The ninth house is where we search for truth: experiences that broaden the mind and help us form our philosophy of life. Here we expand our consciousness, synthesize meaning from facts and experience, adjust personal attitudes to collective ideas, and understand how things are integrated into systems. This house rules higher education, religious and ethical understanding, spiritual visions, in-laws, long journeys, law and the higher courts. Here is what remains of the purification that took place in the Eighth house: its seed or essence. "Religion" comes from the Latin "re-," back + "ligare," to bind, hence, "to bind back," and thus refers to all things that last or endure, such as the truth. Many planets in the ninth are usually an indication of being unwilling to accept the conventional limits within which we were raised.

Astronomically speaking, the ninth house is that one-twelfth sector of the local sky clockwise from the Midheaven (see above picture) occupied by planets two hours after they culminate.

With Mars in your ninth house you’re strongly motivated in your search for knowledge and truth, as well as in developing your personal philosophy. If your Mars is afflicted (in hard aspect to the Sun, Saturn, Uranus, Neptune or Pluto, or in Taurus, Libra, Cancer or Pisces) however, your religious fervor could easily become fanaticism. You have a great desire to travel, and will probably have many long journeys, perhaps becoming a traveler of the world. You're generally quite restless, and are often looking for adventure and excitement. It's best to live at some distance from your in-laws, as you are apt to have strife with them.

If Mars is within 10° of the midheaven it is conjunct the tenth house cusp and much of the above interpretation starts to become weaker. If Mars is in the ninth house AND within 4° or 5° of the midheaven, then it is said to be on the "dark side" of the tenth house, and it influence will be felt in the tenth as well as in the ninth house. The closer a ninth house Mars is to the tenth house cusp, the more it will be interpreted as though it were in the tenth house; when less than 3° from the midheaven, a ninth house Mars expresses itself primarily—and eventually entirely—in the tenth house.