By Jonny Lupsha, Wondrium Staff Writer
Astronomers have discovered the nearest black hole to us yet, NPR reported. The new black hole is just 1,000 light-years away, just one-third of the distance from the previous record holder, in the constellation Monoceros. Black holes are still often misunderstood.
According to NPR, the black hole was found by astronomers at the European Southern Observatory. “They found it hiding in a double-star system known as HR 6819, where scientists say the black hole—rendered effectively invisible by gravity so strong that even light cannot escape—revealed itself in the curious orbit of the star nearer the center of the system,” the article said.
“The black hole is not anywhere near close enough for the average observer on Earth to feel its effects. But it is close enough that, during winter in the Southern Hemisphere, the two stars that are believed to compose its solar system can be seen without a telescope as a single point of light in the constellation Telescopium.”
Popular astrophysicist Neil deGrasse Tyson weighed in on black holes in lecture material for The Great Courses.
What Is a Black Hole?
One of the most obvious questions about black holes is what exactly they are. Most of outer space looks pretty black already, so what gives?
“A black hole is a region of space within which the escape velocity has exceeded the speed of light,” Dr. Tyson said. “The escape velocity is the magic speed at which an object must be launched for it to escape its environment forever. It makes sense that higher gravity objects have higher escape velocities, but for a black hole, that escape velocity is the speed of light.”
Dr. Tyson added that the speed of light is the fastest speed we know of in the universe, so if even light is unable to escape a black hole, nothing else would be able to either. This is why it’s called a black hole. “It’s black because nothing comes out; it’s a hole because if you fall in, you’re gone,” he said. “It’s sensibly identified.”
To provide some context for escape velocities, Dr. Tyson said the escape velocity from Earth is 25,000 miles per hour. The escape velocity from the moon is about two and a half kilometers per second, or one to one and a half miles per second.
Jumping into the Hole
The next question is what would happen if you could, theoretically, jump into a black hole. The answer, Dr. Tyson said, is that you would be ripped apart countless times until you were deconstructed to your individual atoms. Here’s how we get there.
“As you’re descending toward the black hole, the force of gravity is growing exponentially,” Dr. Tyson said. “All this means is you fall faster and, if you’re in free fall, you’re actually weightless. It would be like falling toward Earth or falling toward anything; it’s not the high gravity that kills you.”
What would kill you, he said, is the difference in gravity between your feet and your head. Even on Earth, there’s a minuscule difference in gravity between our feet and our heads, but we barely notice it. The proportions near a black hole are another story.
“Imagine in a limiting case, I’ve got a six-foot diameter black hole and I’m about six feet, and I’m falling toward the black hole,” Dr. Tyson said. “My feet are twice as close to the black hole as my head; if you calculate what that force is, my feet are feeling an acceleration toward the black hole that is four times the acceleration of my head.
“If I were made of rubber, I would just stretch, according to these forces. But I’m not made of rubber. I’m made of human flesh, and that has force limits.”
Dr. Tyson said that while he would be descending, eventually the gravitational forces would be greater than human tissue could sustain and he would separate. Those two pieces would repeat the process and become four, and so on. Unfortunately, the black hole also gets narrower the further in it goes, like a funnel. The end result, which he compared to the mouth of a tube of toothpaste, isn’t very pretty.
Black holes are fascinating, dangerous objects. Thankfully, even the nearest one is too far to affect us.
This article contains material taught by Dr. Neil deGrasse Tyson.