#A black hole how to

Studying black holes relies heavily on indirect detection. You never saw that person in the kitchen, but their effect on the kitchen was evident. You might even be able to identify who in your household was in the kitchen based on what kind of chips they had or what they put on their sandwich. From the evidence, you know someone used the kitchen while you were out in fact, you can even say that they made a sandwich and chips because of the types of crumbs you see on the counter. You know that it was clean when you left, but now there are dirty dishes in the sink and crumbs strewn about the counter. Imagine you arrive home one night to find the kitchen a mess. A black hole, by itself out in the middle of our galaxy would be very difficult to detect. Instead, astronomers observe the presence of a black hole by its effect on its surroundings. If light can't escape a black hole, how can we see black holes?Īstronomers don't exactly see black holes directly.

#A black hole how to

Scientists are actively engaged in research to better understand what happens at these singularities, as well as how to develop a full theory that better describes what happens at the center of a black hole. It's likely that the laws of physics break down at the singularity. It is vanishingly small, so it has essentially an infinite density. With such strong gravity, the matter squishes to just a point a tiny, tiny volume with a crazy-big density. One thing about the event horizon: once matter is inside it, that matter will fall to the center. Its radius is the Schwarzschild radius mentioned earlier. It is not a physical surface, but a sphere surrounding the black hole that marks where the escape velocity is equal to the speed of light. The event horizon is the 'point of no return' around the black hole. There are two basic parts to a black hole: the singularity and the event horizon. (Credit: NASA's Imagine the Universe) Structure of a black hole The event horizon is the boundary that marks where the escape velocity from the mass is the speed of light. The singularity is at the center and is where the mass resides. For something the mass of our sun would need to be squeezed into a volume with a radius of about 3 km.Ī black hole has two basic parts. Any object that is smaller than its Schwarzschild radius is a black hole in other words, anything with an escape velocity greater than the speed of light is a black hole. The radius at which a mass has an escape velocity equal to the speed of light is called the Schwarzschild radius. But the speed of light is the cosmic speed limit, so it would be impossible to escape that tiny sphere, if you got close enough. Just a wee-bit smaller, and the escape velocity is greater than the speed of light. What if we made the size of the object even smaller? If we squished the Earth's mass into a sphere with a radius of 9 mm, the escape velocity would be the speed of light. Even though the mass is the same, the escape velocity is greater, because the object is smaller (and more dense). If, instead, that rocket was on a planet with the same mass as Earth but half the diameter, the escape velocity would be 15.8 km/s. For example, a rocket must accelerate to 11.2 km/s in order to escape Earth's gravity. There are two things that affect the escape velocity the mass of object and the distance to the center of that object. Formally, escape velocity is the speed an object must attain to 'break free' of the gravitational attraction of another body. The concept of a black hole can be understood by thinking about how fast something needs to move to escape the gravity of another object this is called the escape velocity. The simplest definition of a black hole is an object that is so dense that not even light can escape its surface. (Credit: NASA's Goddard Space Flight Center/J. Simulation of hot gas surrounding and falling into a black hole.