okay now here we go here we go let's take a look at a couple of these volcanoes some of these volcanoes are visible from space so for example if we look right here these three little spots those are volcanoes this is a volcano right here there's a couple more volcanoes over here and here's the next question if we can see some of the volcanoes from space what does that tell us about those volcanoes yes they must be very very very big okay so the volcanoes on Mars tend to be very very large in fact the Mars even though it's a relatively small planet the volcanoes it has actually the largest volcanoes in the entire solar system and the very very biggest volcano in our entire solar system is this one right here called Olympus Mons at least if we're going by height okay so the Olympus Mons right here is the biggest volcano in the solar system and I know you probably can't read that very well so I'm gonna bring it up on another slide so up there I have Olympus Mons that's the biggest volcano not just on Mars but also in the entire solar system okay and it's named after Mount Olympus from Greek mythology okay now here we go how big is it well check out the scale down here this right here is 50 kilometers and I know you guys aren't used to dealing with 50 with kilometers if you grew up in the United States but that's very big so this picture of Olympus Mons here is actually about the same size as the state of Arizona okay so if we were to put this volcano onto the earth it would be as wide as the state of all came up the state of volcano this volcano would be as wide as the state of Arizona okay so it is very very large in terms of height this volcano is a little over two and a half times the height of Mount Everest okay so it's two and a half times bigger so you could stack up to Mount Everest so on top of each other and it still would not be as tall as this volcano all right and one more thing I should say to give you guys an idea of how big this particular volcano is is see this hole in the top here where the where the lava comes out that hole is bigger than the state of Rhode Island okay so if you needed to sacrifice some people to this volcano when it was active you could just take the entire state of Rhode Island and throw it into the volcano all at one time and it would fit into that hole of lava it would actually be hard for you if you were standing on one side of the hole atop of the volcano it would be hard for you to see the other side of the hole at the top of that volcano so that's very very very big all right now so why are these volcanoes so big on Mars let's figure that out now to do that I'm going to bring up a picture from I'm gonna bring up my document cam so I can draw a picture there we go butt bump boom so just to make sure let's see okay that's running alright so here we go let's uh let's imagine thinking back to when Mars was fully acted so like think back in the past when Mars used to be active so it had a crust just like us what still has a crust like this there we go well you know what let me get a let me get a better pin choose this red one okay here we go so imagine that that's the crust of Mars bring this down there we go so that's the crust of Mars underneath it back when it was active it had an espheni sphere so this is the crust and this is the asthenosphere and down here we have the the rest of the mantle so crust its thinnest fear rest of the mantle okay now here we go there are places at the bottom of the asthenosphere or rather at the top of the rest of the mantle which are pretty hot and what do we call these hot spots we call them hot spots okay so these spots in the upper part of the rest of the mantle that are hot are called hot spots now if that spot is hot what it's gonna do is it's gonna heat up this part of the asthenosphere so the magma right here above the hot spot will be hotter than everything around it and if it's hotter than everything around it what is it gonna want to do what is that hot magma going to be going to do if it's hotter than all of the material around it yes that's correct it's going to rise it's going to rise because of convection right and what that's gonna do is it's gonna cause hotter material to go up here and it will slowly melt its way through the crust it'll open up a hole if enough hot material Rises there and that hot material will come out so that lava will come out and what's the temperature like on the surface of Mars compared to inside it's colder right and if it's colder what's going to happen to that hot lava when it comes out of the hole if it cools off enough right it'll cool down and it will turn into solid rock so what happens is around this opening above the hot spot you're gonna get a pile of rock around the edges where lava comes out what is that what did we just make on the surface above that hot spot yes that's a volcano that's a volcano does that make sense so what would make this volcano grow so we know Mars's volcanoes got really really really big before they turned off so what makes the volcano grow yeah so I see somebody said a bigger hotspot a bigger hotspot would make a bigger volcano but you don't necessarily need a bigger hotspot you just need that hot spot to stay hot because as long as that hot spot stays hot my material will continue to rise out of that volcano and every time it erupts that eruption will leave more solid rock around the surface or sorry around the on top of the volcano and that means as long as that volcano keeps erupting and erupting and erupting that volcano is going to keep getting bigger and bigger and bigger so the reason that Mars's volcanoes got so big is that they continued to erupt for a very very very long time okay now here's what we have to figure out earth still has active volcanoes we've been active for a longer time so why is it that our volcanoes don't get as big as Mars as volcanoes so here we go let's check this out so what's different on earth so we still have a crust we have Anniston a sphere and we have the rest of the mantle just like Mars used to have when it was still active and we still have hot spots we have hot spots just like Mars used to and wherever those hot spots cause material to rise we will get volcanoes on the surface okay but somebody mentioned the answer to what's going on here why do our volcanoes not continue to grow what does our crust do that Mars is crust did not do what does our crust do that Mars is crust did not do yeah it shifts and moves because of plate tectonics so what happens is the only part that's moving here because of plate tectonics is the crust the hot spot doesn't move so if the crust of Earth were to move that way the volcano would get off of the hot spot and if that volcano gets off of the hot spot what happens to that volcano if it's no longer on the source of rising material what happens to the volcano when it moves away from the hot spot yeah it stops erupting and it dies so it stops growing but that hot spots still there so what happens is the hot spot just makes another volcano where the old volcano used to be but then eventually the the crust will shift again and so what will happen is we'll have two dead volcanoes in a row and a new active volcano showing up so instead of having one big volcano what do we get on earth yeah we get a long chain of dead volcanoes okay we get a lot of small volcanoes what's a good example of that on earth there's a pretty good example of a long chain of volcanoes on earth that we can look to it's part of the United States Hawaii Hawaii someone mentioned the Ring of Fire that's a little bit different because that's volcanoes that pop up on the edge of plate boundaries at fault lines essentially but Hawaii is in the very middle of a plate so it must have come from a hot spot okay and so the Hawaiian Islands are just a chain of volcanoes they basically look like this that's Hawaii are all of the volcanoes in Hawaii active the answer is no does anybody know which which Hawaiian Islands are active yeah it's these big ones over here so these ones over here the really big ones are right on top of the hot spot if we could see underneath them underneath the crust we could eventually look down far enough to see this hot spot and the plate is moving oh sorry the plate is moving like this I got this backwards now the plate plates moving like this right there sorry and what happens is that these volcanoes are carried off of the hot spot where they die and start eroding because of wind and and water okay so eventually the active volcanoes in Hawaii right now will be moved off of the hot spot and it will die right but that's okay because the hot spot will still be there and new Hawaiian Islands will show up over here does that make sense so the Hawaiian Islands we have right now are just the most recent Hawaiian Islands if you look off the coast of Hawaii back here there are dead Hawaiian Islands that have eroded down below the surface of the water actually going all the way back up to Russia basically over time Hawaii leaves this hot spot in a roads below the surface and a new Hawaii pops up later so there's been a series of Hawaii's moving slowly across the Pacific Ocean okay oh no here's the last question I have about this if if if we didn't have plate tectonics how would the Hawaiian Islands be different if we did if earth did not have plate tectonics how would the how would Hawaii be different right it would basically be just one or two very very large volcanoes so one or two very large Hawaiian Islands right on top of that hot spot and ours would probably get bigger than Mars's are because our planet has been active for a longer time but we do have plate tectonics so that robs us of being able to hit the record on the sizes of volcanoes okay