The initial concept

The fundamental and perhaps the most obvious fact about the solar system is that the planets and satellites mostly lie close to the plane of the ecliptic (the Sun–Earth plane) and, with minor and informative exceptions, rotate in the same sense, both around the Sun and about their axes of rotation. Their orbits, although elliptical, have very low eccentricities. In the 18th century, scientists were unaware of the retrograde rotation of Venus and of other irregularities: what they saw appeared to be as well ordered as a clock. This fortunate lack of too much information enabled the French astronomer and mathematician, Pierre-Simon, marquis de Laplace, to propose in 1796 that the solar system originated from a rotating disk of dust and gas [1]. He called this disk the solar nebula. In his model, the planets condensed successively from rings as the nebula contracted. This elegant concept survived in its original form until late in the 19th century. The crucial and ultimately fatal flaw of the original laplacian theory was the failure to account for the concentration of (i) angular momentum in the planets and of (ii) mass in the Sun [2].

The view that the Sun and the planets formed from a rotating disk of gas and dust, the solar nebula, provides such an obvious explanation that it has become axiomatic. Nevertheless, it is wise to question established viewpoints.