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!

Wednesday, September 18, 2013

The view from your app

Yesterday we saw some examples of bad street lighting from Spain. Today app user Andreas Hänel provides us with some good examples of decorative street lighting, from Puente la Reina, Spain. Until recently, Puente la Reina was overlit with lamps that produced a lot of glare, and sent much of their light into bedroom windows and into the sky. Now, you can see that the streets are well lit, but that the house facades are quite dark, and there is almost no glare from the decorative street lamps:

Creative Commons License
Good decorative street lighting, Puente la Reine by Andreas Hänel is licensed under a Creative Commons Attribution 3.0 Unported License.
In this photo from the Plaza Julián Mena, you can see an example of both poor and excellent decorative lighting:

Creative Commons License
Decorative street lighting in Plaza Julián Mena by Andreas Hänel is licensed under a Creative Commons Attribution 3.0 Unported License.

The lamp at top left wastes a large fraction of the light that it produces, by sending much of the light where it's not needed. The lamp at center right casts its light only downward, towards the ground. For comparison, here is the daytime view from Google street view. In Puente la Reina, before they changed the lighting many areas were extremely overlit. By directing the light better and using lower ground lighting levels, the town was able to cut its electricity consumption and energy bill drastically. The result is well lit streets, that are more attractive than they were before the lighting intervention.

Monday, September 16, 2013

The view from your app

App user Susana Malón Giménez showed the following images at the 13th European Symposium for the Protection of the Night Sky, and she gave me permission to post them here.

The first image shows badly glaring parking lot lighting:

Creative Commons License
Parking by Susana Malón Giménez is licensed under a Creative Commons Attribution 3.0 Unported License.
This type of lighting actually reduces your ability to see what's going on, which is not at all desirable in a parking lot!  The second image is titled no common sense:

Creative Commons License
No common sense by Susana Malón Giménez is licensed under a Creative Commons Attribution 3.0 Unported License.

The difficulty of the Spanish economy is awful for everyone in Spain. The only good news that I took from the visit is that Spanish cities are now very seriously confronting bad lighting. There were many talks which presented areas that were formerly over lit, where recent improvements in the lighting system have resulted in a massive energy savings. In many cases, the visibility in such areas has been greatly improved by removing glaring lights. You can see how this works in the following image:

Creative Commons License
Globo luminaria by Susana Malón Giménez is licensed under a Creative Commons Attribution 3.0 Unported License.
At first glance, did you see the two people under the lamps? Click to look at the full size image if you still can't see them. Globe lamps are often particularly bad for visibility, because they are not only glaring, but sometimes provide almost no light directly under them. Globe lamps are also particularly bad for the environment, because they shine more than half of their light upwards. It goes into trees where birds and bats live, and it goes into the sky, masking the Milky Way, and causing the sky to glow.

Later this week, I hope to present images of some of the the very good modernized lighting that we saw in Spain.

Friday, September 6, 2013

Kickstarter project for firefly documentary

I love fireflies. When we used to live in Philadelphia, crowds of people would gather on the edge of Clark Park in the early evenings in summer to watch them flashing. So I'm really looking forward to this new documentary about fireflies: Brilliant Darkness: Hotaru in the Night.

The film team has already gathered material, and now they need support to edit the film and do the voice over. You can help support the project by making a small donation at kickstarter. A $25 contribution gets you mentioned in the credits of the film and a free film download, and $50 gets you a DVD copy.

Crowdfunding only works if lots of people hear about the project, so if you love fireflies, let your friends know about the kickstarter campaign!

Thursday, September 5, 2013


I'm very pleased to say that the Loss of the Night app has now crossed 10,000 downloads, as reported by the Google Play page! The more users and observations we have, the more accurate the results will be, so please continue to spread word about the app. If you visit a friend with an android phone this weekend, you could both try using the app on your different phones, and see to what extent your observations agree with each other.

And if you happen to be on twitter, it would be great if you would re-tweet this tweet.

Wednesday, September 4, 2013

GLOBE at Night announces dates for 2014 campaign!

GLOBE at Night has announced the dates for the 2014 campaign:

This is the first year that the campaign will run all year long, so (depending on your latitude) you might be able to help out scientists like me with some summer stargazing! GLOBE at Night has been building a very useful time series of observations since 2006, and it's essential that it continue into the future. This spring, we published results showing that "citizen science provides valuable data for monitoring global night sky luminance". So please plan to take part in 2014!

