Scientists find link between comet and asteroid showers and mass extinctions

Credit: NASA

Mass extinctions occurring over the past 260 million years were likely caused by comet and asteroid showers, scientists conclude in a new study published in Monthly Notices of the Royal Astronomical Society.

For more than 30 years, scientists have argued about a controversial hypothesis relating to periodic mass extinctions and —caused by comet and asteroid showers—on Earth.

In their MNRAS paper, Michael Rampino, a New York University geologist, and Ken Caldeira, a scientist in the Carnegie Institution's Department of Global Ecology, offer new support linking the age of these craters with recurring mass extinctions of life, including the demise of dinosaurs. Specifically, they show a cyclical pattern over the studied period, with both impact craters and extinction events taking place every 26 million years.

This cycle has been linked to periodic motion of the sun and planets through the dense mid-plane of our galaxy. Scientists have theorized that gravitational perturbations of the distant Oort comet cloud that surrounds the sun lead to periodic comet showers in the inner solar system, where some comets strike the Earth.

To test their hypothesis, Rampino and Caldeira performed time-series analyses of impacts and extinctions using newly available data offering more accurate age estimates.

"The correlation between the formation of these impacts and extinction events over the past 260 million years is striking and suggests a cause-and-effect relationship," says Rampino.

Specifically, he and Caldeira found that six mass extinctions of life during the studied period correlate with times of enhanced impact cratering on Earth. One of the craters considered in the study is the large (180 km diameter) Chicxulub impact structure in the Yucatan, which dates at about 65 million years ago—the time of a great mass extinction that included the dinosaurs.

Moreover, they add, five out of the six largest impact craters of the last 260 million years on earth correlate with mass .

"This cosmic cycle of death and destruction has without a doubt affected the history of life on our planet," Rampino observes.

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Oct 20, 2015
Specifically, they show a cyclical pattern over the studied period, with both impact craters and extinction events taking place every 26 million years.

26*2 = 52

65-52 = 13my(when the last one should have happened)


78-65= 13my

Yup, we have quite a while to prepare, it would seem.

So if you are right, the Solar System gets bombarded by de-orbited comets every 26 million years.

Short article doesn't talk about other science, such as the chemistry and isotopic ratios of the shocked layers under said craters, though admittedly most of these are heavily eroded by now. Idea would be to determine whether each impactor originated in the SS or whether it was an inter-stellar/rogue object.

The Dark Side of the moon is heavily cratered, and no doubt would have been hit by some of these periodic objects, though being smaller than the Earth it could be missed more often.

Perhaps future colonists will be able to find 26my patterns there too.

Oct 20, 2015
Yup, it's good to have a large moon.

Every would-be planet-killer that hits the moon is one less that hits the Earth, though something the size of Chicxulub hitting the Moon would likely eject many small and medium moon rocks into space, where they would eventually hit Earth, Mars, or some other body.

Date the craters on the "Dark" side of the Moon, Date the Craters on Mars, if you see consistent 26My patterns you'll have a good theory.

Now you need more rovers and especially manned missions to both bodies to do that.

But quite honestly I'd worry about something like that as a secondary or tertiary mission, because even if it is true you'd have 13my to prepare, which is incomprehensible in our day to day terms. We might adapt technology far beyond our present understanding or conjecture long before the next threat even remotely happens.

the absence of an impact on a 26my mark could just mean the comet(s) missed that time...

Oct 20, 2015

If you could verify this pattern via studying the Moon and Mars, then it could be used to date the surfaces of the more active, volcanic and cryovolcanic moons of the other planets in the solar system, because you would have a standard metric to prove how fast they resurface themselves.

Pluto seems to resurface itself pretty quickly considering how little energy is available to it.

mars is a good time capsule, because it's apparently been dead for most of it's history, but not as good as the moon.

I guess humans will have plenty of time to do full geologic surveys of both bodies many times over before 13my comes.

Smoking gun would be dating impacts on Mars and the Moon to the exact same 26my cycle as an Earth impact, and preferably more than one cycle.

