‘An exoplanet, or extrasolar planet, is a planet outside the Solar System’ – Wikipedia.
At least 175 multiple planetary systems have been found as of 25 November 2013. Stuart Graham investigates.
Exoplanets are a mixed bunch. Some are 10 times the size of Jupiter, others seem more like moons and may orbit their star in less than 2 days. Here we’ll look first at a small planetary body in the solar system, see how it relates to its neighbours, and then see what similarities and/or differences can be found in a few selected exoplanet systems. There may even be a few surprises.
Less well-known than Pluto is its supposed twin Orcus, or 90482 Orcus to give its full name. It’s a trans-Neptunian object or maybe a dwarf planet. As it even has its own moon Vanth, it has the reputation of being the ‘anti-Pluto’. Its orbit looks like a mirror image of Pluto’s orbit (red: Pluto, blue: Orcus, grey: Neptune).
— Symmetric orbits of Orcus and Pluto – image credit Wikipedia —
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