Did you know that the brightest light source in the sky comes from the area around the black hole in the center of the galaxy? This sounds a bit contradictory, but it is true! They may not appear bright in our eyes, but satellites have found their eggs throughout the universe.

One of these satellites is NASA's Fermi Gamma-ray Space Telescope. Since its launch in 2008, Fermi has discovered thousands of these galaxies, and there are many more!

Black holes are regions of space with so much gravity that there is no light, not particles, and NADA can escape. Most galaxies have super-large black holes in their centers, which are hundreds of thousands to billions of times the mass of our sun. In the active galaxy core (also known as "AGN", or just "active galaxies") the central region is filled with gas and dust that keeps falling on Black hole. When gas and dust fall, they start to rotate and form a disk. Due to friction and other forces, the rotating disk starts to heat up.

The heat from the disk becomes light, not just the wavelengths we can see with our eyes. From more familiar radio and optical waves to more exotic X-rays and gamma rays, we detect light from AGN throughout the electromagnetic spectrum, which we need special telescopes to discover.

About one-tenth of AGN emits the jet of energy particles, and they travel almost as fast as light. Scientists are studying these jets in an attempt to understand how black holes attract everything with a lot of gravity—somehow providing the energy needed to push the particles in these jets.

Many ways we illustrate one type of AGN depend on the way from our perspective. For example, with the help of radio galaxies, we see jets from the side as they shoot a lot of energy into space. Then there is marijuana, an AGN with jets that point almost directly to the earth, which makes the AGN particularly bright.

Since 2008, Fermi has been looking for sources for Gamma Ray. More than half of what it finds is Islam (Blazars). Gamma rays are useful because they can tell us a lot about how particles accelerate and how they interact with the environment.

So, why do we care about AGN? We know that some AGNs were formed in the early days of cosmic history. With its immense power, they almost certainly influence the changes in the universe over time. By discovering how AGN works, we can better understand how the universe is what it is.