The - ecliptic . Because the rotation axis of the Earth is...

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
The "Road of the Sun" on the Celestial Sphere Another important imaginary object on the celestial sphere is the "ecliptic" or "Road of the Sun", which is the imaginary path that the Sun follows on the celestial sphere over the course of a year. As the diagram at left indicates, the apparent position of the sun with respect to the background stars (as viewed from Earth) changes continuously as the Earth moves around its orbit, and will return to its starting point when the Earth has made one revolution in its orbit. Thus, the Sun traces out a closed path on the celestial sphere once each year. This apparent path of the Sun on the celestial sphere is called the
Background image of page 1
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: ecliptic . Because the rotation axis of the Earth is tilted by 23.5 degrees with respect to the plane of its orbital motion (which is also called the ecliptic), the path of the Sun on the celestial sphere is a circle tilted by 23.5 degrees with respect to the celestial equator (see diagram at right). The ecliptic is important observationally, because the planets, the Sun (by definition), and the Moon are always found near the ecliptic. As we shall see later, this is because all of these objects have orbits that lie nearly in the same spatial plane. Shockwave movie illustrating the ecliptic . Motion of Sun through Zodiac in Copernican Model ....
View Full Document

Ask a homework question - tutors are online