Diagrams for the סוגיא of מזלות, Constellations of the Zodiac

To better understand this סוגיא as explained by רשי", the following diagrams presented from an earth-centered perspective, where the earth is standing still.  It is neither spinning, nor orbiting the sun.  The man is standing on the surface of the earth facing south.

There are twelve major מזלות, constellations, that follow the גלגל חמה, path of the sun. One after another, they circle the earth in a day.  Each constellation rises in the east.  It stays on top of the earth (visible) for approximately twelve hours.  Then it sets in the west.  It goes below the earth (not visible) for approximately twelve hours.  Simple division tells us that every two hours (24 / 12) a new מזל will rise in the east as another מזל will set in the west.

The sun travels the same path in front of the מזלות. It circles the earth in exactly 24 hours. (Caution must be used when using the word exactly, but for understanding this סוגיא this will suffice).

The מזלות circle the earth slightly quicker than the sun.  It takes them 23 hours and 56 minutes.  Thus, after a month, a מזל will rise two hours earlier (4 minutes x 30 days = 2 hours).

Note: a מזל that rises together with the sun, or, for that matter, any מזל that is on top of the earth, although it should be visible, it cannot be seen due to the glare of the sun.

The solar year is 365.25 days.  A lunar year is 354.  When discussing the מזלות, we are referring to the solar year.  Just as the lunar year is divided in 12 months, so too is the solar year.  The solar months have the same names as the lunar month (ניסן אייר תמוז ...) but are slightly longer (to make up for the 11.25 day discrepancy between the solar and lunar year)

In the month of ניסן, the מזל of טלה, the ram, begins rising at daybreak (6am) and completes its rising at 8am.  At that point, the next מזל, the שור, rises (from 8am to 10am).

A month later, אייר, the שור, ox, rises at daybreak.  The טלה has already finished rising before day break. It started rising two hours earlier at 4am and finished by 6am.

Six months after that, מרחשון, the טלה rises twelve hours earlier than in אייר, namely, 4pm.

כימה is not one of the twelve major מזלות.  Rather it is part of the מזל of טלה, namely, its tail.

These diagrams are ignoring seasons so sunrise is always at 6am and sunset always at 6pm.

Both the sun and מזלות are rotating counter-clockwise.  As mentioned above, the מזלות are rotating slightly quicker giving the appearance that the sun is traveling around the מזלות in a clockwise direction.

Diagram #1 –The solar month of ניסן at 6am.  The sun is in front of the טלה so that is the מזל of the month.

Diagram #2 –The solar month of ניסן at 8am.  The sun and מזלות shifted two hours relative to the earth.  טלה (and כימה) rose during the day (at sunrise).

Diagram #3 –The solar month of אייר at 6am.  The sun is in front of the שור, so that is the מזל of the month. It is exactly a month after diagram #1.  Since the מזלות rotate around the earth slightly quicker that the sun, the מזלות shifted two hours relative to the sun.  טלה (and כימה) rose at night (just before sunrise).

Diagram #4 –The solar month of מרחשון at 6am.  The sun is in front of the עקרב, so that is the מזל of the month. It is exactly six months after diagram #3. טלה has just finished setting.

Diagram #5 –The solar month of מרחשון at 4pm.  The sun is still front of the עקרב. It is ten hours after diagram #4. טלה (and כימה) are ready to rise during the day (4pm).