First Lesson of Astronomy.

The Lesson:

What exactly is astronomy? Astronomy is the study of our universe. This includes celestial objects (planets, stars, moons, nebulae, galaxies, etc.), the phenomena that originate in space (supernova explosions, gamma ray bursts, cosmic radiation, etc.), and the physics, chemistry and evolution of those objects. Muggles consider astronomy to be a natural science. 

For year one, we’ll be focusing on our Solar System. Earth is located within the Milky Way galaxy. It is comprised of eight planets, all of which orbit the Sun. This simply just means that all eight planets travel around the Sun in an elliptical rotation. All of the planets move in a counter-clockwise direction, but they each go at their own place. While you may imagine that the Sun stays in one spot, this is not correct; the Sun orbits the galactic centre. That makes it fairly important... but that is for a different term, so shelve any questions regarding the Sun until later please!

There are 2 parts to our Solar System; the Inner Solar System: Mercury, Venus, Earth, Mars; and Outer Solar System: Jupiter, Saturn, Uranus, Neptune. They are separated by the Asteroid Belt, which is located between Mars and Jupiter. It is made up of over 7,000 asteroids! It also orbits the Sun, and contains asteroids of various shapes and sizes. During this term, we will learn about each planet, starting with the Inner Solar System and working our way out.

This week, however, we will start by learning a little bit about stars. In just the Milky Way galaxy, there are billions of stars! A star is a ball of hydrogen and helium that has enough mass to maintain nuclear fusion at its core. It’s the nuclear fusion that makes the star luminous in our night sky. 

Since the beginning of recorded time, stars have played a large role in religion and even navigation. You may have heard of the North Star; this star was called the North Star because it always points you north. In ancient civilizations, they noticed that the stars in our sky form patterns. These were called constellations. In 1929, the International Astronomical Union officially recognized 88 constellations. To date, these are the only “official” constellations. Surprisingly, the Big Dipper is not one of them! Because the Big Dipper is found within the constellation of Ursa Major, it is considered to be an asterism instead of a constellation in its own right.