Monday, December 23, 2013

Random post

PNG transparency demonstration 1

I was recently wondering about how good or bad humans are at choosing a single random number, and after a bit of googling I found out the answer was a bit different from what I expected (I'll do an update about it later). That in turn inspired me to try an experiment that's a bit different from the usual "think of a number between 1 and N".

Please click on a single button below:

Choose randomly free polls 

To get a statistically significant result, we will likely need several hundred people to take part, so please share the link to this post with your friends, and then check back again in a week or so.

Saturday, December 21, 2013

View from your app - architectural lighting in Berlin

If you've ever taken a bus past Alexanderplatz in Berlin at night, you probably wondered what the blindingly bright lights along the side of the train station were for:

Bad lighting at Alexanderplatz 1 by Christopher Kyba is licensed
under a Creative Commons Attribution 4.0 International License.
Bad lighting at Alexanderplatz 2 by Christopher Kyba is licensed
under a Creative Commons Attribution 4.0 International License.

The lights are bright enough to hurt your eyes, and as you can see in the two photos above, their glare makes it much more difficult to see the people who are approaching you. From the side, it looks painful and awful, and unless you get off the bus and stand directly perpendicular to the lights you'll never figure out what the lights are for. Here it is:

Bad lighting at Alexanderplatz 3 by Christopher Kyba is licensed
under a Creative Commons Attribution 4.0 International License.

It's pretty! Unfortunately, almost no one ever appreciates this view, because there is literally no reason to go to the place I was standing other than to take that photo. Take a look at the map below. Nearly everyone experiencing these lights walks between the "Berlin Alexanderplatz" marker to the "S+U Alexanderplatz..." marker, and only sees the bad view shown above. To see the nice view, you've got to cozy up with the construction site:

This is architectural lighting at its very worst! It painfully unpleasant to look at from the most common viewing angle of passers-by, and is directly subverting the goal of nearby public lighting: to improve visibility at night.

As a counter-example, check out this building on Friedrichstraße:

Helios Klinik lights by Christopher Kyba is licensed
under a Creative Commons Attribution 4.0 International License.

Very cool! Different, distinctive, attractive, and with relatively low luminance. Unfortunately, it seems like there wasn't a single lighting plan for the building... A blindingly bright white Marquee at the base of the building entirely spoils the effect that the lighting designer was going for:

Terrible Marquee ruins view by Christopher Kyba is licensed
under a Creative Commons Attribution 4.0 International License.

Here's an example of boring, 20th century architectural lighting: Berlin's TV tower

Berliner Fernsehturm with moon by Christopher Kyba is licensed
under a Creative Commons Attribution 4.0 International License.

One thing I think is interesting about this photo is you can see just how brightly the tower is lit - the full moon appears very modest in comparison. The TV tower is always far more interestingly lit during Berlin's festival of lights, and I have the feeling that it's also far more modestly lit during the festival.

Here's an example of what I call "shine a floodlamp approximately in the direction of the building", the Kirche am Sudstern:

Kirche am Sudstern by Christopher Kyba is licensed
under a Creative Commons Attribution 4.0 International License.

The photo was taken from our research aircraft, and shows what a large fraction of light is wasted when architectural lighting is not done carefully. The ironic thing about badly floodlit churches is that in rural Europe the village church is often the most important source of skyglow for a large region. So the poorly designed lighting actually prevents people from seeing the Godly splendor of the night sky! European churches usually have stained glass windows, and every time I see a badly floodlit church I imagine how much more attractive it would be if the church was completely unlit other than a colorful glow from behind the stained glass.

Of course, it is possible to direct floodlights carefully, as this photo of the Berlin Cathedral shows:

Berliner Dom from air by Christopher Kyba is licensed
under a Creative Commons Attribution 4.0 International License.

From the air, Berlin Cathedral doesn't look like much, but from the ground it's spectacular:

Berliner Dom from ground by Christopher Kyba is licensed
under a Creative Commons Attribution 4.0 International License.

The difference between the Cathedral and the Kirche am Sudstern above is that instead of just floodlighting the entire building, the lighting designer for the Cathedral chose to highlight certain elements by using a large number of smaller, more focused floodlights. The lighting is still not ideal, however, both because it's quite a bit brighter than necessary and because from the ground level a significant amount of light blinds you when you are looking away from the Cathedral (towards the flood lights:

Glare from the floodlamps of Berliner Dom.

