Science and Islam present contrasting views regarding the nature of the sky:

According to scientific understanding, the concept of a physical sky does not exist. The blue appearance of the daytime sky is merely a result of our eyes perceiving the scattering of shorter wavelengths of sunlight by air molecules. Beyond this visual deception, there is only dark space in the universe, which remains imperceptible to our vision. During nighttime, the sky appears dark as there is no presence of sunlight.

In contrast, Islam asserts that the sky is a tangible, physical object. It describes the existence of seven skies where various prophets reside alongside their respective nations. Furthermore, each heaven is said to have physical gates guarded by angels, serving as passages to move from one sky to another.

These contrasting views reflect the difference in perspective between science and religious beliefs concerning the nature of the sky and its role within the universe.

Let us see the following Hadith.

Sahih Bukhari, 349:

Allah's Messenger (ﷺ) said, " ... (On the night of night journey, Gabriel) took my hand and ascended with me to the nearest heaven (i.e. the 1st heaven). When I reached the nearest heaven, Gabriel said to the gatekeeper of the heaven, 'Open (the gate).' The gatekeeper asked, 'Who is it?' Gabriel answered: 'Gabriel.' He asked, 'Is there anyone with you?' Gabriel replied, 'Yes, Muhammad is with me.' He asked, 'Has he been called?' Gabriel said, 'Yes.' So the gate was opened and we went over the nearest heaven and there we saw a man sitting with some people ... he said, 'Welcome! O pious Prophet and pious son.' I asked Gabriel, 'Who is he?' He replied, 'He is Adam and the people on his right and left are the souls of his offspring. ... ' Then he ascended with me till he reached the second heaven and he (Gabriel) said to its gatekeeper, 'Open (the gate).' The gatekeeper said to him the same as the gatekeeper of the first heaven had said and he opened the gate. Anas said: "Abu Dhar added that the Prophet (ﷺ) met Adam, Idris, Moses, Jesus and Abraham, he (Abu Dhar) did not mention on which heaven they were but he mentioned that he (the Prophet (ﷺ) ) met Adam on the nearest heaven and Abraham on the sixth heaven. ... Then Gabriel took me till we '' reached Sidrat-il-Muntaha (Lote tree of; the utmost boundary) which was shrouded in colors, indescribable. Then I was admitted into Paradise where I found small (tents or) walls (made) of pearls and its earth was of musk."

This same concept of a physical solid sky has been repeated in the Quran multiple times. 

Quran 34:9:

See they not what is before them and behind them, of the sky and the earth? If We wished, We could cause the earth to swallow them up, or cause a piece of the sky to fall upon them. Verily in this is a Sign for every devotee that turns to Allah (Translated by Yousuf Ali). 

Quran 31:10:

He created the heavens without any pillars visible to you

Quran 22:65:

Have you not seen how Allah has subjected to you all that is in the earth, and the vessels that sail in the sea by His command, and it is He (Allah) Who holds back the sky that it may not fall on earth except by His leave?

Quran 67:3-5:

ٱلَّذِى خَلَقَ سَبْعَ سَمَٰوَٰتٍ طِبَاقًا ۖ مَّا تَرَىٰ فِى خَلْقِ ٱلرَّحْمَٰنِ مِن تَفَٰوُتٍ ۖ فَٱرْجِعِ ٱلْبَصَرَ هَلْ تَرَىٰ مِن فُطُورٍ ثُمَّ ٱرْجِعِ ٱلْبَصَرَ كَرَّتَيْنِ يَنقَلِبْ إِلَيْكَ ٱلْبَصَرُ خَاسِئًا وَهُوَ حَسِيرٌ 

[And] who created seven heavens in layers. You do not see in the creation of the Most Merciful any inconsistency. So return [your] vision [to the sky]; do you see any breaks? Then return [your] vision twice again. [Your] vision will return to you humbled while it is fatigued.

Thus, the Quran claims that we can see the sky with our human eyes, and no matter how many times we look at the sky, we won't find any cracks in it. However, according to science, as far as the reach of the human eye is concerned, there is only darkness, and there is no solid and crack-free sky that we can look at two or three times to confirm that such a solid and crack-free sky exists.

