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zodiac revised

NASA is science and astrology is not. But that doesn’t mean that very logical, well-informed people don’t look at their horoscope once and awhile. And everyone knows what their zodiac (“circle of animals”) sign is supposed to be.

A few months ago, NASA put out some zodiac information that the popular press picked up on and took further than NASA intended.

On the science side of things, NASA made the point that the sky and positions of the stars and constellation is significantly different from the sky that the ancients used when they came up with the zodiac signs that we all have known.

The zodiac signs were created based on the calendar year of the Babylonians who  lived over 3,000 years ago. They divided the zodiac into 12 equal parts pie slices, even though they seem to have known that there were actually 13 constellations in the zodiac.  Twelve just worked neater.

The Earth orbits the Sun, so the Sun appears to pass through each of those 12 zodiac signs. That worked out nicely with their 12-month lunar calendar.

Orion stars

You can see Orion’s familiar 3-star belt. Can you see in this group of stars what the ancient Greeks thought looked like a giant hunter with a sword attached to his belt.?

What is the zodiac anyway? NASA explains it like this:

Imagine a straight line drawn from Earth though the sun and out into space way beyond our solar system where the stars are. Then, picture Earth following its orbit around the sun. This imaginary line would rotate, pointing to different stars throughout one complete trip around the sun – or, one year. All the stars that lie close to the imaginary flat disk swept out by this imaginary line are said to be in the zodiac.

One thing that NASA announced was that the thirteenth sign – which had been there all along – was Ophiuchus. NASA didn’t come with that Latin name either (meaning “serpent bearer”) it had been written about by Greek astronomer Ptolemy in the second century.

I first heard about this “news” because I follow NASA’s Tumblr account. where they said “We didn’t change any zodiac signs, we just did the math.”

In those 3000 years, the Earth, which wobbles a bit as it orbits, has shifted our view of the sky. The Earth’s axis (North pole) isn’t pointing in the same direction it was to the Babylonian viewer.

But the news that there was a thirteenth zodiac sign (Ophiuchus) and the shifting sky meant that more than 80% of us were born under a different sign. That would be true if someone redrew the sky charts and used those revised charts to do your horoscope based on when you were born. The sign you always thought was your sign actually was your sign – three millennia ago.

I had a friend in college who was really into astrology. She did a chart for me and made the point that those horoscopes that you see in magazines and online are so general for a sign that they mean almost nothing. You need a chart done for you based on the day and time you were born. I learned that astrologers use “artificial” constellations that are fixed in the Sun’s path as seen from Earth and use that to track planetary movements. Therefore, the zodiac sign dates remain the same for astrologers no matter what NASA says..

Of course, NASA doesn’t really care about your horoscope. I think their interest in all this is pretty close to my own interest in astrology. It makes you pay more attention to celestial observations.

But, if you have looked at your horoscope and found it not to be so accurate, maybe you want to consider the more modern view of the sky that was up there when you were born.  I moved from being a Libra to being a Virgo. If you were born today you are born under Ophiuchus. Some Capricorns are now finding out they are a Sagittarius. It’s like a commercial for DNA ancestry testing that I see on television – you thought you were a Cancer and now you’re a Gemini. Poor Scorpio went from being about a month to just six days long.

I checked my Libra horoscope while I was writing this. Bummer: “You probably aren’t going to feel very friendly. You’re most likely to want to sequester yourself at home and not see or speak to anyone.”  I checked in on Virgo – not much better: “Today you might get the feeling that someone in your family is hiding something. The atmosphere might be strained and somewhat tense.” Why can’t I have this one? “Venus, your personal planet, enters a dynamic and positive sector of your chart, making this the perfect time to make over your life, attitude and relationships.”

