The Astronomy of Astrology

The planets

Modern astrology focuses on the celestial bodies within our solar system, each planet effecting life on earth in a different way. In earlier days, astrologers only knew of and used the five planets which can be seen with the naked eye, Mercury, Venus, Mars, Jupiter and Saturn, they later added the Moon and Sun to this list of ��wandering�� objects. Much later, after the invention of the telescope Uranus was discovered in 1781, Neptune in 1846 and tiny, distant Pluto in 1930. Galileo, who is credited with the discovery of four moons of Jupiter and the introduction of the earliest methods for modern scientific experiments also believed in the astrological properties of planets. In Galileo's book The Starry Messenger which was partly responsible for his troubles with the Catholic church, Galileo writes about the traditional qualities associated with Jupiter.

"So who does not know that clemency, kindness of heart, gentleness of manners, splendour of royal blood, nobleness in public functions, wide extent of influence and power over others, all of which have fixed their common abode and seat in your highness - who, I say, does not know that these qualities, according to the providence of God, from whom all good things do come, emanate from the most benign star of Jupiter?"

We shouldn��t interpret from this, however, that there was any scientific ��truth�� to Galileo��s beliefs in these properties of Jupiter. On the contrary, it simply points out that in some ways Galileo was subject to the same myths and legends which were common in his time.

You might wonder whether Pluto still counts as an astrological ��planet�� now that it has been declassified as such by astronomers, but astrologers do still use it to make their predictions. Some astrologers include a number of other frozen rocks past the orbit of Pluto.

How could planets affect us?

Within the bounds of our current scientific knowledge it can only be down to one of the two fundamental forces that act over a big enough distance; gravity and electromagnetism. Gravity may sound like a good candidate; after all it does work over an infinite distance. Unfortunately it also weakens rapidly as the distance increases from a source of mass. Isaac Newton described gravitation in 1687 in his Principia Mathematica �V including the equations that govern it��s behaviour, the ��inverse square law��. Although it may sound complicated to those inexperienced with mathematics, this concept is actually quite simple �V if you are in orbit around a planet and attempt to move away from it, when you are twice as far away from the planet as the point from which you started, gravity will be four times weaker �V three times the distance and gravity is nine times weaker �V four times the distance and gravity is sixteen times weaker �V and so on. Therefore, this means that although some of the planets are gigantic, their distance from us renders their gravitational effect negligible when compared to our tiny but nearby moon.

Electromagnetism is the only other force capable of acting over a distance bigger then an atom. Again, this force rapidly drops off with distance, and depends on the positive or negative charge of the object itself. None of the planets can have a positive or negative charge because in large objects the two are only found together, canceling each other out to achieve overall neutrality. Any electromagnetic radiation that was emitted would be dominated by that of the Sun. The Sun would also override any negligible magnetic effects from the few planets that have magnetic fields. In a way, the sun and moon are the only celestial bodies to effect life on earth, for example by causing weather variations and tidal cycles. Bursts of magnetic energy released from the Sun��s corona in a solar flare produce radiation at all wavelengths across the entire electromagnetic spectrum. The X-rays and UV radiation emitted by large solar flares can disrupt communications here on earth, directly affecting us.

It seems that our celestial neighbors do have an impact on our lives, but not in the ways in which astrologers describe. Wouldn��t it be wonderful to have a page in mainstream magazines devoted to the beauty and wonder of our universe, instead of fortune telling?

For more information

A biography of Galileo
http://www-history.mcs.st-and.ac.uk/Biographies/Galileo.html

Bad Astronomy - Astrology
http://www.badastronomy.com/bad/misc/astrology.html