Seventh Years: Lesson One

Professor Nakamura was ready, and a little bit excited. Seventh year was when things got really interesting, in his opinion. He waited for the students to enter before greeting them cordially. “Welcome to seventh year astronomy! My name is Professor Nakamura, in case you're new, and I’ll be teaching you for this semester.” He paused to smile, hoping he was being inviting. “For this evening’s subject, we turn to the sun and stars, and their composition. So please, take out your parchments and quills and get ready to take notes.” Professor Nakamura tapped on the blackboard and writing began to appear in neat print. He read the notes aloud in a clear yet obvious Japanese accent, blended interestingly with a New Zealand one.

Corona: Corona is the outermost layer of the sun. The only time it is visible is during an eclipse. It is very low density because it is a cloud of plasma with high transparency, unlike the inner layers. The corona is the extended atmosphere of the Sun, which has a volume much larger than the volume enclosed by the Sun's photosphere. A flow of plasma outward from the Sun into interplanetary space is the solar wind.

Chromosphere: The next layer of the sun, occasionally seen as a red circle on the outside of the sun. Concentration of hydrogen gives it its red colour. This area is much hotter than the next part of the Sun’s composition.

Photosphere: The visible surface of the Sun, the photosphere, is the layer below which the Sun becomes opaque to visible light. Above the photosphere, visible sunlight is free to propagate into space, and almost all of its energy escapes the Sun entirely. You can find out the composition, temperature, and pressure by analysing the colour spectrum of sunlight. A little side fact, helium was discovered by Norman Lockyer in 1868. He named it helium after the Greek God of the Sun Helio, 25 years later we were able to isolate helium here on Earth.

Convective zone: The Sun's convection zone extends from 0.7 solar radii (500,000 km) to near the surface. The thermal columns of the convection zone form an imprint on the surface of the Sun giving it a granular appearance called solar granulation at the smallest scale and supergranulation at larger scales.Radiative zone: From the core out to about 0.7 solar radii, thermal radiation is the primary means of energy transfer. The temperature drops from approximately 7 million to 2 million kelvins with increasing distance from the core. This temperature gradient is less than the value needed for convection, which explains why the transfer of energy through this zone is by radiation instead of thermal convection.

The Core: the innermost 20-25% of the Sun's radius, where temperature (energies) and pressure are sufficient for nuclear fusion to occur.

“And that’s that for tonight, next lesson we will continue as we seem to have run out of time.” Professor Nakamura smiled once more as the students began to pack their things up. “Don’t forget to read the required chapters! It’ll help you for your exams,” he called out as everyone started to leave.

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Roleplay the lesson
 
With the end of the year looming, Elio was feeling rather more anxious now than he had been before and if Mikael thought he was bad last semester he was about to meet an even more anxious version of his boyfriend, after all, the end of year exams would be in a matter of months and if he failed those he could kiss the chance at a life goodbye. Why didn’t people ever tell them how stressful it was going to be? No one ever said and honestly it was crazy that no one ever said. So as he sat in Astronomy tapping his quill against his parchment, he was only slightly sulking. His handwriting was a little messier than it has been previously in an endeavour to keep pace with Professor Nakamura’s notes.

The class had always fascinated him since childhood. Sadly, though, the heavens still made his head spin. He jotted down helium in its place when the Professor mentioned that it was named after Hēlios, the Greek sun god. That was a nice tidbit. In his notes, he drew a small star next to this bit of information. Though he wasn’t sure how helpful it was really going to be seeing as maybe all of this would be for naught if he couldn’t manage to do this during the exams session. How was he supposed to remember all of this stuff anyway? He blew out a puff of air as the lesson ended, leaned back in his seat and sighed. Yeah, this year sucked.​
 
Savannah walked into the astronomy classroom and took her usual spot in the room. She was rather eager to find out what this NEWT level class would be about. She looked up at the professor as the man got started and then took her quill and began writing down what was on the board behind him. She nodded along as she took the important things down, it was complicated and interesting. She couldn’t wait to delve more into things. The lecture wasn’t long but at the very least they had done something so she was happily able to pack up and head out of the room.
 

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