Wednesday, January 14, 2015

Brief introduction to the Loss of the Night app project

The Loss of the Night app allows citizen scientists to estimate how many stars they can see, and by extension how bright the night sky is. The goal of the project is to track changes in artificial sky brightness in urban areas over the long term (ideally many decades). The app is available for Android and iOS devices. Detailed instructions for using the app are available (Android, iOS).

The day after you've made an observation, you view the details of your observation at the My Sky at Night website. You can also use My Sky at Night to track how skyglow is changing at your location over time.

This blog posts news about the app, and is intended to allow the app users to provide feedback on how we can improve the app in the future. For example, check out this example of one participant's observations. I also do post occasionally about other topics related to artificial light at night, for example this ongoing photo series of examples of good and bad lighting, and views of the night sky.

The Loss of the Night app project is operated in co-operation with the Globe at Night project.


  1. 1.White text on the app is better than black text, but dark blue text on a light blue background or light blue text on a dark blue background is better for humans(white light science, colors of the rainbow)Black text doesn't work at all for information ability.
    2. Night mode red doesn't work well at all, try bright green.
    I like the app...good luck to you in the alphabet vision. We are advancing into light forever and ever hopefully.

  2. Hi Maxcp5,

    In day mode we have white text on a light gray background, but the app really isn't supposed to be used in day mode, so I don't see a real reason to optimize colors.

    In night mode it's absolutely essential to have black and red only, in order not to affect the dark adaptation of the user. If you look at bright green letters, you won't be able to see faint stars when you look back up at the sky.

    You can increase the font size during the star search in User data > Settings > Increase star name font size.

    Thanks for trying the app!

  3. Did a test run run with Loss of the Night app on the iPhone a couple of nights ago. Despite many years of amateur astronomy - I can't say I know the proper names of many stars - just the Latin. I once fielded a phone call from afriend when they were trying to setup the tracking on a GOTO scope - "Where the bloody hell is Hadar?". Ok so now I know it's beta Centauri. Maybe an option to switch between proper names and latin would be useful.


    1. Hi Mike,

      The star names were imported from the Google Sky application (I think). In principle it could be done, but as the app guides you to the particular location in the sky, I'm not sure that this is really so essential. (In other words, I see your point, but at the moment we have no funding, and when we get funding there are a lot of modifications that I think fall higher up on the list.)

      On the plus side - using the app might be a quick way to learn the alternate names :-)

  4. Hi Alberto,

    This usually happens if your phone doesn't have a data or wifi connection. Can you please try quitting the app, and then starting it again when you are sure that you have a stable connection?

    If that doesn't work, try doing a (demo mode) observation during the daytime when you are certain that you have a data connection. Just say you can't see the first star, and then quit and check if the data has been transmitted. If it hasn't, then let me know via email. Contact info here:

  5. Hi Alberto,

    Can you please tell me what kind of a phone you are using, and what version of Android you are running? I am afraid that there are so many possible combinations that we probably aren't able to help you, but it is nevertheless good for us to know what combination is having trouble.

    The app is made only for naked eye observations, ideally within cities. It is not meant for use with telescopic observations. The faintest stars in the app have an apparent magnitude around 5.2, but the app is really not meant to be used in places with a naked eye limiting magnitude greater than about 4.8.

  6. Thanks for providing the information. I am sorry that in the short term we are not able to investigate it further, due to a lack of funding.

    You can always use Globe at Night, which is accurate to +/-1 NELM, and goes out to NELM 7.

  7. An Android phone with no compass is useless? I have the LG Aristo and there's no compass. Can I still get a reading?

    1. Hi yellowplanet,

      The problem with a phone without a compass is that we can't direct people to the right part of the sky. For an astronomer who knows the sky well it might work, but it wouldn't work for most people. (We also didn't have the time or money to create a special no-compass version when we developed the app).

      However, you can still take part in sky brightness monitoring with the Globe at Night experiment:

      It's actually faster and easier than using the app, just unfortunately not as accurate. Still, the data is very valuable for tracking how the sky is changing on regional and global scales.

      Thank you for your interest, and sorry that we can't currently support phones without compasses.

  8. Hello, I live in La Serena, Chile. Today I tried to take measurements, but even though the sky was super clear. But, my phone only recognized 2 or 3 stars. Can I record data manually? I can recognize several constellations in the sky. Greetings and thanks so much!

    1. Hello jpuchima,

      I'm not quite sure what you mean. The phone shows you the stars, and you have to look with your eyes and report (using the app) whether you can see the stars or not. Hope this helps!

  9. :'-( It is'nt compatible with my motorola G9 power.