Stop #8 – The Zodiac

The Zodiac is a circle of 12 constellations arranged around the “equator” of the celestial sphere (along the same path that the sun travels throughout the course of one year).  They were used as an early sort of coordinate system, which split the sky into 12 even 30° degree sections, and they can also function as a sort of calendar.

On any given night, the sun (hiding below the horizon) is within a constellation of the zodiac, or thereabouts (the constellations don’t line up perfectly with their 30° section, but it’s close enough, by ancient Babylonian standards). About half of those 12 constellations will be below the horizon at a given moment, while the other half can be seen on a clear night.

As the celestial sphere spins throughout the night, one of the 12 zodiac constellations will “set” in the west, going below the horizon, about every 2 hours, as another zodiac constellation “rises” along the eastern horizon.

When the sun rises in the east, in the morning, it will still be in the same constellation that it spent all night parked in, but it’s brightness will make it difficult to see the stars of that constellation, and of the constellations before and after it in the Zodiac. The sun moves across the celestial sphere very gradually, advancing to be within the 30° degree “section” of the next zodiac constellation about once per month.

If they say that you’re an “Aries”, that means that on your birthday each year, the sun’s annual course across the zodiac leaves it near the Aries 30° degree section.
(The sun is actually in Aries every year between April 15 – May 15, but Astrology uses the dates March 21 – April 20 for Aries, since the sun’s course through the zodiac has shifted since the first Astrology charts were made, about 3,000 years ago.)

The 12 constellations of the Zodiac are:

# ° Constellation Meaning
1 Aries The Ram
2 30° Taurus The Bull
3 60° Gemini The Twins
4 90° Cancer The Crab
5 120° Leo The Lion
6 150° Virgo The Maiden
7 180° Libra The Scales
8 210° Scorpio The Scorpion
9 240° Sagittarius The (Centaur) Archer
10 270° Capricorn The Sea-Goat
11 300° Aquarius The Water-Bearer
12 330° Pisces The Fishes

That’s a lot to remember! Don’t worry, we’re going to learn a trick to help us:

A Tortoise Generally Can't Lecture Verbally;
Least scary, sad creatures are peaceful.

Aries Taurus Gemini Cancer Leo Virgo;
Libra Scorpio Sagittarius Capricorn Aquarius Pisces