54. Meteorites, Comets, Asteroids and Meteors
Over the past centuries or, perhaps, millennia, people have been awed, shocked and possibly even alarmed by the sight of these four majestic beasts that streak across the sky. Now, I know what your thinking, its not 'beasts' such as dragons and ogres. They're natural space explorers, known as Meteorites, Comets and Meteors. Now, lets delve into the science and history of these stunning floating rocks!
Meteorites & Meteors:
Now, lets kickstart our journey with Meteorites & Meteors! Meteorites and Meteors originate from large groups of celestial objects, often ranging in size from pebbles to houses. There are, in fact, two of these belts of rock, formally known as the Asteroid belt and the Kuiper belt. When the rock collides or is dislodged due to some sort of energy, it is set off course. Most of them don't go to earth, they get pulled towards the other planets. But they don't all go to the other planets.
Now it is all about size. when the rock breaks through the atmosphere, friction slows it down and starts to burn it up. If the rock is too small, it breaks apart and disappears like anything beyond the event horizon of a black hole. It is also called a Meteor if this happens. If it is too big, it is classified an Asteroid. we'll talk about the effects of an asteroid on Give Me Earth soon! If it is just in the middle, it is classified as a Meteorite. The meteorite will pierce through the atmosphere and hit the ground. Even if it is now no bigger than a stone on a beach, it can still do serious damage to the ground it hits.
Comets:
Comets are similar in some ways to Meteors, Meteorites and Asteroids. But they can also be quite the opposite as well. Comets are leftovers from the formation of our solar system and other remote solar systems. When the sun had only just started to get its mass and gravitational pull, rocks were pulled towards it. It is believed how the planets were formed is that the smaller rocks were pulled toward the bigger rocks and were attached to it. the big rocks grew to the size that the planets are today. the rest either were put into the belts, or they were thrown away into deep space. we're going to have a look at the rocks that have been thrown into deep space. depending on how far it goes, it either comes back or it goes to another solar system.
How far it goes will also determine its brightness and size of the tail because the further away it goes, the more ice forms on it's rocky surface. Just for an example, I'm going to use Halley's comet. Its aphelion (farthest distance from the sun) is about 35 astronomical units from the sun, or the distance between the sun and Pluto. The reason that comets come back is because the sun has enough gravitational pull to pull it back . Every 70 years or so, Halleys comet starts to head toward the sun. It goes towards the sun and passes by Earth. Its known as an orbit. When it gets its closest to the sun, all the ice melts away and creates a blue streak of light. This is the time we see it, lighting up the empty space around it. Halley's comet then continues its orbit, goes to deep space and all of its ice comes back.
Asteroids:
Asteroids are bigger and slightly more powerful version of Meteorites & Meteors. Asteroids are usually 10 to 100 times the size of the average meteorite. The average meteorite/meteor in space is about the size of a football field and when it crashes down on Earth, it's probably no more than a human fist or a pebble. A smaller asteroid would be 240km across in space, and about 10 metres across. don't worry, no major asteroids are bound for Earth in a very long time. in fact, an asteroid hits Earth each year about 4 metres across and it doesn't even get to go on the news!. The likes of 'extinction event' asteroids are coming in approximately 20 million years, so there is no way humans are going to be wiped out anytime soon.
In conclusion, I hope this Give Me Space article has illuminated the fascinating world of Meteorites, Comets, Asteroids, and Meteors for you. If you've discovered something new or have suggestions for future topics, please share your thoughts in the comments below. Thanks for diving into this cosmic journey with me—until next time, Give Me Space!
Henry