Asteroids, comets and meteoroids are all described as rocky fragments drifting in space. Even though these words can be used interchangeably, there are many tiny differences between them. If you want to learn more about these, continue reading!
The universe we are living in is much much bigger than what you could imagine. And Earth, which already seems so vast, is just like a grain of sand floating amid the universal ocean. In fact, our Milky Way is just one of the billions of galaxies scattered randomly throughout the vastness of space.
Our lovely solar system is home to one giant star, eight unique planets and around 200 natural satellites and it also accommodates countless asteroids, comets and meteoroids. You may already realize that the star that is being referred to is the Sun, the 8 planets is Earth and its neighbors and natural satellite is another name for moon.
But what about the later 3? If you think these 3 terms all represent one thing and you start to feel a bit hazy on their definitions then don’t worry because so many people also have difficulties spotting the differences between them. In fact, these 3 terms can be used interchangeably. Yet, knowing a bit more about their unique features and how they differ can aid your general understanding of the universe and more importantly, turn you into a potential space expert.
Here, all basic information about asteroids, comets and meteoroids will be provided so keep reading if you want to learn more about the differences between them.
What are Asteroids?
Asteroids, sometimes referred to as planetoids or minor planets, are objects composed of different types of rock and metals that orbit the Sun. They are believed to be the remnants of the formation of our solar system 4.6 billion years ago and are too small to be classified as planets. Their sizes actually vary greatly; Ceres, the largest asteroid in the universe, has a diameter of about 950km, while the smallest bodies are only 1 to 2 meters across.
Asteroids are most densely distributed along the asteroid belt located between the orbits of Mars and Jupiter. Here, you can find millions of asteroid bodies.
What are Comets?
Unlike asteroids that are formed in proximity to the Sun where only rock and metals could remain solid under high temperatures, comets are formed in the outer region of the solar system where it is cold enough for water to freeze, therefore, they consist of only ice and dust. Comets, like asteroids, also orbit the Sun, yet the shape of their orbit is more like an elongated ellipse. This means that there are parts along their orbit path where they come closer to the Sun.
Maybe you have always wondered why comets have these beautiful and unique tails? Now I am going to reveal the reason to you. A comet actually has 2 tails, the bright ion tail and the dim dust tail as it can interact with the Sun in two different ways. As a comet’s orbit leads it towards the Sun, the neutral gas surrounding the comet will be ionized by solar radiation to form the ion tail and ice and dust trapped inside its head will start to melt and vaporize to form the dust tail.
What are Meteoroids?
By looking at their name, meteoroids, you can easily make a guess about what they are. You may be thinking that meteoroids, asteroids should have something in common. Well, you are right! Meteoroids are the pieces that get broken off when two or more asteroids collide so they are basically the smaller, much smaller version of asteroids. They are no wider than 1 meter and can sometimes be the size of just a grain of dust. Due to their littleness in comparison to other celestial bodies, they are often referred to as pebbles of the universe.
Meteoroids can be further classified into 2 smaller groups: meteorites and meteors. To be able to name them correctly, you have to look at their locations, whether they are wafting in space or streaking across Earth’s atmosphere. As detailed above, a meteoroid is a small rocky object floating in space but when it enters Earth’s atmosphere, it will become a meteor. That meteor heads towards us at high speed and will likely to completely vaporize before it can actually make it to Earth’s surface. However, if that meteor does not completely burn up, the small remaining part that will eventually land on Earth is called a meteorite.
A little summary
- Asteroids, comets and meteoroids are all celestial bodies left over from the formation of our solar system.
- They all orbit the Sun.
- Size: The average size of an asteroid (1-2 meters to about 950 kilometers) is larger than that of a comet (approximately 750 meters to 20 kilometers) and out of the 3, meteoroids are the smallest (no larger than 1 meter).
- Formation: Both asteroids and comets are remnants of the formation of our solar system whereas meteoroids are ejected when two or more asteroids collide.
- Composition: Asteroids are made of different types of rock and metals and meteoroids also have the same composition. Comets, on the other hand, consist of ice and dust.
- Location: A majority of asteroids is found along the asteroid belt lying between Mars and Jupiter, comets are located in the outer region, further away from the Sun and meteoroids can be found throughout the solar system.
- Unique feature: Comets have tails while asteroids and meteoroids do not.
In short, the source of all of the differences between asteroids, comets and meteoroids is their locations since the places where they are formed and located apparently lead to them having their own unique sizes, compositions and features. If you are still a bit confused with the above 3 objects, the below diagram can help you.
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