Right next to Berlin Cathedral is another more attractively lit building, the Altes Museum:

Altes Museum at night by Christopher Kyba is licensed
under a Creative Commons Attribution 4.0 International License.

Unfortunately, I didn't have a tripod, so my photo doesn't do it justice. The great thing about the Altes Museum is that the lamps are totally invisible to the public. There's no glare, and the amount of light emitted to the sky is very reduced compared to many designs.

Finally, we come to the Brandenburg Gate:

The Brandenburg Gate. Photo copyright 2011 C. Kyba.

The Brandenburg Gate does shine quite a bit of light directly up into the sky, but it is a single building in the capital of the country. More than that, the Brandenburg Gate is THE symbol of Berlin, as well as a symbol of all of Germany. As a light pollution researcher and dark sky advocate, I have no problem with the Brandenburg Gate being relatively brightly lit. But not every building is the Brandenburg Gate, and not every church and monument ought to be lit!

Now to be fair, in big cities architectural lighting is way down on the list of sources of light pollution. Nevertheless, I think that people interested in lighting their buildings have a social responsibility to ensure that their installations do not affect public safety by reducing visibility, that they make a serious effort to limit stray light, and that they light the building modestly in order to avoid wasting energy.

If you want to reduce light pollution, the most important thing to get right is street lighting. By coincidence, while I was out taking some of the photos above I snapped these examples of some truly awful "decorative" street lamps (filled with dead bugs) on Unter den Linden:

Bug filled decorative streetlamp by Christopher Kyba is licensed
under a Creative Commons Attribution 4.0 International License.
Click to embuggen.

Bug filled decorative streetlamps by Christopher Kyba is licensed
under a Creative Commons Attribution 4.0 International License.

The moon makes an appearance again in the 2nd photo. For comparison, check out these examples of recently installed excellent decorative street lighting from Spain.

Friday, December 20, 2013

Loss of the Night app now available in 11 languages!

I'm very happy to announce that we have released a new version of the Loss of the Night app with expanded language support! The app can now be used in Arabic, Catalan, Chinese, English, French, German, Italian, Japanese, Polish, Romanian, and Spanish! You can read more about it in our press release.

Now we need your help to get the word out!  If you have a friend that speaks one of those languages, please pass them the link to the app, and ask them to promote it in their language using social media. You can also help us find new users worldwide by giving the app a good rating in the play store and leaving a positive comment in your own language.

We would like to publicly recognize the considerable amount of work done by the following volunteer translators:

Arabic: Amr Al-Omari
Catalan: Salvador Ribas
Chinese: Yongguang Zhang
French: Olivier Domingue, Johanne Roby, Martin Aubé, and Romain Clément
Italian: Andrea Giacomelli
Japanese: Nobuaki Ochi
Polish: Ania Wisniewska
Romanian: Catalin Daniel Galatanu
Spanish: Salvador Ribas

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

Note: The next measurement period starts tonight, although there will only be a window of an hour or so to make a measurement because of the rising nearly full moon. By December 25, it will be possible to take measurements right up until midnight. The current measurement period will last until about January 4.

Friday, November 29, 2013

Flashmob for Science (save the date!)

We will hold our next "Flashmob for Science" in Berlin on the evening of February 20, 2014.  Two related conferences will be taking place in Berlin on that day, so they could potentially help make the event really large.

The location and time will be announced later to the date of the Flashmob. If you would like to get email updates about the flashmob, send me an email with the subject "BERLIN FLASHMOB SIGNUP":
my email
Our first Flashmob for Science was a lot of fun! I hope that the weather will cooperate on February 20, and that I'll see you there!

Was ist ein Flashmob für die Wissenschaft? Clicken Sie hier.

Sunday, November 24, 2013

Another problem with kids screen time, and the one app that can solve it

Most apps keep you up at night, but f.lux helps you sleep

Light is the most important signal your body uses to know when to go to sleep and when to wake up. When it's dark at night, your brain produces a hormone called melatonin. Melatonin helps make you sleepy, and also helps fight against some cancers. When you are exposed to bright blue light at night, your brain can't make the hormone, and that can make it take longer for you to fall asleep. Sleep is essential to health, so anything that keeps people up at night is a public health concern.

