"Correct, ladies," Tapendra said, though he wasn't really sure what 'life them up' meant. He inclined his head to Megan. "Mimas's gravitational pull creates the Cassini Division, which you can see here," he said, highlighting the divide on the globe. "Prometheus and Pandora work together to great the F Ring, which you can see here," he added, highlighting the thin ring. "Many other small moons orbit inside the rings, and pull on them as well; the moons like Prometheus and Pandora are called Shepard Satellites."

He smiled, looking at the image of Saturn; somehow he doubted they'd be taught this next question, if things where more or less the same from Sinistra's reign. "There's a few very special moons orbiting Saturn. Can any of you name - or describe - why scientists pay extra attention to the moons Titan and Enceladus?"

It was the start of Sasha's third week back at school.  If one looked at the general trends, his mental focus and capacity were improving though he still had his ups and downs.  And, both were nothing like they'd been back in the fall before his suspension.  But, despite the recent curve balls (the less than heartening conversation with Eirene and the ever present confusion with everything Fergie-related), his performance in class was improving.

And, Astronomy was continuing to climb to the top of his academic preference list.  He liked this class.  No, he was quickly growing to love this class. It kept him engaged (and, therefore, distracted), kept him thinking and, for once, he felt like four years of dividing his time between muggle and wizarding studies was giving him an advantage.  And, his recent trend of spending his free time on the couches in the alcove across the room made the room feel, physically, more comfortable.  The class was a much needed confidence boost. 

He scribbled down the formula Professor Trishna put up on the board and, after drawing a line across the page, turned to the next subject: constellations and Saturn's moons.  Titan and Encladus, specifically.  Sasha knew exactly why they were significant - or at least why he believed they were significant.  They were significant for reasons that enticed and excited even the most non-scientifically minded muggle. 

He raised his hand and waited for recognition before speaking.  Such formality wasn't required in Professor Trishna's class but old habits died hard.  And, things had been best for Sasha back in the days when he'd conducted himself in a careful, formal and straight-edged manner.  If he returned to those habits, maybe things would return to where they once were as well. 

"Well, Titan's the biggest moon and Enceladus is one of the biggest.  Fifth or sixth, I believe.  But, they both are of particular interest because they both appear to have water on their surface.  All of the water on Enceladus is captured in ice but Titan has stable bodies of surface water.  The only other orbital astrological body confirmed to have such stable surface water is our own planet.  As water is still believed to be a prerequisite of life - life has even evolved in ice-based climates.  So - in both cases, it begs the age old 'science fiction' question:  is there extraterrestrial life."

"Partially correct, Schlagenweit," he said, tapping the globe so the image of Titanappeared. "In Titan's case, it is indeed the largest moon of Saturn - it's 50% larger than our own Moon, and is in fact larger than Mercury. As you can see and have studied, Titan has an extended atmosphere - making it the only moon in our solar system with such an atmosphere. And yes, there is water on the surface of Titan, and standing liquid lakes - however, the lakes are not made of water."

He tapped the globe and an image of Titan's surface appeared. "The surface of Titan is far too cold for liquid water - minus 180 degrees Celsius, or in more common terms , 300 degrees below zero. All water on the surface of Titan is ice. The lakes of Titan are made up of liquid methane and ethane - both of those are gases here on Earth. The atmosphere is likewise made up of mostly nitrogen and methane, and appears rather snog-like as you can see from this image." He switched the globe again, and smiled at the image as he spoke. "Titan is the most Earthlike in appearance, but not in composition. However, despite its temperature - its conditions may be simiar to those of early Earth. There is certainly a possibilty that life has formed, either on the surface or in the atmosphere itself - and scientists are always interested in life's formation."

He cleared his throat, switching the image to the second moon. "As for Encladus - you are correct about water on that moon, Sclagenweit. Enceladus has been observed gushing jets of liquid water from fissures in its surface - similar to a geyster here on Earth. Study of the water itself has led to speculation that there may be a liquid ocean undermeath the icy surface. This implies an internal heat source - and, as we currently believe liquid water to be nessisary for life, there is a possibility of life having formed under the ice sheet. The geysers also form Saturn's E Ring, which gives us clues as to how the Rings of Saturn have survived so long."

He rocked on his feet and beamed at the class, then cleared his throat. "Ahem. You should have been studying Jupiter and its moons recently - well, somewhat recently. You should at least know of the main 4 Galilean satellites - can you tell me what makes each of those 4 special?"

Griselle's mind began to wander off again, though it wasn't any one particular thing that had her distracted, just the usual sampling of things on her mind that were more interesting that class work.  Bits and pieces of thought flashed through her mind: her mother, wondering how long before this class was done, wondering what she would do after class, shoes, cheesecake, Professor Trishna's hair.

 She tried to steer it back on track by taking more notes to make herself pay more attention.  Unfortunately, these notes were pretty useless, just a few words and phrases that seemed important but without enough context for them to make sense later.  She hastily scribbled down a few things: Saturn's moons, Titan, water, E ring, and a very sloppy doodle of Saturn.

