Why does the Sun appear larger on the horizon than overhead?
Why does the sun appear so much larger when it is on the horizon then when it is high in the sky?
That the Sun appears larger when it is on the horizon is just an optical illusion. The brain thinks that objects on the horizon should be farther away than objects overhead; since the Sun is the same apparent size in both places, the brain concludes that the Sun is physically bigger when it's on the horizon, and thus tricks you into thinking that the angular size is bigger than when it's overhead. This phenomenon is known as the Ponzo Illusion, and occurs for the Moon as well.
To convince yourself that this is, in fact, an optical illusion, put your head between your legs and look at the Sun upside down when it's on the horizon: it should look the same as it does when overhead.
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 42894 times since September 18, 2002.
Last modified: November 6, 2002 11:13:39 AM
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)