The Difference Between Astronomy and Astrology

I'm not going to assert that belief in astrology is right or wrong. Everyone has their own truth and their own reality. It's important to respect that. What I would like to explain is the difference between astronomy and astrology and why astronomers have such a difficult time with astrology.

A little History: Astronomy and astrology were the same thing before the modern era, because predictive and divinatory knowledge was one of the motivating factors for astronomical observation. Astronomy is simply the observation and measurement of celestial bodies, while astrology is an attempt to find some sort of "meaning" or "influence" in the planetary positions. The interesting thing is that astrology gave birth to astronomy. Oddly enough, considering that astrology has to do with planetary movements, astrologers no longer look at the sky, and haven't for hundreds of years.

Modern astronomers find it difficult to connect with astrology because the data used by astrologers bears no relation to what is actually seen in the sky. Astrologers have ignored the slow "wobble" of the earth on it's axis, called the precession of the equinoxes, even though Hipparchus discovered it as long ago as 100 BC. It means that the position of the ecliptic in the sky has shifted quite a bit in the last two thousand years, so that the zodiac is not the same as it was in the year 0.

As an example, I'm always told that I'm a Cancer, since I was born in July, because the sun is in Cancer in July. Well, the sun was in Cancer 2000 years ago, but in the year I was born the sun was in Gemini, not Cancer. Anyone with a simple astronomy or planetarium program on their computer can input the year and day they were born and see for themselves what "sign" they were born under. I use Starry Night.

By the way, the plane of the earth's ecliptic now crosses the constellation Ophiuchus (it didn't 2000 years ago) so there are currently 13 zodiacal constellations in the northern hemisphere, not 12. Go to a bookstore and look at any star chart that shows the ecliptic and you will see it soaring happily through Ophiuchus! Some astrologers have suggested that the borders of the constellations are too wide. If we narrow the borders, then the constellation that gets excluded is Scorpius, not Ophiuchus. Here's a chart showing how many days the sun spends in each constellation:

Constellation:        Dates:      No of days:
Sagittarius Dec 18 Jan 18 32 Capricornus Jan 19 Feb 15 28 Aquarius Feb 16 Mar 11 24 Pisces Mar 12 Apr 18 38 Aries Apr 19 May 13 25 Taurus May 14 Jun 19 37 Gemini Jun 20 Jul 20 31 Cancer Jul 21 Aug 9 20 Leo Aug 10 Sep 15 37 Virgo Sep 16 Oct 30 45 Libra Oct 31 Nov 22 23 Scorpius Nov 23 Nov 29 7 Ophiuchus Nov 30 Dec 17 18

Even the Ancient Mayans had a Zodiac with 13 Constellations

          The ancient Mayan zodiac was composed of 13 constellations, including the constellation Ophiuchus, which is exactly what is seen in the sky today. The description of the 13 constellations of the Mayan zodiac is found in The Paris Codex, (Codex Peresianus), one of the very few texts of the pre-Conquest Maya that survived the book burnings by the Spanish clergy during the 16th century. As everyone by now knows, the Mayans were famous for their precise astronomical observations and their accurate predictions of eclipses and of Venus rising.

Also, astrologers consider retrograde motion to be an important influence on their lives. In astrology, this backward movement was traditionally thought to be unlucky or inauspicious, as it went against the 'natural' order of movement. The problem is, retrograde motion is purely an optical illusion, caused by the line of sight when looking at an outer planet that is being overtaken by a faster-moving, inner planet. (There are many animated, graphic demonstrations of this on the internet). Astronomers (and many other people) have trouble believing that any part of their lives can be influenced by an optical illusion.

A personal note: I can see how Astrology could be a lot of fun, like any other game devised for amusement. I just can't understand how it could help me in my quest for self-improvement. Here's what I find empowering about astronomy that I don't find in astrology:

Astronomy is a science that compels me to seek beyond myself and our small world, a science of discovery that enriches my life by exercising my brain and my intellect. It empowers me to think clearly and rationally. It improves and sharpens critical thinking skills.

I believe that astrology just wouldn't empower me in the same way. I believe that my destiny is in my own hands, and not in the accidental configuration of planets and stars.

