 Greetings and welcome to the Introduction to Astronomy. In this week's special topic in astronomy, we are going to look at three terms that can refer in some ways to the same thing. We will look at meteor, meteoroid, and meteorites and see what the difference is between these three. So what are meteors? Well let's start off with those because those are probably the one of the most familiar to you. A meteor, sometimes called a shooting star, is a small bit of material that's strikes Earth's upper atmosphere. When it does that it vaporizes. So here we see an example of one of these meteors and we can see that off here in our image and how it was streaking through the sky as it struck Earth's atmosphere. When it does that it is vaporized in the upper atmosphere and we see the trail it leaves behind. Now we can also have what we call a meteor shower where you get more than one of these at once and let's take a look at one of those. Here's one with showing about three of these different meteors and you can see here we have one and here we have one and here we have one. So several different ones. They're all part of the same shower and that is when these occur together and when they are all associated with the same object generally a comet. So while I say large numbers here you actually would get more depending on a good meteor shower you might see one or two a minute if you get a really good meteor shower. You're not going to see them just going continuously across the sky but you will be able to catch a good number of these traveling across the sky. Now a meteor never strikes Earth's surface for the most part. It's very rare that they actually strike Earth's surface. The vast majority of these are absolutely no danger. They simply vaporize in the Earth's upper atmosphere giving us a very nice meteor shower and maybe a nice show depending on the conditions of that exact shower. Now a meteorite on the other hand is this same object. A meteor came from a meteorite. A meteorite is just that same bit of material in space. So I'm not showing you a picture of it here because there's really not much to see. This would be a small grain of sand, little flake of ice, some little tiny bit of material and they strike Earth's atmosphere at extremely high speeds and vaporize and that's what gives us then they become a meteor. Now I said they generally never reach Earth's surface. There are cases where they do reach Earth's surface and when they do we get a meteorite. That's an actual bit of material that we can hold here on Earth. So here is an example of one of those meteorites and it's first of all the meteorite is just a larger piece of material, something big enough to survive that trip through the atmosphere and land on the ground. Again most of these are grains of sand and they never make it down. Now this is actually a metallic meteorite so this is actually metal. Now this is not how it would have been found. You would find this it would have then been cut and you can see the crystalline growth inside as the metal cooled. Now a large object like this, a large chunk of metal stands out when you find it here on Earth and that's one of the reasons that iron meteorites such as this one are much easier to find than stony or ordinary rocky meteorites. An ordinary rocky meteorite once it's landed and has been sitting for a while it gets worn and it looks just like any other earth rock and it would take specialized knowledge and testing to be able to determine that it was actually a meteorite whereas a hunk of metal is much more unusual and much easier to identify. So let's go ahead and summarize a little bit what these three terms mean and what we looked at we had a meteor sometimes called a shooting star which is a small bit of material burning up in Earth's atmosphere. A meteoroid is the same material here but out in space. So before it strikes Earth's atmosphere it's a meteoroid once it does and that while it's vaporizing in the atmosphere it's a meteor. If it is large enough to land on Earth then it becomes a meteorite that is the large object that survived the trip through the atmosphere to land here on Earth for us to be able to study. So that concludes this lecture on Meteor, Meteoroid, and Meteorite. We'll be back again next week for another special topic in astronomy. So until then have a great day everyone and I will see you in class.