Lesson 1) One Earth, Four Worlds

Astronomy Year 4: A Genealogy of Gaia

Lesson 1: One Earth, Four Worlds

Good afternoon, students, and welcome back to the most stellar class at Hogwarts - Astronomy. I am thrilled to see everyone again after the long break, and I am honored that you have chosen to take this class, especially since we meet on a Friday afternoon. 

New Courses and Career Path 

Before I start class, I would like to mention the two other classes that I will be teaching this term. Interstellar Travel will focus on the literature of space travel. We will discuss how astronomical discoveries fueled curiosity and interest about outer space as well as the impact of space-related fiction works have affected society. Quarks, Quasars, and Cosmology will introduce the concepts of Cosmology. We will discuss universal scale, formation and geometry. Although this class will contain many Muggle science concepts, they will be taught in a way that appeals to students of all educational interests and strengths. Both classes are open to all students who have completed Year Three, and both classes are taught on the third week of every rotation.

In addition, I will be offering the Cosmology Career Path. This career path is an interdisciplinary career path that focuses on the wonders of the universe. 

The required Cosmology Career Path courses are as follows: 

- 2 Core Classes: Astronomy; History of Magic 
- 3 Elective Classes: Ancient Studies; Magical Transportation; Muggle Studies 
- 2 Career Path Exclusive Classes: Quarks, Quasars, and Cosmology; Interstellar Travel 

In addition, I recommend that you select additional courses related to your field of specialty. Choosing one of the specializations listed below is recommended, as they will round out your experience in the career path; however, it is not required that you choose a specialization and thus none of the classes listed below are required for the career path. That being said, choosing a specialization will make you more competitive for being selected for future Astronomy-related opportunities outside of Hogwarts.

The recommended Cosmology Specialities are as follows: 

- Theoretical Astronomy: Transfiguration; Ancient Runes 
- Magi-Astronomical Engineering: Potions; Alchemy 
- Astronomical Art and Literature: Magical Art/Magical Literature; Defense Against the Dark Arts 
- Interplanetary Exploration: Defense Against the Dark Arts; Culinary Theory 
- Astrobiology: Herbology; Care of Magical Creatures 


Since we are returning from a long break, I would like to review the expectations for this class. If you have any questions about these expectations, please do not hesitate to contact me through owl or email.

Please do the best you can in this class. Those who try will be rewarded, and those who do the minimum will have their grades reflect this. You can ask any Year 4 PA or myself for help on any assignment. There are also opportunities for essays that go above and beyond the requirements to receive extra credit.

Please do your own work. Plagiarism in essays will result in a 1%, and plagiarism in SAs will result in the SA marked as incorrect. Copying my words verbatim from the lesson will result in a mark for plagiarism. The PAs will also look for similarities between your work and Muggle sources - any plagiarism will receive a 1%. Although you may appeal a 1%, if it is found out that you have indeed plagiarized then you will not have a chance to redo the assignment.

Please show the same respect to my PAs that you would to me. They volunteer their own time to grade Astronomy assignments, and therefore they cannot be online all the time. That being said, they will return your assignments in a timely manner. Should you suspect that your assignment has been lost, please message me privately and I will try my best to include it.

Please have fun in Astronomy. I enjoyed preparing these lessons for you, and I hope that you will enjoy learning from these lessons. As I said earlier, if anything is confusing to you, please do not hesitate to message me or my PAs. I want your time in Astronomy to be  fun

Class Schedule

This year, we will be learning about the most magical planet known to us today - Earth. Of all of the planets known to us today, Earth is the only planet that we know for sure supports life. There are many scientific reasons that make Earth able to host life - everything from the planet’s distance from the sun, the availability of liquid water, the amount of certain gasses in the air, and even the presence of tectonic activity allows the presence of life on Earth today. Muggle scientists today refer to life on Earth as extraordinary because of the many factors that must be present for the planet to support life.

The Muggles’ view of the Earth is incomplete. In addition to scientific processes, the formation of the Earth itself as well as the life on it is made possible through magic. An alternative term for our planet, especially when used in the context of magical applications, is “Gaia” - both “Earth” and “Gaia” can be used interchangeably in these contexts. In early literature, the magic of the Earth itself was personified as a goddess named Gaia. As wizards learned more about the magic of the Earth, they chose the name “Gaia” to refer to Earth in a magical context.

Each week, we will look at an aspect of the Earth and its development. The schedule for Year Four is as follows:

Week 1: One Earth, Four Worlds

The Earth’s history is divided into four main sections. Today’s lesson will cover the basics of all four of these sections. This information will be the foundation of the other lessons in this class, so please make sure you know the material from this lesson very well.

