Meteorite – Definition, Classification and Components.

Sep 9, 2022 | Turito Team USA

You look into the clear night sky, where the stars glitter. Suddenly, light flashes across the sky before disappearing. You remark, “Wow, a shooting star.” The meteor. Or perhaps, is that a meteorite? Meteoroid?

Well, it is a meteor. A meteor is the flash of light you observe in the sky when a tiny fragment of comet or asteroid debris hits the atmosphere quickly and burns up due to frictional heating from the piece’s impact on the molecules and atoms in the atmosphere. A meteoroid is a small fragment of asteroid or comet debris drifting across the outer solar system before entering the earth’s atmosphere.

In most cases, meteoroids that reach the Earth’s atmosphere evaporate immediately. However, occasionally a meteoroid does not burn up and reaches the earth’s surface. A meteorite is a piece of a meteoroid that has sustained its explosive journey.

This article will detail the distinctions between meteors, meteorites, and other types of meteorites based on their structural composition.

Distinction Between Meteor and Meteorite

Meteors

A meteor is formed when a meteoroid comes into contact with the planet’s atmosphere and evaporates.

The light is produced from an asteroid or meteoroid as it reaches the earth’s atmosphere and fades away. The meteoroid will move through space unaltered, but when it enters the Earth’s atmosphere, it experiences extreme friction and starts to evaporate. They often have a millimetre or smaller size.

A grain-sized meteoroid will produce a meteor tail that is roughly a metre broad but may extend for many kilometres due to the tremendous speed of the falling debris. A meteorite travels quickly through the atmosphere as it strikes the ground, giving it the appearance of a fireball.

Meteors can be classified into various categories based on their dimensions and brightness. 

  • Bolides
  • Fireballs
  • Earth grazers

The meteors that appear closest to the earth’s horizon and have the longest and multicoloured tails are known as earth grazers.

Fireballs are the most commonly seen type of meteor. These are brighter and last longer than earth grazers. 

Bolides are larger than fireballs, and most of the time, they explode in the atmosphere. They cause a sonic boom that we can hear and feel on the earth.

Meteorite

A meteorite is a tiny fragment of rock or metal that entered outer space and retained itself while travelling through the earth’s atmosphere as a meteor before hitting the planet’s ground.

A meteorite is a tiny asteroid that can be between a few millimetres and a metre in size. Meteoroids travel between 11 and 72 kilometres per second as they approach the earth’s atmosphere. Typically, meteorites are quite tiny. However, they can be as large as 100 kilos or a fraction of a gram (220 lbs). We categorise meteorites that are smaller than 2 mm as micrometeorites.

We divide meteorites into three major groups based on their structure, molecular isotopic content, and mineralogy. 

  • Stony Meteorite
  • Stony Iron Meteorite
  • Iron Meteorite

Rocks formed of silicate minerals are referred to as stony meteorites, while metallic iron-nickel makes up the majority of iron meteorites and the majority of stony-iron meteorites.

Meteorites were also discovered on Mars and the moon. Scientists believe the meteorites on earth originated from the moon, Mars, the asteroid 4 Vesta, and the comet Wild 2.

Types of Meteorites: Detailed Explanation

Although there are many subclasses, the meteorites can be grouped into the following three categories—Iron meteorite, stone meteorite, and Stony-iron meteorite. In reality, a significant portion of meteorite categorisation is predicated on how much iron a rock contains.

Iron Meteorite

An iron meteorite is thought to have originated in the asteroid belt between Mars and Jupiter and was once a core element of a long-extinct planet or giant asteroid. They are some of the densest substances on the earth and will attract powerful magnets quite firmly. 

Interesting Facts:

An iron meteorite is significantly heavier than the rocks on the earth- If you’ve ever lifted a hand grenade or a slab of high-strength steel, you’ll have a sense.

In the majority of the samples from this group, nickel and trace metals make up the remaining 90 to 95 per cent of the iron content. An iron meteorite can be classified into various sub-classes based on their physical and chemical compositions. The structural classifications are done by examining the two iron-nickel alloys: kamacite and taenite.

Following the description of the occurrence in the 19th century by Count Alois von Beckh Widmanstätten, these alloys developed into a unique interconnecting crystalline pattern called the Widmanstätten Pattern.

An iron meteorite is typically only visible after it is cut into blocks, smoothed, and washed with a diluted solution of nitric acid. This unique lattice-like arrangement can be quite stunning. The kamacite crystals released during this technique are measured, and the average band range is utilised to categorise iron meteorites into several structural groups. A “fine octahedrite” is an iron that has very small bands (less than 1 mm), whereas a “coarse octahedrite” has large bands.

