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Diagram of positional astronomy. In positional astronomy, two astronomical objects are said to be in opposition when they are on opposite sides of the celestial sphere, as observed from a given body (usually Earth). A planet (or asteroid or comet) is said to be "in opposition" or "at opposition" when it is in opposition to the Sun.
In the reference frame of the Earth, where the terms were originally used, the inferior planets are Mercury and Venus, while the superior planets are Mars, Jupiter, Saturn, Uranus and Neptune. Dwarf planets like Ceres or Pluto and most asteroids are 'superior' in the sense that they almost all orbit outside the orbit of Earth.
For Jupiter, the maximum is 11.1° and for Saturn 6°. [ 1 ] The brightness of an object is a function of the phase angle, which is generally smooth, except for the so-called opposition spike near 0°, which does not affect gas giants or bodies with pronounced atmospheres , and when the object becomes fainter as the angle approaches 180°.
The axial tilt and eccentricity of Earth (and Mars) are by no means fixed, but rather vary due to gravitational perturbations from other planets in the Solar System on a timescale of tens of thousands or hundreds of thousands of years. Thus, for example Earth's eccentricity, currently about 1% regularly fluctuates and can increase up to 6%.
Orbit of Mars relative to the orbits of inner Solar System planets Orbit of Mars and other Inner Solar System planets An animation to explain the (apparent) retrograde motion of Mars, using actual 2020 planet positions Mars seen through a 16-inch amateur telescope, at 2020 opposition. Mars has an orbit with a semimajor axis of 1.524 ...
The word is often used in reference to the Sun, Earth, and either the Moon or a planet, where the latter is in conjunction or opposition. Solar and lunar eclipses occur at times of syzygy, as do transits and occultations. The term is often applied when the Sun and Moon are in conjunction or in opposition . [4]
Saturn is surpassed by the numbers by one and a half degrees." Using modern computer programs, Gingerich discovered that, at the time of the conjunction, Saturn indeed lagged behind the tables by a degree and a half and Mars led the predictions by nearly two degrees.
The following outline is provided as an overview of and topical guide to Mars: Mars – fourth planet from the Sun and the second-smallest planet in the Solar System , after Mercury . Named after the Roman god of war , it is often referred to as the " Red Planet " [ 1 ] [ 2 ] because the iron oxide prevalent on its surface gives it a reddish ...