November 1, 2006
|As Earth orbits the Sun each year, the Sun appears to cross in front of more than a dozen constellations. As observers on a nearly circular path that takes 365 days to complete, we find the Sun moves approximately 1° per day against the background stars. This movement defines a line, called the ecliptic, around the celestial sphere. The ecliptic is inclined 23.5° to the celestial equator because this is the amount Earth's rotation axis is tilted relative to its orbit. |
You are currently not logged in. This article is only available to Astronomy magazine subscribers.
Already a subscriber to Astronomy magazine?
If you are already a subscriber to Astronomy magazine you must log into your account to view this article. If you do not have an account you will
need to regsiter for one. Registration is FREE and only takes a couple minutes.
Non-subscribers, Subscribe TODAY and save!
Get instant access to subscriber content on Astronomy.com!
- Access our interactive Atlas of the Stars
- Get full access to StarDome PLUS
- Columnist articles
- Search and view our equipment review archive
- Receive full access to our Ask Astro answers
- BONUS web extras not included in the magazine
- Much more!