Named after the Roman god of war, Mars is often called the ‘Red Planet’ due to the iron oxide prevalent on its surface, which gives it a reddish look. Mars has been known since prehistoric times. The fourth planet from the Sun and the second smallest planet in the entire Solar System, Mars has a diameter of about half the Earth, measuring only 6,800 km across. The total mass of Mars is only about 10% the mass of Earth.
Early in its history, Mars was much more like Earth, with almost all of its carbon dioxide used up to form carbonate rocks. But lacking the Earth’s plate tectonics, Mars was not equipped to recycle any of this carbon dioxide back into its atmosphere. The surface of Mars, therefore, is colder than that of the Earth would be at that distance from the Sun.
The distance from Earth to Mars shows considerable variation, because Earth’s orbit around the sun is much smaller than Mars’ orbit. While Earth is the third planet from the sun, Mars is the fourth. The shape of Earth and Mars’s orbits are elliptical rather than circular, and tilted in relation to one another, which means the distance between them can vary a great deal. Every 26 months, the two planets will ‘approach’ one another, as they line up with each other on their individual ellipses. This is called a ‘Mars Close Approach’ or ‘inferior conjunction’. The minimum distance from Earth to Mars is about 54.6 million kilometers, whereas the maximum distance at which they can be is about 401 million km. The average distance is about 225 million km.
Mars was seen to be closer to Earth than it had ever been on the night of 30th May 2016, and is expected to appear brighter than usual until 3 June. In 2003, Mars was less than 56 million kilometres away – the closest it has been for 60,000 years. NASA predicts that this will reoccur in 2287. When the two planets are at their closest, it’s the best time to go to Mars. Many Mars missions have taken advantage of the close distance to visit the red planet. Additionally, it is a perfect time to gaze at the sky and see the two planets embrace each other, that too with the naked eye!