Most of us use computers, tablets, and smartphones at night, exposing ourselves to the bright, blue light that keeps people awake. A very clever free program called f.lux has been developed to hopefully help reduce this problem, by cutting the amount of blue light we are exposed to at night. At sunset, f.lux changes the white balance of your screen, so for a minute or so everything seems orange:

f.lux works by reducing the amount of blue light your screen emits

But your brain is designed to adjust to changes in color throughout the day, so you very quickly get accustomed to the warmer light. In fact, if you switch back to the standard setting, then everything will at first appear to be weirdly blue:

After a few moments, the f.lux screen will look "white" and
if you switch back the standard setting will now look cold

By installing the program, you will reduce your exposure to blue light at night. That might help you sleep better, and could potentially improve your long-term health. It's free, so you should install it on your computer, tablet, and smartphone right now!

If you're a first time visitor, this blog is about the Loss of the Night app and citizen science project. In brief, we need people living big cities to tell us how many stars they can see (no stargazing experience necessary). But the blog also occasionally has other stuff related to light at night, for example photos of good and bad street lighting from around the world, and this calendar of moon phases for 2014.

Additional notes:

1) I am not aware of any study that examines to what extent f.lux reduces the melatonin suppression caused by looking at a screen. It's basically a band-aid for the societal problem of improper light exposure. If you really want to sleep better and live longer, spend as much time as possible outside during the daytime (even if it's cloudy), and avoid bright white lights at night.

2) Some tasks (such as editing the color balance of a photo) should probably not be done with f.lux turned on. You can temporarily disable f.lux for one hour with just two clicks.

3) I have nothing to do with f.lux, and I don't know the people who created it. But I study light at night, and I am just doing my part to spread the word about this great program.

4) Have friends that have trouble going to bed at night? Tell them about f.lux!

Wednesday, November 20, 2013

Moon phase calendar for 2014

Loss of the Night app user Andrew Cool from Australia has produced this very cool calendar of the phases of the moon in 2014:

A higher resolution version is available here, and you can buy the poster on zazzle. (I got a coffee mug, and I don't recommend it because Zazzle's printing resolution on the cup is too low.)

Update: Andrew has made 2015 moon phase calendars with different designs and for the Northern and Southern hemispheres.

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!

Friday, November 15, 2013

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

Note: This guide is for an outdated version of the app (v1.0.2). Here are the new directions for Android and iOS.

Friday, November 8, 2013

View from your App

Paul Marchant is a chartered statistician from Leeds, England, who is investigating whether or not brighter street lights improve traffic safety or reduce crime. He showed this image of a burned out car directly beneath a streetlight during his talk at the recent international conference on Artificial Light at Night.

Burned out car under streetlamp by Paul Marchant is licensed under a
Creative Commons Attribution-NonCommercial 3.0 Unported License.

The point of the photo is that lighting by itself can't prevent crime, and simply making lights brighter is not a very effective way to try to reduce crime. So far, Dr. Marchant has observed that changes of lighting in London have not had a measurable impact on crime rates. He worries that earlier studies showing effects due to change in lighting have been affected by similar problems to many medical studies. This includes publication bias (researchers are more likely to publish exciting results) and statistical errors (e.g. crime and fatal traffic accidents have been falling for years in many countries, so regardless of what the intervention is, you could incorrectlly see it as "causing" a drop in crime).

Thursday, November 7, 2013

A (nonscientific) survey of twitter users (updated)

It is estimated that about 20% of people worldwide can't see the Milky Way from where they live, and it's therefore believed that many young people have never seen the Milky Way in their life. Since lots of young people use twitter, let's see what twitter users tell us!

If you use twitter, then click the retweet button that applies to you below.

Never seen the Milky Way:

Have seen the Milky Way:

Please note that this is most certainly not a scientific survey! If the tweets go viral, I think it will be interesting to see the results nonetheless.

Update 2013/11/11: So far, only 3 of 40 respondents (7.5%) say they have never seen the Milky Way.

First time blog visitors: This blog is about apps that are used to figure out how bright the sky is. You can read about the apps here.

Saturday, November 2, 2013

Looking for stars in Berlin

Last week we hosted the first ever international conference on artificial light at night, ALAN 2013! After two evening events of the conference, I took advantage of being out on a night with clear skies to use the Loss of the Night app in three places. I've labelled their approximate locations on this map of Berlin at Night from the Suomi-NPP VIIRS image:

The first location, "Dahlem" is in a suburb at the edge of Berlin. The second, "Spreebogen" is an unlit park across the river from the brightly lit main train station. The third was a block away from Friedrichstraße, which is the brightest place in the center of the city (at least according to VIIRS). The results of the three measurements are shown below:

The plots are similar to the ones I showed in an earlier blog post. The vertical axis shows how bright or faint the stars are. Stars I said I couldn't see are shown in red, stars I wasn't sure about are shown in blue, and stars that I said I could see are shown in black. The horizontal axis shows the time since the measurements were started (each small tick is one minute).

