Assalaamu alaikum warehmatullahi wabarakatuhu,
Here are few translations from other Authors for Qur'an 31:29
Muhammed Asad
Art thou not aware that it is God who makes the night grow longer by shortening the day, and makes the day grow longer by shortening the night, and that He has made the sun and the moon subservient [to His laws], each running its course for a term set [by Him] and that God is fully aware of all that you do?
M. M. Pickthall
Hast thou not seen how Allah causeth the night to pass into the day and causeth the day to pass into the night, and hath subdued the sun and the moon (to do their work), each running unto an appointed term; and that Allah is Informed of what ye do?
Ali Quli Qara'i
Have you not regarded that Allah makes the night pass into the day and makes the day pass into the night; and He has disposed the sun and the moon, each moving for a specified term, and that Allah is well aware of what you do?
See you not (O Muhammad ) that Allah merges the night into the day (i.e. the decrease in the hours of the night are added in the hours of the day), and merges the day into the night (i.e. the decrease in the hours of day are added in the hours of night), and has subjected the sun and the moon, each running its course for a term appointed; and that Allah is All-Aware of what you do.
Conclusion:- there are various meaning to أَلَمْ تَرَ [here] i.e., (see, understand, regard, aware etc). See literally does not mean to actually 'see' but it means to have an understanding to how the miracle of Allah Azzawajal of the reduction in the day and addition to night, decrease in the night hours with increase in day-hours is explained (during winter and summer respectively).
Other explanations:-
(merges the night into the day,) meaning, He takes from the night and adds to the day, so that the day becomes longer and the night shorter, which is what happens in summer when the days are longest; then the day starts to become shorter and the night longer, which is what happens in winter.
(and has subjected the sun and the moon, each running its course for a term appointed;) It was said that this means, each runs within its set limits, or it means until the Day of Resurrection; both meanings are correct. The first view is supported by the Hadith of Abu Dharr, may Allah be pleased with him, in the Two Sahihs, according to which the Messenger of Allah said: (O Abu Dharr! Do you know where this sun goes) I (Abu Dharr) said: "Allah and His Messenger know best.'' He said: (It goes and prostrates beneath the Throne, then it seeks permission from its Lord, and soon it will be said: "Go back from whence you came.'') Ibn Abi Hatim recorded that Ibn `Abbas said, "The sun is like flowing water, running in its course in the sky during the day. When it sets, it travels in its course beneath the earth until it rises in the east.'' He said, "The same is true in the case of the moon.'' Its chain of narration is Sahih.
Also in verse 20 in Surah Luqman, it has a similar start! I hope this explains!
