Alimae/Bingley's second link shows Sedna's orbit graphed as an elipse. Anyone know anything about eliptical orbits? Are they the products of acceleration and deceleration and, if so, what causes the latter? -- Is it the same gravitational force that causes acceleration? Does this mean that such orbits are 'flattening' over time, or that the objects following them are, very slowly, falling into the sun?