The horizontal lines show the estimate (maximum likelihood fit) of how bright the sky was at each location. With a few assumptions, it's possible to turn this value into a very rough estimate of how many stars you can see. In Dahlem, about 300 stars could be seen with that level of skyglow, in Spreebogenpark about 200, and near Friedrichstraße around 100. By comparing the three datasets you can see that the app is really working, and that in each location my results are quite self-consistent. Unfortunately, I didn't happen to have an SQM with me to check how closely these results compared to the actual sky radiance.

I am continuing to learn a lot about the stars and constellations by using the app!  Since September I now know learned the stars Vega and Deneb and the constellation Cygnus (the swan) very well.  I am also slowly getting used to Perseus. I think that all of the stars I wasn't sure about were in the (very sparse) constellation Draco.

Friday, October 25, 2013

Moon free observing period has started

We're back into a period where the moon sets early enough to allow moon-free observations of the sky brightness in the evening. This can be done using either the Loss of the Night app (Android) or Dark Sky Meter app (iPhone). The moon-free observing period will last until November 7 (exact dates depend on your latitude).

After November 7, the next observing periods this year will be:

November 21 - December 6
December 20 - January 4 (2014)

The dates are based on Berlin sun/moon rise/set times, and will be slightly different depending on where you live and what time of night you intend to make your observation.

Please try to make observations especially in urban areas with lots of light pollution, and please encourage your friends in urban areas to do the same!

If the weather co-operates, we are going to hold two "Flashmob for Science" events next week as part of the ALAN conference.

October 28, 19:30-19:45 in Mendelssohn-Bartholdy-Park, Kreuzberg
October 29, 18:49-19:00 in Kaiser-Wilhelm-Platz (U3 Podbielskiallee), Dahlem

More information to come soon...

Monday, October 21, 2013

Berlin at Night - in color!

We flew over Berlin last Friday night, taking thousands of photographs in order to create a new color mosaic image of Berlin. Here is our original black and white mosaic:

One of the things that makes Berlin particularly interesting for those of us studying artificial light at night is that Berlin makes use of a wide array of lighting technologies. You can even still see the former border between East and West Berlin at many places because of a change in the color of the lamps. Here is a zoom-in of such a region imaged by the astronauts on the International Space Station:

image courtesy of the Image Science & Analysis Laboratory, NASA Johnson Space Center.

The big black area is the former Tempelhof airfield. To the right of it are two streets, one orange, one more white-ish. Here is what the area looks like in our aerial images:

click for high-res view

You can see that the aerial images have far higher resolution, allowing us to see a lot more detail and understand better what the sources of the light were.

The flight was taken during the Berlin "Festival of Lights". Here is one of the areas of the city that participates in the festival:

The Reichstag and Brandenburg Gate are at top center, Potsdammer Platz is bottom center.

Alejandro has also produced a video showing the view from the aircraft as we fly over Berlin. The video consists of multiple tracks across the city. Note that when the aircraft was flying Eastbound, the reflection of the moon is periodically visible from small lakes and the Spree river (e.g at 2:37).

Flight video by Alejandro Sanchez de Miguel

This work was done as part of the Verlust der Nacht research project, and was possible thanks to the Short Term Scientific Mission of Alejandro Sanchez de Miguel to Berlin, which is funded by the Loss of the Night Network.

New visitors: this blog is dedicated to the Loss of the Night app and citizen science project. For more information, you can read our first blog post, or even better, click the link and try out our app!

Wednesday, October 2, 2013

Preliminary results of our first Flashmob for Science

Thanks to everyone who braved the cold to come out on this crisp October night for our first ever Flashmob for Science! Alejandro Sanchez de Miguel made this video of the proceedings (more photos at the bottom):

I've glanced at the data, and have some very preliminary results: Based on the SQM measurement (18.35 mag/arcsec2) we would estimate a naked eye limiting magnitude around 4.25, but the seeing wasn't the greatest, so I'd expect something smaller. Using my (very preliminary) maximum likelihood estimation code, the average of each of the observations was 3.9, with a standard deviation of 0.7. If we include only the "highly consistent" observations, then the mean was 3.8 with a standard deviation of 0.5. This is quite promising, because we found that the standard deviation of GLOBE at Night observations from March, 2012 was 1.2 stellar magnitudes.

