not_exactly_rocketscience

What exactly are black holes? A black hole is a region of space with a gravitational pull so powerful that nothing can escape from it, not even light. The visualization simulates the appearance of a black hole where infalling matter has collected into a thin, hot structure called an accretion disk. Credit: Event Horizon Telescope Collaboration How do black holes develop? A large star collapsing in on itself creates a region of space with a very high gravitational pull, which is how black holes are created. Artist's conception depicting the growth channels of black holes in the nearby and distant universe. In the nearby universe, smaller black holes grow by accretion while larger black holes grow by mergers. In the distant universe, the opposite is true. Credit: M. Weiss How large can black holes grow? Black holes can be as big as billions of times the mass of the Sun or just a few times it. Black holes are some of the most fascinating objects in space.  (Image credit: solarseven vi...

Space is big! Science is cool! Let’s talk about it. WHAT IS A SUPERNOVA? Stars are kind of like people. They are born, live their entire lives, and then die. Except, that’s an oversimplification. Stars are giants. But they’re also giant chemical reactions. Just like a fire, though, stars will eventually burn through their fuel supply. The difference is that when a fire exhausts its fuel, it doesn’t blow up into something multiple of its original size, nor does it collapse back on itself to form super-dense matter. When a star “burns out,” many things can happen. But the main one is that the forces that balance out this giant object fall into an imbalance. Here’s how NASA explains it: “Massive stars burn huge amounts of nuclear fuel at their cores or centers. This produces tons of energy, so the center gets very hot. Heat generates pressure, and the pressure created by a star’s nuclear burning also keeps that star from collapsing. A star is in the balance between two opposite forces. Th...

  WHAT IS A QUASAR? The word  quasar  stands for  quasi-stellar radio source . Quasars got that name because they looked starlike when astronomers first began to notice them in the late 1950s and early 60s. But quasars aren’t stars. Scientists now know they are young galaxies, located at vast distances from us, with their numbers increasing towards the edge of the visible universe. How can they be so far away and yet still visible? The answer is that quasars are extremely bright, up to 1,000 times brighter than our Milky Way galaxy. We know, therefore, that they’re highly  active , emitting staggering amounts of radiation across the entire  electromagnetic spectrum . Shining so brightly that they eclipse the ancient galaxies that contain them, quasars are distant objects powered by black holes a billion times as massive as our sun. These powerful dynamos have fascinated astronomers since their discovery half a century ago. In the 1930s, Karl Jansky, a physi...