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.

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.

Future upgrades to the app

How can we improve the app?

A bit more than a year ago I asked for your help in how we could improve the app. I updated the list as suggestions came in through comments, email, and in-person discussion, and with the release last fall a lot of the improvements made it into the app.

Now that the new version has been out for a few months, I want to start a new list for a future third - and ideally final - release. We have no source of funds at the moment, but I think it's valuable to keep track of what needs changing/fixing. If you have more suggestions, 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) to make the display more comfortable
• When screen is frozen, allow navigation by sliding finger 
• Allow the user to adjust the number of stars displayed on the screen to match a given skyglow level? (a bit dangerous, as this could potentially cause biased observations)
• 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 

Usability

• 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?
• Arrange "my measurements" by date
• 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?)

Community

• Have the database in the background: users can log in see their observations - where they were taken, how they relate to those of others, see the observations of others, tools to examine how it is changing over time, see the accuracy of the data they gathered themselves
• Graphical web display of your like I have shown on the blog in the past
• Option to share your observation via facebook and twitter
• 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
• Find a way to calibrate the compass within the app (on Android, iOS already has this)
• Port to WindowsPhone and Blackberry
• Allow observing below 45 degrees and making maps of the stellar visibility on the full sky dome
• 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
• Check whether the phone has a compass, and don't allow install if there is no compass
• Ability to export your observations (e.g. to an email)

Technical

• Change behavior of star search with "averted vision" decision (technical)  
• 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

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

Effect of a single floodlamp in a natural area

Updated May 4, 2015

Zoltán Kolláth took these amazing images of the shadow a church tower cast on the clouds in Torniella, Italy:

Floodlit church shadow by Zoltán Kolláth is licensed under
a Creative Commons Attribution 4.0 International License.

Fisheye church shadow by Zoltán Kolláth is licensed under
a Creative Commons Attribution 4.0 International License.

The church tower is lit by a single poorly directed floodlight that shines much of the light into the sky rather than onto the tower. It dramatically demonstrates the effect that individual poorly directed lamps can have on the night environment in a natural area.

The village had turned off the public street lighting for a light pollution measurement campaign organized by the Loss of the Night Network, so we were able to compare the effect from that single lamp to the villages streetlights (which are mostly well directed). At our measurement location on a football pitch 250 meters from the church, the single lamp produced about 5% as much skyglow as the entire town's ~100 street lights put together! Keep in mind that since we can see the shadow the church projects on the sky, we're not actually under the beam of light - in other areas the effect is likely even larger.

The floodlit tower from closer up

The single floodlight that causes the problem

Whenever floodlighting is directed upward and only a portion of it hits the intended target, the rest of the light is simply wasted in brightening the night sky. However, you usually aren't able to see it because of all of the other wasted light shining into the sky. We were only able to take such an image because the village was kind enough to turn off all of the entire public lighting system for several hours each night during our measurement campaign:

The official announcement that streetlights would be turned off, displayed in a local bar

The church tower in the example above is at least an attractive element in the city. This evening in Florence we happened to notice an upward directed floodlight that was "needed" to illuminate a boring brick hotel wall. For a brief moment, we introduced a bit of darkness to make it a bit more interesting:

Light shone into the sky isn't just a waste of money and energy, it destroys one of Earth's most threatened habitats: the night. If you want to help bring the night back to Earth, consider making a donation or becoming a member of the International Dark-Sky Association.

Update 2014/05/04:

Costas Bouroussis shared these two additional images for the village with the church tower lit and off:

Torniella church light on by Costas Bouroussis is licensed under
a Creative Commons Attribution 4.0 International License.

Torniella church light off by Costas Bouroussis is licensed under
a Creative Commons Attribution 4.0 International License.

Costas also produced this time-lapse video where you can see the shadow of the church on the clouds. The three circles show approximately what a Sky Quality Meter would have reported at each of the zenith angles.

Note for new visitors: This blog is about the Loss of the Night app project, in which citizen scientists to track how skyglow is changing worldwide with the introduction of LED lights. I also have a photo series in which I profile good and bad lighting.

Globe at Night in other languages

Here is the link to the download page for Globe at Night information in other languages.

The webapp is currently available in:

• Catalan
• Chinese (simplified)
• Chinese (traditional)
• Chilean Spanish
• Czech
• English
• Finnish
• French
• Galician
• German
• Greek
• Icelandic
• Indonesian
• Italian
• Japanese
• Persian
• Polish
• Portuguese
• Romanian
• Serbian
• Slovenian
• Slovak
• Spanish
• Swedish
• SwissFrench
• SwissGerman
• Thai
• Turkish

Globe at Night auf Deutsch

Der "Globe at Night" Projekt hat leider keine Deutsche Website, der es gibt ein Deutsche Version von der webapp. Es gibt auch Infos für Lehrer/in und Familien die mitmachen wollen, hier zum Beispiel für Orion. Für andere Sternbilder, klicken sie hier. Der Deutsches GeoForschungsZentrum (GFZ) hat auch Infos über die internationale Nacht der Himmelsbeobachtung veröffentlicht.

Wir danken für Ihre helfe die Veränderung unser Nachthimmels zu beobachten!

The Globe at Night revisit project (2015)

The goal of the Loss of the Night app is to track how skyglow is changing worldwide. But since it was only released in 2013, it will be a while before we'll really be able to see the changes. But the Globe at Night program is already in its tenth year, so the time series is already relatively well developed.

The best place to make a skyglow observation is someplace very close to your home, so that you can observe there again in the future. But if you are willing to travel a kilometer or two in order to help us track how is changing, you could help us out by making an observation near the same place one was made in the past.


The map above shows 5,000 locations on Earth where someone made an observation in the past but there hasn't been a new observation within the last five years. If you can make an observation near to one of these points (or if you have a friend who lives close to one of them), it would be extremely helpful.

You don't need to go to the exact point shown (in fact, I shifted the points by some distance to preserve anonymity). An observation within about 100 meters is close enough.

Update January 6, 2015:  During last year's Globe at Night campaign, 24 of these locations were re-sampled. Big thanks to those who took part! The relatively small number means that the revised map for 2016 looks very similar to this map, so I will just leave this one up for now and will probably revisit this idea next year. In any case, with the new My Sky at Night webpage you can generate maps for your own city, which will make it easier to find a location closer to where you live.