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Finding the height of the sun at noon

Again, this problem is similar to the problem of finding the maximum height of a star. Remember that finding the height of the sun at noon is equivalent to finding its maximum height-- at the noon the sun is as high in the sky at it will get on that particular day. This always occurs when the sun is on the meridian, and to a good approximation, the sun is on the meridian at noon. To solve this problem, simply locate the sun using the back of the astrolabe, then place the sun on the meridian (the vertical line passing through the center of the astrolabe.) Read off its height using the scale on the almucantars. You may find this exercise useful later on when we discuss the use of the seasonal hour arcs.

Example: What is the maximum height the sun will attain on the 29th of January? Using the back of the astrolabe, locate the sun on the ecliptic. As in the previous problem, it will be in the 10th degree of Aquarius on that day. Now using the front of the astrolabe, place the 10th degree of Aquarius on the meridian (see below). By reading the almucantar scale, we see that the sun is between the 30 degree almucantar and the 20 degree almucantar (which is just off the edge of the disk.) We can estimate that the sun will be about 28 degrees off the horizon at noon on January 29th. Many people are surprised by how low the sun is in the sky in winter. The reason this value seems so low is that people tend to overestimate angular distances near the horizon (that's the reason a full moon appears so large.)