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Rants, Raves, Interesting Science & Awful Puns
January 20, 2000

Jupiter As A Planet Factory

Alternative Theory of Origins

An aspect of Velikovsky's Theories that caused no end of acrimony from the Establishment orthodoxy was the proposal that Venus was not only a young planet but originated by fission from Jupiter's core. I used the idea as the basis for Cradle of Saturn.

In 1969, the British astronomer W.H. McCrea published a paper in Nature, "Density of the Terrestrial Planets," Vol. 224, pp. 28-29, contending that the inner planets could never have formed in the way that the standard textbook accretion or tidal models describe, owing to the disruptive effect of Jupiter. This came after R.A. Lyttleton's Manís View of the Universe, 1961, which included a fluid dynamic analysis of Jupiter's core, showing that with its accretion rate and rotation speed it would periodically go unstable and shed excess mass. To my knowledge, neither of these hypotheses have been refuted.

Now, Rob Racansky has sent me the following from http://news.bbc.co.uk/hi/english/sci/tech/newsid_555000/555473.stm:

Wednesday, 8 December, 1999, 21:48 GMT
Jupiter gave birth to Uranus and Neptune

By BBC News Online Science Editor Dr David Whitehouse

New suggestions that the planets in our Solar System have not always been in their current orbits have been put forward by two teams of astronomers.

This work, along with recent speculation that Jupiter may have formed much further from the Sun than its current position, and the discovery of other planetary systems orbiting other stars, is forcing a reappraisal of our understanding of how the planets were formed.

Writing in the journal Nature, researchers from Queen's University in Kingston, Canada, propose that all of the giant planets in our Solar System formed in a narrow region of the gas and dust cloud that surrounded the early Sun. They suggest that they ended up in their present orbits as a result of violent and chaotic scattering.

This would mean that when Jupiter, our Solar System's largest planet, formed, it triggered the birth of other giant planets nearby. In a way, Jupiter was the "midwife" of the Solar System.

Rocky cores

The four major planets in our Solar System are classified into two "gas giants" (Jupiter and Saturn), that have a small rocky core surrounded by a large hydrogen and helium atmosphere and also two "ice giants" (Uranus and Neptune), that have icy mantles around their cores and only a thin atmosphere.

Scientists have always been slightly puzzled by the positions of Uranus and Neptune because in their present locations it would have taken longer than the age of the Solar System for them to form.

The scientists from Queen's University suggest that the four giant planets started out as rocky cores in the Jupiter-Saturn region, and that the cores of Uranus and Neptune were tossed out by Jupiter's and Saturn's gravity.

In the simulations, the ejected planets went into highly chaotic orbits for a few hundred thousand years after which they settled down and gradually migrated to their present, nearly circular orbits.

Stable orbits

Another group of scientists, also writing in Nature, from the University of Toronto, have simulated how planets such as Jupiter may have formed in the first place.

They found that gas and dust circling the early Sun that starts to accumulate to form a proto-Jupiter creates a spiral density pattern in the surrounding disk material. The proto-planet accretes mass rapidly through the spiral arms but when the planetary mass reaches four-to-five-times Jupiter's mass, the disk rapidly fragments into smaller proto-planets.

Over hundreds of thousands, or millions of years the proto-Uranus and proto-Neptune would be flung outwards by the now smaller proto-Jupiter's gravity.

Not too long ago, scientists regarded the orbits that the planets circle our Sun as being the ones they were born in. Now they are realizing that this is not the case. Uranus and Neptune may have migrated outwards and Jupiter may have come in from the outer cold.

One of the questions scientists would like to answer is whether the Earth has always been where it is now?

Another example of revolutionary ideas that Velikovsky proposed fifty years ago being quietly wheeled into the domain of "respectable" science through the back door. But any credit or recognition to one of the truly original thinkers of this century? Not a word of it.

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