Wow! The black hole at the center of a nearby galaxy is incredibly dynamic!

In 2017, the magnetic fields near its event horizon were spiraling around one way. By 2018 they settled down. But by 2021, they were spiraling in the opposite direction!

This black hole is incredibly massive: about 6 billion times heavier than our Sun. But it radius is only 120 times the distance between the Sun and the Earth. That's big, but it doesn't take light very long to go that far: just 16 hours. So it's theoretically possible for magnetic fields to change quite fast.

But what's making these magnetic fields? It's hot ionized gas called plasma, spiraling down into the black hole like water going down the drain of your bathtub.... if your bathtub was huge and full of plasma. Did the swirling motion of this stuff change significantly in just a few years? Or just the magnetic fields?

This black hole is called M87* since it's in the middle of a galaxy called M87, which is 55 million light years away. For comparison the Milky Way is 90 thousand light years across, and Andromeda is 2.5 million light years away. But M87 still counts as "close" because its redshift is tiny. The Universe is really big.

This black hole is famous for getting its photo taken back in 2019. So how come we know what it looked like back in 2017? Dunno.

Anyway, the cool part here is that we're starting to *see* the dynamics of magnetic fields near a supermassive black hole. It's like black holes have "weather'. As usual, things are more interesting than the simple theoretical models we had before we saw what's actually going on. Imagine trying to understand weather before you looked at it.

https://eventhorizontelescope.org/new-eht-images-reveal-unexpected-polarization-flips-at-m87