For thousands of years, humans were completely unaware of the existence of the solar system. They believed that Earth was the center of the universe.

We have since been proven very wrong. Scientists have discovered that the solar system was created when a supernova exploded and the resulting gas and dust combined around 4.6 billion years ago.

How exactly our planet was formed still remains a mystery.

What is the discovery, and why is it important?

Northwest Africa (NWA) 11119 is a small, baseball-sized rock. It's formed from sparkly green meteorite and has an unusual light green fusion crust. Broken fragments of the interior have revealed bright green and grey crystals that are up to 3mm in size. Scientists expect that it is approximately 4.6 billion years old, almost as old as the solar system itself.

The rock was acquired by a meteorite dealer in Mauritania, Africa, in 2016. It weighs 453g, and it is currently located at the Maine Mineral and Gem Museum.

For those who don't know much about meteorites, distinguishing between a terrestrial rock and an actual meteorite can be challenging. To make matters worse, there are many sellers who try to disguise terrestrial rocks as meteorites to scam their customers.

Many people are surprised that meteorites can actually be bought, sold, and collected outside of museums and labs. However, since the invention of the Internet, there has been a surge in the number of collectors and dealers.

eBay is actually one of the most popular websites for people to buy and sell meteorites. However, before using such websites, it is important that you take the required precautions and buy from reputable dealers. For example, websites like Meteorite Exchange has a page that summarizes the listings from known dealers in order to help buyers make more informed decisions.

To make the process of buying and selling meteorites safer, meteorite dealers are often hired to confirm that what the customer is buying is an actual meteorite (this means it came from space) and not just a rock.

At first glance, this meteorite didn't look like much

When the rock was first found, the planetary geologist and meteorite curator at the University of New Mexico, Carl Agee, didn't think that it was a meteorite at all. In fact, he thought it was a rock from Earth.

He then passed it on to his doctoral student, Poorna Srinivasan, to examine it.

Despite the rock bearing a close resemblance to volcanic rocks on Earth, its chemical composition revealed that it was definitely from space and that it wasn't just a regular meteorite.

What is special about the meteorite?

NWA 11119 was revealed to be 4.6 billion years old. This makes it the oldest igneous meteorite (meaning that it was formed by the cooling and solidification of either magma or lava) ever discovered. Scientists have discovered several non-igneous meteorites that are even older than this.

About 30% of the meteorite is comprised of tridymite, which are essentially large silica crystals. Such a high tridymite content is virtually unheard of in meteorites. It's comparable to the levels found in volcanic rocks on Earth.

How often do we come across things that are older than Earth?

It's easy to see why this discovery is so exciting. It's not very often that we come across things that are older than our planet—but there have been a couple of instances over the past few years.

In fact, analysis of NWA 11119 has revealed that it has a strong chemical resemblance to two other known unusual meteorites: NWA 7235 (discovered in 2011), and Almahata Sitta (discovered in 2008). The link is strong enough to suggest that all three of these space rocks could potentially have originated from the same parent body.

In November 2015, geologists working in outback South Australia recovered a primordial meteorite from Kati Thanda-Lake Eyre. This meteorite was thought to be a chondrite or stony meteorite and serves as an example of the material that was created when the solar system was being formed over 4.5 billion years ago.

What's more, as little as a couple of months ago, scientists discovered stardust particles on Earth that are even older than our solar system. Its chemical composition, which shows us how far the particles had traveled, suggested that the grains had to be significantly older than 4.6 billion years.

What happens next?

There is still so much we have yet to understand about how planets are formed, and in particular, how the Earth's crust might have been formed.

However, every once in a while, new discoveries like this one bring us a small step closer in piecing together what an earlier version of Earth might have looked like. Over the past few years, scientists have even discovered frozen meteorites in the Antarctic.

Hopefully one day we might be able to collect enough pieces of such evidence to come to a reasonable conclusion.