Why is it easier to see a star if you look slightly to the side?
I'm just a curious person who has never been able to find an answer to this question: Why is it sometimes easier to see a star with the naked eye if you look slightly to the side of it rather than directly at it? Is there a name for this effect?
There are two kinds of light-detecting cells in the retina of your eyes: "rods" and "cones". The cones are designed for high light-level observing, while the rods are designed for low light-level observing. The cones are more concentrated in the center of your eye, while the rods are somewhat more spread out. So by looking just off to the side, you rely more on your rods, which allows you to see dimmer objects better. This effect is called "averted vision".
Exactly how far off-center you should look to maximize this effect varies from person to person. For most people, it's between 5 and 20 degrees away from looking straight ahead.
Get More 'Curious?' with Our New PODCAST:
- Podcast? Subscribe? Tell me about the Ask an Astronomer Podcast
- Subscribe to our Podcast | Listen to our current Episode
- Cool! But I can't now. Send me a quick reminder now for later.
How to ask a question:
If you have a follow-up question concerning the above subject, submit it here. If you have a question about another area of astronomy, find the topic you're interested in from the archive on our site menu, or go here for help.Table 'curious.Referrers' doesn't existTable 'curious.Referrers' doesn't exist
This page has been accessed 15414 times since February 7, 2004.
Last modified: February 7, 2004 2:49:22 PM
Ask an Astronomer is hosted by the Astronomy Department at Cornell University and is produced with PHP and MySQL.
Warning: Your browser is misbehaving! This page might look ugly. (Details)