American researchers have a new theory about how an object hit Earth and caused the dinosaurs to die.
Most scientists agree where impact it happened about 65 million years ago. They say a huge object struck an area off the coast of what is now Mexico. Astronomers have said that the most likely cause of the attack was a asteroid or a Kite.
In recent years, researchers have presented evidence that the impact was caused by an asteroid. The theory suggests that the asteroid came from an area between the orbits of Mars and Jupiter.
But a study by two Harvard University astronomers comes up with a new theory: that the collision was caused by a comet. Researchers say the comet came from an area containing ice debris on the edge of the solar system. The area is known as the Oort cloud.
His theory states that the comet was pulled into the solar system by Jupiter’s gravity. Then the comet came very close to the sun, whose tidal force made it break into pieces. The researchers believe that one of the pieces crashed into the place that scientists have identified in Mexico.
The team based their theory on a model created to predict the probability that a long-period comet from the Oort cloud would hit Earth. Long-period comets take more than 200 years to orbit the Sun.
Because comets come from icy areas of the outer solar system, they are colder than asteroids. They are known to leave long trails of gas and dust as they melt.
The new study was recently published in Scientific reports. The lead author was Amir Siraj, an astrophysics student at Harvard. “Jupiter is so important because it is the most massive planet in our solar system,” he told the French news agency AFP.
Siraj said the findings showed that Jupiter’s strong influence pushes “these long-period incoming comets into orbits that bring them very close to the sun.” Comets experience such a great tidal force from the sun “that the most massive of them break in a thousand fragments, “he said. Each of those fragments would be large enough to produce a crater the size of the Mexican site, he added.
That massive impact is estimated to be equal to the force of some 10 billion nuclear bombs. The US space agency NASA has estimated that the impact created a huge crater about 180 kilometers wide and 900 meters deep.
The event is believed to have caused wildfires, earthquakes and ocean waves. It also released chemicals into the atmosphere, causing intense cooling. Scientists blame the event for destroying more than 70 percent of plant and animal life. Also, all dinosaurs that weren’t birds went extinct.
The researchers say their theory can be tested by further studying the crater in Mexico, as well as possibly those on the moon. Furthermore, space explorers could also be dispatched to collect comet material for examination.
The study also suggests that similar impacts can be expected to hit Earth roughly once every 250 to 730 million years. But the other principal investigator on the project, Harvard professor Avi Loeb, noted that that’s just an estimate.
“You never know when the next one will come,” he said. “The best way to find out is to search the sky.”
I am Bryan Lynn.
Bryan Lynn wrote this story for Learning English, based on reports from Agence France-Presse and The Harvard Gazette. Mario Ritter, Jr. was the editor.
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Words in this story
impact – North. an act or event in which something hits something else
asteroid – North. a space rock, which can be small or the size of a large moon, orbiting the sun
Kite – North. an object from outer space that is made of material such as gas and ice that remains in its orbit when it approaches the sun
debris – North. pieces left after something falls apart
tidal force – North. a secondary force of gravity involving two objects
break – v. suddenly break into many pieces
fragment – North. a broken piece of something that was once greater
crater – North. a round hole made by an explosive force such as a bomb or an object falling from the sky