Written by Ana Luiza Bastos Barbosa Guimarães

Translated by João Miguel Matzenbacher



    Since the beginning of the humankind, the sky observations were results of studies and contemplation, either for identifying a star, a planet or even a general phenomenon. Evidently, the same happened with comets, asteroids, meteoroids, meteors and meteorites, but how to identify and, most importantly, differ the concepts from each other?

   Well, this column has as the objective to clear up some doubts that people, me included, could have while talking about these concepts. To make it more understandable and easier for the reader, it will be divided in small topics:


COMET: We can say that a comet is a big “ice ball” formed by the junction of many gases that roam through space. A comet is kind of a “residue” leftover in the formation process of the big gas planets Jupiter and Saturn, for example. They also could be provoked by the Oort Cloud.



ASTEROID: While comets are big ice balls, asteroids could be said as large “space rocks”. Asteroids are the universe raw material and this can be observed in the solar system throughout the formation of the rocky planets, as Earth and Mars. It has an irregular shape and in average has a diameter of 1 km, although, it could in some cases, reach hundreds of kilometers.

METEOROID: Meteoroids are small fragments of the big spatial rocks (comets or asteroids) which had detached from the principal object. The meteoroids have smaller dimensions than asteroids and bigger ones when compared with cosmic dust or, as it is also known, interstellar dust. To summarize the idea, meteoroids are small boulders that had detached from big rocks and now are drifting in the space.


METEOR: Meteors are all about the light effect generated by any object that immerse in the terrestrial atmosphere. Meteors are commonly known as “shooting stars” and the name “meteor” refers ONLY to the light effect, that is, the glow which streaks the sky.    

  

METEORITE: Meteorites are the spatial fragments which arrive to the terrestrial surface. Therefore, any spatial rock which passes through the atmosphere and reaches the Earth’s surface, like an asteroid or a meteoroid, is consider to be a meteorite.


  To summarize: an asteroid or a comet could lose some fragments named meteoroid, which continues drifting in the space. When this meteoroid reaches the atmosphere from Earth or from any other planet, it causes a light effect called meteor.