Astronomy Lesson #3

[Kaiia Blackthorn]

"Good. Two housepoints. There is another type called a Proxigean Spring Tide, which happens only rarely. It's an unusually high tide. For one to occur, the moon must be unusually close to the earth - at its closest perigee, in fact, and must also be in its New phase - in other words, it is between the Sun and the Earth. At most, a proxigean spring tide occurs only once every eighteen months."

A flick of her wand, and the image, as well as the title Tides were erased. Now she could move on to something a little more interesting.

"You should all have read Chapter Seven of your textbook, in preparation for the next subject." The second title Formation of the Solar System became larger and moved to the top of the blackboard. "In order to understand the formation of the solar system, we first need to determine exactly what it comprises. Can someone give us a brief definition of the solar system?"

[isabellapeters]

Bella smiled as she earned two points for Ravenclaw then raised her hand. "It's an area in space that's within the Sun's gravitational pull, which keeps everything in orbit." The solar system was definitely a cool thing to learn about, even if it was with a teacher that supported the dark arts. She remembered how the twins already knew her and wondered how they were feeling about this lesson.

[Aidan Fischer]

Aidan shifted in his seat, half-listening to the lesson. He'd noticed a change in Professor Blackthorn from her days teaching at Durmstrang. She was thinner, paler, and her manner was remote. He almost missed the ferocious sarcasm she used to employ. Really, she seemed positively tame these days. He half-grinned to himself, remembering the rumours about her and the High Master - whatever had really been going on between those two was presumably over. Maybe it was the lack of a man in her life that had changed her...

[Kaiia Blackthorn]

"Mr Fischer!" Kaiia's attention had been drawn by the smile. Up to no good, most likely. When Aidan looked up at her, slightly startled, she said, "Since you appear to be in such good spirits, perhaps you could entertain the class with an explanation of the objects that make up the solar system."

[Aidan Fischer]

Aidan jumped slightly, when Professor Blackthorn snapped out his name. Well, this was a little more like it, he thought to himself, as she continued. But he was a bit lost, he'd done the required homework, but hadn't bothered to read the chapter... "Umm - well, there'd be planets and - and their moons, and asteroids and things. Comets. Meteors..." He racked his brains. "I think that's about it..."

[Kaiia Blackthorn]

Kaiia listened to his stumbling answer. When he ground to a halt, she regarded him with a glint in her eye. "That's it? Really? Well fascinating as your explanation was... can anyone enlighten Mr Fischer as to what he left out?" She looked round at the rest of the students.

[angel]

Angel frowned slightly as she heard Aidan being told off, he hadn't been doing anything wrong. She raised her hand though and said, "There's also ice dwarfs, the Oorf Cloud, and Kupier's belt in the Outer Region." She hadn't read the book that much but the words had seemed weird so she'd remembered them. Glancing at Aidan she smiled before turning her attention back to the front.

[Kaiia Blackthorn]

Kaiia listened to Angel's contribution. For some reason she was starting to enjoy herself. "Indeed. Those things reside in the Outer Region. But is there, perhaps, something a little closer to home?" Her tone was light, the faintest undercurrent of sarcastic amusement. "Something - shall we say - more obvious?"

[Caeleb Dracus]

"And er...the Sun" Caeleb added with a smirk, smiling at Angel. He just found it amusing that the one thing they all seemed to forget was the the great big star at the center of it. "I believe it's name is 'Sol'." he added.

[Kaiia Blackthorn]

"Hence the name Solar system," Kaiia added, not quite succeeding in suppressing her grin at Caeleb's tone. Quite clearly, he appreciated the humour in the way the other students had overlooked the screamingly-obvious. "Without the sun, there would be no solar system. Two points, Mr Dracus."

She conjured up a very basic diagram. "As we see, with the sun in the centre, there are several distinct regions. The inner region, the asteroid belt, the gas giants, and the outer region. Let us fill in the details. Which planets reside in the inner region?"

[Aidan Fischer]

Aidan mentally slapped his forehead. How could he forget the sun? He grinned rather sheepishly, at Angel, then quickly switched off the grin. Not wanting to draw the Professor's attention again so soon. He surreptitiously opened his textbook at the appropriate chapter and started to skim through it.

[angel]

Angel felt like hitting her head as she remembered the sun. When did she get so blonde?.. ignoring the colour of her hair. She smiled at Caeleb and then glanced at Aidan again returning his sheepish smile. "The first four planets are in the innner region," she said. "Mercury, Venus, Earth and Mars. Professor is the asteroid belt in the inner region as well?" She could never remember that bit.

[Kaiia Blackthorn]

"Correct. Two points to Hufflepuff." Kaiia added the four inner planets to the floating diagram. Then she added the asteroid belt, and said, "That's a good question. The Asteroid belt is generally seen as the demarkation point between the inner region and the gas giants, so it's usually regarded as a distinct region in itself." She glanced around. "Does anyone know the most popular theory as to what formed the asteroid belt?" This wasn't in the textbook; it would be interesting to see who - if anyone - was interested enough in the subject to do some additional reading of their own.

[Caeleb Dracus]

Caeleb frowned to himself.
"Some people believe it used to be a planet that was it by a comet. That would explain why the debris has its own orbital path around the sun. I don't know if that can be true, though." he said thoughtfully.

[Kaiia Blackthorn]

Kaiia looked at Caeleb with interest. It appeared he was interested in her subject. "Yes, that's the theory you'll hear most often. Two points to Slytherin. Incidentally, it illustrates one of the problems we encounter when studying the origin of the solar system - and, indeed, the entire universe. Much of what we 'know' is actually just theory. Muggles are constantly sending up their spaceships to explore, and take samples. But they - and we, in the wizard world, for that matter - can observe only a tiny fraction of what's out there, so it's difficult to know how acurate those observations are."

Kaiia stepped back a little, so that they could see more of the diagram. "The next region is the one that contains the gas giants. Which planets are these? And why do we call them 'gas giants'?"