Comet rain theory on dinosaurs

Press, 7 February 1985, Page 13

Comet rain theory on dinosaurs

NZPA-AP Tucson, Arizona

A mysterious planet X that periodically pulls swarms of comets into a collision course with Earth may have been responsible for the extinction of the dinosaurs, says a new theory. According to the theory, some of the comets strike Earth, creating vast dust clouds that can change the weather enough to cause death for some species of animals and plants. Mr Daniel Whitmire, one of the scientists who described the new theory at a symposium on the galaxy and the solar system sponsored by the University of Arizona, said that planet X would circle the sun in a shifting orbit outside the nine known planets of the solar system. Every thirty million years the orbital shifts would carry the planet into a belt of comets. The planet’s gravity would then pull some of these comets into the collision course with Earth.

The theory by Mr Whitmire and his co-author, Mr John Matese, both of the University of South-west-tern Louisiana, is an attempt to explain two phenomena — a pattern of fossils that suggests mass extinctions may have occurred on Earth approximately every

26 million years, and unexplained slight variations in the orbits of Neptune and Uranus, the seventh and eighth outermost planets of the solar system. The effect of planet X’s gravity on the two planets could explain the orbital variations, the scientists said.

Dinosaurs disappeared 65 million years ago, and extinction peaks also occurred 34 million years ago and, to a. lesser extent, 11 million years ago. Other theories have been put forward to explain the apparent extinction peaks. Some researchers theorise that giant interstellar dust clouds are responsible, and others suggest that Nemesis, a “death star” rather than a planet, causes comets to rain down on Earth.

In the publication of their theory in the British scientific journal “Nature,” Messrs Whitmire and Matest suggested how astronomers might find planet X. Mr Matese said it was likely that the planet, if it existed, would be discovered in five or 10 years. If Nemesis exists, it too was likely to be found in the next decade, he said.

“If neither is found, that may be evidence that there is no periodicity in prehistoric extinctions ne saiu.