29 December 2014, 08.43 PM
The first asteroid was discovered very long ago in 1801 by Giuseppe Piazzi. He was the director of an observatory in Sicily, and actually discovered the asteroid by accident. He named it Ceres, in honor of a Roman goddess. It is a fact that Ceres is the biggest object in all the asteroid belt.
Although now we have a better idea of what an asteroid is, we need to go more into detail to really know all about them. Their characteristics, their formation and classification among others.
So, let’s start from the beginning. We know that asteroids are leftover rocks, but how did they become leftovers? It all happened around 4.6 billion years ago. When Jupiter was formed, it prevented all other planetary bodies from forming between it and Mars, this caused the small objects to collide with each other and fragment into what we know today as asteroids.
Now, about their characteristics. The size of an asteroid can vary a lot; for example Ceres reaches a length of 940km (583 miles) across. But there are also others considered the smallest that are only six meters across (around 20 feet).
Most asteroids don’t have a regular shape. Very few are considered almost spherical –one of them being Ceres. The majority of them have hollows and indentations on the surface. For example, one asteroid named Vesta has a crater of 460km (285 miles) in diameter.
Another fact that most people don’t know is that more than 150 asteroids have a small companion moons, and fewer even have two moons. Some asteroids are thought to have been captured by the gravity of a planet and become a moon. For instance, Phobos and Deimos, two of Mars’ moons are possible candidates of the theory.
The average temperature of an asteroid is of -73º C (-100º F). But some of them are not solid bodies, small piles of rubble bound together by gravity are a common way to form an asteroid. And of course, all asteroids need to be classified.
Some of those classifications are: Type M, they are metallic asteroids and usually of a reddish color; Type S, stone or silicaceous asteroids that are reddish or greenish and Type C, carbonaceous asteroids of grayish color and the most common type of all, 75% of all asteroids being that type.
Moving on to another subtopic, asteroids impacting on Earth is always a popular subject when it comes to movies or even theories about the end of our planet. According to NASA, dangerous asteroids are very rare. An asteroid capable of global disaster would have to be more than a quarter-mile wide.
Scientists and researches have concluded that such an impact would raise the enough amount of dust into the atmosphere to create a “nuclear winter”. But to calm ourselves a little but, NASA has also stated that those kinds of asteroids strike Earth only around 1,000 centuries on average.
One of the biggest asteroid impacts of our time happened in 2013. An asteroid slammed into the atmosphere over Chelyabinsk, a Russian city. The shock wave created by the impact injured around 1,200 people. The exact measure of the asteroid is unknown, but it is believed to have been 20 meters wide (65 feet) when it entered the atmosphere.
But as popular as asteroids may be, a lot of people tend to confuse them and inappropriately call them differently. It is impossible to know how many times people have called and asteroid a meteor or meteorite and vice versa. It is common to think that “it is all the same”, but there are differences between those terms.
A meteor, is an object –usually a small piece of comet dust– that enters the Earth’s atmosphere from space. But meteors will burn up before they are able to reach the ground. When they start to vaporize they leave a fiery trail we all like to call a shooting star, though it is not a star.
So, if that is a meteor is a small piece of comet dust, what is a meteorite? A meteorite is what people mostly confuse an asteroid with for several reasons. A meteorite is a rock that falls from space, and it is commonly a piece of an asteroid. There is a clear difference.
Although most people might find it irrelevant, knowing the difference between these space objects is important.
Through the years, we have gathered a lot of information about asteroids and space in general. But space is bigger than our minds can comprehend, there is a lot more we have not discovered yet. And not only about asteroids.
For instance, JAXA –the Japan Aerospace Exploration Agency– is planning to launch in 2015 an improved space probe. The mission of this space probe is to return approximately by 2020 with asteroid samples, specifically a Type C asteroid.
This mission and many others in the future will help us understand more about asteroids and all their extraordinary characteristics and mysteries that we have yet not found out about.