so we're going to be talking about this planet right here does anybody know what this planet is what's this planet right here this guy what's this planet yeah that's Mars that's Mars and Mars is very famous for its color it's sometimes called the Red Planet you can't really see it very well on this part right here but if you look at the picture further over with the rover on it you can see that red color does anybody know what why it's red zoom I know what is in the soil and in the rocks that makes this this planet red yeah it's iron and a couple of you guys are saying this iron is normally black but if if if it gets a little bit of moisture mixed in with it yeah what happens to iron what happens to iron when he gets a little bit wet and what color does it turn when that happens yeah so this is essentially rusty iron mixed in with the dirt here okay so there's a lot of iron content in the in the crust of Mars and it has turned to rust so it's technically called iron oxide that's just the technical term for rust so keep that in mind now have you ever seen any dirt or rocks on earth that look kind of like this do we have any of this kind of stuff here on earth yeah yeah we definitely do this kind of stuff is actually all over the place it doesn't I see somebody saying that it sometimes near volcanoes not necessarily but that's okay this steps all over the place most of the time we don't notice how red the dirt is in some places because it's typically covered up with plants and another stuff here but for example if you go up into Georgia a lot of the a lot of the dirt and rocks are this color it's sometimes called Georgia clay and there's all kinds of places like out west and all over the world that so this is not unusual terrain here Mars is basically covered with it we aren't 100% covered with it but it's not that strange that Mars is red we have plenty of red patches oh now here's my next question does Mars right here when we're looking at it does it appear to have more or less craters than mercury as Mars up have more or less craters than mercury yes less definitely less and so if it has less craters than mercury what did it probably use to get rid of some of its craters what did Mars use to get rid of some of its craters volcanoes that's correct geological activity in this case probably mostly volcanoes however it has a decent bit more craters per area than Venus or earth do and so that tells us that it's not it was not as active as Earth and Venus and why would we expect it to be less active or at least for its activity to turn off faster than the activity on earth and Venus why would Mars's activity turn off faster than Earth and Venus that's correct okay so if you guys remember I showed you this picture of the sizes of the planets and here we go there it is and Earth and Venus are still active they're still pretty hot in size because they're very large they haven't lost that much of their internal heat yet mercury is we said has lost most of its internal heat it's never really had a chance to have that volcanoes Mars you can see is in between in size so Mars was able to have volcanoes for a while and that erased some of its craters but now as far as we can tell all of the volcanoes have gone dead okay but unlike mercury which has been completely dead for you know billions of years Mars has probably only been dead for at least it's volcano have only been dead for a few 10 maybe 20 to 200 million years ago okay is when that's volcanoes seem to have last erupted so we as far as we can tell it's probably a mostly dead planet that said it still has occasional Mars quakes and Mars quakes are essentially like earthquakes but they're happening on Mars and we are not entirely sure why it still has those because earthquakes on Earth come from plate tectonics and does Mars have plate tectonics that's correct as far as we understand it Mars does not have plate tectonics so why does Mars have Mars quakes we're working on it but it's still not really well understood so let's just call Mars a mostly dead planet seems like it's volcanoes are all dead but it does have some Mars quakes okay all right Oh somebody asked if it could have flake tectonics and it does not appear to have that so as far as we we know most of that asthenosphere layer underneath the crust should have should be at least mostly solidified at this point to the point where volcanoes can't stay active anymore okay now let me show you guys a close-up of or so let me show you a map of the entire surface of Mars so if we go right here here we go and in this picture you should be able to see the craters a lot better you can see craters pretty much all over the place there's craters craters craters creator's craters craters but Mars has a little bit of a weird divide going on when we look at these craters what do you notice about the amount of craters in the south is that a pretty good bit of craters or only a few is this a pretty good bit of craters down here in the south are only a few so a lot or a little down here in the south yeah it's a lot it's a lot so the southern part of Mar the southern hemisphere of Mars has a lot of craters and what do you notice about the amount of craters up here in the northern hemisphere compared to the southern hemisphere what's the amount of craters like in the northern hemisphere yeah it's not as many it's much smoother up there in the north and that's not actually the only difference between the north and the south so the South has a lot of craters and the North has only a few but what you can't see in this picture is that the elevation is also different okay so the southern hemisphere is all at a higher elevation than the northern hemisphere so the crust is probably thicker in the South than it is in the north so all of the southern hemisphere is at a high elevation and all of the north is at a low elevation so that's why we call these two regions the northern lowlands which are very smooth and down here we have the southern highlands which are very covered in craters so northern lowlands up here these are smooth this is the northern lowlands and then down here we have the southern highlands which are very covered in craters looks like I got a question coming up let's see what that is is there a reason that the northern cap looks like it has more has more what Oh we'll get to that in a second hold that thought hold that thought okay um he was asking about the ice up there we'll talk about that in a little bit let me let me finish this crater business first okay what we will loop back around okay now so northern lowlands smooth southern highlands sap southern highlands rough okay so other than that though even though there is a elevation difference between the south and the north overall Mars is a lot flatter than the earth is now why is that what does earth have that makes it overall a lumpier planet than Mars here yeah so there's no mountain ranges on Mars no like over all mountain ranges like the Rocky Mountains because there is no plate tectonics on Mars and I did see that question there about about possible oceans I will get to that in a second okay so here we go here we go so here's the next follow-up question okay if the north is smoother than the south there must be a reason for that and that is in one of these regions the volcanoes kept going for a longer period of time now can you figure out which region the volcanoes kept going for a longer period of time was it the northern lowlands or the southern highlands which one had volcanoes going for a longer period of time you could just say north or south yeah that's correct the north and there's a pretty simple possible explanation for why the volcanoes kept going in the north for longer remember I said that the crust was thinner in the north and a little bit thicker in the south that's why the south is a little bit higher so the reason that the volcanoes could go longer in the north is that as the planet cooled off it got harder and harder for lava to rise through the crust and where the crust was thicker it stopped being able to go through it where it was thinner it could continue to go through the crust and make volcanoes and have volcanoes erupt for a longer period of time does that make sense so in the North because the volcanoes could go for a longer period as I because the crust was thinner the volcanoes could erupt for a longer period of time as the planet cooled off okay