A Brief Romp Through Our Solar System

   I’m going to ask you a question. Are you ready? And that wasn’t the question lol. Do you get kind of confused when people talk about meteors, meteorites, asteroids, comets, and other astronomical terms? I bet a lot of you do, and it’s nothing to be ashamed about because it’s really quite common. Many people use these terms without fully recognizing what they mean. And how about meteoroids? I bet a many of you have never even heard of that one lol. So I’m going to try to explain what these actually are.
   Ready? Here we go.
   Now, let’s start with the basics. We have the Sun around which eight major planets orbit with Neptune being the farthest out. Yep, I said Neptune because Pluto got demoted so to speak and is now considered a dwarf planet in the Kuiper Belt. And what’s the Kuiper Belt? We’ll get back to that in a minute. The order of the major planets starting closest to the Sun is Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune. Moons are celestial objects that orbit around planets (including major planets, dwarf planets, or minor planets), and let me tell you, our Solar System has quite a few (Jupiter alone has over 80).
   Ok, let’s first delve into asteroids. Asteroids are bodies of rock orbiting around the Sun that are much smaller than planets but larger than pebbles. They’re usually irregularly shaped with sizes typically ranging from that of boulders to diameters of a few thousand feet, though some are larger with diameters up to a few hundred miles. The majority of asteroids in the Solar System are located between Mars and Jupiter in what is known as the Asteroid Belt. As to how this belt came into being, we have to go back in time to when the Solar System was forming. Dust and rock orbiting around the Sun coalesced together to form planets, but it appears this process did not succeed between Mars and Jupiter. The large size and presence of Jupiter was likely a strong factor in why a planet didn’t form and the Asteroid Belt resulted instead. Some have wondered if a planet did form in the area and was later destroyed by a cataclysmic event, but most scientists think this theory is highly unlikely. And here’s a fun tidbit: if you combined all the asteroids in the Asteroid Belt into one object, NASA believes it’s mass would still be smaller than that of the Moon which orbits our planet.
   So let’s go farther out into the Solar System. Beyond Neptune, we come across an area known as the Kuiper Belt. Now, remember that the distance from Earth to the Sun is one astronomical unit (AU). The Kuiper Belt begins about 30 AU out from the Sun. It consists of millions of objects of ice and rock ranging in size from very small to hundreds of miles across or more. Pluto is one of these bodies with a diameter of 1473 miles. The inner region of the Kuiper Belt goes out to around 50 AU. Then there’s a second zone that goes beyond this referred to as the scattered disc that reaches to almost 1,000 AU.  There are more icy objects found even farther out than the Kuiper Belt in a region referred to as the Oort cloud. The inner edge of this zone begins somewhere between 2000 and 5000 AU and extends out to somewhere from 10,000 to 100,000 AU from the Sun. Yeah, that’s pretty far out isn’t it lol. And if you’re wondering whether these regions of icy objects are the sources for comets, then give yourselves a gold star because you’d be right!
   Comets are small icy celestial objects made up of frozen gases, rock, and dust. As a matter of fact, some astronomers refer to them as dirty snowballs. They have highly elliptical orbits so that most of the time they are out in the Kuiper Belt and Oort Cloud. The time it takes a comet to complete one orbit is highly variable depending on how far out it’s elliptical orbit takes it. While Halley’s Comet comes around every 76 years, there are others that take hundreds of thousands of years to complete a single orbit. When you think about how far out the Oort Cloud extends, that makes sense. Comets have a nucleus that is made up of frozen gases, rock and dust and is usually about 6 miles in diameter or less. During most of a comet’s orbit, that is all you’d see if you were close enough to look. But when the comet gets closer to the Sun, a cloud called a coma forms due to ice turning into gas, and as the comet gets hotter the coma can extend out hundreds of thousands of miles. Sunlight and the solar wind may then blow the coma to form a tail which extends out millions of miles away from the Sun. Another fun tidbit is that there are actually two tails: one of dust and one of gases.
   Wait a minute! We’re not done yet! What about meteors, meteorites, and even those pesky meteoroids? Well, let me tell you. Meteoroids are objects in space orbiting the Sun made up of rock, metals, or a combination of both. They range in size from grains of dust to small asteroids, and many are likely pieces that broke off of larger bodies such as asteroids, comets, moons, or other planets. Most are probably the result of asteroids running into each other. If a meteoroid ends up running into a planet with an atmosphere, it races through the atmosphere’s molecules and atoms which in turn creates frictional heat. This heat causes gases to glow and starts essentially burning the meteoroid up. This is when it’s called a meteor, or shooting star. Most the time, this process burns the meteoroid up to such a degree that nothing of significance reaches the ground, but there are occasions where a chunk of it survives and impacts the planet. After impact, it’s called a meteorite.
   So there you go. That wasn’t too painful was it? Hopefully now, these terms make a little more sense, and perhaps you understand the universe in which we live a little better.