It is not palm lines that are related directly to astrology. Instead, it is palmistry (the knowledge of reading the palm lines), which is linked to astrology as one of its branches.
Astrology
India is a country which rests its faith in various Gods and it is this faith which takes the worshipping of Gods beyond and includes the heavenly bodies in it as well. That’s where astrology enters. According to the planetary motions, and the date and time of certain significant events (like someone’s birth and death), our fate and fortune are interpreted and determined.
Palm lines and Palmistry
You must have often heard that your palm lines can tell your fortune, and the basis of this saying is none other than the knowledge of palmistry. According to palmistry, our palm lines have everything about our life hidden in their folds and twists. These lines, their interpretation, and reading can unfold anything about a person –his/her life, death, or any other occurrence.
So according to astrology, our palm lines tell us about our life just like planets, stars and their movements do.