She thought she knew the answer to the question about the Galilean satilites.  At least, she knew there was something important about them, and she had an idea of what it might be.  She raised her hand and gave her answer.  Admittedly, her confidence in its correctness was minimal.  "It's they're size, isn't it?  They're...abnormally large, or something."

When the Professor informed her about what effect the moon had on the tides, Naomi’s eyes rolled well no duh—of course she knew that, he asked about love potions not that. It was something that was elementary when you spent so much time in a country entirely surrounded by water and barraged by hurricanes.

But considering this was class she just shut up, trying to decide whether or not a lighthearted joke or prank was more acceptable for the professor, or if it was even worth it. Maybe she’d just complain to her mother about the class in general and see if Trishna got a howler. Then maybe his desk would blow up.

Content with her thoughts, Naomi started to write out the notes on all the formulas and discussion going on. Baxter’s answer about Ophiuchus made her a little confused, since she had seen that one used a bit more, but admittedly, only by her aunts and mother. After Sasha partially answered the question correctly, Naomi wrote down the Proffesor’s explanation and then listened to the next question, and Giselle’s extremely lacking answer.

She sighed and raised her hand to answer it, “Dey’re Jupiter’s biggest, ‘tree of ‘em are th’ biggest in di’ system.” She shrugged a shoulder, “’Dey ‘ave lotsa t’ings ‘bout ‘dem that are special.” She flicked her quill a bit, annoyed about how much information there was about them, “’Dey get less dense ‘di farther out ‘dey go and Io’s th’ innermost and densest.” She said, signaling the only moon she was going to talk about. She didn’t feel like talking for an eternity.

“Eet’s covered wit’ more ‘dan four-hundred active volcanoes, makin’ da’ air sulfuric and dat moon th’ most active t’ing…” She paused and then thought to correct that, the English were picky, “geological body,” she corrected as she looked back at the teacher, “In th’ system.” Then she relaxed and through off the last thing she knew about the planets, “‘Eet’s ‘di fourth largest in ‘da system.” She stopped and cradled her head in her bracing hand again, she felt a bit fidgety, and like a ridiculous know-it-all. Some of that information may have been a bit more advanced for a 3rd year, but her mother had gotten her to study harder due to the last teacher’s rather lax class.

Baxter was incredibly disappointed that he had not earned class points with his correct answer to Trishna's question. He was a third year and knew what was going on- that had to be worth something! He scowled for a few moments before finding himself distracted by the discussion which quickly carried on to another topic.

The discussion seemed to be getting more and more complex. He wondered idly why the professor had chosen to combine them for this particular class, when most of the people in his year had no clue what was being said and never been exposed to half of it. Baxter was excited to learn more, and to get a glimpse at advanced material, but also felt that the professor ought to be capable of explaining things on the level of someone who did not use astronomy on an every day basis or make their living at it. A lot of professors seemed incapable of extracting themselves from their own level of intellectual comprehension in order to make things easier to learn. Apparently Trishna would be no different.

He raised his hand cautiously after quickly writing notes on everything that was being said. When the astronomy professor recognized him, Baxter cleared his throat quietly. "I do not mean to be offensive, professor, but is there any way you could... Slow down? I'm having a hard time following the discussion. I don't know most of this material, and a lot of it is hard to understand. I'm not a scientist, and neither are we, so it isn't simple to keep up with the discussion and what's going on... So far all I've got is that the rings are made of ice, and the moons pull them apart. But I can't keep which moon is which straight, or what the ice and water has to do with anything. I'm getting lose." It was an embarassing thing to admit, especially for a know-it-all like Baxter Fox. But he didn't want to pretend he got it, when he didn't- because he needed to know this stuff for the class.

"Do you have an outline that we could copy?" he asked. "So I can keep all of the information from getting mixed up? That would be very helpful." If not, he could go through the books and make one himself, he supposed, but Baxter wasn't sure if his book would have all of this information.

"Indeed, Miss Foley, you are correct about Io," he said, flashing her a beaming smile despite her tone. "And you're right as well, Miss Knolly - they are some of the largest moons in the Solar System - Ganymede, as you should know, is the largest of all."

He looked at Baxter and frowned uncertainly. He wasn't being that cryptic, was he? He hadn't even mentioned ring dynamics and gravitation. He pressed his lips into a thin line and looked down at his feet as he thought, then looked up at Baxter. "I'm sorry, Mister Fox," he said, a bit sadly. "I'm honestly not sure how to simplify it down more without omitting information you will be tested on. However," he contiinued, lifting a hand in a gesture of assurance, "The subjects you're confused about are beyond your year - do not feel bad that you're a bit behind." He smiled as reassuringly as he could. "You third years will be returning to your regular schedule next week - this was only to give you an idea of what your OWLs will be like." He leaned on the globe as he spoke, wand beginning to tap his palm. "I don't have an outline I can give you - but, next week, I can give you a write up to help you, if you like." He looked at the globe for a moment. "If you like, Mister Fox, I can explain the rings and moons in more detail - but we only have an hour, and well, the dynamics of Saturn's rings is a scientific branch in an of itself."

