Thursday, December 10, 2015

Amazing new photos from the International Space Station

The astronauts on the International Space Station have recently taken some absolutely outstanding photos of cities at night. Let's start with my former home of Berlin:

Berlin, Germany

That's quite possibly the best photo of Berlin I've ever seen taken from the ISS!

The orbit of the ISS limits it to a band of latitude from about 52° S to 52°N. During a recent pass, the ISS reached its northern limit as it flew over North America. That allowed the astronauts to snap:

Tacoma, Washington, USA

Seattle, Washington, USA

Calgary, Alberta, Canada

Saskatoon, Saskatchewan, Canada

Winnipeg, Manitoba, Canada

I don't know which town this is, it's somewhere near the Atlantic coast.
If you know, let us know in the comments!

You can click on the names above to get access to the full resolution images.

These are some of the best nighttime photos I've ever seen taken from the ISS. Here's a zoom in of the Calgary photo to show just how amazing it is in full resolution. You can see the pattern on the ground from the individual lights, and the outline of buildings with illuminated surrounding areas:

Zoom in of the Calgary image

I accessed these images from the NASA website, who ask that if you use the image you provide this caption: "Image courtesy of the Earth Science and Remote Sensing Unit, NASA Johnson Space Center". However, I'm not sure which astronaut took the photos, so thanks may also be due to one of the other space agencies, and getting such imagery is only possible thanks to the European Space Agency's Nightpod instrument.

If you like looking at images of cities at night, you can help out our research by classifying images and identifying cities! We will use your classified images to understand the sources of light pollution, and to track changes in lighting technology to understand whether cities as a whole are really saving energy or not with the transition to LEDs.

I'd also like to thank Alejandro Sanchez de Miguel (leader of the cities at night project) for forwarding me the links to the Berlin and Calgary images.

UPDATE Dec 11, 2015: Alejandro passed on another amazing image of Frankfurt:

Frankfurt, Germany

Check out the amazing detail of Frankfurt Airport:

Zoom in of Frankfurt Airport

Monday, December 7, 2015

Ideas for future app releases

Update: Changes have been made to the app since this post. For a more recent update list see here.

Thursday, December 3, 2015

Putting citizen science data back in the hands of citizens!

I'm very pleased to announce that our new web application for viewing skyglow data taken by citizen scientists is now online, at!

It allows you to view where data has been taken:

Skyglow observations in Europe and northern Africa

It lets you view individual Loss of the Night app observations:

A single Loss of the Night app observing session by a citizen scientist

It allows you to do trend analyses to see how skyglow is changing:

Trend analysis for Globe at Night data in Tucson, Arizona
 And it also allows you to access all of your own data, using the "My Measurements" tab.

It will take a few years of observations before the trend analyses start to be really useful, so go out and observe your night sky often! Bur right now, head over to, and have some fun exploring the data collected by tens of thousands of citizen scientists from around the world!

Tuesday, November 24, 2015

Gift idea

Here's a chance to give someone a gift and do something to help conserve the night at the same time: give them an IDA t-shirt!

There are 3 different styles to choose from (the one pictured here is my favorite), and the proceeds from all three will go to support IDA's work, such as managing the International Dark Sky Places.

Monday, November 23, 2015

Submitted photos

I have some photos to share taken by friends of the blog. First, a photo of the skyglow caused by poorly shielded lamps at the Great Leighs Racecourse in Essex, United Kingdom:

Skyglow from Great Leighs Racecourse is licensed
under a Creative Commons Attribution 4.0 International License.
Click for more dramatic photos of the skyglow and lamps.

Liz Perkin (@riverperkin on twitter) snapped this photo of lamps that don't prevent animals from getting inside:

Spiderwebs in a lamp by Liz Perkin, originally posted on instagram
This of course slightly reduces the light that gets to the ground, and also greatly increases the amount of light that gets emitted into the sky. In the worst case, lamps that let arthropods inside can get downright gross.