Here are NASA’s revised 13 signs and dates:

Capricorn: Jan. 20 – Feb. 16
Aquarius: Feb. 16 – March 11
Pisces: March 11 – April 18
Aries: April 18 – May 13
Taurus: May 13 – June 21
Gemini: June 21 – July 20
Cancer: July 20 – Aug. 10
Leo: Aug. 10 – Sept. 16
Virgo: Sept. 16 – Oct. 30
Libra: Oct. 30 – Nov. 23
Scorpio: Nov. 23 – Nov. 29
Ophiuchus: Nov. 29 – Dec. 17
Sagittarius: Dec. 17 – Jan. 20

zodiac-beit_alpha

Mosaic pavement from a 6th century synagogue at Beth Alpha, Israel showing the zodiac surround the central chariot of the Sun (a Greek idea) and the corners depict the 4 “turning points”  of the year, solstices and equinoxes.

zodiac light

Sunset, Milky Way and the zodiacal light above the platform of the Very Large Telescope (VLT) on Cerro Paranal.

It is September and it feels like the end of summer in that school is back in session. For almost all of my life, the beginning of the school year as a student or as a teacher meant it was the “fall semester” even if the temperature and nature still looked like summer.

Of course, it is still summer and will be officially until the 2016 autumnal equinox on September 22.

This is the best time to observe the odd “zodiacal light” (AKA the false dawn). For the next two weeks, the Moon is not visible in the morning sky.

Unfortunately, where I live in Paradelle (northern U.S.) and in Canada, it’s not as visible. Right time, wrong place.  Best viewing is in latitudes closer to the equator, as in the southern U.S., which is where I saw it only once.

In a rural area with less light pollution and open spaces, you might see what looks like the lights of a city on the horizon or it might seem that dawn is arriving an hour or two early.

What is zodiacal light? It has been poetically described as looking edgewise into our solar system. At this time of the year, the ecliptic (path of the sun, moon and planets) is nearly straight up with respect to the eastern horizon before dawn. The sunlight is reflecting off space dust particles that move in the same plane as Earth and the other planets orbiting our sun in the zodiacal cloud. After sunset in spring, and just before sunrise in autumn, the zodiac is at this steep angle to the horizon. This light is quite faint and moonlight or light pollution makes it vanish.

Sliding our perspective to the Southern Hemisphere, it’s approaching spring equinox and this strange light will appear in the west, about an hour after the sun goes down, as it will in Paradelle next spring.

In both astrology and historical astronomy, the Zodiac is a circle of twelve 30° divisions of celestial longitude that are centered upon the ecliptic. The ecliptic is the apparent path of the Sun across the celestial sphere over the course of the year.

Although the zodiac remains the basis of the ecliptic coordinate system in use in astronomy besides the equatorial one, the term “zodiac” and the names of the twelve signs are today mostly associated with horoscopes and  astrology.

The paths of the Moon and visible planets remain close to the ecliptic, within the belt of the zodiac. They are regular divisions and do not correspond exactly to the twelve constellations after which they are named. We commonly call these twelve divisions “signs.” You can say that you were born under the sign of Libra, or take the scientific path and see the zodiac as a celestial or ecliptic coordinate system, which takes the ecliptic as the origin of latitude, and the position of the Sun at vernal equinox as the origin of longitude.

The term “zodiac” derives from Latin zōdiacus, which in its turn comes from the Greek zōdiakos kyklos, meaning “circle or pathway of animals.” Half of the signs of the classical Greek zodiac are represented as animals (plus two mythological hybrids).

You may think that you were “born under a bad sign”  (which is really a  blues song by Albert King) and that “If it wasn’t for bad luck, I wouldn’t have no luck at all” but what if you were born under a forgotten sign?

The 12 signs of the Zodiac that are familiar to us from astrology and horoscope advice (Aries, Taurus, Gemini, Cancer…) does not include the 13th or “forgotten” constellation: Ophiuchus.

If there is a “bad sign” I would guess it might be Ophiuchus with its number 13 and forgotten status.  The sun moves in front of Ophiuchus from about November 30 to December 18 each year but I doubt that you have ever heard someone say they were born when the sun was in Ophiuchus.

Every year at this time, I notice a post from earthsky.org to look for this faint constellation, also known as the Serpent Bearer, as it appears in the southwest sky on late August and September evenings. It is above the bright ruddy star Antares, which is the brightest in the constellation Scorpius the Scorpion.

sheep

The Google Doodle decided it is the Year of the Sheep

Today is Chinese New Year which is the longest and most important holiday in the Chinese calendar. It is estimated that almost 3 billion trips will be made across China as people make the journey home to celebrate with their families.

