(ORDO NEWS) — Our planet hides scars well. This is actually a shame, as evidence from previous asteroid impacts could help us better plan for the next catastrophic impact.
In fact, James Garvin, Chief Scientist at NASA‘s Goddard Space Flight Center, believes we may have misunderstood the footprints of some of the most serious asteroid impacts to have occurred in the last million years.
If he’s right, the chance of hitting something dangerous could be higher than current estimates predict.
As Garvin so eloquently put it during his keynote at a recent conference on lunar and planetary sciences, “That would be on the verge of serious crap.”
The most famous of all meteorite impacts is the dinosaur. the deadly blow that tore a hole in the crust of what is today the Yucatan Peninsula about 66 million years ago stands out for its devastation of life on Earth.
It was a 10-kilometer (about 6-mile) giant-sized that hit our planet roughly 100 million years ago or so.
However, the much smaller pacts can still shake up enough dust to cast a shadow over the planet and potentially lead to years of starvation.
By some estimates, kilometer-wide asteroids hit the Earth’s surface in an explosion of heat and dust every 600,000 years, give or take, on average.
Of course, there is no timetable for such events, and estimates are only as good as the data we use to make our predictions.
While we can scan the skies for evidence of rocks large enough to potentially hurt us, the geological record is like a running belt of actual meteorite impacts stretching back into the past.
Unfortunately, this record becomes more and more difficult to read the further we look into the past, all because of the dynamic winds, water and tectonics of the Earth, constantly wearing down its surface. Even later events can be difficult to interpret due to dust accumulation and biology.
Garvin and his team used a new catalog of high-resolution satellite images to take a closer look at the weathered remains of some of the largest impact craters formed in the past million years to better estimate their true size.
Based on their analysis, some of these craters have faint rings outside of what is generally thought to be their outer edges. , which actually makes them larger than previously thought.
For example, a trough approximately 12 to 14 kilometers wide called the Zhaminshin in Kazakhstan is believed to have been created by a meteorite 200 to 400 meters in diameter that hit Earth about 90,000 years ago – the most recent impact could have triggered a “nuclear winter” style event.
However, based on the new analysis, this already large event could have been even more catastrophic, leaving a crater that is actually closer to 30 kilometers across.
The rim diameters of three other large craters have also been recalculated, all doubled or tripled. The conclusions are great: every few tens of thousands of years, kilometer-sized objects fall from the sky.
While it’s good to shake old models from time to time, these newly opened rings don’t necessarily ripple on impact.
Possibly, it could be debris ejected from the impact, which falls back in concentrated rain. Or maybe they don’t represent anything significant at all – just a phantom in the data.
Garvin isn’t sure the debris fields will remain clean after so many years of weathering and erosion. However, science does not move based on a single observation.
This hypothesis is worthy of discussion. While we’re busy building systems to try and avoid a major asteroid impact, chances are good that Earth’s path will be clear for a while.
One thing our planet doesn’t know is to hide the scars.
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