According to a new study, the 180km-wide Chicxulub crater in Mexico that led to the extinction of dinosaurs was created not by an asteroid but a comet.
Scientists have long established that the creation of the 180km-wide Chicxulub crater in Mexico fast-tracked the extinction of dinosaurs and wiped out approximately 70 percent of the earth's living organisms. Now, a new study has found that contrary to previous beliefs this crater was created by a smaller object. Many scientists have said that it was a slow moving asteroid that was likely the culprit. Now, this new finding has led scientists to conclude that it was a comet and not an asteroid.
"The overall aim of our project is to better characterise the impactor that produced the crater in the Yucatan peninsula [in Mexico]," Jason Moore, from Dartmouth College in New Hampshire, told BBC News.
The space rock that created that crater reportedly also gave rise to a global layer of sediments rich in the chemical element iridium, in concentrations much higher than naturally occurs.
Scientists also stated that for a small object like a comet to create such a big crater, it must have been moving relatively fast. After some research, scientists were able to find a long period comet that fitted the description better than other comets.
"You'd need an asteroid of about 5km diameter to contribute that much iridium and osmium. But an asteroid that size would not make a 200km-diameter crater," said Dr Moore. "So we said: how do we get something that has enough energy to generate that size of crater, but has much less rocky material? That brings us to comets."
Long period comets are known to be highly eccentric trajectories around the Sun. They are made of dust, ice and rock. They take thousands, sometimes even millions of years to complete a single orbit.
The enormous collision of the comet with the earth would have triggered fires, earthquakes and huge tsunamis, scientists say. The dust and gas thrown up into the atmosphere would have lowered global temperatures for several years.
