《普通高中地理课程标准(实验)》明确提出,要通过选修“宇宙与地球”(选修1),使学生学会“运用天球坐标系简图,确定主要恒星的位置”。要达到这样的要求,必须首先学会确定天球各大圈在天空中的实时位置,建立起清晰的“天球坐标系”概念。天球坐标系主要涉及4个重要的大圆圈:地平圈、子午圈、天赤道、黄道,它们在天球上两两相交,且彼此相互平分。由于它们是天球坐标系中最重要的大圈,所以,要描述天体在天空中的位置,观测者头脑中必须对这4个大圆圈在天空中的实时位置和走向有清晰的了解。上述4个重要的大圆圈 The General High School Geography Curriculum Standard clearly states that students should learn to “use the celestial coordinate system sketch to determine the position of major stars” through the elective “Universe and Earth” (Elective 1). To meet such a requirement, we must first learn to determine the real-time position of the major circle of the celestial sphere in the sky and establish a clear concept of “celestial coordinate system.” The celestial coordinate system mainly involves four major large circles: the horizon ring, the meridional ring, the equator, the ecliptic, and they cross each other on the celestial sphere, and are mutually equal. Since they are the most important large circle in the celestial coordinate system, so to describe the position of celestial bodies in the sky, the observer must have a clear understanding of the real-time position and direction of the four large circles in the sky. The above four important big circle