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:


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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.