It's the sheer fascination for space and the possibilities of worlds beyond our own and a science beyond our current understanding that encourages astronomers to think outside the box and develop his or her intellect to the fullest. From the time of Galileo, our lives have been enriched beyond measure by scientific discovery.

Carl Sagan wrote : "Some of science is very simple. When it gets complicated, that's usually because the world is complicated, or we're complicated. When we shy away from it because it seems too difficult, or because we've been taught so poorly, we surrender the ability to take charge of our future." (The Demon Haunted World, Ballantine, 1996, p29).

Be in charge of your life. Experience the mystery, awe, and excitement of observational astronomy. Find your local astronomy club, go to a star party, and look up!


Ask yourself, "Who sees them?" I find it really interesting that professional and amateur astronomers don't report UFO's. Astronomers are experienced, knowledgeable sky observers. They have collectively spent millions of hours staring into the night sky. So why don't we get UFO reports from this group on a regular basis? They take thousands and thousands of photos of the night sky. Why don't all the astronomy magazines have photos of flying saucers?

One reason is that astronomers are are more likely to recognize what they are actually seeing, and a UFO quickly becomes an IFO (identified object). An astronomer is more likely to be acquainted with the optical atmospheric phenomena that uninformed observers mistake for flying saucers. For instance, there are frequent sightings of iridium flares (satellites that flare up brightly), regular satellites, sun dogs, moon dogs, parhelia, sun pillars, halos, glories, devil clouds, and St. Elmo's Fire. There are also arcs, patches, and other specific optical effects that can only be seen from an airplane.

Here is a really spectacular atmospheric phenomenon on YouTube: UFO-like clouds spotted in Romania. Ask yourself, what teaser is going to get more viewers for a TV news program: "Interesting clouds in Romania"? or "Scientists deny that weird lights in the sky were flying saucers"?

Then there are Sprites, dancing lights that have appeared above most thunderstorms throughout history. Lightning from the thunderstorm excites the electric field above, producing a flash of light called a sprite. Sprites can take the form of fast-paced balls of electricity, streaks or tendrils. Fiery balls have been videotaped 35 to 80 miles high, moving up and down at one-tenth the speed of light. Both jetliner pilots and astronauts have previously reported sightings of sprites, along with a different but equally mysterious phenomenon known as blue jets.

How many airplane pilots have studied rare atmospheric phenomenon and know what any of this stuff is? Much easier to just report a disc of light that seemed to follow the plane. Remember, a UFO is just that -- an Unidentified Flying Object, not a flying saucer.

Ask yourself, "What does the person reporting this sighting have to gain?" The most typical report comes from someone living in a small town in a remote place (often Texas) where there isn't much going on. Typically, several people in the town will jump on the UFO bandwagon in hopes of focusing national attention on themselves and their town. The local press is all too happy to get the attention of the national news media, and the national news media is even happier to sell stories. The fact that the same thing happens every year in some small town somewhere doesn't seem to bother anyone. It still makes headlines.

Finally, it's completely pointless to attempt to reason or argue with people who believe in flying saucers because, as psychologists tell us, many people believe things for emotional, not intellectual reasons. They simply have a deep-seated need to believe, a need that can never be influenced by logic or reason.

Personally, I'm still waiting to hear "Klaatu Barata Nikto".

Photos by Pauli Hänninen. These are sun halos or 22 degree halos, which are produced by the ice crystals in cirrostratus clouds. The crystals bend direct sunlight, projecting it elsewhere into the sky, and at a certain angle -22 degrees – a halo can be seen around the sun.

Paul described that night in his village in Finland, “It was cold and very foggy, the temperature was around -10 degrees Celsius. When the clouds began to break, there were rainbow colors in the sky and a halo spanning 360 degrees! It was worth taking a picture or two.”

The spots on either side are called sundogs. Sundogs may appear as a colored patch of light to the left or right of the sun, 22° distant and at the same distance above the horizon as the sun, and in ice halos. They can be seen anywhere in the world during any season, but they are not always obvious or bright. Sundogs are best seen and are most conspicuous when the sun is low.

