Expert: Philip Stahl - 8/29/2010

Question
What is the best way to illustrate in a diagram the eastern horizon going from northeast to southeast? Also, where on the diagram would the rising point of the sun be for the following: summer solstice, winter solstice, vernal equinox, and autumnal equinox? I am just beginning to learn about these out of curiosity of learning something outside my comfort zone, and the websites I have visited in my search for knowledge have not made me understand the concept very well. I am unsure as to where the suns rising points would be on each of these 4 occasions when on the eastern horizon. Thank you very much in advance!

Answer
Hello,

What you need is a good introductory astronomy (college) text which has a chapter on the celestial sphere - wherein the Earth is shown in relation to it, as well as the ecliptic, and the celestial equator. (The ecliptic is represented as the projected path of the Sun through the year).

Also, many popular books (such as in math, e.g. 'Mathematics for the Million' by Lancelot Hogben) have such diagrams, cf. page 338. In that diagram all the reference points are shown, including the equinoxes and solstices relative to an observer's horizon, ecliptic and the celestial sphere. Alas, copyright protections disallow me scanning it and posting it - but the book should be available at any library, or maybe even at amazon.com

As to how to work out rising points for the Sun (dependent on the latitude and date) this was already dealt with some time ago, e.g.

http://en.allexperts.com/q/Astronomy-1360/sunrise-1.htm

If you need further assistance with this, let me know.