Lastly, a photo by Roland G. Dechesne of the Royal Astronomical Society of Canada:

Thursday, November 19, 2015

Moon phase calendar for 2016

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 2016:

Northern Hemisphere moon phases, by Andrew Cool

You can download his original images in low, high or poster quality resolution on his SkippySky website. He also has a Southern Hemisphere calendar. Andrew says:

Please feel free to download the calenders. Print them by all means, but I do ask that you play nicely and retain the discrete Copyright information in each image.

If you find that the Calendars are useful, I'd be very happy to receive a small donation via PayPal to help keep the SkippySky website and my single home PC running.

Use the PayPal buttons on the website at

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!

Sunday, November 1, 2015

Photos of Berlin at night

On Saturday I flew over Berlin and took a number of photos. I posted them to twitter, and all of them are collected below:

If you liked the photos, please share your favorites along with this post on twitter and facebook!

Check out these 15 photos of Berlin at night from 9,500 feet up!

Posted by Verlust der Nacht - Loss of the Night on Sunday, November 1, 2015

Tuesday, September 29, 2015

Europe during last night's lunar eclipse

Yesterday morning the moon passed into the Earth's shadow. The period of totality happened to occur just as the Suomi NPP satellite was passing over Europe and northern Africa. Suomi carries the Visible Infrared Imaging Radiometer Suite (VIIRS), which includes a "Day Night Band" which is the best (and only) full-Earth nighttime imaging sensor. That makes for a very pretty picture:

Image and Data processing by NOAA's National Geophysical Data Center,
cropped and enhanced by me. This image can be used with credit to NOAA and me.

Blogger has limits on the image size, so you probably want to see this higher resolution version (the full resolution version is hundreds of Mb, if you want to download it you can for the next two weeks here).

When the moon is full, Suomi can see clouds and land extremely well, and oceans and lakes appear extremely dark. The brightest spots are artificial light from human settlements. For example, check out this zoom in of the Nile delta, Israel, and the Gulf of Suez from the same image:

Image and Data processing by NOAA's National Geophysical Data Center,
cropped and enhanced by me. This image can be used with credit to NOAA and me.

But during the eclipse, the moonlight is temporarily gone, and the areas of Europe and northern Africa were plunged into starlight, which is just a bit too dim for good imaging from the sensor. Luckily for us, much of Europe had clear skies, meaning that we can see the city lights shining through!

Nearly a year ago I posted an image of a lunar eclipse over North America that is maybe even cooler because of the different gradient in moonlight.

Wednesday, September 16, 2015

Clouds and aurora in a natural setting

Ray Stinson recently shared these beautiful images of aurora and clouds with me. They were taken in Glacier National Park in Montana, USA.

This image by Ray Stinson is licensed under a
Creative Commons Attribution 4.0 International License.

This image by Ray Stinson is licensed under a
Creative Commons Attribution 4.0 International License.

This image by Ray Stinson is licensed under a
Creative Commons Attribution 4.0 International License.

This image by Ray Stinson is licensed under a
Creative Commons Attribution 4.0 International License.

The orange glow at the horizon in some of the photos is skyglow from Browning, Montana, over 50 kilometers away.

A few years ago, Ray took some photos of dark clouds passing over the Milky Way for me to use in this article that looks at the effects of clouds on skyglow. For nearly all of Earth's history, clouds made the night darker, just like they do in the day. It's only recently that this has been reversed, and we have now observed overcast skies over 2,000 times brighter than the natural star filled sky. We don't yet have models that can tell us where clouds make the sky brighter, but we do know that the affected area is enormous.

Nocturnal animals specialized to live under nighttime light levels. Over much of the Earth's land surface, the night no longer occurs, there is only daytime and twilight. Unfortunately, there has been almost no research into whether and what this change has done to ecosystems.

Wednesday, September 2, 2015

on losing my right to vote

This is a story about citizenship, told by a Canadian barred from voting for working outside of the country.

My grandmother was born in 1911, in Leofeld, Saskatchewan, Canada. My grandfather was born in Germany in 1907, and immigrated to Canada in 1912 before he turned five years old. Following their marriage, my grandparents worked the Canadian prairie as farmers. For the first two years of their marriage, they walked to church, because their horses needed rest from the six days of fieldwork. They purchased their own farm in 1942, and they brought some of that land under cultivation for the first time. My grandfather died in 1959, leaving my grandmother to take care of a farm and support seven of their twelve children.

