Wednesday, April 27, 2016

Model of exponential growth in skyglow at one location

Andrej Mohar produced a video modeling skyglow changes from 1950-2040 at Matajur mountain on the border of Slovenia and Italy:

The simulation is based on a calibrated all-sky image taken at the site, with an estimate of 5% annual growth in skyglow (which is a pretty reasonable assumption for the later half of the 20th century). But there's no reason that skyglow must continue growing at such a rate! If we get smart about how, where, and when we light, we could recover the starry skies that many of us remember from our childhood.

Wednesday, March 16, 2016

VdN App and MySkyAtNight wishlist

How can we improve the app?

Your feedback helps us improve the app. We don't currently have funding for further development, but hopefully that will change in the future, and we can do one final change to the method, and then fix it for a long period. If you have more suggestions for how to improve the app, please let me know in the comments.

Things to change/improve in a future version of the app

Star search

  • Further improve star selection based on app data (preferentially use easier stars)
  • Make more use of "pointing stars"
  • Allow search to start with Venus or Jupiter
  • Allow the user to change the sensor settings (speed and/or damping)
  • When screen is frozen, allow navigation by sliding finger 
  • Option in settings to not lock screen when star is found
  • Shaking the phone unlocks the locked circle (goes back to arrow) 
  • Try to work out that the user is standing on a balcony, and don't suggest stars in that direction 
  • Allow the user to adjust the number of stars displayed on the screen to match a given skyglow level? (we don't want to do this, as this could potentially cause biased observations)


  • Figure out what causes the occasional crash on startup
  • Better way to deal with very bright locations
  • Strategies for classifying areas with NELM>5
  • Interface to allow advanced users to submit what their estimate of the limiting magnitude is
  • New "constellation mode". Highlights a single constellation, and the user has to click on a star to declare it visible (turns from dot to star) and click a second time to declare it invisible (turns from star to empty circle or x), click third time for "just at visible limit"
    •  Or extend this mode to cover several hundred stars over the whole sky, and the observer can just pick which ones she wants to label?
  • Manual way to calibrate the compass to remove azimuth error 
    • Add a compass-free option in "settings" menu for places with weird magnetic fields
  • Investigate behavior of auto brightness on Android (does it turn to full on app startup for some phones?)
  • Allow "SQM only" install for phones without gyroscope/compass


  • Badges - you've observed 7 stars, you've repeated an observation at the same location ~1 year later, you've done 10 observations, 5 times in a single city, 5 locations, etc...
  • Guide users to locations that we particularly need measurements (e.g. repeat measurements from previous years).
  • Incentivize good data: Have a friendly competition where the best quality and quantity is rewarded (with a visit to the closest telescope and a personal lecture from an astronomer). Reward observations in particularly important locations

Extra features

  • A "talking" tutorial that tells you how to find the stars, asks you to turn in different directions, etc.
  • Video tutorial
  • Allow observing below 45 degrees and making maps of the stellar visibility on the full sky dome (expert mode)
  • Check the clock using GPS and warn the user if their phone's clock is off by more than 2 minutes (and then exit app). Prevents records having a false time
  • Allow option of displaying user's location on a map to make sure it is correct 
  • Find a way to calibrate the compass within the app (on Android, iOS already has this)
  • Port to WindowsPhone and Blackberry


  • Start looking for GPS location on app start up, verify again before star search
    • Especially for SQM report, GPS should run in the background while typing value
  • Reduce the size/thickness of the circle during the star search on Android
  • Better messaging in "Not dark enough" menu during high latitude summer 
  • Allow users to add SQM serial number, and SQM-L or SQM

My Sky at Night

  • Allow users to customize font size and color, and background color

Now it's your turn. What other changes should we make to the app?

Wednesday, March 2, 2016

Globe at Night turns 10!

The Globe at Night project turned 10 years old this month! Citizen scientists have contributed tens of thousands of data points over the last 10 years:

Clear-sky moon-free Globe at Night observations, 2006- Feb 2016.
Explore the data yourself at!
In its early years Globe at Night wasn't a year-round campaign, so for time series analyses March is the most important month for new Globe at Night observations. So if you have clear skies between now and March 10, take a moment to look for Orion, and let Globe at Night know how many stars you can see by filling out this form (available in 28 languages).

Wednesday, February 24, 2016

The new version of the Android app is out

The Android version of the Loss of the Night app has been updated (new version is 2.1.5). The main changes with this update were to target the boundary between averted vision and not visible (it was incorrectly set to target the boundary between visible and averted in the last version), and to deal with the (rare) problem that some phones sometimes reported incorrect GPS positions.

The solution we introduced to solve the GPS problem may unfortunately prevent some phones from using the smoother gyroscope function that was introduced with the second version of the app. If you notice that the display of the stars seems jittery, try immediately quitting the star search and starting it again. If that doesn't work, please contact me to let me know what model of phone and which version of Android you are using. While we do not currently have funding to do further development, your input could help us figure it out more quickly in the case we do find additional funding.

Monday, January 11, 2016

Do you want to translate the Loss of the Night app into your language?

I currently have offers to translate the Loss of the Night citizen science app into 3 additional languages. When I have at least 5 additional languages, I can arrange a new release. Please let me know if you are interested in helping by volunteering to translating two XML files and the text for the play and app stores into your native language. You can expect the job to take about four hours of translation time, plus about 20 minutes verifying that the translation works correctly in the app.

The app is already translated into: Arabic, Catalan, Chinese, Czech, French, German, Hebrew, Italian, Japanese, Polish, Romanian, Slovak, Spanish, and Turkish. If you are interested volunteering a new translation, please send an email to Christopher Kyba.

Wednesday, January 6, 2016

Top 5 posts of 2015

Here's the top five most read posts from this blog last year:

1) A brief introduction to the project - Hurrah for brevity!

2) The Globe at Night revisit project - Help us re-sample locations to see how the sky has changed.

3) Effect of a single floodlamp in a natural area - If you haven't seen the photo yet, check it out now!

4) Citizens push back on LED lighting - Want good lights? Talk to city hall!

5) Amazing new photos from the International Space Station - High-res photos of cities at night.

Thanks for reading! The current moon-free period runs until about the 10th. Help us track how the sky brightness were you live is changing with our app, Globe at Night, or the Dark Sky Meter app! Once you've made an observation, you can view it at My Sky at Night.

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