Quran 17:90-93:

And they (the polytheists of Quraish) say, "We will not believe you until you break open for us from the ground a spring. Or [until] you have a garden of palm trees and grapes and make rivers gush forth within them in force [and abundance] Or you make the SKY FALL UPON US IN FRAGMENTS AS YOU HAVE CLAIMED or you bring Allah and the angels before [us] Or you have a house of ornament [i.e., gold] or you ascend into the sky. And [even then], we will not believe in your ascension until you bring down to us a book we may read."  Say: "Glory to my Lord. I am only man and a messenger." 

In this verse, the Quran mentions the dialogue of polytheists (Quraish) who challenge Muhammad to do these miracles to prove he's a prophet, Muhammad replies that he can't cuz he's just a "human". However, one thing to note here is that one of the challenges put forward by the Quraish is "Make the (physical solid) sky fall upon us in pieces as you have claimed". The Meccans are asking Muhammad to make the sky literally fall on them because he had CLAIMED to do so (in the verse mentioned above). This shows that even the Quraish understood it literally that sky is a solid physical object, and Allah doesn't respond by saying that "It was a Metaphor" but instead replies by saying that Muhammad is just a human so he can't do it.

Quran 52:44:

وَإِن يَرَوْا۟ كِسْفًا مِّنَ ٱلسَّمَآءِ سَاقِطًا يَقُولُوا۟ سَحَابٌ مَّرْكُومٌ

{ even if they were to see some fragments of the sky falling down they would still say: It is only a mass of cloud.”} 

Here are a few more verses, which repeat the same concept of a solid physical sky.

Quran 82:1: إِذَا ٱلسَّمَآءُ ٱنفَطَرَتْ {When the sky breaks apart} ... (i.e. only a PHYSICAL object can break)

Quran 21:104: يَوْمَ نَطْوِى ٱلسَّمَآءَ كَطَىِّ ٱلسِّجِلِّ لِلْكُتُبِ ۚ {The day We shall roll up the heavens like a written scroll } ... (i.e. only a physical object can be 

Quran 50.06: أَفَلَمْ يَنظُرُوٓا۟ إِلَى ٱلسَّمَآءِ فَوْقَهُمْ كَيْفَ بَنَيْنَٰهَا وَزَيَّنَّٰهَا وَمَا لَهَا مِن فُرُوجٍ {Did they never observe the sky above them: how We built it and beautified it; and it has no cracks;} ... (i.e. cracks can only be present in a phyisical object, not in the space). 

Quran 78:19: وَفُتِحَتِ ٱلسَّمَآءُ فَكَانَتْ أَبْوَٰبًا {and when the sky shall be opened up and will become all doors;} ... (i.e. only a physical object can be opened and becomes a door)

Quran 70:8-9: يَوْمَ تَكُونُ ٱلسَّمَآءُ كَٱلْمُهْلِ وَتَكُونُ ٱلْجِبَالُ كَٱلْعِهْنِ {The day the sky becomes like molten copper, and the mountains will become like dyed tufts of wool} ... (i.e. only a physical object can become like a molten copper).

Quran 15:13-15: وَلَوْ فَتَحْنَا عَلَيْهِم بَابًا مِّنَ ٱلسَّمَآءِ فَظَلُّوا۟ فِيهِ يَعْرُجُونَ {They will not believe in it (i.e. the Message), while there has already occurred the precedent of the former peoples. Even if We open a door in the heavens and they ascend through it in broad daylight. Even then they would say, “Our sights have been hypnotised – in fact, a magic spell has been cast upon us.”}

 

Muslim Excuses:

1st Excuse: From sky, it means Celestial Bodies

Islamweb.Net, a prominent Islamic website, presents a single excuse for the phrase "fragments from the sky" in Quranic verses.  (link):

Ibn ‘Aasshoor said in his Tafseer: “The term {… let fall upon them fragments from the sky} means, a piece of the celestial bodies.

