365daysDate: May 30, 2009

Title: The Power of the Force! (Astrology Part 2)


Podcaster: Patrick McQuillan

Organization: Incorporated Research Institutions for Seismology (IRIS)

Description: Which has more influence on you at birth: the planets of the solar system or your doctor? For thousands of years people have tried to use the locations of the planets at the time of a person’s birth as a means of predicting life’s future events. We’ll take a close look at the idea from an astronomical viewpoint to get perspective on the merits of the power of Planetary Force. What about Uranus and Neptune, only discovered since the invention of the telescope, and unknown to the ancients? How about Pluto: unknown, then a planet, now not a planet? And what about the Earth: closest planet to us, but not used in astrological calculations? We will examine the gravity of the situation.

Bio: Patrick McQuillan earned a B.S. degree in Physics from the College of William and Mary. His senior research project involved determining the period of variable stars, most notably Alpha Auriga. This was at a time when collecting data meant going to the roof of the physics building, locating the research star by hand, and tracking the star manually by following a guide star in the finder scope. No GPS-auto-guiding-from-a-climate-controlled-remote-location! In the twenty plus years since then, he has explained astronomy to the general public as a Planetarium Director, the Education Manager for Challenger Center for Space Science Education, a NASA Solar System Ambassador, and currently explains Earth Science as Education and Outreach Specialist for IRIS. You can view current earthquake activity using the Seismic Monitor located on the IRIS website.

Today’s sponsor: This episode of “365 Days of Astronomy” is sponsored by Joseph Brimacombe.


Patrick: Hello, I’m Patrick McQuillan, Education and Outreach Specialist with IRIS, the Incorporated Research Institutions for Seismology, a NASA Solar System Ambassador and a former Planetarium Director. Welcome to the May 30th edition of the 365 Days of Astronomy Podcasts.
May the Force be with you!

This ubiquitous line from the Star Wars movies evokes thoughts of an unseen mysterious force that helps shape our destinies. As Obi Wan Kenobi said, “The Force is an energy field created by all living things. It surrounds us, it penetrates us, it binds the galaxy together.”

Which sounds great. Except the Star Wars movies are wonderfully enjoyable fiction. The Force of Star Wars does not exist.

In our real universe, people have been trying to understand the universe’s workings since the dawn of time. The constellations and planets of the night sky were taken as likely tools that could be used to unravel the past, present and future course of the universe and the people living in it.

The constellations and planets were likely suspects due to their location in the heavens and the permanence they exhibited. The constellations returned to the same locations each year with unchanging precision. The planets moved with clockwork regularity that could be plotted and predicted into the future.

If you want to hear the details of how and why astrologers used the constellations to predict the course of future events, head back and listen to the February 27 edition of the 365 Days of Astronomy Podcasts. It is all explained there.

The constellations are not the only things astrologers use to predict the future course of people’s lives, the planets are especially important.

According to astrology, the location of the planets at the time of a person’s birth will determine all kinds of important aspects of their future life, such as their personality type, length of life, possible occupation, you know … all the important stuff.

Anyway, how could the planets influence your personality? What force could they possibly exert on you?

Let’s look at this mystery from a scientific point of view. We know of four fundamental forces that act on all matter in the universe: the electromagnetic force, the weak nuclear force, the strong nuclear force and gravity.

The weak and strong nuclear forces act over very short distances. Weak and strong act over distances less than the diameter of an atom.p
The electromagnetic force and the gravitational force have infinite range. The main difference being that the electromagnetic force only acts between electrically charged objects while gravity acts universally on all matter. Since people are electrically neutral most of the time, with the possible exception of during winter when wearing socks on the carpet, gravity is the only force that acts on people at great distances.

So maybe the mystery force is gravity. The unique location of the planets on the day you are born might cause the combined gravitational forces of those planets to tug and pull on you in a unique way that could align your personality.

Interesting theory. Let’s take a closer look at this idea. All matter has gravity. Isaac Newton figured out the mathematics that govern gravity. Newton showed that gravity is a force that acts at a distance.

That’s why astrologers claim astrology works. The force of gravity from the planets acts at a distance. Even though I’m far from the planets, they can effect me. The combined gravity of all the planets acts at a distance and, supposedly, sets the course of my life the moment I am born.

