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The Origin of the Architecture of the Solar System
Published online by Cambridge University Press: 30 March 2012
Abstract
This article relates two topics of central importance in modern astronomy – the discovery some 15 years ago of the first planets around other stars (referred to as exoplanets), and the centuries-old problem of understanding the origin of our own solar system, with its planets, planetary satellites, asteroids, and comets. The surprising diversity of exoplanets, of which more than 500 have already been discovered, has required new models to explain their formation and evolution. In turn, these models explain, rather naturally, a number of important features of our own solar system, amongst them the masses and orbits of the ‘terrestrial’ and ‘gas giant’ planets, the presence and distribution of asteroids and comets, the origin and impact cratering of the Moon, and the existence of water on Earth.
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- Focus: Knowledge Management in Contemporary Europe
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- Copyright © Academia Europaea 2012
References
References and Notes
1. Further details of all of the topics covered in this article, and comprehensive references to the work cited, can be found in Perryman, M. (2011) The Exoplanet Handbook (Cambridge, UK: Cambridge University Press). An online compilation of the current status of exoplanet discoveries, The Extrasolar Planets Encyclopedia, is given at http://exoplanet.eu.CrossRefGoogle Scholar
2. Jupiter is the most massive of the solar system planets, some 300 times the mass of the Earth. It orbits the Sun, at a distance just over five times that of Earth, in about 12 years. The other ‘gas giant’ planets (Saturn, Uranus, and Neptune) range between 15–35 Earth masses, with Neptune orbiting the Sun at some 30 times the distance of the Earth in about 160 years. The other ‘terrestrial’ planets (Mercury, Venus, and Mars) are all less massive than Earth, with Mercury being the lightest (at one sixteenth that of Earth) and orbiting closest to the Sun in just 88 days.Google Scholar
3.As seen from Earth, Mercury transits the face of our Sun 13 or 14 times per century, the last time in 2006, and the next on 9 May 2016. Transits of Venus are rarer, with pairs eight years apart separated by intervals of more than 100 years; the last occurred on 8 June 2004, the next will occur on 6 June 2012, but thereafter only in December 2117. These somewhat complex transit event patterns result from the fact that we are viewing one transiting planet from another orbiting planet.Google Scholar
4.J.H. Jeans (1917) Monthly Notices of the Royal Astronomical Society, 77, pp. 186–199.Google Scholar
5.H. Jeffreys (1929) Monthly Notices of the Royal Astronomical Society, 89, pp. 731–739.Google Scholar
6.The nearest stars to the Sun are at a distance of around 3–4 light years, meaning that light, travelling at its extravagant 300,000 kilometres per second, would take 3–4 years to travel from them to us. Stars with planets around them are typically being found at distances of 50–100 light years, although the closest exoplanet system discovered to date lies at just 10 light years. If intelligent life existed there, the round-trip communication time to this system, using light or radio waves, would take some 20 years.Google Scholar