Astronomers’ eyes may glaze at the mention of the Zodiac and horoscopes but the rest of the world glazes at the mention of astronomy. I know. I teach astronomy to 8th Graders and while some may have no interest at all in celestial coordinates or the inclination of Earth’s axis, they sit right up when I mention their horoscope and they are surprisingly well-versed on the subject. And thanks in part to Marilyn McCoo, the Dawning of the Age of Aquarius holds a mystical appeal for older folks of my generation. The more I know about astrology the better I can engage my audience of any age in astronomy. And surprisingly, the one thing both astronomers and astrologers agree upon is – the Dawning of the Age of Aquarius.
Ancient astronomers were revered for their ability to predict the change of seasons, when to plant and when to harvest, when the rivers will rise and when it will be dry. In this way, the stars determined the future. Peoples lives and whole civilizations depended upon an accurate knowledge of the stars and so the patterns and predictions divined by astronomers were embedded in the culture.
All the planets of the solar system, including Earth, lie in a plane around the Sun called the ecliptic. The constellations of the Zodiac lie along this plane as well. As the Earth orbits the Sun, the Sun and planets appear to follow a path through the constellations or "houses"of the Zodiac.
Ancient astronomers were able to determine where the Sun would be among the background stars through the year even though the stars around the Sun are not visible during the day. During a total solar eclipse though, the bright Sun is blocked by the Moon and the stars behind the Sun are visible. The Sun will appear to be in a "house" of the Zodiac and as Earth orbits the Sun, the Sun will appear to move from one house to another through the course of a year, and then the cycle repeats.
The Earth’s axis is tilted and as we orbit the Sun each year, the amount of sunlight the Northern and Southern Hemispheres receive changes causing our yearly change of seasons.
If the axis wasn't tilted, every location on Earth would have equal length daylight and night and the weather would be the same throughout the year.
Try This
You can model the seasons by holding a pencil at arm's length to represent Earth's axis and imaging that your head is the Sun.
Hold the pencil straight up and down and move the pencil from your right side to your left side. This is how the Earth would move if the axis didn't have a tilt. Every location on Earth would have equal length daylight and night all through the year as the Earth orbits the Sun.
Now hold the pencil in front of you and tilt the pencil away from you. For this "pole" this would be the Winter solstice, the shortest day of the year and the start of Winter. For the opposite pole leaning toward you, this would be the Summer Solstice, the longest day of the year and the first day of Summer.
Keep the pencil tilted in the same direction and hold it in your right hand with your arm stretched out to the right. Neither pole is tilted toward or away from the Sun; the axis is perpendicular to the Sun. In this position, every location on Earth will have equal length of daylight and night. This day is called the Equinox.
Keep the tilt in the same direction and move the pencil from your right side to in front of you, from the Equinox to the Winter Solstice for the pole tilted away from the Sun and the Summer Solstice for the pole tilted toward you.
Keep the tilt in the same direction and move the pencil from in front of you to your left side, from the Summer and Winter Solstices to the Equinox on your left side. For the pole that was tilted away from you, this would be the last day of Winter and the first day of Spring. For the pole that was tilted toward you, this would be the last day of Summer and the first day of Fall.
Keep the tilt in the same direction, held in your left hand, and turn around so that now you're holding the pencil in your right hand, still tilted in the same direction. Again, move the pencil from your right side to in front of you. Now the opposite pole is tilted toward you. This is the Summer Solstice for this pole and the Winter Solstice for the pole tilted away from you.
Solstices and Equinoxes
On the Spring and Fall Equinoxes, the Sun (your head) is in line with the Equator (the middle of the pencil). The Sun doesn't cast a shadow at exactly noon at the Equator on the Equinox and as the Earth turns, the Sun will appear to be on the horizon from the North and South Poles. Everywhere on Earth receives equal length daylight and dark on the Equinoxes.
It's more difficult to model the Solstices without a globe. A ball with a stick through the center will help.
On the Summer Solstice the Sun is in line with the Tropic of Cancer, 23.5 degrees North Latitude. The Sun doesn't cast a shadow at exactly noon along the Tropic of Cancer on the Summer Solstice and as the Earth turns, the Sun continues to shine on the North Pole. There is 24 hours of daylight from the North Pole to the Arctic Circle and the terminator, the line between light and dark on the Earth, just touches the Antarctic Circle. As the Earth turns, sunlight never extends south of the Antarctic Circle, the Sun never rises above the horizon and it is dark for 24 hours from the Antarctic Circle to the South Pole.