Week 2: Falling Together

Did you know that the Earth originated from the dust cloud that created the rest of the Solar System? Through accretion, or the gravity-assisted clumping together of smaller bits of matter to make larger bits of matter, Earth grew in size similar to how a snowball becomes larger when rolled through a field of snow. Learn about how accretion works and how this affects the elemental makeup of the Earth.

Week 3: Alternative Rock

This week, we will learn about the Late Heavy Bombardment - a time in which many asteroids hit the Earth - and therefore added its chemical makeup to the Earth. We will also learn how the asteroids in the bombardment brought magical energy to the Earth.

Week 4: Lunar Birth

This week will focus on the formation of Earth’s Moon. The Moon has not only played a major role in various Wizarding and Muggle cultures, but it also is important to explaining various aspects of the Earth such as ocean tides. As the Moon is very large when compared to the size of the Earth, many are curious as to how the Moon was formed.

Week 5: Three Atmospheres

The atmosphere of the Earth is crucial to life today. However, the atmosphere of Earth has not always been the same as it was today. Learn about the composition of the Earth’s atmosphere during different points of the Earth’s history, and learn how important gases such as oxygen became part of the Earth’s atmosphere.

Week 6: Make it Rain

It is often said that water is the key to life. We will discuss how water came to the Earth as well as how the amount of water on Earth changed over time. We will also discuss desert planets and how they are affected by the lack of water.

Week 7: Shake and Bake

Plate tectonics has played a major role in not only the appearance of the Earth, but also on the overall evolution of the Earth. We will discuss the effect of plate tectonics on the Earth and how plate tectonics - or the lack thereof - affect the environment of other moons and planets.

Week 8: Magic of Life

Life on Earth started due to a combination of science and magic. Learn about the scientific and magical forces that make life on Earth possible, and examine the possibility of these elements occurring on other planets.

Week 9: In the Zone

Learn about the habitable zone, a theory that explains the places within a star system that are capable of supporting water-dependent life. How does the Earth fall into the zone?  What other planets fall into this zone? If there are many planets in this zone, why is life not more common in the universe.

One Earth, Four Worlds

The Earth’s history can be broken into four eons - the Hadean Eon, the Archaean Eon, the Proterozoic Eon, and the Phanerozoic Eon. 

Hadean Eon - 4.6 to 4.0 billion years ago

Imagine a hellish world - sizzling temperatures, asteroids that frequently and repeatedly pound the Earth’s surface, and surfaces of red hot molten rock. This is the reality of the Earth during the Hadean Eon, the earliest part of the Earth’s long history. No wonder this eon is named after Hades, the Ancient Greek name for the god of the underworld.

The transition between the Hadean Eon and the Archaean Eon is marked by the change of the nature in the Earth’s crust. As soon as the Earth’s crust begins to become a solid, the Hadean Eon ends and the Archaean Eon begins.

Archaean Eon - 4.0 to 2.5 billion years ago

Although the Earth during the Archaean Eon is more similar to the present state of the Earth than the Earth during the Hadean Eon, the Earth in the Archaean Eon still was very different. Not only was the Earth much hotter than it is today, but life - limited to simple ocean-dwelling single-celled organisms - was still only microscopic in size. Although these organisms released oxygen into the atmosphere, the atmosphere in this eon still has much too little oxygen to support most modern life.

The transition between the Archaean Eon and the Proterozoic Eon is marked by the appearance of complex organisms. Complex organisms can be single-celled or made out of many cells, but only simple unicellular organisms were present during the Archaean Eon.

Proterozoic Eon - 2.5 billion years ago to 541 million years ago

During the Proterozoic Eon, two very important changes happened to the Earth - complex and multicellular life evolved, and the atmosphere was able to accumulate much oxygen. During the early part of the Proterozoic Eon, bacteria that can perform photosynthesis replaced the carbon dioxide in the atmosphere with oxygen. Other types of bacteria - the ones that do not utilize oxygen and are poisoned by oxygen - died off in response to the oxygenated atmosphere. Later on in the Proterozoic Eon, life got more complex and but stayed in the water.

The transition between the Proterozoic Eon and the Phanerozoic Eon is marked by the appearance of very complex animals. When coral and trilobites appear, the Proterozoic Eon transitions into the Phanerozoic Eon.

Phanerozoic Eon - 541 million years ago to present

The Phanerozoic Eon is the current eon. In this eon, one can find life that is capable of living on land. Life in the water also became more complex. Although this eon is very short, it is an exciting one because of the diversity of organisms living in this eon.

Thank you for your time. Assignments will be posted within the next few hours. Once they are all posted, I will note the assignments here.

This course is currently being re-written, the new material will be available soon!
Course Prerequisites:
  • ASTR-301

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