Jacques Laskar of the Paris Observatory and a team of astronomers have been carrying out computer modelling of the future orbits of the solar system's planets. Under some scenarios cosmic collisions seem a remote possibility.
Planetary Paths not Stable
According to BBC News (June 10, 2009), “Astronomers had thought that the orbits of the planets were predictable. But 20 years ago, researchers showed that there were slight fluctuations in their paths.” Working with this knowledge, Professor Laskar and his team plotted the courses of the planets through more than 2,500 simulations.
What they discovered was that in a small number of cases, Mars and Venus collided with the Earth.
“It will be complete devastation,” Professor Laskar told the BBC.
“The planet is coming in at 10 km per second – 10 times the speed of a bullet – and of course Mars is much more massive than a bullet.”
Other Planets May Collide
In a letter published in the June 2009 issue of Nature, Laskar also says there is a possibility that Mercury and Venus might bump into each other. However, he says that such a crash would not greatly affect Earth.
“If there is anyone around billions of years from now, they’d see a burst of light in the sky and the two planets would be merged.
“The new planet would be a little bit bigger than Venus, and the solar system would be a little more regular after the collision, but the Earth’s orbit would not be affected.”
In addition, Professor Laskar and his colleagues suggest that the orbit of Mars might take it a little too close to Jupiter at some distant time in the future. If that happens, Jupiter’s massive gravitational force would likely hurl the red planet out of the solar system.
Worlds Have Collided in the Past
In September 2008, astronomers reported discovering a violent collision between two terrestrial planets some 300 light years away from Earth. The scientists at UCLA, Tennessee State University, and the California Institute of Technology were studying a binary star known as BD+20 307 in the constellation Aries. This star is surrounded by dust one million times more dense than that surrounding the Sun.
The finding was covered by the science news website EurekAlert.org (September 23, 2008). It quoted Benjamin Zuckerman, UCLA professor of physics and astronomy and one of the people involved in the discovery as saying, “Astronomers have never seen anything like this before. Apparently, major catastrophic collisions can take place in a fully mature planetary system.”
Another member of the team, Tennessee State University astronomer Gregory Henry, said, “The planetary collision in BD+20 307 was not observed directly but rather was inferred from the extraordinary quantity of dust particles that orbit the binary pair at about the same distance as Earth and Venus are from our sun.”
The fact that this is the first planetary collision to have been discovered testifies to the fact that such events are rare.
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