their knowledge.

Ibn Rajab said: “The branch that one is allowed to study is ʿilm al-tasīr (the science of celestial motions), not ʿilm al-taʾthīr (the science of stellar influence); for the latter is false and prohibited, whether practiced little or much. As for ʿilm al-tasīr, a person may learn from it what he needs for navigation, determining the qiblah, and knowing the routes, and it is permissible according to the majority ….” End quote.

Likewise, one may study the courses of the sun and the moon in order to determine the qiblah, the prayer times, the seasons, and the moment of zenith.

Al-Khattābī said: “As for the astral knowledge gained through observation and reliable reports—by which one discerns the sun’s zenith and thereby learns the direction of the qiblah—it does not fall under what has been forbidden. Knowing how to track the shadow is nothing more than this: while the shadow keeps shrinking, the sun is still rising toward the middle of the sky from the eastern horizon; when it begins to lengthen, the sun is descending from the middle of the sky toward the western horizon. This is something that can be grasped by direct observation. Nevertheless, the practitioners of this craft have systematized it by means of instruments that spare the observer continuous watching and repeated measurement ….” End quote.

Ibn al-Mundhir transmitted from Mujāhid that he saw no harm in a man’s learning the phases of the moon.

To conclude: a Muslim’s creed is his most precious asset, for his deliverance and happiness depend upon it. He must therefore take care to avoid anything that might blemish or undermine it—whether forms of shirk, superstitions, or innovations—so that it remains pure and radiant. This is accomplished by adhering to the Quran and the Sunnah and to what the righteous predecessors followed, and that cannot be achieved without learning this creed and recognizing the doctrines that contradict it. The need is all the greater today, when impostors and charlatans proliferate among Muslims, and when many cling to graves and shrines to seek favors and relieve distress just as the early idolaters did—or even worse—in addition to taking masters and leaders