Just stumbled on this Skeptico post from a couple of years ago about how astrology does not work.

People want to believe this stuff for some reason. I don’t believe it at all and yet I am still a Libra in many ways. I suspect that I just relate to those parts of my personality that are Libra-like when discussing astrology. If I were some other sign, I would relate to the qualities of that sign. People are complex and we all probably have attributes related to all of the signs of the zodiac.

This is why many people believe their horoscope as well. They ignore those parts that don’t ring true or don’t happen and remember those parts that do. So you read a horoscope that says a friend will have bad news and you’ll have a happy surprise. If those things don’t happen, you don’t really think about it, but if they do you say “Wow, my horoscope was true!”

One trick you can do is read someone their horoscope but actually read one for a different sign. Same thing: they’ll pick out the “true” stuff and ignore the not true stuff.

From an astronomical basis, astrology is bullshit as well. I did a little calculation comparing the gravitational force of the other solar system bodies with that of the earth. Here they are in decreasing order of influence:

Body    Force
Earth 100.00000000%
Sun     0.24077994%
Moon    0.00125292%
Jupiter 0.00001312%
Venus   0.00000752%
Saturn  0.00000095%
Mars    0.00000029%
Mercury 0.00000010%
Uranus  0.00000003%
Neptune 0.00000001%
Pluto   0.00000000%

So on average the Sun has 0.25% of the gravitational influence on you as the Earth does. The moon has 0.001% of the influence. And those are the STRONG ones. Jupiter, which is the biggest planet and fairly close, has 0.00001% of the influence as the Earth.

The notion that these minuscule forces are going to affect whether you have good luck today or not is daft.