Tuesday 3 October 2017

Mars approaches Aphelion.

The planet Mars will reach apihelion (the furthest point on its orbit to the Sun) at 11.08 pm GMT on Saturday 7 October 2017, when it will be 1.67 AU (250 000 000 km) from the Sun. This is 0.49 AU (73 000 000) more distant than the planet's periphelion (closest point on its orbit from the Sun), as Mars has one of the eccentric circular orbit of any planet in our Solar System, this is about half the distance between the Earth and the Sun, or 33% of Jupiter's average distance from the Sun.

 The planet Mars. NASA/JPL/Caltech.

Because Mars is further from the Sun then the Earth, it's orbital period (year) is also longer, lasting 1.88 Earth years. This means that Jupiter will next reach perihelion on 16 September 2018 and aphelion on 31 July 2021. The orbit of Mars makes relatively little difference to the appearance of the planet from Earth; this does vary considerably over the course of a year, but is affected far more by the relative positions of the planets on their orbits (they are currently separated by about 60 degrees) than by the distance of either planet to the Sun. Nor does this variability have any notable affect on the planet's climate, which, as with Earth, is influences far more by the tilt of the planet.

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