Professor Zumwalt was ready for the fourth-year lesson. She sat at her desk, grading some assignments before "Welcome back! Today, we are going to focus on types of galaxies and what exactly a galaxy is," she said looking over the young faces. Though her fourth years were in the middle of their time at Hogwarts they all seemed so small despite having been able to watch them grow over the past few years.
"Galaxies are giant groups of millions or even trillions of stars. And if you remember from last week, we learned all about stars." Adorah paused for a moment. "Our local galaxy is the Milky Way. There are believed to be twenty trillion galaxies in the universe. At the moment, there are only three galaxies visible to the naked eye from Earth besides the Milky Way - the Large and Small Magellanic Clouds and the Andromeda Galaxy. There are four main types of galaxies, and we're going to quickly run through them all as they will appear in your exams. First, spiral galaxies are spinning, Kart-wheel galaxies with a dense core and spiraling arms. The Milky Way is a spiral galaxy. Second, barred spiral galaxies have just two arms. These are linked to the galaxy's middle bar from which they trail like water from a muggle spinning garden sprinkler." Adorah smiled at the students allowing them a moment to write down the types of galaxies.
"Third is elliptical galaxies - they are vast, very old, egg-shaped galaxies, made up of as many as a trillion stars. And lastly are irregular galaxies, which are galaxies with no obvious shape. They may have formed from the debris of galaxies that crashed into each other. And the last thing I will mention is that galaxies are often found in groups called 'clusters'. They can have as many as thirty galaxies in one cluster." Adorah concluded the lesson. "So, make sure you have notes, and once you have done that you may leave, no homework today guys."
For full credit, RP the lesson.