These preliminary numbers should be taken with a grain of salt, both because my code is a work in progress and because we didn't have a very big crowd. Now that we've gained some experience, I hope that we'll be able to hold a much bigger event either near the end of October or else when it warms up in the spring. If you live someplace warmer and would like to host your own "Flashmob for Science" event in the coming months, please contact me!

Still photos:

Citizen scientist doing fieldwork by Alejandro Sanchez de Miguel is licensed
under a Creative Commons Attribution 3.0 Unported License.

The youngest star of the night

Star observations with the Loss of the Night app by Alejandro Sanchez de Miguel is licensed
under a Creative Commons Attribution 3.0 Unported License.

Learning more about the constellations after the event

Thanks to everyone who came!

Tuesday, October 1, 2013

Flashmob für die Wissenschaft

[click here for English version]

Sehen Sie genau so viele Sterne wie Ihre besten Freunde, wenn Sie den Nachthimmel ansehen? Das ist die Frage, die wir mit dem ersten "Flashmob für die Wissenschaft" beantworten wollen. Soviele Personen wie möglich sollen die Loss of the Night app am exakt gleichen Ort zur exakt gleichen Zeit benutzen. Indem wir die Sterne, die die Flashmobber sehen können, vergleichen, können wir herausfinden, wie gut die Ergebnisse der App sind.

Der Flashmob wird in Berlin stattfinden, aber Sie können uns von überall helfen, indem Sie die Veranstaltung auf Facebook posten, darüber twittern oder Ihnen bekannten Bloggern davon mitteilen. Wenn Sie in Berlin wohnen, sagen Sie auch Ihren Freunden und Kollegen Bescheid! Sie können Ihnen den Link zu diesem Blogpost schicken.

Und falls es klar ist wo Sie wohnen, können Sie sich natürlich mit Freunden treffen und Beobachtungen aus Ihrer eigenen Stadt hinzufügen!

So funktioniert die Veranstaltung:

Flashmobber sollten die App im Voraus installieren. Android-Nutzer brauchen die  Loss of the Night app, und iOS-Nutzer können mit der Dark Sky Meter-App teilnehmen (free oder full version), die die Telefonkamera anstatt Ihrer Augen benutzt. Wenn Sie möchten, können Sie die App vorher tagsüber testen, um ein Gefühl dafür zu bekommen.

Sie sollten planen, die Mitte des Gleisdreieck-Parks in Berlin (den grünen Pfeil, nicht das "A" auf dieser Karte) gegen 20:30 Uhr zu erreichen. Sie können die App sofort starten, damit das Telefon schon im Nachtmodus ist, wenn die Messzeit beginnt. Schauen Sie die Sterne an und lassen Sie Ihre Augen an die Dunkelheit gewöhnen - Sie werden überrascht sein, wie viele Sterne man auch in der Mitte von Berlin sehen kann!

Sobald um 20:35 Uhr die astronomische Dämmerung endet und die echte Nacht beginnt, werden wir den Anwesenden mitteilen, dass die Zeit zum Sternensuchen gekommen ist.

Wenn Sie 7 Sterne gefunden haben, teilt die App mit, dass Sie aufhören können. BITTE HÖREN SIE NICHT AUF!  Mehr Sterne sind immer eine große Hilfe für uns, und werden für die Auswertung der Flashmob-Daten besonders wichtig sein. Daher wären wir sehr froh, wenn Sie mindestens 12 Sterne suchen würden. Wenn Sie die Geduld für 15-20 Sterne haben, wäre das noch toller, und wenn Sie 30 Sterne erreichen, verdienen Sie den Titel des Bürgerwissenschafts-Superhelden!

Wenn Sie mit der App fertig sind, können Sie sie einfach schließen und nach Hause gehen - Ihre Beobachtungsdaten werden beim Schließen der App automatisch an uns übertragen. Falls Sie in der Nähe Ihrer Wohnung einen guten Beobachtungsort haben (z.B. einen Park, Spielplatz oder eine Dachterrasse), dann wäre es ein super Bonus, wenn Sie dort noch eine zweite Beobachtung mit der App vornehmen würden. So könnten wir auch mehr Informationen über Berlin verteilt erhalten. Bitte nutzen Sie die App nur, wenn Sie eine zweite Person zur Sicherheit dabeihaben (die Sie zum Beispiel vorm Stolpern warnen kann, während Sie nach oben schauen!).

