Unformatted text preview: and the sky segment diagram containing Sirius are different. In the celestial sphere diagram one is imagining an outside view of the celestial sphere (from a vantage point beyond the most distant stars that we see with the naked eye). In the diagram showing the position of Sirius in the sky the view is instead the actual sky as viewed from the Earth (that is, from the center of the sphere in the first diagram). Thus, the directions get reversed: moving to the right from the vernal equinox in the first diagram will look like moving to the left as viewed from its center, which is the perspective of the second diagram (that is, the actual view of the sky from Earth). That direction, by convention, is chosen to be the positive direction for right ascension....
View Full Document
- Fall '10
- Anthropology, Sirius, Celestial coordinate system, right ascension