My parents met each other while working in a hospital in the remote northern village of Île-à-la-Crosse, Saskatchewan. The same spirit of adventure that drove them to live in the North led them in the 1970s to New Zealand. During my parents time there, my grandmother applied for a Canadian passport in order to visit them. Her passport application was denied because, in the words of the passport office, she was “no longer a Canadian citizen”.

The Canadian government considered my Grandfather an alien during the Second World War, and revoked his citizenship. This meant that my grandmother (who remember was born in Canada) was also no longer a Canadian citizen because… well, because women weren’t entirely people yet in those days, as far as many governments were concerned. As my grandmother had no other citizenship, this meant that she had actually been a stateless person for several decades!

We don’t know if my grandfather was informed about the revocation of his citizenship. If he was, he never told his wife. Imagine the shock and sense of loss she must have felt at being told that she was no longer a citizen of the only country she’d ever known! Thankfully, the wrong was righted, and my grandmother eventually had her Canadian citizenship restored.

I was born in Wetaskiwin, Alberta, and lived there until I moved to Edmonton to go to the U of A. In 2000, I moved from Canada to USA, to do a PhD in particle physics. The experiment I worked on was oddly enough located in Sudbury, Ontario, so in some years I actually spent over 100 days in Canada! While living In the USA as an international student, I met my wife, who is German. We moved to Germany in 2008, because I wanted to learn to be able speak fluently with my family. (It worked.)

I love Canada. I’ve been to every province (seven of them multiple times), and I hope to have the chance to someday visit my family living in Nunavut. We travel to Canada with our two children as often as we can, usually a bit less than once per year. Our children are both proud Canadians who listen to Raffi, are learning to ski and skate, and can sing “O Canada” at the drop of a touque. I hope that at some point in the future, academic jobs will open up for my wife and I, and we’ll be able to return to my home and native land.

Unfortunately, because I’ve resided outside of Canada for over five years, Canada’s election law bars me from voting in Canadian federal elections. Voting is one of the most fundamental rights and responsibilities of a citizen, so when you are barred from voting it means that you are in a very real sense not a full citizen of your country.

It’s hard for me to describe how it feels to be disenfranchised. It certainly makes me very angry. Sometimes it feels almost painful, like somehow, spiritually, a part of me is missing. There is also sadness at being excluded. Prevented from expressing my true patriot love. Unable to stand on guard for the country, by helping to choose its leadership.

The most frustrating part about this exclusion is that it is so unnecessary. The Canadian Charter of Rights and Freedoms spells it out in black and white:

3. Every citizen of Canada has the right to vote in an election of members of the House of Commons

The Canada Elections Act is clearly unconstitutional, and I hope that the Supreme Court will find it so when a challenge eventually comes. (You can help with that!) In the meantime, I hope that whenever you hear about Canadian expats, you’ll think about people like me. We are people with deep roots in Canada. We love our country, and we want to continue to be a part of it. It’s just that for reasons of family, occupation, or adventure, we happen to be away for a while.

Monday, August 31, 2015

Flashmob for Science - Berlin September 12, 21:30

September 12 is the second-ever International Night of Skyglow Observation, an official event of UNESCO's "International Year of Light". Around the world, citizen scientists will observe how much light pollution is in their community by looking at the stars. The link above is a very short tip on how to do it.

In Berlin we'll be holding a special event that night, a Flashmob for Science, in which many people will show up to make observations simultaneously at a single location. The flashmob will take place in Park am Gleisdreieck at 21:30 on September 12. More details will be on the Facebook Event page. If you plan to come, please sign up there so that we can communicate with you (e.g. in case of cancellation due to rain).

Here's a map, we will do the observation right on the spot marked by the pine tree.

Hope to see you there!

Wednesday, August 19, 2015

Guest post by Allen Versfeld

Allen Versfeld recently took a trip to capture images of good and bad lighting near where he lives in South Africa, and sent the best images he captured to me. I always welcome images of both good and bad lighting for the "view from your app" series.

