Neutron stars are remnants of exploded stars. As more matter falls into a neutron star, its mass increases; and as its mass increases, its gravity increases. A point will be reached where gravity would have grown so much, that not even light could escape, thus a black hole forms.
Most neutron stars discovered today are in the form of radio pulsars. They are called radio pulsars because they emit radio waves. We can simply connect a radio telescope to a loud speaker and hear a pulsar. Pulsars sound like someone persistently knocking. In short, we can hear a pulsar knock; and if matter continues to fall into this pulsar, a black hole will eventually form.
wa-mā ʾadrāka mā ṭ-ṭāriq
[By the heaven and the “Knocker” (ṭāriq in Arabic)
How could you know about the “Knocker”?
The piercing star (thāqib in Arabic)]
― Al-Qur`ān, sūrah al-Ṭāriq (The Nightly Visitor), Chapter 86, Verses 1-3
The Arabic word “Thukb” means a hole; “thāqib” means the one who makes the hole. The Qur`ān is describing a knocking star that makes a hole.
❛fa-lā ʾuqsimu bi-l-khunnas
[I swear by those that are invisible (Khunnas خنس),
that move, that sweep]
― Al-Qur`ān, sūrah al-Takwīr (The Winding Up), Chapter 81, Verses 15-16
Shayṭān (Satan) is invisible and is described in Arabic as “Khannas” in the Qur`ān, al-Nās (Humans), Chapter 114, verse 4. The Qur`ān uses the same word “Khunnas” to describe the celestial bodies that are invisible. All celestial bodies have gravity and can sweep everything in their way, but the only ones that are invisible are blackholes.
Our sun is a very small star. Our solar system (including the atoms that you are made of), came from a dying star 100 times more massive than our sun. Some stars are even bigger than our solar system, so one can imagine how large stars are.
However, according to the Bible, these stars are so small, that they could fall on Earth: In Mark 13:24-30 Jesus [ʿĪsā ] said, that stars will fall on Earth before his second coming.
Actually he said that the stars will fall on Earth before even that generation passes away. However, that generation passed away a long time ago and no star ever fell on Earth nor ever will. Because Earth will vaporize before it even contacts a star.
So the events prophesied in the Bible are supposed to occur on Earth when Earth is already vaporized!