Thanks, Vardhan!

300px-BH_LMCAnother request we’ve had recently for a blog entry comes from user Vardhan, who would like to know about an amazing phenomenon called a Black Hole.

The following, then, is an excerpt from Out There – A Small Guide to a Big Universe, a book written by our own Joe Latrell and Steve Shurtleff:

The Earth, along with all the other planets in our Solar System, revolves around the Sun because of gravity. This is the same force holding you to planet Earth. We also know that galaxies revolve around their cores because of gravity, and lots of it. So what is at the center of a galaxy that has so much gravity that it causes an entire galaxy to revolve around it?

The answer is a rather scary object called a Black Hole. A Black Hole is an area of space where there is so much mass in such a small area that its gravity sucks in everything nearby, including light. Because of that, we can’t see a Black Hole directly, but we can tell that it’s there because of the effect it has on the space around it, the same way we can’t see the wind but we can see tree branches sway back and forth because of it. A Black Hole creates very dark areas surrounded by lots of radiation as matter twists and collides with itself as it falls farther and faster into the center.

If an astronaut was to travel toward a Black Hole, he or she would first notice that they were accelerating toward a very dark area, surrounded by things that started to appear more and more distorted. Even time would start to do weird things as they got closer. At some point, they would cross an invisible line called the Event Horizon, which is the point at which they wouldn’t be able to escape the Black Hole’s pull. Think of it as a hole that you can’t climb back out of. As the astronaut got closer still, their spaceship, and eventually they themselves, would begin to get stretched into a long, thin strand, kind of like a noodle, which in time would vanish into the center of the Black Hole, a very small point that scientists often call a Singularity. In fact, some scientists refer to this process of getting stretched as “spaghettification.” It sounds like a goofy and strange thing to have happen, but some scientists even think it might be fun, though they’d only get to try it once.

So is the Earth in danger from a Black Hole? Will we get turned into a massively long string of spaghetti? No, not really. Scientists estimate that the nearest Black Hole, called V404 Cygni, is about 7,800 light-years from Earth, far too distant to be a threat to us here on Earth.

And Black Holes are only one type of many wonders that await us.

Would you like to know more?

Check out…and dream!


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