So I went on a trip especially to collect some images for a light pollution talk I'll be giving soon.  I started at a new shopping mall that was recently built on the edge of town, and then drove out to my home in the country, stopping to photograph whatever notable lights I saw.  In practice it didn't quite work out - I saw some pretty shocking examples that I could not photograph because there was no safe place to stop the car (often, the lights themselves were part of the safety problem).

So the two good examples are from a recently built shopping mall. Although their signage out front is very brightly  lit so that it can be seen from far away by fast moving traffic on a nearby freeway (not pictured), they put a lot of thought into their parking lots. Good full cut-off fittings that illuminate the ground beneath very well, and they're well placed so that there are no shadows in doorways, stairwells, behind walls, etc.

Example of good lighting (closeup) by Allen Versfeld is licensed
under a Creative Commons Attribution 4.0 International License.
Example of good lighting by Allen Versfeld is licensed
under a Creative Commons Attribution 4.0 International License.

Only a kilometer away, I found street lights with bad glare - The photo shows how evenly the road is lit, but the glare is so bad from the lights that potholes and other defects on the road surface become hard to see when moving. Further down the same road is a small shop serving a rural community. In the name of security they have put up a number of floodlights in their parking lot. Unfortunately, every one of these lights shines towards the road and into the eyes of oncoming traffic. Very dangerous. (Bonus point: see if you can find the Stop sign in that image, hidden by the glare!)

Glaring street lights by Allen Versfeld is licensed
under a Creative Commons Attribution 4.0 International License.
Glaring security floodlights by Allen Versfeld is licensed
under a Creative Commons Attribution 4.0 International License.

Finally, even further out from the city, in a bend on a particularly dangerous and badly maintained road, is somebody's home. There is a crime problem in the area, so the owners have obviously gone for the Easy option here: A single enormous floodlight to illuminate the yard. As with the shopping centre above, this means that every passing motorist gets blinded at the worst possible time. And of course, every feature in the garden now casts deep shadows where the bad guys can hide.

Glaring home floodlight by Allen Versfeld is licensed
under a Creative Commons Attribution 4.0 International License.

Citizens push back on LED lighting

If you don't like what you see, why don't you fight it?
If you know there's something wrong why don't you right it?

TLDR: Citizens around the world are raising hell over LED streetlights they don't like. Cities should consult with citizens before undergoing a citywide replacement.

Around the world, people are seeing the LED streetlights that their city is installing, and many don't like it. In this situation, there are two possible responses: living for a few decades with light you don't like, or pushing back against city hall.

In Berlin, citizens challenged the city's intention to switch from gas lighting to LEDs. The city listened, and a compromise was reached: The Technical University of Berlin invented LED lamps that perfectly mimic the color and brightness of gas lamps.

In Davis, California, a citywide replacement was halted when enough citizens complained. The city listened, and set up a test street to let citizens have a choice in which LED lamps should be installed. The citizens chose lamps that were warmer and less bright. In fact, the citizens choice to reduce the brightness below what the city had planned meant that the city ended up saving even more money than it had originally planned!

But cities don't always listen. The mayor of Honolulu is so far ignoring citizen complaints about a plan to install lights similar to the hated ones in Davis. The city also won't consider dimming or turning off lights in low-traffic areas after midnight, despite the fact that a recent study in the UK showed that this has no measurable impact on traffic accidents or crime. (UPDATE 2015.11.04: Honolulu cancelled their original plan, presumably due to citizen action! Hopefully this will lead to better lights for the city.)

Here is an example of a city official from another city trying to "answer citizen concerns" by telling them how it's going to be, rather than coming up with a solution together:

LED street lighting has a lot of potential benefits. If properly installed, LED streetlights are less likely to shine directly into the sky than older lamps. With careful design, it's possible to avoid illuminating people's bedroom windows. A complete re-design with better uniformity could allow cities to use far less light with equal or greater public acceptance.

