Thread by @whereisyvette

Astronomer here! With all the black hole news lately, it's worth a reminder that black holes are NOT like giant vacuum cleaners that "suck everything in" or similar. This is a common misconception and not at all how black holes work! 🧵

First of all, worth covering what a black hole *is*. It is a region where the gravity is so strong that nothing- light, particles, etc- can escape. The area beyond which things can't escape is called the "event horizon" marked in this @ehtelescope pic of the black hole M87*.

When people study black holes via taking a pic with @ehtelescope, studying them shred stars like I do in my research, etc, it's worth noting we are taking measurements OUTSIDE the event horizon. Think the stuff that gets really close, but not falling beyond. /3

@ehtelescope Now, the black hole isn't "sucking in" anything, any more than our sun is actively sucking in planets that orbit it. Put it this way, if our sun suddenly became a black hole THIS SECOND, it would shrink to the size of just ~3 km (~2 mi)... /4

... but nothing would change about the Earth's orbit! We would still experience the same gravitational effect (but sure would miss that sunshine). /5

Could things fall into our new black hole sun? (heh) Sure, if it were on the right orbit! We see this w comets regularly w the sun btw- many come in on the wrong trajectory and get swallowed now as it's a star (see gif). But that is just how orbits work, no black hole magic

So, what DO we know about getting too close to a black hole? Well, turns out they're messy eaters, and MOST of the material gets flung out when you get too close! Here's a simulation of a star getting too close to a BH and getting shredded- a "tidal disruption event" (TDE)

When a TDE happens we believe ~half the star's material falls towards the black hole to form an accretion disk just outside the event horizon, and half the material is flung out in an outflow. Worst vacuum cleaners ever! /8 (I think?)

If you want to more know about how black holes shred stars btw, I study them for a living, and recently wrote a piece for @AstronomyMag about them bc I hated there was no good piece explaining it. So check it out! /9

Now, this ISN'T to say black holes aren't REALLY WEIRD and dramatically affect their surroundings... but it's mainly bc of what they throw OUT, not bc they're cosmic vaccuum cleaners! And wild stuff WOULD happen if you went on a wrong trajectory and fell into one... /10

For example, tidal forces are so strong around a black hole it's different at your head vs feet, and would pull you apart in a long thick strand. This process is called, no joke, "spaghettification." 🍝 /11

Anyway, I hope that was helpful! I learned recently a lot of laypeople are afraid of black holes BECAUSE of this misconception, and as I said, it's not warranted. But give a shout if you have any other black hole questions, I'll try my best to answer! /fin

PS for some reason the @AstronomyMag article didn’t paste right, so here is the article I referred to earlier on how black holes shred stars! astronomy.com/magazine/news/…