Astronomy Lesson four (Second years)

Colin let the door to the astronomy room flop open with a flick of his wand. Time for another lesson.

Iris went inside the tower and greeted the professor before feeling the cold wind on her face yet again, "Good evening professor."

"Hello Professor," Iris greeted as she entered the class. "Hey Eye!" She grinned at Iris. "What's up?"

Alex walked into the Astronomy class, as silent and cool as last time.
"Good Evening Professor, Eye, Iris." She took a seat beside Eye.

Iris removed her gaze at the sky and waved at Alex and Grayson, "Hey. I love this day really. Everything went out great! Have you completed your star charts?" she asked them out of curiosity and the sudden thought.

Anna entered the classroom, star chart in her hands. She sat at the back, making sure she didn't miss out on anything.

Tobi arrived to class and took a seat. He was excited to hear what they would be learning about today. Looking around he noticed there were only a few students there.

"Yeah I did."Alexis smiled, "And I had a great time lying on the roof on my back and observing the Sky."
"What about you, Eye?"

Iris smiled and thought back then sighed dreamily, "I did too. Back at the muggle-world, you know. It was a very nice experience."

Caleb walked into the class and had a seat. "Hello professor" said Caleb. Caleb got what he needed from his bag and placed it on his desk.

Anna looked around just to double check who was there. There was... Iris, Alexis, the Iris in Gryffindor... and someone from Slytherin she had never met. She nodded curtly at him before going back to her star chart.

"Oh yeah, thanks for reminding," Iris said and took out her star chart and placed it on her desk. "I actually had a pretty good time while doing the chart," she grinned.

"Since we started with the sun, and stars last time let us talk about the death of them. What does any of you know on that?"

Alexis raised her hand, "At the last stage of the star, a big explosion takes place, and it's called... um, Supernova, I think, And then it becomes a source of huge attraction force, The muggles call them Black Holes."

Iris nodded and added an answer, "They become like that when there's already too much heat in them. They can no longer be suitable to heat us since when they explode, we already died then. Muggles say End of The World actually, or the Apocalypse to be exact which they predicted long before."

"Correct both of you - that can be five points each." Colin nodded.

"Though, Ms. Hope, it is true that only some stars become Black Holes - not all of them," he corrected the girl's statment some, "Does anybody know what makes the difference? What is it that a star needs to have or do to make it a black hole?"

"A star needs to die then explode to make a black hole," Anna replied. "But only stars that collapse onto themselves can become black holes, I think."

Alexis nodded and raised her hand again, 'I think only stars with large mass and gravity can become a black hole.'

Iris nodded in agreement and added some facts she knew, "While for the stars with small masses, they can be a white dwarf and become sort of neutral since they have no heat at all."

Iris nodded and replied, "Yes Professor, and after a black hole has formed it can continue to grow by absorbing mass from its surroundings. By absorbing other stars and merging with other black holes, supermassive black holes of lots of solar masses are formed."

Colin nodded, "Good, good. I believe you all covered the points there.

"Yes, when a star obtains a certian size, which brings in its own weight and gravity, it becomes so heavy that the core can't support it and the star collapses in on itself - this is in fact a super Nova - but with stars that are too big they just continue to fall in on themselves for all time and thus creating a black hole. Of course the actually science is much more complicated, but for our work here, that will work."

"now..." he said slowly, smiling slightly, "Does anybody know what a blackhole leads to? What happens to something that gets sucked into it?"

"I believe you'll be brought into nothingness, sir. There's no explanation yet about what's inside a black hole." Iris answered with confusion, relying on her own sense now.

"Thank you Ms. Frances - yes, that was a bit of a trick question; no one knows what is on the 'otherside' so to speak of a black hole," Colin twirled his wand in his hand as he spoke, "there are theories of course, some more fanciful than others, but there is no conclusive proof either way. It is an interesting thought for those of you who wish to dwell on it."

"Our evening is shortening on us, so we are just going to move things along here. If you haven't done so already, please hand in your first star chart, and use whatever time you have left to work on your second one."

Iris nodded and took out her star chart from her bag. Giving one glance at it and at the sky, she passed it to professor then waited for the final dismissal.