This celebration, known as chun yun, is the longest national holiday in China, spanning a total of fifteen days. Day one is the most important day but the first three days of the new year are a statutory holiday and many people will be off for the first 6 days.

Yes, China has been using the same Gregorian calendar we use here in Paradelle since 1912, but the ancient Chinese lunar calendar is what creates this New Year.

In that lunar calendar, the New Year is changeable and  falls on the second New Moon after winter solstice. That puts it somewhere between January 21 and  February 19.

2014 was the Year of the Horse (though the lunar year is not always comparable to our January-December calendar year) and that has ended but this new year is a bit unusual because you may see it named the Year of the Goat or the Year of the Sheep. The confusion is because the Chinese character “yang” can be translated in colloquial Chinese as either sheep or goat.  I’m reading that in France, it is being called the Year of the Goat. In America, sheep has favor. In China, they are less concerned with the distinction.

I read at the end of 2014 that some people in China were concerned about births and marriages occurring in a sheep year as it was a “bad year.” The common impression is that sheep are meek, doltish “followers.”  Some of this seems to come from the late Qing dynasty (late 19th century)  when the Empress Dowager Cixi and several other high officials were despised. They all happened to be born in the Year of the Sheep/Goat and so it becamse associated with a negative spin. Followers of the Chinese zodiac say that all 12 signs are auspicious, so don’t worry.

 

Aldebaran

Remember back in 2006 when poor, old planet Pluto was demoted? A group of scientists decided that there are three main categories of objects in our solar system:
Planets: 8 from Mercury to Neptune.
Dwarf Planets: Pluto and any other round object that “has not cleared the neighborhood around its orbit, and is not a satellite.”
Small Solar System Bodies: All other objects orbiting the Sun.

plutoI felt bad – and so did a lot of other Earthlings – for Pluto.

This past week I read that the waxing gibbous moon outside my window was moving toward the star Aldebaran, the brightest star in the constellation Taurus the Bull. Nothing odd about that. Normal movement.

But what I had not known was that Aldebaran also had a kind of demotion. It used to be the North Star, also known as the Pole Star. How does a star lose its rather prominent name in the sky?

You probably learned that Polaris is the North Star, but a long time ago Aldebaran had that honor. That was 450,000 years ago.

Back then, it appeared several times brighter in the sky then than it does now. In a way, it shared the title because it was very close to another very bright star, Capella, so they served as a double pole star. (This was 447,891 BCE, if you like precision.)

That’s pretty amazing, but it was a long time ago. But what really hit me was that in this little solar system of ours and in our beautiful galaxy and this almost unimaginable universe, everything is always moving.

Even the sky looked different hundreds of thousands of years ago.

sky chart

This illustration shows the view as seen from present-day Arizona in 447,000 B.C., when Aldebaran and Capella served as double pole stars. Illustration via Carina Software and Instruments and earthsky.org

The identity of the pole star shifts over time, due to the 26,000-year cycle of precession. To read more about that, click into this article about Thuban, another former pole star.

Still, how can it be, you might wonder, that the stars Aldebaran and Capella were once so near each other on the sky’s dome? They’re not especially close together now. Aren’t the stars essentially fixed relative to one another? The answer is that, yes, on the scale of human lifespans, the stars are essentially fixed. But the stars are actually moving through space, in orbit around the center of the galaxy.

The Moon is moving across the constellation Taurus and, in the Zodiac, Aldebaran is important. It is part of that merry band of stars in front of which the Sun, Moon, planets, dwarf planets and small solar system bodies dance their rounds.

The Earth is spinning as I sit here typing. It is making the moon and Aldebaran shift westward but the Moon is moving to the east relative to the “fixed” stars because of the Moon’s orbit around us. It is all so amazing. Some people think that looking up into that giant sky makes them feel so small. I disagree. It makes me feel a part of something so enormous and grand.

Hello, Aldebaran. We didn’t forget you.

 

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