It is true that the gravity of the planets does exert a force on you. However, the force of gravity between two objects decreases as the distance between them increases. Specifically, the force decreases as the inverse of the square of the distance between the two objects.

OK, hang on. I see your eyes glazing over.

Listener: Whoa dude! Complicated mathematical terminology. I was expecting a simple podcast about pretty stars in the night sky. Next thing he’ll be telling me is that this really isn’t that complicated. Then I’ll be sucked in. Must switch to music…

Patrick: It really isn’t that complicated. Simply stated, it means that the gravitational force between two objects decreases very rapidly as the distance increases. If you take two objects a given distance apart and move them twice as far apart, the gravitational force between them is not half as strong, it is one quarter as strong.

And with the planets being millions of miles away from you, the force of gravity that they exert on you is extremely small.

But, it is not zero. Maybe it doesn’t take much force to direct the future course of our lives.

Let’s assume that gravitational forces can affect the future course of your life. Jupiter is by far the largest of the planets. It has more mass, and thus gravity, than all the other planets combined. The largest planet should have the greatest effect on our future.

We can calculate the gravitational force that Jupiter exerts on us by filling in the appropriate values to Newton’s gravity equation. If we plug in the mass of Jupiter, your mass at birth, and the distance between you and Jupiter, we find that Jupiter exerts only 0.000029 pounds of force on you at birth. That is 2.9 millionths of a pound of force. That’s a very tiny number.

Let’s compare that to the gravitational force that the doctor who delivered you, exerts on you at birth.

Plug in the appropriate values to Newton’s formula. And we find that the doctor, even a really skinny doctor, exerts 0.00098 pounds of force. 9.8 hundred thousandths of a pound of force. That’s more dude!

The doctor exerts 34 times more gravitational force on you than Jupiter. So shouldn’t any prediction of your personality and future life include a large contribution due to your doctor? Astrology doesn’t consider “doctor location” important.

Furthermore, if the gravitational force of the planets is important in determining our future course, then all astrological predictions before 1930 are inaccurate.

Ancient astrologers only knew of the planets they could see with the naked eye. The telescope wasn’t invented until the 1600s. Uranus was discovered in 1781, Neptune in 1846, and Pluto in 1930. Ancient astrologers had no idea that these planets even existed.

You might think that means astrological predictions are more accurate today.

Not really. Uranus, Neptune, and Pluto are all much smaller than Jupiter. Their combined gravitational influences do not add much more to Jupiter’s. The doctor still wins.

Plus since Pluto is now considered a dwarf planet, all predictions that include Pluto as a planet are inaccurate. And if you leave Pluto out of the calculations, the doctor wins by a bigger margin.

OK, maybe its not the gravity of the planets that influences our lives. Maybe its some mysterious, as yet undiscovered cosmic force that surrounds us, penetrates us and binds the universe together.

OK Jedi wanna-bes, if there is some all powerful force that guides us, and most of it comes from the planets, how come no astrologers take into account the effect of the force from the planet that is closest to us? The Earth!

The Earth is not included in astrological calculations. If the planets are so influential on our future lives, why doesn’t the Earth have an effect. Gosh we’re standing on it. The gravitational force due to the Earth keeps us stuck to the surface of this planet. It would have to have a larger effect than all the planets combined. And if that were true, the Earth is always below us when we are born, so shouldn’t it have the exact same effect on all people?

Which means that the exact same events would happen to everyone that has ever lived. And they would all have the exact same personality!


Wrong Dude!

Which is probably why George Lucas set the Star Wars story a long time ago in a galaxy far, far away. Unfortunately, the Force just isn’t with us.

End of podcast:

365 Days of Astronomy
The 365 Days of Astronomy Podcast is produced by the New Media Working Group of the International Year of Astronomy 2009. Audio post-production by Preston Gibson. Bandwidth donated by and wizzard media. Web design by Clockwork Active Media Systems. You may reproduce and distribute this audio for non-commercial purposes. Please consider supporting the podcast with a few dollars (or Euros!). Visit us on the web at or email us at Until tomorrow…goodbye.