What do the months and hours mean in Tomas Filsinger's Map of The Universe I have had one of these in my room for decades:


I don't have the booklet that seems to usually come with it, can someone explain to me what the months (with days below it) and hours mean? I imagine it has to do with the position of the earth and therefore the part of the universe that is possibly observable, but I get confused when I try to get the months in the equation.

Thank you very much
The hours show the lines of right ascension, where right ascension is one of two coordinates used to specify a point on the sky. (The other coordinate is declination, measured in degrees from the celestial equator.) Right ascension and declination are similar to longitude and latitude on the Earth.

The month and day show the right ascension of the Sun on a given date. The dotted circle passing through the zodiacal constellations (Pisces, Aries, etc.) is the actual path of the Sun (the ecliptic). Therefore, the position of the Sun on any day can be determined from the chart.