so we're starting test two material which is going to focus on a few things but we're gonna start with our solar system okay I'm gonna start with our solar system and if you want to follow along in the book that's gonna be checked starting with chapter six but it's actually gonna go over several chapters okay so here we go here we go our solar system what's the solar system okay normally I would ask that in class but and take a little while for you guys to type that out it's kind of a long definition a solar system is a star and anything that orbits that star okay a star and anything that orbits that star another way to say that is is a star and anything that is gravitationally bound to that star so stuck in the gravity of that star and there people typically think of like planets being part of a solar system but it's not just planets it's not just the star it's anything that orbits and you can also have things passing through but those things that are passing through that aren't stuck in the gravity would not be considered part of our solar system okay so our solar system is not the only one as we said along a while back we have found planets around other stars so we have found other solar systems do any of you guys know what the name of our solar system is you me guys what is the name of our solar system let's see if you guys have any guesses on that what's the name of our solar system uh and this is what everybody always tells me everybody always brings up Milky Way the Milky Way is our galaxy okay our solar system is just a part of the Milky Way so it not the Milky Way that's okay that's what everybody always guesses first that's because people don't typically think of the name of our solar system yeah it's just the solar system our solar system is called the solar system with capital asses okay kind of like what what's the name of our moon what's the name of our moon the moon right the name of our moon is the moon and there's other moons so we call our solar system the solar system because it's ours right so I don't know maybe we'll come up with another name if we meet some aliens someday and they're like no ours is the solar system you can't have those solar system so I don't know so but for right now it's just the solar system okay here's my next question what is the biggest thing in the solar system what's the biggest thing in the solar system as you guys are guessing I'm gonna prepare a picture of it what's the biggest thing we got yes yes it's just the Sun right the Sun is the biggest thing so right here here's a photograph of the Sun the Sun is not a planet okay the Sun is just a giant ball of gas is anything else in the solar system close to the size of the side is anything else close to the size of the sudden yes or no no absolutely not nothing in the solar system is anywhere near the size of the Sun I think a lot of people don't even realize how big the Sun is here's another photograph of the Sun where they put the earth in the picture so you can see how big it is compared to the earth right so here's a here's the Sun and they put earth right here so you can see how much bigger the Sun is than the earth we always think of the earth as big but uh man that thing man the Sun is big right you could fit over a hundred earths from one end to the Sun to the other end of the Sun and if you wanted to fill up the Sun with Earth's it would take over a million of them you think you could fit over a million earths inside of the Sun and yeah there are planets that are bigger than us but nowhere near the size of the Sun so in fact if you took everything that's orbiting the Sun just all the things all the planets all the asteroids all of that stuff and you squished it together and made one object that object would have less than one percent the mass of the Sun so the Sun is the largest in our solar system okay so after we're done talking about our solar system what we should eventually talk about the Milky Way and galaxies remember our galaxy contains billions of Suns billions of stars so our solar system is just one stop one solar system amongst possibly billions of them in the Milky Way and our Sun is not actually a particularly big star there are stars out there that are much bigger than our Sun so our Suns just kind of average right now on the other hand on the other hand like I said everything else in the solar system is less than 1% the mass of the so the Sun contains almost all of the material of the solar system and if it's that big it's gonna have to be made out of stuff it's gonna have to be made out of elements that are very very very common in order to have something that big there's not a lot you can't have something that's rare be the main thing the Sun is made out of or else that thing wouldn't be rare in our solar system right so let's see if we can figure this out based on what we know about elements what elements is the Sun probably made out of if it has to be very very very very common materials let's see if you guys can guess at least one element that the Sun has inside of it basically you're looking for the most common elements that exist see if we can remember we actually talked about this helium is one of them helium is one of them in fact helium is the second most common thing in the Sun and hydrogen is number one remember we said that 75% give or take of the universe is hydrogen and then close to 25% is helium so the only things if the Sutton is 99% of the solar system and the solar system just like the universe is going to be about seventy-five percent hydrogen close to 25 percent helium then that means this thing's gonna have to be made out of hydrogen and helium so yes and as some of you guys pointed out it's a big ball of gas it's gas all the way down to the middle there's no solids there's no liquids just a giant giant hot ball of gas