Aqaaid

Keeping textbooks containing words that may affect one's beliefs

Q: I am a science student and I have a bunch of math textbooks. These are strictly math textbooks as I understand. In one of the books, the author mentions solving equations in their multiple variable "incarnations". I assume the author means "form" because there is no religious meaning here as far as I can tell. In a different book, the author tells a short biography of a mathematician who was also an astrologer. The presence of such words disturbs me. I would like to know if there is something wrong with me continuing to read these textbooks and can I keep them or not. 

Difference between predictions based on the movement of clouds and predictions based on the movement of planets

Q: What is the difference between making a prediction based on the movement of the clouds versus a prediction based on the movement of planets?

For example, the weather man will analyze the clouds and their movements. He will say that there will be severe flooding in a certain area. People will understand that severe flooding in that area causes mudslides and damage to houses and death. Everyone accepts this upcoming natural disaster warning and it is not regarded as fortune telling or haraam.

On the other hand, the man acquainted with the planets will analyze their movements. He will say that, for example, the planet Venus is coming closer in orbit and the cold nature of Venus will have a cold effect in a certain area. He too will predict flooding or severe weather in a region. He too will conclude mudslides and damage and death. However, people will regard his analysis as fortune telling and haraam.

Whereas outwardly both parties analyzed natural phenomena of natural entities and made conclusions based on their experience and study. There is no invoking of devils or making an offering or doing a ritual with blood and najaasat.

Why is one permissible and the other astrology and haraam? Please can this be explained.