The best stargazing apps can take your observation of the night sky to the next level, whether that’s using augmented reality (AR mode) to identify stars or looking up the next lunar eclipse.
However, the bright light emitted by smartphone screens can prevent your eyes from adjusting to the dark. If you’re using one of the best telescopes, you’ll want to preserve your night vision even more. Fortunately, there are ways to all but eliminate this problem.
Why are bright screens bad for stargazing?
When you step out into the dark, it can take up to 20-30 minutes for your vision to adjust. The rod cells in your eyes build up a chemical known as rhodopsin, which gives you night vision.
However, bright light bleaches that chemical, negatively impacting your night vision. So when you look through a telescope, binoculars or just turn your eyes to the night sky after peering at a bright phone screen, it’ll be harder for you to pick out fainter objects such as galaxies and nebulas.
One way of fixing this problem is simply to put your phone away and wait another 20-30 minutes. But if you’re using a stargazing app to help you navigate the night skies, that’s not really an option.
The good news is that, between individual stargazing apps and your phone’s own built-in features, you can minimize the impact of your smartphone’s screen light.
How to block white light in stargazing apps
SkyView: Tap the screen, tap the horizontal lines, tap on Settings, then Display, then Night Mode and Red.
Star Walk 2: Tap the horizontal lines, tap on Settings, then tap the button next to Night Mode.
Sky Tonight: Tap the horizontal lines, tap on Settings, then Tools, then Night Mode.
All these modes will minimize the amount of white light coming from the app. However, be aware that this is only within the app. Once you go back to your phone’s main menu, it will be at full color. With the red screen naturally looking darker, you may have turned up the brightness on your phone, so making the switch away from the app will be quite the shock.
If you want to dim your whole phone or put it into red light mode, here’s how to do that on Android or iPhone.
How to block white light on Android phones
On Android, there are several ways to minimize the impact of bright light, depending on the model and make of phone you have.
One near-universal option is to dim your smartphone. Swipe down the notification panel from the top of the screen and you’ll see a brightness slider. Slide this to the left to dim your phone.
We’d also recommend disabling adaptive brightness in the Display section of your phone’s settings. You may also have an Extra Dim option in the Accessibility menu — just don’t dim the screen to the point of not being able to see it at all!
Some Android phones, such as recent Samsung and Google Pixel models, also offer a Red Filter. On some, you’ll find this in Accessibility, then Vision Enhancements, then Color Filter. You can then choose the color you want and also tweak the opacity.
All the above options will let you continue to use your smartphone for stargazing, while minimizing its negative impact on your night vision.
How to block white light on Apple iPhones
As with Android phones, iPhones have a built-in option to dim the screen brightness. In this case, you swipe down from the top of the screen and look for the vertical brightness slider, represented by a sun icon. Reduce the slider as much as you’re comfortable with, dimming the screen while still keeping it visible.
Beyond that, recent iPhones also offer the ability to apply a color filter, again via their Accessibility options. Here’s how to do that.
First, tap on the Settings icon, then pick Accessibility. Select Display & Text Size and go to Color Filters. Tap the Color Filter button. Then, pick Color Tint and move the Hue and Intensity sliders all the way to the right.
Chris McMullen
Chris is a freelance journalist who, when not writing, skywatching, gaming or building Lego, indulges his taste for horror, sci-fi and the post-apocalyptic. As well as Space.com, you can find his work at GameSpew.com (where he’s the weekend editor).
