Good August Window to #MeasureTheSkyBC

Looking for Stars with the Loss of the Night App.
Image credit: Christopher Kyba, CC BY-NC 4.0

August 22nd to 31st are great dates to help with our #MeasureTheSkyBC campaign to measure light pollution.

It’s easy – all you need is your phone & your eyes!

And… get a chance to win a prize by sending us an email at [email protected] that you did it. This month, we are giving away a copy of the RASC book “Explore the Universe Guide” and free registration to the Lightning Lake Star Gazer’s Package at Manning Park’s Dark Sky Astronomy Weekend, on October 18-20 & 25-27, 2019.

Here is how to participate:

Loss of the Nigh App Logo
  • Install the LOSS of the Night app from the Apple App store or the Google Play store.
  • Start the app and enter some basic user information in the user data section such as your age, whether you wear glasses/contacts, and your observing experience.
  • Go outside on a clear night. Try to pick a location where you can see a large part of the sky and that is away from bright lights. Ideally, pick a time after 10:00 pm when the sun is well below the horizon (after the end of astronomical twilight).
  • Follow the instructions in the app to start measuring stars.
Loss of the Night app Screenshot  with direction arrow
Follow the arrow to find a target star.

Using the app is a fun, video-game like experience – great for kids. It works by helping you find target stars and then asking if the star is visible with your eyes. There is a demo mode so you can even try it out during the day. The app does not need internet (after it is installed) so you can use it when camping or out at a remote location.

Start by aiming your phone/tablet at the sky. The app displays a star field over-laid with a circle and an arrow.

Move your phone/tablet in the direction of the arrow. Go slowly and turn your whole body as necessary to follow the arrow.

Is the target star visible with your eyes?

When you locate the target star, a large orange circle is displayed, a smaller flashing yellow circle appears around the target star, and the display freezes.

Now you can lower your phone/tablet and look to see if the target star is visible with your eyes. Finish with this target by clicking the appropriate button.

Repeat on 8 target stars to get a good measure of the light pollution at your location. Expect some target stars to be easily visible, some barely visible, and some not visible, as the app tries to narrow down what you can see at your location.

After you’ve finished your measurement, the app will display your “limiting magnitude” which can be used as a measure of light pollution. Your data can be sent anonymously to a global database of light pollution measurements. You can see your measurement on a map, track changes over time, and compare it to other observations from around the world at

Don’t forget to send an email to [email protected] for a chance to win a prize – please include your location and limiting magnitude in the email if possible.

Milky Way from Cascade Lookout at Manning Park