Theories of exoplanet formation and migration can be confronted with a wealth of diverse observational constraints from the solar system, of which this chapter provides an incomplete and selective summary.
Amongst them are the orbital motions of the planets (including spacings, eccentricities and inclinations, dynamical stability and resonances), planetary masses and rotation (and their angular momentum distribution), the existence of planetary satellites and rings, the occurrence of other minor bodies (comets, asteroids and meteorites, including the presence of the Oort Cloud and the Edgeworth–Kuiper belt), bulk and isotopic compositions, radiogenic isotope ages, and cratering records.
The publications listed in Table 12.1 provide more detailed perspectives, with a recent synthesis given by de Pater & Lissauer (2010). Early theories of the formation of the solar system are summarised in §10.4.1.
Birth in clusters
Most stars are born in molecular clouds as members of stellar clusters although, rarely, some stars might be born in isolation (Lada & Lada, 2003). Whether the Sun was formed in isolation or in a cluster remains uncertain (Adams, 2010). Evidence for the latter includes the dynamical structure of the Edgeworth–Kuiper belt which suggests a nearby encounter with another star (Morbidelli & Levison, 2004), and short-lived radionuclides and their decay products in the proto-solar nebula (Hester et al., 2004; Hester & Desch, 2005; Gounelle & Meibom, 2008), explicable in terms of a supernova explosion within 1–2 pc of the young Sun (Looney et al., 2006).