Unfortunately, it's also possible to make things worse with LEDs, and one of the aspects that really bothers some people is the color of LED street lights. If you've bought LEDs for your home, you've probably noticed that they have a "color temperature": either a number between 2000-6500K, or perhaps "warm white" or "cold white". As a rule of thumb, the higher the color temperature, the higher the luminous efficiency of the LEDs. But as color temperature increases, LEDs are also generally perceived as harsher, more glaring, and colder. To reduce skyglow and glare, the International Dark-Sky Association recommends using lamps with 3000K or lower.

The lesson from Davis, Berlin, and other cities, is that citizens don't have silently accept what city hall decides is best. If you and your neighbors "raise a little hell", you could end up with lighting that's much better and more comfortable than you have today, with a reduced impact on the environment.

Trooper says:
Nobody's going to help you
You've just gotta stand up alone
But that's not true in this case. Plenty of your neighbors will also share your concern, you can find support from local environmental and city beautification groups, and you can get technical information about what's worked for other cities from the International Dark-Sky Association.

Attractive and effective lighting is something everyone from conservatives to greens can support. So if your city is about to do something stupid, don't be afraid to raise a little hell!

Friday, August 7, 2015

First community experiment!

During the coming week (until August 14), we are running the first in a series of Loss of the Night app community experiments. This month we're asking people to make multiple observations as the stars come out during twilight. Since many observers live in places without much light pollution, twilight offers a way to do an apples-to-apples comparison.

The more people that take part, the more likely that we'll have a result that's statistically interesting. So if you have a clear sky sometime in the next week, try making an 8-star observation after the first star is out but before it's gotten all the way dark. Try to do the measurements quickly, so that the sky doesn't darken too much while you are observing.

I will present the results of the experiment at the webinars in September, but there will probably be a sneak preview for everyone on our mailing list.

Thursday, July 2, 2015

Webinar about the app

The Helmholtz Association* is setting up a webinar for me to connect with Loss of the Night app users! I will give a presentation over streaming video, and then you will have the opportunity to ask me questions (text from within an online platform). If you're interested, you need to sign up in advance here, and the organizers will mail you instructions on how to participate.

The webinar will take place twice, here are the dates and times:

Thursday September 10, 2015, 16-16:30 (Berlin time)
Tuesday, September 15, 2015, 11-11:30 (Berlin time)

Both the presentation and discussion will be in English.

*My institute, the GFZ German Research Centre for Geosciences, is a member of the Helmholtz Association.

Saturday, June 20, 2015

ALAN conference sign up

If you'd like to receive notifications about the Artificial Light at Night conference, you can sign up here:

Sign up to receive conference notifications

* indicates required

Sunday, June 7, 2015

Using the Loss of the Night app while traveling

In the last week, two people have asked me about using the Loss of the Night app while on vacation. The short answer is yes, you don't have to do anything special, the app will work when you are traveling and don't have access to a data network, and the data will be sent to us when you return home.

The slightly longer answer is that there are two minor things to keep in mind:

1) Getting a GPS fix will likely take much longer (in the worst case up to 10 minutes), because the app can't download the GPS satellite positions and has to wait for the satellites to broadcast their "ephemeris data". Please be patient, it should eventually work. You can debug whether things are working using a GPS app like "GPS Visualizer".

2) Your observation data will not be sent to us until the next time your phone connects to the Internet (e.g. via WiFi). You can check the status of the measurement in "User data > My measurements". The status will either be "waiting" or "successfully sent". Once you are connected to the Internet, the app should send the measurements by itself automatically.

In the past, there were two minor bugs that affected using the app during international travel. I think they've both been fixed, but these are hard bugs to test, because to properly test them you need to fly halfway around the world!

The first bug affected the position of the stars. The first time you used it overseas the app would display the stars over your home. The workaround was to simply run the app twice, the second time the stars would be displayed correctly.

The second affected sending the data when you connected to WiFi. On some occasions, it didn't happen automatically. A workaround is to do another observation when you have a WiFi or network data connection - you can even run the app in the daytime in "demo mode", and after you finish the observation the app will send both the new and old data.