For both the Loss of the Night app and GLOBE at Night, it's important the moon is set, and that's why the campaign only runs about 10 days per month. The GLOBE at Night dates are a bit conservative, but are a good guide for when the app will work. For example, in Berlin, we will have moon-free periods of astronomical darkness on January 17 (for 10 minutes), January 18 (1:14), and January 19 (2:19). With the app, you can try to make a measurement at any time. If the moon is out or twilight isn't over, then the app will warn you that it's "not dark enough".

The plan is that next year the Loss of the Night app data will be an official part of the GLOBE at Night campaign, so you should be able to see your observations on the GLOBE at Night interactive map. We're still sorting out the details, but I hope we'll have this ready in time for the campaign's start!

Tuesday, September 3, 2013

The view from your app

David Hayes, a blog reader from New Zealand, recently sent me this beautiful photo:

"Milky Way over Piha Beach", by David Hayes, is released under the CC BY 3.0 license.

It's taken from Piha Beach on the West Coast of the North Island. David's photo gave me the idea that maybe we could finally establish something like APOD for light pollution. With a nod to Andrew Sullivan's famous "View from your Window", let's launch a "view from your app".

While you can find some examples of good and bad lighting in various places around the web, there isn't one good go-to location. Furthermore, since most of the images don't have license information, you can't use them in public talks or flyers, books, etc. about light pollution. With this in mind, in order of importance I'm looking for photos of:

1) Good lighting installations (these are the most desperately needed, to show municipalities what their streets could look like)
2) Awful lighting installations (especially examples where the lighting is so bad that it defeats the intended purpose, e.g. an illuminated sign that can't be read because of the glare of a bare bulb)
3) Polluted night skies and skylines (ideally showing a handful of stars poking through the skyglow)
4) Photos (or videos) of insects attracted to lamps (including daytime shots of dead insects under/inside the lamp) 
5) Paired images showing polluted and natural skies taken with the identical camera and settings
6) Time lapse video of urban scenes at night
7) Photos of people using the app
8) Beautiful celestial views, like the one sent in by David (to remind us of what we're missing). Images with clouds obscuring the Milky Way would be particularly welcomed (since they are so difficult to find online) or images that show a historical site (e.g. Stonehenge) authentically lit.

If you want your work to be featured, you must include the following in the text of your email:

I, [Full name], the author of the attached work entitled "[Title]", hereby release it under the terms of the Creative Commons Attribution 3.0 Unported License.

This will give anyone in the world the right to use and modify your image (including for commercial use), provided that they attribute you as the author. This license will also allow your image to be used on the Wikipedia, and in any pamphlets, books, or talks about light pollution, without the authors needing to contact you.

Since APOD already exists, I don't intend to feature "standard" astrophotography, and because this blog is a side project, please understand that it won't be a daily feature, and I may take considerable time to reply and to post your image. Please include some information about where and when the photo was taken. Looking forward to seeing your photos!

Sunday, September 1, 2013

Which stars are people observing?

The Loss of the Night app works by having people report whether they can see stars or not - but which stars are they looking for? Here are all of the stars that had been searched for up to August 22:

The big dipper and cassiopia are big and colored red, to help your orientation (it's an equal area projection, so it looks kind of weird compared to what you see in the sky). The plot is not filled in evenly, because the app has only been around since April (more about this in a moment).

Our app only asks users to look for the 1601 bright stars that were already part of Google's Sky Map app. But it doesn't ask people to look for each star with the same probability. It always starts with a bright star, and the subsequent selected stars depend on what you can see. Because there are so many more faint stars, some stars are searched for much more frequently than others. Here's a plot showing how often each of the stars has been searched for:

Black dots are 1-4 times, red 5-19 times, blue 20-100 times, and purple over 100 times. The most commonly searched for stars so far are Arcturus (602 times), Altair (327), Vega (322), Alioth (260), and Dubhe (184). The most commonly searched for stars are all in the upper half of the image above, because most of the app users live in the Northern Hemisphere.

You might also have noticed the big gap of missing stars on the right. That's there because the stars in the sky change throughout the year, as the night side of Earth points in a different direction as the Earth orbits the Sun. Each month when the moon goes down, users will be confronted with a new set of stars, in new positions, and with new magnitudes (brightnesses).

Here are the stars that were searched for at least once during April/May:

And during June: 

During July:

And up until August 22:

You can see that the searched for stars are marching slowly but surely "left", as the year advances. Very soon, Orion will be a risin', and hopefully many users will tell us whether or not they can still see his stars a blazin' from the middle of Central Park!