Why do we not have eclipses every month?
Can you tell me what causes eclipses of the sun and moon? Why do they not happen every month?
A lunar eclipse occurs when the Moon enters the Earth's shadow. A solar eclipse occurs when the Moon's shadow falls on the Earth. They do not happen every month because the Earth's orbit around the sun is not in the same plane as the Moon's orbit around the Earth.
If you were to draw a little Earth in orbit around a little sun on a piece of paper, then you would not be able to accurately draw the Moon's orbit on that same piece of paper. Sometimes the Moon will be above the paper, other times below it. Only when the Moon is crossing the plane of the Earth's orbit (the paper) just as it is lining up with the Earth and Sun will an eclipse occur.
More details on this phenomenon can be found at this page from the Earth View website.
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.
- Are there eclipses on other planets?
- What is the best time of the year to see eclipses?
- How do I explain to my children why the Moon has phases?
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 64756 times since May 9, 2002.
Last modified: March 7, 2003 5:27:00 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)