Giant asteroid impact risk might be greater than previously thought.

 

(Mark Garlic/Science Photo Library/Getty Images)

Our world effectively conceals its wounds. Actually, it's a pity because information about earlier asteroid impacts could have aided in better planning for the upcoming catastrophic impact.

 

In reality, James Garvin, chief scientist at NASA's Goddard Space Flight Center, believes we may have been misreading signs of some of the more severe asteroid strikes that have happened in the last million years.

If he is correct, the likelihood of being affected negatively may be greater than current predictions.

 

It would be in the realm of serious crap occurring, as Garvin so eloquently stated during his presentation at the recent Lunar and Planetary Science Conference.

 

The dinosaur-killing smash that ruptured the crust off of what is now the Yucatan peninsula some 66 million years ago is the most well-known meteorite impact and sticks out for its destruction of life on Earth.

It was a behemoth about 10 kilometers (about 6 miles) wide, similar to those that struck our globe about 100 million years ago.

 

However, much smaller impacts can still stir up enough dust to cover the globe in gloom and possibly cause years of famine. According to some calculations, kilometre-sized asteroids hit the planet's surface about every 600,000 years on average, give or take.

Of course, there is no schedule for these types of events, and estimates are only ever as accurate as the information we use to make them.

 

The geological record is like a ticker-tape of real meteorite strikes going back in time, while we can search the skies for signs of rocks big enough to possibly hurt us terribly.

Because of the dynamic winds, water, and tectonic activity that continually wear away at the surface of the Earth, this record unfortunately becomes more difficult to read as we go further back. Even more recent events can be challenging to understand due to biological buildup and dust accumulation.

 

In order to better understand the weathered remnants of some of the largest impact craters created within the last million years, Garvin and his team used a new collection of high-resolution satellite images.

According to their analysis, several of these craters have faint rings that extend beyond what has usually been thought of as their outer rims, making them larger than previously thought.

 

For instance, a meteorite with a diameter of 200 to 400 meters that struck Earth about 90,000 years ago is believed to have created the roughly 12- to 14-kilometer-wide depression known as Zhaminshin in Kazakhstan. This impact may have been the most recent to have the potential to trigger a 'nuclear winter'-style event.

The new research indicates that this already significant event might have been even more disastrous, leaving a crater that is more like 30 kilometers across.

 

Three additional big craters' rim diameters have also been revised, and they have all doubled or tripled in size. The consequences are significant because they imply that kilometers-sized objects fall from the sky roughly every ten thousand years.

Even though it's beneficial to occasionally shake things up a bit, these recently found rings might not actually be the result of the impact.

 

It's conceivable that they are pieces of the strike's debris that were ejected and then rain down again in a precise pattern. Or they might not even be there at all—just a phantasm in the data.

Garvin is doubtful that debris fields would remain clean after so much erosive weathering and deterioration. Nevertheless, science does not advance as a result of a solitary observation.

 

It's a theory that merits discussion. The likelihood is good that Earth's path will remain clear for some time to come even as we work to put systems in place to try to avoid the pain of a major asteroid collision.

 

Our world doesn't need any more scars to cover up, that much is certain.

Reference: sciencealert.com