Is the Sun always up for exactly 12 hours at the equator?
What is the length of day at the equator? I recently told a friend with great certainty that at the equator the sun rose and set at exactly 12 hour intervals at roughly 6 a.m. and 6 p.m. (depending on the time zone) every day of the year. Now I'm not so sure.
You're right. It is always exactly 12 hours. There are a couple of different ways you can convince yourself that this is so, but I think the easiest one is this symmetry argument:
In the Northern Hemisphere, the length of the day is longer during the months when the North Pole is tilted towards the Sun and shorter during the months when it's tilted away from the Sun. The reverse is true for the Southern Hemisphere. The Equator is exactly halfway in between the poles. So it wouldn't make any sense for a day on the equator to be longer when one of the poles is tilted towards the Sun, and shorter when the other one is.
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 35079 times since December 14, 2002.
Last modified: February 3, 2006 11:56:24 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)