Astronomy - Intro

Good evening, students, and welcome to Hogwarts! I hope that you are enjoying yourself and your classes. Astronomy is a deeply fascinating subject, and it is one of the only fields of study at Hogwarts which has a direct equivalent in the Muggle world. In our classes, we will be learning the names of stars, constellations, and planets, as well as their location and movements, and describing the environments of planets and moons. Let's dive right in!
Stars are giant, luminous spheres of plasma. There are billions of them — including our own sun — in the Milky Way Galaxy. And there are billions of galaxies in the universe. So far, we have learned that hundreds also have planets orbiting them. Since the dawn of recorded civilization, stars played a key role in religion and proved vital to navigation. Astronomy - the study of the heavens - is the most ancient of the sciences. Contrary to Muggle belief, humans are not the only astronomers, and they are not the best by a long shot. Centaurs have studied the skies for centuries, and they are far better at it than Muggles and Wizards alike.
The invention of the telescope and the discovery of the laws of motion and gravity in the 17th century prompted the realization that stars were just like the sun, all obeying the same laws of physics. In the 19th century, photography and spectroscopy — the study of the wavelengths of light that objects emit — made it possible to investigate the compositions and motions of stars from afar, leading to the development of astrophysics.
This can be a lot to take in, so make sure you take your notes carefully. Feel free to ask if you have any questions on the homework.