Answer:

However, there is a significant flaw in using Ibn 'Aasshoor's interpretation as evidence. Ibn Aasshoor (link) lived in the last century and relied on the understanding prevalent during his time. Modern science has since established that the concept of a physical sky does not exist, but rather, there is only space. As a result, Ibn 'Aasshoor's explanation attempts to reconcile the concept of a solid physical sky with the scientific understanding of space.

Earlier Islamic scholars interpreted the sky literally, understanding it as a physical entity. 

Furthermore,  clouds look similar to the sky to the naked eye. Thus, the Quran is very clear that the portions of the sky which will fall, will not be like any celestial body (like the sun or moon or stars), but they will look like clouds. 

Quran 52:44-45:

وَإِن يَرَوْا۟ كِسْفًا مِّنَ ٱلسَّمَآءِ سَاقِطًا يَقُولُوا۟ سَحَابٌ مَّرْكُومٌ فَذَرْهُمْ حَتَّىٰ يُلَٰقُوا۟ يَوْمَهُمُ ٱلَّذِى فِيهِ يُصْعَقُونَ

{ Even if they were to see some fragments of the sky falling down they would still say: “It is only a mass of cloud. So, leave them until they face their day (of doom) when they will be stunned.} 

Thus, from this verse, we can conclude:

  • The falling of the sky is not metaphorical, but it is real. 
  • And these fragments will not look like celestial bodies (sun, moon, meteors) but like a mass of clouds.
  • And the polytheists will not die, but survive its destruction although whole fragments (of the size of mass clouds) will fall so near to them that they will be able to see them from their eyes and thus they will claim that these fragments of the sky are only a mass of clouds. Actually, this is a scientific blunder of the Quran, as if the sky, or even a celestial body of this mass, fells on the earth, then the whole world will destroy and no one will survive. But obviously, the writer of the Quran (i.e. Muhammad) was free to make such fantasy stories, as people of the time of ignorance were unable to catch his lies. 
Islamweb.Net is unable to present any other excuse other than this to protect the Quran from this scientific mistake.
 

2nd Excuse: Mohammad Hijab claims that the Quran does not say that sky is a solid object

Mohammad Hijab, a prominent Islamic apologist, offers only two excuses in his video to defend the Quranic passage about the sky:

So, Mohammad Hijab was able to present only TWO excuses in this whole video:

  • The 1st excuse he made is of Ibn 'Aasshoor that he claimed from the sky it could mean celestial bodies. But we have already answered regarding Ibn 'Aaashoor above. 
  • And the 2nd excuse that Mohammad Hijab made, is when he argued: "If really the Quran's picture of heaven is that of a solid object, my question to this how could the prophet (saw) went on Miraj (i.e. the Night Journey) through a solid object."

Response:

We have already presented the Hadith of Night Journey from Sahih Bukhari, 349 above. According to this Hadith:

  • A sky is a PHYSICAL Object. 
  • There are 7 skies where different prophets are living along with their nations. 
  • And there are PHYSICAL Gates in every heaven, which are guarded by angels. You have to pass through these gates if you want to go from one sky to another.

So, Mohammad Hijab is thus refuting his own prophet by making such a claim. 

Additionally, Quranic verse 15:13-15 presents a scenario where people, even if shown a door in the heavens to ascend through during daylight, would still reject the message, dismissing it as a magical illusion. This verse reinforces the Quran's depiction of the sky as a physical entity.

Quran 15:13-15: وَلَوْ فَتَحْنَا عَلَيْهِم بَابًا مِّنَ ٱلسَّمَآءِ فَظَلُّوا۟ فِيهِ يَعْرُجُونَ {They will not believe in it (i.e. the Message), while there has already occurred the precedent of the former peoples. Even if We open a door in the heavens and they ascend through it in broad daylight. Even then they would say, “Our sights have been hypnotised – in fact, a magic spell has been cast upon us.”}

 

Conclusion:

  • Islamic apologists are unable to present any other excuse, except these two excuses. They are in a very helpless position, as this is the best what Islamic apologists can do to defend this scientific blunder of the Quran.
  • Please don't forget, Islam claims that Allah is 100% PERFECT. This means, even if there occurs a SINGLE mistake by Allah, then the remaining 99.99% of Islam will also be automatically demolished.