[Rida]

Question: If a person goes to the Moon, in which direction must he or she pray, since the Ka`bah is on Earth. I know that I m not there and do not need the answer for practicle purposes, but I would still be interested in the answer for my general knowledge.

Answered by the Scientific Research Committee - IslamToday.net

This is a simple matter. The same rulings in Islamic Law regarding the determination of the qiblah on the Earth are employed for the Moon.

The general rule of Islamic Law is that a person must pray in the general direction of the Ka`bah, not the specific point of the Ka`bah. Since the Moon is so far away from the Earth, the Earth itself would be the general direction of the Ka`bah. Since the Moon is tidally locked to the Earth (it always shows the same face to the Earth), the direction of the Earth never changes relative to any place on the Moon.

Since the Moon, like the Earth, is basically spherical, the qiblah would be determined by reference to the point on the surface on the Moon nearest to the direction of the Earth. The qiblah direction for any location on the Moon would be determined by the shortest straight-line trajectory over the surface of the moon to that point. This is the same way it is determined on Earth. On Earth, the shortest straight-line trajectory to Mecca over the Earth’s surface from any other location in the world is the Qiblah direction for that location.

And Allah knows best.

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P.s.
Also when you are in outerspace and earth is on the opposite side and the Ka'ba is on the far side of the earth, you'd find the direction by shooting a beam of light that goes from both sides of the kaabah out into space, and the shortest horizantal distance towards the beam would be the direction of the kaabah.