The solar system consists of eight planets,Each moves around the Sun in its own orbit. The orbits of these planets have a shape approximating to an even circle, and are located almost on one plane, called the ecliptic.
In fact, these orbits are elliptical: they are slightly flattened from one side and stretched from the others.
Orbits of smaller inner planets
Mercury, Venus, Earth and Mars are part of the groupSo-called smaller inner planets or planets of the terrestrial group: they are small, solid, composed of metal silicates and are closest to the Sun. Mercury has one of the most elongated orbits, least like the shape of a circle. Its eccentricity, the numerical expression for the deviation from the circumference, is 0.205. The orbit of Mercury is located almost 58 million kilometers from the Sun. On the plane of the ecliptic, it also lies unevenly, at an angle of 7 degrees.
The planet moves in orbit at a speed of 48 kilometers per second, making a revolution around the sun in 88 days.
The orbit of Venus is very close in shape to the circle, inThe difference from Mercury (eccentricity is 0.0068). The slope to the plane of the ecliptic is also very small: about 3.4 degrees. The planet turns with a speed of 35 kilometers per second, making a full turn for 225 days.
The Earth's orbit is elliptical, its length is more than 930 million kilometers. The speed of the planet's motion along the orbit is not constant: it is minimal in July and maximum in February.
Mars is 55 million kilometers from EarthAnd 400 million kilometers from the Sun. Its orbit has the shape of a very pronounced ellipse, but not as elongated as in Mercury, with an eccentricity of 0.0934. It is inclined to the ecliptic plane under a degree of 1.85.
Orbits of gas giants
The remaining four planets of the solar system -Jupiter, Saturn, Uranus and Neptune - are called gas giants or outer planets. The ellipse of Jupiter's orbit has an eccentricity of about 0.0488, so the difference between the closest and furthest distance from the Sun is about 76 million kilometers.
Jupiter most rapidly rotates around its axis in comparison with the rest of the planets of the solar system, and around the Sun it makes a complete revolution in almost 12 years.
Saturn's orbit is slightly more elongated thanJupiter (eccentricity 0.056), because of which the difference in distances to the Sun is as much as 162 million kilometers. Saturn is moving at a low speed - about 9.7 kilometers per second. The orbit of Uranus is almost circular, but with slight deviations to the shape of the ellipse. The discrepancies in the calculations between the supposed and observed orbit made it possible to assume in the middle of the XIX century that beyond Uranus there is another planet.
Neptune has a small eccentricity of .011. Its orbit is so long that it makes its full turn in 165 years - so much time has passed since the discovery of the planet.