Stone Meteorite

The stones, which comprise most meteorites, were formerly a component of a planet or asteroid’s outer crust. Most stone meteorites, especially those on the earth’s surface for a long time, commonly resemble terrestrial rocks. It can be challenging to identify meteorites while searching on the field. 

The newly fallen stones will feature a black fusion crust that was generated as the surface ignited while landing, and most of these stones have adequate iron to hold to a strong magnet readily. The stone meteorites can be further classified into the following two categories: Chondrites and Achondrites.

“Chondrules” refers to the tiny, vivid, grain-like inclusions in some stone meteorites. The oldest known material currently available to us for research, these tiny grains are thought to have originated in the solar nebula and therefore predate the creation of our planet and the entire universe. “Chondrites” are the term coined for stone meteorites that contain these chondrules.

Achondrites are space rocks that do not include chondrites. These volcanic rocks from outer space developed as a result of igneous activity inside their parent bodies, where recrystallisation and melting eliminate all traces of ancient chondrules. Achondrites are significantly harder to discover than most other meteorites because they contain little to no extraterrestrial iron. Yet, specimens frequently show an amazing glossy fusion crust resembling enamel paint.

Stony Iron Meteorite

Less than 2% of all known meteorites are stony irons, the least common of the three major kinds. A stony iron meteorite can be classified into two categories: pallasites and mesosiderites. The stony-iron meteorites are believed to have developed at the core/mantle gap of the parent bodies.

Pallasite meteorite is the most appealing form of a meteorite. And therefore, private collectors are undoubtedly very interested in them. The pallasite meteorite is composed of an olivine crystal-filled nickel-iron matrix. When olivine crystals are sufficiently pure and exhibit an emerald-green hue, they are referred to as peridot gemstones. The German biologist and explorer Peter Pallas gave the Russian meteorite Krasnojarsk, discovered in the vicinity of the same-named Siberian metropolis in the 18th century, the name Pallasite meteorite. The pallasites’ crystals turn translucent when delicately polished and carved into slabs, giving them extraordinary unearthly beauty.

Mesosiderites are the second form of stony-iron groupings. They include nickel-iron and silicates, and when cut and polished, they typically exhibit a beautiful, high-contrast black and silver matrix. The seemingly arbitrary arrangement of inclusions results in some extremely stunning characteristics. The words “mesosiderite” and “iron” originate from the Greek words for “half” and “iron,” respectively. Less than a hundred of the thousands of meteorites formally catalogued are mesosiderites.

Lunar Meteorite

Lunar meteorites are achondrites from the Moon or the neighbouring planet Mars. Approximately 0.2 per cent of lunar meteorites come from Mars and the Moon. These achondrites are the consequence of meteorite collisions on Mars and the Moon. Large meteorites struck the surface of Mars and the moon, blowing off small fragments of rock. A lunar meteorite rock fragment rarely enters the earth’s atmosphere as meteors and hardly do these rock fragments strike the earth’s surface.

Conclusion

So, we can conclude that a meteorite is a piece of space matter that crashes to a planet’s surface. The Asteroid Belt is the major source of most meteorites that hit the earth. At the same time, the fireballs or “shooting stars” are dubbed meteors when the meteoroids approach earth’s atmosphere (or that of another planet, like Mars) at a great velocity and burn up.

Frequently Asked Questions

1. What is the connection between a meteor, a meteorite, and a meteoroid?

Ans. Space rocks called meteorites are those that hit the earth’s land. Meteorites are the final stage of the evolution of these kinds of space rocks. These space rocks were meteors before they became meteorites. Before they became meteors, they were meteoroids. Rock or metal chunks called meteoroids circle the sun. When meteoroids collide with the earth’s atmosphere, they turn into meteors, and the gases around them briefly flare up as “shooting stars.” Many of these space rocks hit the earth’s surface as meteorites, but most meteors burn up and evaporate in the atmosphere.

2. What do stony meteorites consist of?

Ans. Minerals that contain silicates—a substance consisting of silicon and oxygen—make up stony meteorites. They also contain two metals, iron and nickel. Chondrites and achondrites are the two main categories of stony meteorites.

3. Which type of meteorite is the rarest?

Ans. The rarest sort of meteorite is called a stony-iron meteorite, which has almost equal proportions of iron and stone.


Book a free demo

Grade*

+91

By proceeding to create an account you are agreeing to our Terms of conditions and Privacy Policy