The possibility of the sun turning into a black hole is an interesting thought experiment. What would happen if the sun suddenly became a black hole without changing its mass?
Solar mass black holes are the most common type of black holes. As the name suggests, these monsters are formed from masses of matter equivalent to many Suns. When a star dies, it collapses in on itself and becomes a glowing ball of gas called a white dwarf.
If the Sun turned into a white dwarf, it would not affect Earth much. We would probably get colder, but that is about it. Luckily for us, this is not going to happen!
The question can be expanded to include what would happen if the Sun suddenly became any type of black hole. Would Earth be destroyed? Would we notice anything before it happened? And what would happen after? All of these questions will be answered in this article.
The Earth is swallowed up by the black hole
Let’s imagine for a moment that the sun suddenly became a black hole without changing its mass. What would happen to Earth?
We know that in the case of a normal black hole, the event horizon — the point of no return — is what swallows up everything and nothing can escape it.
But what if the sun became a black hole? How big would its event horizon be? Would Earth fall into it? What would happen to our planet? Would anything unusual happen before it did?
As it turns out, our incredibly intelligent scientists have already thought of this and have come up with some pretty conclusive answers. We’ll share these with you, so you can know what will (probably) happen if the sun suddenly became a black hole.
The atmosphere rises up towards the sun and falls down towards the black hole
If the sun suddenly became a black hole, its effect on Earth would be catastrophic.
As the sun is currently a normal star, its pull is stronger due to its mass. This causes the atmosphere to flow towards it.
If the sun became a black hole without changing its mass, this would not change. The pull of a black hole is stronger, but only because anything that gets close to it is pulled in and never comes back.
The difference here is that the sun would become a black hole with an event horizon, or a point of no return. Anything that moves toward it will be pulled in and never comes back out, even radiation such as heat.
Because of this, the temperature on Earth would drop significantly due to the lack of radiation being emitted from the now-black sun.
Molecules break down
If the sun suddenly became a black hole without changing its mass, the solar system would be in big trouble. Not only would life on Earth likely cease to exist, but all the planets would reorient themselves.
As Dr. Loeb explained, the gravitational force exerted by a black hole is constant regardless of whether an object comes close to it or not.
If our Sun suddenly became a black hole, Earth would continue to orbit it, but its axis would reorient itself so that the opposite side of the planet faces the Sun. All of our seasons would be reversed!
The reason for this is because gravity is strong on Earth and other planets, so when there is a change in orientation, it takes time to figure that out and correct itself.
Although we might think of gravity as being constant, on a smaller scale it actually can change direction depending on what’s affecting it.
Everything that had been pulled into the black hole evaporates
If our Sun were to become a black hole, everything that had been pulled into the black hole would evaporate. What does this mean?
As matter is pulled into a black hole, it is accelerated due to the strong gravitational force. This acceleration causes the matter to heat up. Since black holes are characterized by their absence of internal activity, this means that there is no place where the matter can cool down.
The evaporation process would continue indefinitely, gradually reducing the amount of matter that had been drawn into the black hole. After a while, our Solar System would be composed of just planets and moons, with no stars!
If our Sun became a regular supermassive black hole (with the same mass as it is now) without changing its size, everything in our Solar System would continue to orbit as normal around what looks like a normal sun.
The universe changes shape
If the mass of the sun were to suddenly drop, its outer layers would be pulled away by gravity, leaving only a dense inner core.
This inner core would be a neutron star, and it would still have the same magnetic field as our sun. The difference is that this field would be 100 times stronger.
Surrounding the neutron star would be an extremely strong magnetic field, one that is a million times stronger than our own. This magnetosphere would be called a solar magnetosphere.
If the sun became a black hole without changing its mass, its effect on space-time would not change. Only things that interact with its magnetic field would be affected. Things such as light, dust, and other charged particles would still be pulled into the black hole.
There is a fundamental change in physics
According to Dr. Chris Slavov, a professor at Dickinson College, if the sun suddenly became a black hole without changing its mass, there would be several dramatic consequences.
First, all of the matter in the solar system would be pulled into the black hole that was formerly the sun. Since gravity depends on mass, this change in physics wouldn’t affect anything else.
Second, since time and space are affected by gravity, these things would not change. The fact that there is no such thing as “space-time” just makes it easier to talk about these concepts.
Third, planets would continue to orbit what was previously the sun, but they would do so around a black hole instead.