On the Winter Solstice the Sun is in line with the Tropic of Capricorn, 23.5 degrees South Latitude. The Sun doesn't cast a shadow at exactly noon along the Tropic of Capricorn on the Winter Solstice and as the Earth turns, the Sun continues to shine on the South Pole. There is 24 hours of daylight from the South Pole to the Antarctic Circle and the terminator just touches the Arctic Circle. As the Earth turns, sunlight never extends north of the Arctic Circle, the Sun never rises above the horizon and it is dark for 24 hours from the Arctic Circle to the North Pole.
Precession of the Equinoxes
Right now, the Spring Equinox, when our axis is perpendicular to the Sun, is around March 21st, our Summer Solstice is around June 21st, our Fall Equinox is around September 21st and our Winter Solstice is around December 21st.
The Earth's axis wobbles like a top as it spins on its axis; one full wobble takes about 26,000 years. As the Earth slowly wobbles, the North Pole traces a large circle and the angle of the axis to the Sun slowly changes. As the direction of Earth's axis changes, the Solstices and Equinoxes "precess"; they occur earlier in the year, the seasons start and end earlier in the year, slowly moving around the calendar during the Earth's 26,000 year wobble.
13,000 years from now, half-way through the 26,000 year wobble, the Spring Equinox will be in September, the first day of Summer be in December, the Fall Equinox will occur in March and Winter will start in June.
The North Pole now points nearly to Polaris, the North Star, and as the Earth turns on its axis, all the other stars appear to turn around the North Star.
In 13,000 years, half-way through the 26,000 year wobble, the North Pole will point close to the star Kochab, at the other end of the Little Dipper from Polaris, and for all the millennia in between, we won't have a North Star, just as we don't have a South Star now.
The Difference between the Astrological and Astronomical Calendars
The Zodiac begins with Aries because the astrological calendar begins on the Spring Equinox, March 21. This is the first day of Aries in the astrological calendar because the Sun appeared to be in the constellation Aries on the Spring Equinox when the calendar was created, between 2,500 and 5,000 years ago.
Because the axis slowly wobbles, the Sun is now in the constellation Pisces on the Spring Equinox, March 21st.
The Sun appears to be in each constellation of the Zodiac about 1 month earlier than the dates for each constellation on the astrological calendar because wobble of Earth axis has caused the seasons, the Equinoxes and Solstices, to arrive earlier in the year. The seasons have "precessed." For this reason, the astrological calendar, the dates corresponding to the constellations of the Zodiac, are all about 1 month later than the astronomical calendar, dates in which the Sun now appears in each constellation.
The Sun appears to move into a new constellation of the Zodiac on the Spring Equinox about every 2,250 years on average (26,000 years / 12 constellations ~ 2,250 years)
The designations of 23.5 N latitude as The Tropic of Cancer and 23.5 S latitude as the Tropic of Capricorn are not accurate according to astronomical observations.
Celestial navigation developed during the Age of Navigation starting around the 16th Century. Astronomy was not sophisticated enough at this time to determine the position of the Sun relative to the constellations along the ecliptic since these constellations cannot be seen during the day when the Sun obscures their view. The Tropics of Cancer and Capricorn were designated according to the Zodiacal calendar.
On the Summer Solstice, June 21st, the Sun in directly in line with the Tropic of Cancer, 23.5 degrees North Latitude, but the Sun appears to be in the constellation Gemini.
On the Winter Solstice, December 21st, the Sun is directly in line with the Tropic of Capricorn, 23.5 degrees South Latitude, but the Sun appears to be in the constellation Sagittarius.
The Zodiacal year is evenly divided among 12 constellations but astronomically, the Sun transits 13 constellations along the ecliptic and it's time in each "house" varies considerably. Astronomically, the Sun's transit along the ecliptic is much more complicated.
The Zodiac designates the beginning and ending of each constellation on or about the 21st of each month. I've never heard a good explanation of the significance of the 21st or why our calendar doesn't start with the shortest day of the year, the Winter Solstice.
The Sun transits 13 constellations along the ecliptic. It enters the constellation Ophiuchus beginning on or about November 29th when it leaves Scorpio and ending when it enters Sagittarius starting on or about December 17. The astrological calendar skips Ophiuchus and makes Scorpio start on October 21 and end on November 21.
