A team of astronomers noticed a jet of light coming out of a black hole that was faster than the speed of light. Normally, nothing in the universe is faster than the speed of light, making this very strange.

Matter speeds toward the black hole and, as it gathers speed, becomes hotter. The black hole can sometimes eject this hot matter, creating jets of light.

Astronomers can see these beams with sensitive telescope arrays. These arrays are groups of telescopes that all observe the same thing. To see the light jets and the black hole, they used the Event Horizon Telescope (EHT) array. The EHT observes at a very precise resolution; it's able to see an orange on the Moon.

Fun Fact: This is the same array that helped us take the first clear pictures of a black hole last year!

So, was the beam moving faster than the speed of light? The astronomers found that what they saw was actually an optical illusion!

The jet of light shines in many directions, including toward Earth. The array captured the part of the jet that moved toward it, not the main jet itself. This gave the feeling that the ejected matter was moving several times faster than light. However, the matter itself was actually a little slower than the light it gave off (about 0.5% slower). Therefore, the jet was not faster than light, but it was chasing the light it gave off - an interesting outcome!

This outcome surprised astronomers. However, the EHT and arrays like it will reveal more mysteries like this, without a doubt. These are key to not only learning the mysteries of black holes, but those of the entire universe.

Citation: https://www.vice.com/en_us/article/m7qyvv/a-black-holes-energy-beam-is-seemingly-breaking-the-laws-of-physics