The Oldest Known Asteroid Strike On Earth Is Australian.

We were just a little bit chuffed to hear that the asteroid strike outside of Meekatharra is the oldest known to us, dating back around 2.2 billion years ago.

Officially named the Yarrabubba Crater found on Tjupany traditional land, it was first discovered in 2003.

Now we know the Yarrabubba predates the former oldest crater Vredefort Dome in South Africa by a cool 200 million years.

Yarrabubba impact crater shown from above

But that's not the only thing that's cool.

Data collection dictates that no new glacial deposits were found for 400 million years after the Yarradubba strike.

Meaning...

The Yarrabubba Asteroid may have ended the ice age

Our asteroid may have ended the ice age!

Scientists now aim to unravel the mystery surrounding the Yarrabubba strike and its role in thawing Earth at the end of a time affectionately known as "Snowball Earth".

At the time of impact, the Yarrabubba site had been covered by a glacial upwards of 5km thick, which would have been instantaneously vapourised and sent into the atmosphere. 

A cross section of the Yarrabubba impact crater

In theory, an asteroid strike as significant as that found in Meekatharra could have evaporated enough water, a known greenhouse gas, to effectively warm the planet.

While not solely responsible for warming the entire Earth from a complete ice age, scientists believe that the Yarrabubba strike was the "straw which broke the camels back" and started the great thaw. 

"But how do we know that?"... we hear you say.

Good question!

The Yarrabubba impact crater shown today

Firstly, the crater is dated by the crystals housed within the site of impact.

These crystals are formed when an object hits the Earth's surface with extreme pressure and heat.

This creates specific crystals like zircon and monazite which then go under a spectrometer to determine the ratio of uranium to iron.

After enough time, uranium turns into lead therefore the levels of iron are the evidence needed to date the crater. 

A close up of a Yarrabubba zircon crystal.

The above zircon crystal shows the original structure in blue and the snap heated pink outer layer when the asteroid struck.

 The dating therein puts Yarradubba smack bang in position when the Earth started thawing almost overnight.

Something big had to have happened at exactly the time the Yarrabubba happened and thrown enough water vapour into the atmosphere (about 5km deep worth) and the dating of the Yarrabubba crystals puts 2 and 2 together.

We're very proud to be home of the oldest known asteroid strike on Earth!
#Space_Aus