Credit: Photo by: Alan Dyer/VW PICS/Universal Images Group via Getty Images) Using red lights at your observing site will help retain your dark-adapted vision. If you're observing in a dark location and need to see where you are going or choose a different eyepiece, read a star-chart, reference book or consult a planisphere, a red light torch will help preserve your night vision.įind out how to construct your own with our guide to making a red LED torch. Now wait 30 minutes and look again.You should be able to see many more stars than you could at first. Step outside one clear, dark night and look up at the stars.

Credit: mikroman6 / Getty Imagesĭark-adapted vision is useful for navigating your kitchen to get a glass of water in the middle of the night, but it also helps you see more stars in the night sky.

Staring at your smartphone even for a second will ruin your dark-adapted vision.

Read more about the science of seeing in our guide to averted vision. Returning to a light-filled room, shining a white torch or looking at a bright smartphone screen can ruin your dark-adapted vision, meaning you will have to wait for your eyes to re-adapt to the darkness. When you first turn off your bedroom light or step outside on a dark winter's night, you'll notice you can barely see anything.īut after about 30 minutes you'll be able to see objects much more clearly.This is because your eyes acclimatise to darkness over time. What is dark-adapted vision? Give your eyes a moment to adapt and you should start to see more stars. If you have an iPhone, however, you can set up a handy shortcut that will turn on a red filter, which is much more gentle on the eyes and helps preserve dark-adapted vision. Many stargazers and practical astronomers will be familiar with the situation: you spend 30 minutes at your favourite night-time observing spot, waiting for your vision to adapt to the dark so you can pick out more stars in the night sky, only to check your smartphone and ruin your precious night vision.

How to turn your iPhone screen red for astronomy

For apple download I See Red