Friday 4 April 2014

The planet Mars passes the Earth.

The planet Mars will make its closest pass to the Earth since December 2007, coming within 92 000 000 km of us on 14 April 2014. This will make the planet a particularly bright object, visible in the night sky from anywhere on Earth in the constellation of Virgo, close to the star Spica.

The relative positions of Earth and Mars on 14 April 2014 (not to scale). Windows to the Universe.

Mars orbits the Sun at a distance of approximately 1.52 AU (i.e. 1.52 times the distance at which the Earth orbits the Sun), completing one orbit every 687 days. However this does not mean it passes the Earth every 687 days, since the Earth is also completing one orbit every 365 days, the two planets passing approximately once every 26 months. Nor are the two planets equally separate at each pass, eccentricities in their orbits (i.e. variations in the distance between the planet and the Sun) mean that these passes cyclically become closer and more distant. The next such pass will come in June 2016, when Mars will come within 75 000 000 km of the Earth.

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