Mars will make its closest approach to Earth for almost 60,000 years at the end of August. Dr Robin Catchpole, senior astronomer at the Royal Observatory, Greenwich, London, explains how to witness the event.
Every 26 months, the Earth overtakes Mars on the inside track as they both orbit the Sun.
Every 15 to 17 years, this happens when Mars is closest to the Sun.
On 27 August this year they will pass at a distance of 55,760,000 km or 0.3727 AU (1 AU is the distance of the Earth from the Sun), closer than any time during the last 60,000 years.
At its closest, Mars will be 25 seconds of arc in diameter, the size of a tennis ball at a distance of 528 metres.
However, on the scale of the tennis ball, this approach is only 18 centimetres closer than in 1924, although 110 metres closer than in 2001.
Throughout July, August and September, Mars will be easy to see with the naked eye. Each night it will rise earlier, until by late August it will be just above the horizon, south of east, soon after sunset.
Once risen, it will be the brightest object in the sky, appearing orange red. From the latitude of the UK, it will never rise higher than 22 degrees and you will need an unobstructed view to the south to see it.
Mars will appear at its very best from the Southern Hemisphere, where by the middle of the night it will be high in the sky and its brightness and colour will make it very obvious.
