Curious Kids: can Earth be affected by a black hole in the future?
If you have a question you’d like an expert to answer, send it to curiouskids@theconversation.edu.au.
Can Earth be affected by a black hole in the future? – Rakovi, age 12, Dimapur, India.
That is a great question.
As you know, black holes are called that because the gravity in their centre is so strong, it sucks all nearby light in. None can escape. That’s how strong a black’s hole’s gravitational pull is.
Black holes create the strongest gravitational pull in the universe (that we know of). So you really don’t want to get very close to one.
If you get too close, the pull of gravity from the black hole is so strong that you would never be able to escape, even if you were travelling at the speed of light.
This point of no return is called “the event horizon”.
Another reason you don’t want to get too close to a black hole is because of something we call “spaghettification”.
Read more: Curious Kids: How do wormholes work?
Turning a star into spaghetti strips
Imagine an object in space, like a star. As the star gets closer to a black hole, one side of it is pulled harder than the other. That’s because one side of the star will be closer to the black hole than the other.
The pull from gravity will be stronger on the side closest to the black hole, and weaker on the side that’s further away.
This difference in the pull of gravity (which is called a “tidal force”) would cause the star to get pulled apart. It’s kind of like pulling a lump of pasta dough into spaghetti.
Sometimes astronomers can observe this happening in other galaxies. The technical name is a “tidal disruption event” but it just means that a star got too close to a black hole and got pulled apart.
Here’s an artist’s impression of what spaghettification might look like:
The closest black hole is too far away to hurt us
Thankfully, though, we don’t need to worry. There are no black holes close enough to Earth to affect us. The closest black hole to Earth that we know of is named V616 Monocerotis. It is also known as A0620-00.
This black hole is 6.6 times more massive than our Sun. (That means it has a lot of mass, which means it has a really strong gravitational pull – much stronger than even our Sun’s gravitational pull.)
If Earth gets within about 800,000 kilometres (3.7 light seconds) of this black hole it will get pulled apart. But that’s unlikely to happen and certainly not in your lifetime.
V616 Monocerotis is about 3,300 light years away. That’s very, very far away.
Read more: Curious Kids: Where do black holes lead to?
Hello, curious kids! Have you got a question you’d like an expert to answer? Ask an adult to send your question to curiouskids@theconversation.edu.au
Janie Hoormann receives funding from the Australian Research Council.
Authors: Janie Hoormann, Postdoctoral Research Fellow, Astrophysics, The University of Queensland...