13 is considered to be unlucky which may explain why Ophiuchus is excluded. It would seem to make more sense to leave out Scorpio, although Scorpio is one of the easiest constellations to identify since it looks so much like a scorpion. Libra is the only constellation of the Zodiac which is not represented by a living creature, person, animal or some combination, inhabiting the “zoo” of Zodiacal constellations. I haven't found a good explanation for why poor Ophiuchus got the boot.
The constellations along the ecliptic vary greatly in size and orientation causing the Sun’s transit time to vary for each constellation. The Sun is in Scorpio for six days, Ophiuchus for about 18 days and Libra for about 23 days while Virgo stretches across the night sky in Autumn and the Sun spends about 40 days among her stars.
The Sun is in the constellation Scorpio for the shortest period, six days from November 23 - 29. It is which makes it the shortest transit of any constellation along the ecliptic at 18 days.
The Dawning of the Age of Aquarius?
Astrology is embedded in our culture as well. We are now in the astronomical era of Pisces, when the Sun is in the House of Pisces on the Spring Equinox. Before Pisces was the era of Aries and before Aries was Taurus. We live within these great expanses of time. Now, on the Spring Equinox, the Sun is in the constellation Pisces, much closer to the constellation Aquarius. But as the Earth’s axis wobbles over the 26,000 year cycle, the Spring Equinox will occur earlier. As the Spring Equinox “precesses” around the calendar, the seasons associated with the calendar months and the constellations of the Zodiac will change.
www.stellarium-web.org Desktop version 0.19.3
Select "Show ecliptic of date" and "Show equator." Move the field of view until you see the ecliptic and equator cross, now in the constellation Pisces.
Use date/time to observe the position of the Spring Equinox for any year.
The Age of Aries
The Sun has appeared in Pisces for about 2,000 years, around the beginning of what we call our current era. Before that, the Sun appeared in the Constellation Aries for 2500 – 3000 years. Before Aries was the era of Taurus. Who or what event does our culture associate with this significant change from the era of Taurus, the Bull, to the era of Aries, the Ram? God told Abraham to sacrifice his son, Isaac, but before Abraham could obey this command, God delivered a ram, tangled by his antlers in a bush, for Abraham to sacrifice instead of his son, and so began the era of Abraham and Aries the Ram, the age of monotheism which replaced human sacrifice with offerings of animal sacrifice.
The Age of Taurus
After Moses received the commandments from God, he descended the mountain and threw the stone tablets to the ground because he was angry that the Israelites were praying to Baal in the form of a golden calf. Moses was angry because the Israelites were praying to the old god, Taurus the Bull, while he brought guidance for the new era of Aries the Ram, which he received from a burning bush. Aries could have been the era of the bush but it’s hard to find the pattern of a bush in the stars, unless you consider all the stars to be a bush which surrounds us, just as God is everywhere. But all the constellations of the Zodiac are figures of humans or animals or some combination of the two, except for Libra, the scales, but that constellation was introduced by Caesar Augustus, long after the others were established, and throwing a burning bush that speaks with the voice of God into the Zodiac would only make more confusion.
The Age of Pisces
Who or what heralded the end of the era of Aries the Ram and the beginning of the era of Pisces the Fish? The Fisherman of Souls, Jesus Christ of Nazareth. We live in the era of Pisces, the Christian era.
The Dawning of the Age of Aquarius
The Sun has appeared to be among the stars of Pisces on the Spring Equinox for over 2000 years. As the precession of the axis continues, the Equinox will occur earlier in the year until the Spring Equinox will occur when the Sun appears in the House of Aquarius - and it will be the “dawning of the age of Aquarius.” Models predict that this will occur in 1,000 to 1,500 years, depending upon where one chooses to draw the astronomical boundary between Pisces and Aquarius.
We can’t predict who or what will herald the end of the era of Pisces and the Dawning of the Age of Aquarius, the Water-bearer, but rising sea-levels seem appropriate along with the rise of “New Age” mysticism, the new age that will begin with the Dawning of the Age of Aquarius. Perhaps Marilyn McCoo will return to lead us over the endless ocean as we sail into the stars, into the 5th Dimension.
Andy Cohen, October 18, 2021