If you want to learn more about unusual atmospheric phenomenon, here are some excellent sources:

Rainbows, Halos & Glories
By Robert Greenler (1989) CUP
ISBN 0521388651

Seeing the Sky
By Fred Schaaf (1990) John Wiley ISBN

The Nature of Light & Colour in the Open Air
By M/Minneart (1954) Dover
ISBN 486201961

Wonders of the Sky
By Fred Schaaf (1983) Dover
ISBN 0486244024

Light from the Sky
(Scientific American articles by various authors)
Freeman & Co
ISBN 0716712229

Pseudoscience (Far too many TV documentaries)

Scientists are often quoted as saying, "Extraordinary evidence is needed for extraordinary claims".

An extraordinary claim is one that contradicts a fact that has been well established and is widely accepted in the scientific community. "Scientific facts" are really just statements that have a very high degree of certainty. To contradict such a statement, you had better have evidence available that is even higher up the certainty scale. A "leap of faith" is not evidence. An emotional attachment to an idea is not evidence.

So why don't scientists bother to refute the claims of all the pseudoscientists running around? Easy--first, there are so many false claims out there that the legitimate scientist wouldn't have any time left to do anything else. If an extraordinary claim doesn't come from a credible source in the first place, that is, from someone who has the credentials to propose the idea, then it just doesn't make any sense to dignify it with a response. If you want to propose a theory about an ancient civilization, you better have a verifiable, reputable background in that field with at least some history of publications and recognition. That is to say, you better have put in the work. If you haven't, why should someone who has put in the years of work required to understand that field bother to respond to your claims?

Why do some people want to believe so desperately in the nonsense that they espouse? Bad science is everywhere, not only in print and on the web, but especially on television.

The most obvious reason for the proliferation of bad science is that it helps create a bigger audience, good ratings and increased advertising revenues. Similarly, no newspaper editor can be convinced that he will increase his paper's circulation by canceling the astrology column and replacing it with an astronomy column. Publishers have found that books on astrology make money for them. But beyond the obvious profit motive, why do some people actually believe the nonsense that they are peddling?

An article in the May 2003 Archaeology magazine sheds some light on the trend and the people who preach nonsense. "They tend to be anti-establishment, suspicious of authority, suspicious of science. They like to strike this populist pose of the little man fighting against the big university professors. Pseudoarchaeology fans get attracted to all sorts of odd notions. Their ancient civilizations, for instance, are better than ours, more peaceful, more spiritually attuned. Like anybody else, they are attracted to good stories, and pseudoarchaeology tells sensational stories."

Carl Sagan spoke directly to the point. Real science, he pointed out, is hard. It requires critical thinking skills that many people simply never develop, and it's much easier to believe a simplistic version of, for instance, creation, than to study the facts and discover what really happened. Pseudoscientists "long for the scientific seal of approval, but are unwilling to put up with the rigorous standards of evidence that impart credibility to that seal."

Finally, psychologists tell us that some people are so desperate for attention of any kind that they even welcome negative attention. For this reason, they take to the web and cross-post their ridiculous notions everywhere. Their posts may show up on a newsgroup that you subscribe to, even though they don't subscribe to it themselves and never read it! Responding to their posts only feeds into their desperate need for attention. The best way to respond to such people is to completely ignore them. It makes absolutely no sense to engage them in a discussion about their beliefs because their motives for believing nonsense are purely emotional, not logical. To attempt any sort of discussion at all quickly becomes hopeless.

A piece written by Michael Shermer for Scientific American, "Smart People Believe Weird Things", August 12, 2002, explains this phenomenon quite well. Here are some excerpts:

"Smart people believe weird things because they are skilled at defending beliefs they arrived at for non smart reasons."

"Students are taught what to think but not how to think."

"For those lacking a fundamental comprehension of how science works, the siren song of pseudo science becomes too alluring to resist, no matter how smart you are."

These Links are both fun to read and informative:
  • Bad Astronomy Astronomy mistakes in film and the news media.
  • CSICOP encourages the critical investigation of paranormal and fringe-science claims from a responsible, scientific point of view and disseminates factual information about the results of such inquiries to the scientific community and the public.
  • Astrology FAQ--Who cares? A critical look at astrology and who is making money with it.
  • The Scientific Method

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