"And since I'm on the subject of next week - for you 5th years, you have a test coming up," he said, holding up a hand at their expressions. "Again, not graded - just to see how behind you are for your OWLs. It's a test on general knowledge - some of what we've discussed here will be on it. Hopefully, we can get a better handle on where we need to start."

Baxter nodded, glad he wasn't an idiot for feeling behind. "I think it's more how fast it's going," he commented. "I can't keep up because I'm trying to take notes, and then it's moved on to a different topic and I get lost. But thank you, sir, for taking the time do an outline. I just want to make sure that I haven't missed anything, that's all. It's like all the information builds up to make one big point, and I'm losing part of the information because you're going too fast." That was a part of it, too. Sure, he didn't understand a lot of it- but he could understand more if he was able to keep up with the pacing.

But he would be glad when they were apart again. If OWLs were going to be this difficult, then Baxter was glad that he was able to take another two years to get caught up to that point. With Trishna teaching, maybe they wouldn't miss out on so much. Woolfolk had seemed a little too loony to teach the class properly, what with his squid obsession and all. At least Professor Trishna was relatively normal and seemed to know exactly what he was talking about.

"I'm sorry if it's too quick for you third years," he said. "For the 5th years, they shold already be somewhat familiar with this - hence, less detail should be needed - but please, let me know if Woolfolk didn't cover the moons of Jupiter yet." He leaned against the globe, the light from the image illuminating his face as he smiled at Baxter. "It's not a problem, Fox - talk to me after class. As for the rest of you taking notes, let's do this -" he pointed he wand at the board and terms began to write themselves. "If I add it to the board, consider it on a test, by the way," he added, probably to the class's dismay.

He looked at the class at large. "If you 5th years don't mind, I think a bit more detail on these answers will be in the 3rd year's benefit, eh? Now then - the Galilean moons - I'll try to be a bit slower for the 3rd years."

He cleared his throat. "The Galilean satellites are the 4 largest moons in Jupiter's system," he continued. "As Miss Knolly stated, they are some of the largest in our Solar System overall - and thus were discovered by the muggle astronomer Galileo in the early 16th century, from whom they take their names. For those of you who have covered Greek Mythology, they are named after lovers of the god Jupiter - Io, Europa, Ganymede and Callisto. In a magical sense, they can be used - but usually only on concert with Jupiter itself. For the most part, any magic they enhance a planet does better - Io, for example, can aid in fire spells, but Mars would be a better choice for such casting." He grunted. "Unless you want a particular challenge, chart-wise."

He tapped the globe and Io appeared, its pockmarked surface orange and red. "We'll start with Io. As Miss Foley accurately states, Io is the most geologically active moon in our solar system - the surface is a chaotic one, covered in hundreds of volcanoes. Of the Galilean moons, it is the closest to Jupiter, and the smallest of the 4. You may notice a large red ring on the moon's surface in this image," he said, looking down at the rotating moon. "That is the fallout from the volcano known as Pele - not to be mistaken with the mountain of the same name here on Earth." He glanced up. "While on Earth volcanoes create large plumes and clouds and their lava rarely spews too large above the caldera's surface, Io has low surface gravity - the plumes blast up to 200 miles into the air, and in Pele's case, the sulfur and other combounds leave that distinctive ring." He tapped the globe and a black and white image of an eruption appeared. "The reason the eruption appears so geyster-like is due to the effective lack of wind. The gas from these eruptions feeds the ring of Jupiter."

He looked up at the class. "The force which causes such spectacular volcanism is called Tidal Heating. As you should all remember, our moon causes our Earth's tides by pulling gravitationally on the planet - tidal heating is simply that same force taken to extremes."

The globe switched to a top-down view of Jupiter with the orbits of its 3 resonating moons in diagram form. "Unlike our moon, Io is in what we call orbital resonance with its sisters Europa and Ganymede - in layman's terms, they pull on it just as Jupiter does. This causes Io to be something like, for example, a ball of clay - as the planet and moons tug on it, the interior it forced to stretch and reform. It's tidal bulge - the shift in the moon itself due to these forces - has been measured at about 100 meters." He smiled. "This interior friction causes the moon to be so active - think of it as stress pressing and pulling the moon apart in small ways."

He looked up again. "By the way - you 5th years have an essay on these moons coming up in a few weeks. The standard curriculum has you doing an essay on all 4, but it'll be a bit different - I'll let you pick one to focus on." He smiled. "Though there's a bit more focus on Io and Europa than on Callisto and Ganymede."

---

Links:
Galilean Moons
Io

• Tidal Heating
• Pele
• Volcanism on Io

OOC Note: Words in White are board terms.

As the professor lectured, she was fairly certain that all of this, was, quite literally over her head.  Unfortunately, Erin knew she would have to know this sometime soon.  Wondering if she should bug Naomi for her notes, Erin contemplated the idea.  Naomi seemed to already know most of this stuff, and Erin wondered if she used it relatively frequently. 

As her brain tried to comprehend the overload of information the astronomy professor was feeding her, it failed.  Erin decided to do what she usually did when fed too much boring information.  She fell asleep, with her head in the doodles of the star chart she had made.