution photograph of Calgary at night.

The last step is to scroll down on the NASA page to the two "view" buttons. Click on the bottom one:


and voila, here is your full resolution image:

Calgary at Night from the ISS, ISS034-E-44268

The images from the NASA site are all free to use, provided you acknowledge the photo source (there is a recommended citation at the bottom of the page). To make it easier for other people to find the photo in the future, be sure to always include the image designator that starts ISSxxx.

If you use the Atlas to find a photo and then publish the photo somewhere, then please also cite this paper: Alejandro Sánchez de Miguel, et al., Atlas of astronaut photos of Earth at night, Astronomy & Geophysics, Vol. 55 no4. August 2014 (in press).

Going forward

The best part about the Atlas website is that it includes three citizen science projects to ensure that future photos are cataloged, and to find other older images "hidden in the dark of the database".

Dark Skies of ISS allows citizens to sort images between different types: Images of cities, images of stars, and other images. It requires no previous knowledge, and is only available online. It is the simplest of the three projects.

Night Cities aims to allow citizens to apply their lay knowledge of local and international geography. The project shows paired images of cities with maps. Project volunteers identify points in the night images and match them to positions on the maps. With this help we can generate light maps of cities.

Lost at Night is the stiffest challenge for citizens with good geographical knowledge of a region. Their goal is to identify which city is in an image without any identification. The position of the cities in this case is only known to within about 500 km.




Note: If this is your first-ever visit to the blog, welcome! The blog is about a citizen science app called "Loss of the Night". We need your help to understand how changes in street lighting technology are changing the night sky. You can read our introduction to the blog here, and instructions on how to use the app here.

There's lots more to see, including:

You can see bring up our entire photo series via this link. Thanks for visiting!