Skip to main content Accessibility help
×
Hostname: page-component-848d4c4894-8kt4b Total loading time: 0 Render date: 2024-06-21T05:53:49.031Z Has data issue: false hasContentIssue false

2 - Two spheres: modeling the heavens and the Earth

Published online by Cambridge University Press:  18 March 2019

Todd Timberlake
Affiliation:
Berry College, Georgia
Paul Wallace
Affiliation:
Agnes Scott College, Georgia
Get access

Summary

The stars move from east to west across the sky each night. The ancient Greeks realized that the apparent movement of the stars would make sense if the stars were stuck on the inner surface of a giant celestial sphere that rotated around the Earth once every sidereal day. The Sun also moves from east to west across the sky, but not quite in the same way as the stars. The Sun’s motion can be tracked using shadows, and it appears to move eastward relative to the sphere of the stars along a path that is tilted relative to the celestial equator. The Sun completes its motion around the celestial sphere in one year, traveling through the constellations of the zodiac along a path called the ecliptic. As an observer moves around on Earth the apparent motions of the stars and Sun change in a way that shows the Earth to be spherical. The stars also display a very slow motion known as the precession of the equinoxes with a period of about 26,000 years.

Type
Chapter
Information
Finding our Place in the Solar System
The Scientific Story of the Copernican Revolution
, pp. 13 - 48
Publisher: Cambridge University Press
Print publication year: 2019

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

Save book to Kindle

To save this book to your Kindle, first ensure coreplatform@cambridge.org is added to your Approved Personal Document E-mail List under your Personal Document Settings on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part of your Kindle email address below. Find out more about saving to your Kindle.

Note you can select to save to either the @free.kindle.com or @kindle.com variations. ‘@free.kindle.com’ emails are free but can only be saved to your device when it is connected to wi-fi. ‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.

Find out more about the Kindle Personal Document Service.

Available formats
×

Save book to Dropbox

To save content items to your account, please confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account. Find out more about saving content to Dropbox.

Available formats
×

Save book to Google Drive

To save content items to your account, please confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account. Find out more about saving content to Google Drive.

Available formats
×