Astrology is the idea that the movements of the planets in the solar system impacts events on earth. Most commonly this is used to split the year into 12 segments and attribute an astrological sign to everyone born in a time period which apparently give personality traits to each sign. Astrology survives to the modern day and has gone in and out of fashion in recent decades. The daily horoscopes in newspapers mean astrology is part of everyday life.
Astrology and astronomy were intrinsically linked historically. Many early astronomers such as Copernicus were also astrologers from the royal families of Europe. As the science of Astronomy developed it became separated from astrology and became a separate field of study. Current understanding of the gravity and the solar system rule out the planets having any impact on our personalities here on earth.
There is, however, interesting research about how where you are born in the school year impacts your development. Those children born in July and August are the youngest and usually smallest in their year group so are more likely to be bullied or suffer in sports.