Bitte erzählen Sie so vielen Personen wie möglich über diese Veranstaltung, und schicken Sie ihnen den Link zu diesem Blogpost. Je mehr Personen teilnehmen, um so erfolgreicher wird dieser erste Flashmob für die Wissenschaft.

Ich freue mich darauf, morgen viele von Ihnen zu sehen!

I werde die Himmelshelligkeit mit einem Lichtmessgerät messen, und das Ergebnis mit dem der Flashmobber vergleichen.


(1) Mehr Informationen darüber, warum wir Individuen für Beobachtungen rekrutieren, anstatt Satelliten oder andere Sensoren zu verwenden, finden Sie in unseren ersten Blogpost, oder diesem Scientific American-Artikel. Hintergründe zur Bedeutung von Forschung zur Lichtverschmutzung gibt es in den Artikeln in Die Welt, The Guardian, oder den Why Files.

(2) Falls sich direkt über dem Gleisdreieckpark eine kleine Wolke befinden sollte, die vermutlich schnell weiterzieht, werden wir die Teilnehmenden bitten, 15 Minuten mit den Messungen zu warten.

Flashmob for Science

[Deutsche Version hier]

When you look at the night sky, do you see the same number of stars as your best friend? That's the question we want to answer with our first ever "Flashmob für die Wissenschaft". We want to get as many people as possible to use the Loss of the Night app in the exact same place at the exact same time. By comparing the stars the flashmobbers can see to each other, we'll learn how consistent the results from the app are.

The event will take place in Berlin, but no matter where you live we could use your help to get the word out. Post it to Facebook, tweet or email it to bloggers you know, and if you do live in Berlin tell your friends and colleagues about it. You can pass them the link to this blog post.

And of course, as long as it's clear where you live, you can meet up with friends and do observations in your own city!

Here's how the event will work:

Flashmobbers should download the app in advance. Android users should download the Loss of the Night app, and iOS users can take part using the Dark Sky Meter app (free or full version), which uses the phone's camera instead of your eyes. If you want, you can test out the app in the daytime to get a feel for it works.

Plan to arrive in the middle of Gleisdreieck Park in Berlin starting around 20:30 (the location of the green arrow, not the "A" on this map). If you want, you can start the app as soon as you're there, so that your phone is already in night mode when the measurement time starts. Spend some time looking at the stars and letting your eyes adapt to the dark - I promise you'll be surprised how many stars are still visible from Berlin!

As soon as astronomical twilight ends and true night starts at 20:35, we'll signal the crowd that it's time to start searching for stars.

Once you've observed 7 stars, the app will tell you that you can stop if you like. PLEASE DON'T STOP! Observing more stars is always a huge help to us, and will be particularly important for getting the most out of the flashmob data. So we'd really appreciate it if you look for at least 12 stars. If you have the patience for 15-20, that would be amazing, and if you get to 30, you'll be a Citizen Science Superhero!

When you're done looking for stars, just turn off the app and head home - your data is sent to us automatically when you quit the app. If you have a good location from which to observe the app close to your home (e.g. a local park, playground, or rooftop balcony), then it would be really fantastic if you would do a 2nd observation. In this way, we'll also get a huge amount of data from around Berlin. But please only use the app if you've got a partner with you who can watch out for potential hazards (e.g. making sure you don't trip over something while you're looking up!).

Please share news about this event with everyone you know, by passing them the link to this blog post!  The more people that show up, the more successful the event will be.

I hope to see many of you tomorrow night!

I will measure the sky brightness with a light meter, and compare the result to the Flahsmobber's observations.


(1) If you want more information about why we want people to do observations rather than satellites or other sensors, take a look at our first blog post, or this Scientific American article. For background on why light pollution is important, read this article in The Guardian, or this one from the Why Files.

(2) If there is a small cloud right above Gleisdreieck Park and it looks like it's going to move out of the way, then we'll ask everyone to delay for up to 15 minutes before starting the observations. If it is completely overcast then we will have to cancel the Flashmob and try again at the end of October.

Update: Here are the results of our first Flashmob for Science.

Sunday, September 29, 2013

The view from your app

Last night Alejandro Sanchez de Miguel and I made measurements of sky brightness as we drove from Berlin to an area close to lake Müritz in the German state of Mecklenburg-Vorpommern. That region has one of the most pristine night skies in all of Germany, and we had a beautiful view of the Milky Way:

Milky Way over Müritzsee by Alejandro Sanchez de Miguel is licensed
under a Creative Commons Attribution 3.0 Unported License.

