A giant star slammed into what is now Mexico’s outer ocean 66 million years ago, triggering a cataclysmic “impact winter” that eventually led to the extinction of three quarters of the Earth’s species, including dinosaurs.
Two Harvard astronomers say they have solved a long-standing mystery about the nature and origin of the Chicxulub impactor.
Harvard astronomers Siraj (Amir Siraj) and Loeb (Avi Loeb) published this week in the scientific journal “ScientificReports” (ScientificReports) analysis of the study shows that Mexico’s Chicxulub (Chicxulub) crater is the culprit is a comet from the icy debris region at the edge of the solar system, and the largest planet in the solar system Jupiter is also responsible for the comet’s impact on Earth. Comets of similar size hit the Earth at a frequency of 250 million to 750 million years.
Their paper disproves previous theories that the object was debris from an asteroid in the main asteroid belt of the solar system (Main Belt).
Amir Siraj, the study’s first author, told AFP, “Jupiter is very important because it is the largest planet in our solar system.” Jupiter plays a role somewhat similar to a pinball table, “kicking these incoming long-period comets into orbit and bringing them very close to the Sun.”
The so-called long-period comets come from the Oort cloud. Scientists speculate that the Oort cloud is a giant spherical shell that envelops the solar system like a bubble, made up of icy debris at least the size of a mountain.
Long-period comets take about 200 years to orbit the Sun and are also called sun-skimming comets because of their close proximity to the Sun during passage.
Because they come from the extreme freezing zone of the outer solar system, comets are colder than asteroids and have always been known for producing a surprising amount of gas and dust to form tails when they melt and evaporate.
However, Sira said the evaporative impact of solar heat on comets is far less than the massive tidal forces experienced by the side of the comet facing the sun.
“These comets experience such powerful tidal forces that they cause most of themselves to break up into about a thousand fragments, each of which is large enough to create a Shiksurub-class impactor.”
Another piece of evidence supporting this comet origin claim is that the composition of the Hixulub crater is a carbonaceous spheroidal meteorite, which only about 1/10 of the asteroids in the main asteroid belt between Jupiter and Mars possess, whereas most comets do.
Evidence suggests that the Hixulub crater and other similar craters such as the Vredefort crater in South Africa, which formed about 2 billion years ago, and the Zhamanshin crater, which was impacted in Kazakhstan a million years ago, have a carbonaceous spheroidal meteorite component.
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