Two aspects come to mind when we think about life on other planets:
- Are there any signs of life, existence or living beings on other planets? Is it possible for human beings to live on other planets? And, can Man travel to these other planets?
Of course, answering these questions is the responsibility of astronomers and researchers in the field of natural sciences.
- If living on these other planets is possible then what is Islam's ruling on human beings living there? And how can one carry out his or her Islamic duties there?
However, these questions must be answered by Islamic Legal Authorities and Religious Scholars. According to the general laws and regulations of Islam, if an action does not have any harm to an individual or society as a whole or so long as it does not create any other problems then it is okay to do that action. And as for carrying out one's Islamic duties, one must refer to the Legal authority which he or she follows.
Living on other planets is a legitimate modern day question. And two aspects come to mind when we think about living on other planets:
- Is it possible for human beings to live on other planets?
Of course, answering these questions is the responsibility of astronomers and researchers in the field of natural sciences. After the possibility of living on other planets has been proven, then this issue will face the next question, as to what are the responsibilities which one would have and how would one carryout his Islamic duties there? This second question is what pertains to Islamic scholars and legal authorities. It is their job to use the ayats of Quran, authoritative hadith, and the general laws of the principles of Islamic law to answer these questions, and fortunately they have been able to do this in an exceptional manner.
First and foremost we can rule that according to the general laws and rulings [of Islam], living on another planet is okay so long as it does not necessitate any individual or social harm or any other kind of problem for Man; assuming that if it did, then by using the same general laws, the ruling will modify accordingly.
But as far as, how Islamic instruction should be carried out, it should be said that we must refer to a legal authority to resolve issues such as how to find the direction of the qibla and the times of salat, etc.
For example, take a look at a question which was asked by a marja of taqlid: (religious authority)
Question: with today’s advanced technology, in a single day and night man can circle the earth several times, so in this case what is his duty in making five salats a day.
Answer: whenever a man circles the earth with a type of spacecraft, he must make five salats during the course of a single night and day, and he can designate the salat times, in space, in accordance with the salat times where he lives on earth.
With the open-minded and positive approach Islam takes towards Man’s life and its changes, there are ayats of Quran alluding to the seizure (controlling of) of the sun, moon etc. certainly such a control is beyond the travel of spacecrafts. In the Quran it talks about life in the stomach of a whale, and if God were not to have forgiven Yunus (Peace be upon him) he would have been stuck there until the day of Resurrection, something which may not even cross the minds of Man today.
We have many narrations from the Noble Prophet on gaining knowledge; in one narration the Prophet states, “If there is knowledge on ‘Thurba’ (one of the stars in the sky), a people from amongst the tribe of this man (referring Salman Farsi) will acquire it.”
 Such as the use of principal of exemption in a ruling which is ambiguous. Haqa’equl Usul – Vol.2 Sayyid Muhsin Hakim Pg.223
Religious Questions Answered by Grand Ayatollah Makarim Shirazi – Vol.2. Pg.74
 He made subservient (given control of)
Ayah 33 – Ibrahim; Ayah 12 - Nahl; Ayah 32 – Ibrahim; Ayah 14 - Nahl
Sura Safat – Ayats 139 - 148
Safinatul Bahar – Sheikh Abaas Qomi, Vol.2, Pg.707