The area (particularly Nationalpark Müritz) could surely become a Dark Sky Park or Dark Sky Reserve in the future. It would without question make Silver grade, and I think it would have an excellent chance of obtaining Gold. Other than occasional cars (see below), there were no sources of glare whatsoever, and we happened to be sitting just off of the highway. We weren't even actually anywhere near the Nationalpark itself, so I'm sure that you could find far better locations than where we happened to stop to take pictures:

Light pollution researchers in the office, Christopher Kyba (left) Alejandro Sanchez de Miguel (right).

Light domes were confided to very close to the Horizon. Here is the light dome from Berlin, 100 km away:

Light dome of Berlin from 100 km by Alejandro Sanchez de Miguel is licensed
under a Creative Commons Attribution 3.0 Unported License.

 Here are the light domes from Malchow (left power pole, 22 km away) and Röbel (center pole, 5 km away). The two blue beams from Malchow are presumably from a church with badly installed floodlighting, and even after seeing the photo we still couldn't see them with the naked eye.

Minor light domes near Müritzsee by Alejandro Sanchez de Miguel is licensed
under a Creative Commons Attribution 3.0 Unported License.

We would have liked to explore the area further, but the moon rose, making further observations pointless and forcing us to head back to Berlin:

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

We measured 21.4 mag/arcsec2 with a Sky Quality Meter (with the Milky Way at zenith) which means that the top of the sky in the area is nearly free of artificial light. If anyone from Mecklenburg-Vorpommern is reading this blog: Everyone knows how beautiful Müritz is in the daytime, now it's time to let people around the world know what a beautiful night sky you have!

Friday, September 27, 2013

Grandfather of Loss of the Night app wins IDA Galileo award!

Yesterday I had the wonderful opportunity to present the International Dark Sky Association's "Galileo Award" to Dr. Günther Wuchterl!

Günther Wuchterl (left) receiving the Galileo award.

The Galileo Award is awarded for outstanding achievements in combating light pollution issues on the European continent. Günther was recognized for many activities, but and one among them was his involvement in the "How Many Stars?" citizen science project, which GLOBE at Night partially descends from. The Loss of the Night app was intended to bring these projects into the smartphone era, and Günther was one of our testers during the development phase of the app.

Congratulations Günther on your well-deserved recognition!

Wednesday, September 25, 2013

The view from your app - birds eye view of a searchlight at night

Update: Welcome visitors from EPOD! After you look at this blog post, try out our app! You can read what the app is for here.

I was browsing through some photos from one of our night flights from last year when I came across this image (click to emblinden):

Birds eye view of a searchlight by Christopher Kyba is licensed
under a Creative Commons Attribution 3.0 Unported License.
It's a "birds eye view" of what it looks like when you pass close to the beam of a searchlight. The city appears dark (other than the blinding spot) because I was trying to minimize motion blur. I've enhanced the image below to give you a bit more of a feel for how bright these things look when you view them with your naked eye.

To help give a scale of how insanely bright the spot is, to the bottom left of the big dark park is Potsdamer Platz, and at the bottom right of the photo is Alexanderplatz, two of the brightest areas in the entire city of Berlin. When we fly over a city at night, I occasionally see points of light that are actually painful to look at, even from 10,000 feet up, and in most cases my best guess is that they are floodlights, not searchlights. I can only wonder how migrating birds react to these kinds of lights. Are they blinded? Do they fly towards them?

I am pretty sure that we didn't pass into the exact beam of the searchlight, both because that is statistically very unlikely and because the view looked similar for several seconds (several hundred meters). But you can actually see the beam coming from a long way away, here is a photo from 72 seconds earlier (~3.5 km away), you can still see that the spot is far brighter than anything else in the city:

Distant Searchlight by Christopher Kyba is licensed
under a Creative Commons Attribution 3.0 Unported License.
It's possible that the searchlight was sweeping across the sky, in which case I had a better chance of getting an image just when it was pointed roughly towards me. But of course for a bird flying slowly over the city at night, that will happen over and over and over again!

Note for new visitors: "The view from your app"is a regular feature on this blog, and is intended to highlight good and bad outdoor lighting. The main purpose of the blog is discussing the Loss of the Night citizen science app for android phones.

Tuesday, September 24, 2013

Moon free observing period starts tonight!