Finally, we really appreciate it when you take data in additional locations! The more places that are sampled, the more accurately we'll be able to measure the global rate of change in skyglow.

Sunday, May 31, 2015

Lighting in Sherbrooke, Quebéc

The Third International Conference on Artificial Light at Night just wrapped up today in Sherbrooke, Quebéc. Walking through the city this evening, I took a few photos of some street lights that caught my eye. Sherbrooke has made a major commitment to minimizing the city's effect on the nighttime environment, and one of the ways they do this is by replacing older lamps with newer fixtures that don't send light up into the environment. You can see this really well in the photo below, where the fixtures aren't visible from above, but by the reflection in the water you can see how bright they are:

Full cutoff lights reflecting from a river by Christopher Kyba is licensed
under a Creative Commons Attribution 4.0 International License.

Of course, near a waterway the ideal light shines only on the path and not into the water... But I think it's a great photo for demonstrating how full cutoff lights work. In most cities, there would be two bright spots - one from the lamp and the second from the reflection.

The same lamps were on the bridge I was crossing over the river when I took the photo, and I was impressed that in addition to not producing any upward directed light, they also have very little glare. Compare the two photos below - which street would you rather drive on?

Low glare streetlamps by Christopher Kyba is licensed
under a Creative Commons Attribution 4.0 International License.

Glaring streetlamps by Christopher Kyba is licensed
under a Creative Commons Attribution 4.0 International License.

In a few weeks, the Artificial Light at Night conference will start to fill up with pdfs and videos of the presentations. There will even be a video of me, talking about the Loss of the Night app!

Tuesday, May 19, 2015

Star trails over Milow, Germany

Blog reader

Polaris by JC Cabrejas is licensed under
a Creative Commons Attribution 4.0 International License.

Tuesday, May 12, 2015

LED color temperature

A new contact that works on lighting castles sent me the photo below. It compares the light provided by an incandescent lamp (left) to the "warmest" white LED that their group could find (right).

Image used with the permission of the
Prussian Palaces and Gardens Foundation Berlin-Brandenburg

The problem with the LEDs, from her perspective, is that the blue light component is too large, and the colors of the objects in the castles are not properly represented. LEDs can be adjusted to provide nearly any color that's desired, but their "luminous efficiency" is often worse than a very cold, blue-white LED. This is the main reason why so many LED street lights glare with such an ugly, cold light. But it doesn't have to be this way!

An overly narrow focus on the luminous efficiency of lamps misses the point about saving energy. For example, regardless of how high the luminous efficiency of the lamp in this photo is, it's not being used in an efficient and sustainable way:

Light on during the day by Christopher Kyba is licensed under
a Creative Commons Attribution 4.0 International License.
Some colleagues and I wrote an article about how a more common sense view of the "efficiency" of a lamp its energy use per year, not the efficiency with which it converts electricity into light causes a human visual response.

While making a decision about how to light a space, energy consumption is a very important consideration, but the people who will use the light should never be taken out of the equation! In Davis, California, the city decided to let citizens choose which lamps they liked after residents  had protested the installation 4,000 K LED streetlights. The public ended up choosing warmer 2,700 K lamps. In addition to being more liked (or at least more tolerated), warmer LED lamps also have a smaller impact on the night sky than the most efficient white LEDs.

When the Nobel prize was announced last year, I wrote:
"It's possible to imagine a future in which driverless cars run without headlamps ... 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."
For that to come to pass, the focus of sustainable lighting is going to have to shift beyond luminous efficiency, and keep the users of light in the center of focus.

Saturday, May 9, 2015

The night sky over Westhavelland, Germany

A few weeks ago I was in Sternenpark Westhavelland (International Dark-Sky Reserve Westhavelland) to try to measure the degree to which individual streetlights affect the night sky in a pristine area. The lamps are part of a biological and ecological field experiment of the Verlust der Nacht (Loss of the Night) project, funded by the German Ministry of Education and Research (BMBF).

Together with a colleague, we walked different distances from the lamps and then remotely the lights them off and on. In addition to measurements with a continuous logger, I took a few all-sky images. This one is from the middle of the field when the lights were off:

Verlust der Nacht field at night by Christopher Kyba is licensed
under a Creative Commons Attribution 4.0 International License.

