How to Tell the Difference....Comets, Asteroid, Meteors, Meteoroids, Meteorites and Shooting Stars

Do You Know The Different Between These Different Types Of Space Rock? Comets, Asteroid, Meteors, Meteoroids, Meteorites and Shooting Stars.

Introduction

There are a lot of rocks in space, some of them tiny and some of them we live on like the Earth. It can easy to confuse the different names we give to the different types of rocks that float through space, and some destined to fall to Earth. If we put large bodies aside a moment, we wont consider planets and moons, just those mentioned in the title. Comets are the largest type of space "rock" we find, some of you maybe familiar with Halley's Comet that orbits the Sun every 72 years, passing us by with stunning effect as it goes.

Halley and his Comet

The smallest of the rocks is actually Cosmic Dust, which slowly falls to Earth and doesn't burn up in the Atmosphere, like Meteoroids (Shooting Stars) for example.

Cosmic Dust

In this Article we will briefly look at the differences between the different names and what they mean for us.

Comets

Comets can be considered the largest of the Space Rocks, they have a nucleus or a center that is usually in the range of 10's Kilo meters. Halley's Comet for example has a nucleus of 11 Km, at it's most distant point from the Sun called the Aphelion it reaches an orbital radius of 35 AU, and a Perihelion of 0.5 AU. The density of Comets is very low Halley's Comet has a density of 1.5 grams per cubic centimeter, it's made up from water, carbon-dioxide and dust. You cam imagine a Comet as a big dirty snow ball that is quite "fluffy" and not dense. Halley's Comet has a mass of 220,000 million Kilo grams, even though it isn't dense, it is still very massive.

Something strange happens to Comets as they approach the Sun, they start to expand, and can expand from the size of the nucleus to 10-100 times the size. The ice starts to melt and the low pressure of Space vacuum allows for lower temperatures of evaporation. The Solar winds from the Sun then blow over the comet carrying away the gases that have evaporated. It is this evaporation trail that gives comets the unique tail.

Comets although not dense are extremely big compared to standard meteors. It's this large size and mass means that they are very dangerous threat if it were on a collision course with the Earth. Small rocks burn up in the atmosphere as they fall, the burning falling rock is what we call usually a Shooting Star. The problem for comets is that they are very large in size, and will still be very large after travelling through the atmosphere and burning up a bit.

Comet impact

Fortunately, comets are very big and we know where any precarious comets are orbiting and their orbital path. At least for the next 100's of years, we don't need to worry about a Comet impact.

Asteroids

Asteroid is the name given to the Space rocks that originate from the Asteroid Belt, which lies in an orbit between Mars and Jupiter, there are other asteroids but they originate from the same source. The size of asteroids varies greatly from the size of little pebbles to the size of Ceres of 975 Km. Some of these asteroids can be composed mainly of Iron, which has a density of 8 grams per cubic meter, over 5 times denser than a comet.

Ceres, a Dwarf Planet of the Asteroid Belt

The formation of such dense objects is not thought to be possible in space through coalition of material. Infact, some Astronomers believe that the Asteroid Belt is the remanents of a Planet that used to exist in that orbit between Mars and Jupiter. A scientist called Johann Bode came up with an equation called Bode's Law that would predict the position of a planet around the orbit of the Sun. All the known planets matched their calculated position, but there was one missing in between Mars and Jupiter. So there is strong evidence to suggest the Asteroid Belt are the left overs of a Titanic collision of a Planet sized object.

Let me make something clear, that if you were in the Asteroid Belt, you would probably not see any Asteroids, they are very spaced out and nothing like you seem on the movies, where huge rocks must be avoided. It's nothing like that, it is very very improbable for Asteroids to hit each other, but none the less it can happen.

Meteors, Meteoroids, Meteorites and Shooting Stars

You can see illustrated in the image below the difference between Meteors, Meteoroids, and Meteorites. A Meteoroid the name we give when a space rock is just outside the atmosphere, it is a Meteor when it has entered the atmosphere and is burning up, and if it makes it through and hits the ground, it is then a Meteorite.

99.9% of the Meteorites that strike the Earth originated from the Asteroid Belt, and rarely a Meteorite is found that originates from Mars or the Moon. The composition is usually a mixture of Silicates and Iron, having densities of about 7 gram per cubic centimetre.

During the Meteor phase when it is burning up through the atmosphere, something special can be seen which we call a shooting star. The rock is falling with so much speed that the friction caused by rubbing against the atmosphere at great speeds causes the rock to glow white hot and expel some of the material. So a shooting star is not a star but a Meteor trying to become a meteorite on Earth.

Shooting Star, Exposure Image

On Feburary 15th 2013, in Russia, a rare event occurred in a town called Chelyabinsk. A Meteor fell and exploded over the town. Below is a beautiful video to show you the effects of the explosion. It exploded instead of hitting the ground because the angle it travelled into the atmosphere was very shallow so it meant that the Meteor would travel through a lot of gas heating up even more. The huge energy caused by heating caused the Meteor to explode, just like when stones explode in a fire. Luckily it had snowed at the time, so people were able to find the holes in the snow and locate Meteorites before they were lost and could erode. A large part of the Meteorite was found in a lake as it made a big hole in the Ice, the residents were lucky in this respect, but not so lucky is they felt the explosion. Take a look for yourself.

You can see that the effects were quite extreme.

This is something I like to talk about, so Iwill make an article focusing more on Meteorites them selves and how we know where they came from, what are the different types, where you can find them and buy them. Also how we can avoid disastrous impacts.

So now you know the difference between Comets, Asteroid, Meteors, Meteoroids, Meteorites and Shooting Stars.

I hope enjoyed and learnt something fun. Feel free to Upvote, Follow for more, and Resteem.

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