This evening, the moon sets early enough that many people should have the possibility to make moon-free observations of the sky brightness using the Loss of the Night app (Android) or Dark Sky Meter app (iPhone). The moon-free observing period stretches from about September 24-October 9 (exact dates depend on your latitude).

After October 9, the next observing periods this year will be:

October 23 - November 7
November 21 - December 6
December 20 - January 4 (2014)

The dates are based on Berlin sun/moon rise/set times, and will be slightly different depending on where you live and what time of night you intend to make your observation.

Please try to make observations especially in urban areas with lots of light pollution, and please encourage your friends in urban areas to do the same!

The view from your app

Last night marked 167 years since the planet Neptune was first observed from the Berlin Observatory, within 1° of where Urbain Le Verrier had predicted it would be. I recently took a photo of the sky from the crossing of Friedrichstraße and Unter den Linden (which is close to the site of the original Berlin Observatory, but about about 2 km from the location where Neptune was observed). Here's the sky over Berlin today:

Night sky over central Berlin by Christopher Kyba
is licensed under a Creative Commons Attribution 3.0 Unported License.

For comparison, I used the same camera and same settings to take another image of the sky during a star party at Naturpark Westhavelland, 82 km from where the first image was taken. The sky over Berlin was probably only a little bit brighter than this when Neptune was discovered:

Night sky over Naturpark Westhavelland by Christopher Kyba
is licensed under a Creative Commons Attribution 3.0 Unported License.
By 1913 the Berlin Observatory was forced to move outside of the city for three reasons: increasing light pollution, air pollution (aerosols), and shaking of the instruments caused by the passing of the nearby S-bahn trains. Researchers still work the Leibniz-Institut für Astrophysik Potsdam (as the Berlin Observatory is known today), but they generally no longer make optical observations at the site due both to the skyglow of Berlin and our area's tendency to inclement weather.

Neptune is quite bright, so it should still be possible to observe it from the center of Berlin today with binoculars, as long as you know where to look. Thanks to Axel Schwope from Leibniz-Institut für Astrophysik Potsdam for telling me about the history of Berlin Observatory yesterday.

Friday, September 20, 2013

Urban Astronomy with the Loss of the Night App

I made a presentation about the loss of the night app at the 13th European Symposium for the Protection of the Night Sky, and I wanted to share two important slides here. The first shows what fraction of our app users live under bright, or very bright skies:

The "Cinzano pop" tables show what population of the given countries were estimated in 2001 to live under skies 9 times or 27 times brighter than natural. At the bottom, we see that contributors to GLOBE at Night and our app users are drawn from a population that is biased towards less polluted areas. This is a problem, because the app is designed for urban astronomy! It only has the ~1000 brightest stars in its database, all of which have a magnitude less than 5.  This means that more than 80% of all of our app users are making observations in areas that are too dark for the app to function properly!

There are three reasons why we don't have fainter stars in the app. First, we were on a tight money/time budget, so we just used the stars that were already in Google's Sky Map app. Second, if you are in an area with little skyglow, there are just so many stars in the sky that it's hard to tell which one the app is asking you to look for! Third, at some point the screen of the mobile phone will be bright enough that it will ruin your night vision and make it impossible to see the stars. Based on our testing, this isn't a problem in cities, but it would be in the countryside.

Does this mean that 80% of the data we have collected so far is useless? Far from it! Take a look at the next slide:

Here we compare two stars that are no so far away from each other in the Northern Hemisphere, Megrez in the Big Dipper and Edasich in Draco. You can see where the stars are relative to their constellations in the next two images:

Ursa Major IAU
Megrez is the central star of the Big Dipper.

Draco IAU
Edasich is a part of a much larger constellation.

The two stars have a very similar brightness, but Megrez is part of the Big Dipper, probably the most familiar constellation in the Northern Hemisphere. Edasich, on the other hand, is part of Draco, a much more difficult constellation to observe. Because of this, our app users are able to make a decision about Megrez more quickly (20 seconds on average), and their decision is more accurate (nearly all of our app users should have been able to see both stars).

By using the app in an area without light pollution, you are helping us to understand which stars are easier to make quick, accurate decisions about, and which are harder. Once we have enough data about the 1000 stars in the database, we'll be able to preferentially assign easier stars to users. This will reduce the number of incorrect classifications, and will probably also make the app more fun. So use the app wherever you happen to be, but please tell your friends living in cities to try out the app!