You can download the full resolution version here. The sky is blue because it is lit by lunar twilight. The glow at the right (East) is a combination of the moon and the city of Berlin. The glow at top left (southeast) is the nearby town of Rathenow.

The next photo shows the view a few hundred meters from the field when the lights are turned on (the field is the bright glow at right):

Verlust der Nacht field lit at night by Christopher Kyba is licensed
under a Creative Commons Attribution 4.0 International License.

Finally, this animation shows how the whole environment near the field changes as the lights turn on:

Verlust der Nacht field turning on by Christopher Kyba is licensed
under a Creative Commons Attribution 4.0 International License.

I think the lighting up of the nearby tree and grass is the most dramatic - just think of what a complete difference this is for the insects and birds that live there! Here's a higher resolution version.

UPDATE Nov 23, 2015: We have published a paper describing the field site and a few of the first experimental results. You can read about it for free at the journal Sustainability.

Tuesday, May 5, 2015

Sign up for our new monthly newsletter

We're starting a newsletter to remind project participants each month when the moon phase allows Loss of the Night app measurements to be taken. In the monthly mail, we'll also occasionally share news, such as announcements of new versions or project milestones that we've passed. You can sign up for the newsletter here, or just fill in the form below.

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Wednesday, April 22, 2015

The Loss of the Night app is two years old!

April 22 is the second anniversary of the Loss of the Night app! Since that time, tens of thousands of people have installed the app on their phone, and thousands of those people have used the app to make at least one observation of the night sky.

Here are some statistics from the first two years (for data up to April 18):

20,170 individual observations have been submitted from 9,825 unique devices from around the world (see map below). This number includes "demo mode" cases when people are just testing the app, and observations with clouds and sunlight or moonlight. Most devices have only ever observed once, but over 100 people have submitted ten or more observations.

App observations up to April 18. Black points are all observations,
red points are observations with no twilight, moonlight, or clouds
and at least 7 stars observed.

In the first few months, only about 10% of the submitted observations were suitable for analysis (no clouds, moonlight, twilight, and at least seven stars observed). This fraction has steadily increased over time, and is now close to 30% of the observations submitted. The number of good observations per month is also climbing, but slowly. The more participants we have, the quicker we'll be able to measure the average change in sky brightness worldwide, so tell your friends about the app!

Citizen scientists have searched for a total of 30,323 stars (under nighttime conditions). The star most commonly searched for so far is Capella (694 times), followed by Vega (593x) and Altair (554x). Since the new version was released, many of you are now submitting more than the minimum seven stars. We really appreciate it, because observing more stars leads to a more precise result.

The mean time to observe a star is 34 seconds, but the most frequently occurring time needed to make a decision is 11-15 seconds. Your data help us understand which are the "best" stars for us to ask you to look for. I hope that we will do one last update to the app's "star selection algorithm" in the next year or two, so the more stars you observe, the more you'll improve the app.

In addition to the naked eye observations which are the main purpose of the app, citizen scientists have also used the app to submitt 239 observations taken with Sky Quality Meters under nighttime conditions. Of these, 188 of which were taken with with no cloud cover.

Thank you to everyone who has taken part in this project to measure how Earth's night sky is changing. It wouldn't be possible without you! The next moon-free observing period starts around May 7. If you don't yet have the app, here are the links for downloading it for Android and iOS.

Tuesday, April 21, 2015

Minor bug report

Users at high latitudes (like Germany) may have noticed today that the app crashed after it acquired a GPS signal. The bug was caused by an expectation that the "next good time" to observe should be within 30 days, but during the summer at high latitudes the twilight extends past the time we thought people would be interested in observing.

The bug has been fixed, and in the next few hours the update should be available in the Play and App stores. We didn't notice the bug in testing, because our testing took place after the midsummer twilight was over last year.

Observers in Germany that are willing to stay up past midnight are able to observe from about May 7-18. If you live at a lower latitude, the bug probably didn't affect your phone.