Oct 20, 2015
It would take roughly one billion years for our fastest spacecraft to cross the galaxy, if you ignored the fact that it would likely get trapped and sucked into the SMBH at the pathetic speed it is currently moving.

Even if it doesn't collide with something macroscopic, I suspect it would be destroyed/corroded by ablation from EM radiation and particle radiation over such a long time scale....but who knows, if it passes through a nebula, maybe it could serve as the "seed" for a new planetesmal or star to form as it collects mass and slows down...

Just a weird thought.

Could mankind create a planet or star?

The answer is yes.

Disturb a delicate balance...give it a little...push...

Just send a space probe into a nebula at just the right speed. Preferably you want something with a high surface area to attract ice-dust to accumulate mass more quickly. The added mass will trigger a collapse more quickly and in a different location than the natural outcome.

Oct 21, 2015
Could mankind create a planet or star? The answer is yes?

Are you making this up?

Oct 21, 2015
As one tend to ask in front of crackpots, this again!? Rampino & Caldeira has, together with Raup et al, pushed this hypothesis for over 20 years. [ http://articles.a...000.html ] Every time I check they use weak or erroneous statsitical methods, and the description of time series like 23 years ago make me think this is another such paper.

It is starting to become dated, but personally I take Alroy's 2008 paper as definitive. By using autocorrelation - which is what immediately comes to mind as the most powerful technique here - and a then updated fossil record he could show that there was no periodicity. [ http://www.pnas.o...full.pdf ]

As one would expect, because the 26 Myrs period that R&C and others look for is the passage time in the galactic disk - and, surpise, surpise - they always 'find' whate they want.


Oct 21, 2015
Errata: surprise, surprise. On my first coffee for today, grumpy and fumble fingered.

No one has ever tied that passage to increased cratering, or even pointed to a likely mechanism.

Not that any of that bothers crackpots. :-/

@IHQ: If you haven't read him (less likely a her due to the correlation to crankiness), Returners is a crackpot on the scale of Rampino & Caldeira. Don't mind him - no one else does - and you know what they say about encouraging cranks and trolls. =D

Oct 23, 2015
Perhaps the cycle is a little shorter.

(14) HEADING TOWARDS THE NEXT ICE AGE? - 16 November 2001
The cycle of sunlight intensity roughly follows a 1,500-year pattern, based on analysis of the past 12,000 years. The 1,500-year cycle of warming and cooling corresponds to data from tree ring studies, another way of measuring the sun's strength over time. He said the findings also agree with studies that measured the chilling of the Earth based on the advance and retreat of alpine glaciers in Europe.

Oct 23, 2015

Others have observed this 1,500 year interval also.

There would be no way to turn a cluster of fragments such as that aside. And we are beginning to realize that there is nothing to indicate impact storms like that are rare. The one the hit the Southwest a few thousand years ago may have been the worst in 65 million years. But smaller ones that devastated tens of thousands of square miles on land, or generated giant impact Tsunamis, when they hit an ocean, seem to have been happening about 1,500 years apart for the past 20 or 30 thousand years. They come out of the Taurid meteor stream.

Oct 23, 2015
That 1,500 year number really is more like 1,656 years:

Vulcan draws in Kuiper belt objects that fragment into meteor or comet swarms if they pass near the Sun. Figure 7 shows how these Vulcan related swarms move about the Sun. These swarms are labeled A' & A and B' & B respectively. Their periods (~3313 years) are about are two thirds that of Vulcan's, but vary slightly due to Vulcan's distant presence. The 3:2 resonate orbit means that the comets orbit the Sun three times every time Vulcan orbits it twice.

The A and B swarms seem to be the big ones and are 180 degrees out of phase with one another.

Oct 26, 2015
Uh, Y, you neglect the *recent* IR and other surveys which falsify your hypothesis. Adios.

Oct 26, 2015
Absence of evidence is not evidence of absence.

But our astronomers are so good they would not miss any celestial object in our solar system, except Pluto, that Russian bolide, etc.

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