Inclination of the planets

Axis of rotation of planets or obliquity

All planets suffer the vagaries of gravitational forces in the solar system and nearby planets. The planets are "buffeted" on the four-dimensional tissue of space-time, as on the surface of a giant trampoline modified by the gravity of planets, Sun and stars. This permanent deformation or curvature of space-time, creating the chaotic waves of gravity. If we could look at the solar system from the outside, far above the Earth's north pole, we would see the planets orbit the Sun in the opposite direction of clockwise.
We should observe that the disc rotation of the planets is remarkably plane only Mercury has an inclined orbit relative to the other. But you should not notice the planets rotate on themselves. Each planets revolve around a different axis of rotation. The axial tilt or obliquity is the angle between the axis of rotation of a planet and perpendicular to its orbital plane. The planets glide majestically on an orbit around the Sun, leaving perceive no trace of the gravitational constraints that lead. Yet an orbit is the path followed by a planet to respond to constraints of the gravitational effects of multiple celestial bodies, particularly the Sun. In the solar system, all objects, planets, asteroids and comets move in the same direction around the Sun. But no orbit is not perfectly circular or perfectly coplanar i.e. on the same plane around the equator of the central object. If the orbits of the planets have very low inclinations relative to the plane of the ecliptic, the much less massive bodies as Pluto, Eris, asteroids or comets have highly inclined orbits to the plane.
Orbits have a perihelion Ancient Greek peri (around, close) and hêlios (sun). This is the closest point Sun on the orbit of a planet or celestial object. and aphelion Ancient Greek Apo (below) and hêlios (sun). This is the farthest point from the Sun to the orbit of a planet or celestial object. therefore eccentricity The eccentricity (e) is the difference between the two distances are the aphelion and perihelion. eccentricity for the Earth is 0.01671022. and an inclination In celestial mechanics, the inclination (i) of a planet is the rotation angle of the plane of its orbit and the plane of the ecliptic, that is to say the plane of the orbit of the earth., an ascending node orbital node is the intersection of an orbit and a reference plane. node ascendant is the point in the orbit where the object crosses the plane from bottom to top (south to north)., a vernal pointOn the celestial sphere, the equator and the ecliptic intersect. The apparent motion of the Sun crosses these two points called descending node and ascending node. When the sun passes over the equator, it crosses the vernal point or point the spring equinox. The ascending node is crossed between 20 and 22 March, while the point is passed down between 20 and 22 September. and an argument of perihelion In celestial mechanics, the argument of perihelion is a property of the orbit. The argument of perihelion (ω) describes the angle between the direction of the ascending node and the perihelion. It is measured in the orbital plane and in the direction of movement of the body..
Orbits of planets are all roughly in the same plane. The orbital plane is called the ecliptic we called the ecliptic great circle of the celestial sphere traversed by the Sun in its apparent motion around the earth. Describes the Earth around the Sun, an orbit whose plane makes an angle of 23 ° 27 'with the celestial equator (the projection of the equator). The Sun appears to move in and browsing the twelve signs of the zodiac: Aries, taurus, Gemini, Cancer, Leo, Virgo, Libra, Scorpio, Sagittarius, Capricorn, Aquarius, Pisces..
All the planets have orbits that are all roughly in the same plane called the ecliptic, but do not have the same obliquity. This rotation axis is never perpendicular to the orbital plane of the planet, but inclined at an angle varies according to the planets (see picture against). In the case of Earth, this angle was 1 January 2013 to 23 ° 26'15, 32 ". Inclination of the axis of the Earth loses in our days about 0.4686" per year.

This inclination during the movement of the planet's orbit causes the succession of the seasons. Unlike all the other planets of the solar system, Uranus is strongly tilted on its axis is almost parallel to its orbital plane (97.77 °), it gives the impression of riding on the rail of its orbit alternately exposing its north pole and the south pole of the Sun. The rotation of Venus is retrograde, the tilt of its axis is greater than 90 °. We could say that its axis is tilted "-2.64 °" (see picture against). Several theories exist on reversing the direction of rotation of Venus. The thick atmosphere of Venus could slow it down in his round around the Sun as a brake to rotate in the opposite direction.

NB: The rotation period refers to the time taken by a aster (star, planet, asteroid) for a ride on itself. The rotation of the Earth is 86,400 seconds. The second is the duration of 9,192,631,770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the cesium 133 atom (definition by the International System of Units).

NB: The Earth moves like a top around its orbit. The extremity of the axis slowly describes a circle in a horizontal plane, to the north celestial pole, it is the movement of precession. A complete cycle of precession takes 25,765 years, called great Platonic year. Added to this is the attraction of the Moon and the Sun disrupts the precession slightly by adding small oscillations with a period of 18.6 years. This effect is called nutation.