A Date With Mars !

Would you like to really befriend Mars - the Planet of war? There is no time like the present. On August 28th this year Mars is going to be closer to Earth than it had ever been in all of recorded history! A close encounter of a thrilling kind!

In a mutual dance of near and far approaches that all Planets indulge in - Mars and Earth come close to each other once every opposition - about once in two years - but, not every opposition is the same - some are closer than others.

Opposition happens for the superior Planets - that is, for Planets that have orbits outside the Earth's. At Opposition, the Superior Planet would appear exactly opposite - 180 degrees away from the position of the Sun, in the sky, and is the closest to Earth, in physical distance, during that particular trip around the Sun.

Planetary orbits are elliptical rather than circular; therefore, some oppositions bring the Planet closer to Earth than others. This effect is the most pronounced for Mars. Oppositions when Mars is at Aphelion (farthest distance from the Sun) keep Earth and Mars much further apart than oppositions when Mars is at Perihelion (closest to the Sun).

Some oppositions are closer than the others - and the coming one - the closest since the last 73,000 years - with the Earth Mars distance being about 55.8 million kilometers!

The figure below shows the orbital positions of Earth and Mars during any opposition---

Do not miss the opportunity of viewing this Planet and learning more about it at this time - Mars will not get closer than this to Earth until the year 2287 when it will be 70,000 km closer. And, this is a treat for all Earth observers - this can be seen from anywhere on Earth, although lower latitudes - not too North and not too South of the equator - gives better opportunities for viewing, as Mars will be seen higher up in the sky from lower latitudes.

Usually Mars is a poor lookout for Telescope viewers as it presents such a small disk for view - but oppositions usually give a better look at Mars. Amateur Astronomers, the World over, wait for favorable Mars oppositions to painstakingly view this Planet.

What is one expected to see at this time - different from other non-favourable occasions of Mars viewing? One usually looks out for subtle surface markings and polar ice caps while viewing Mars. These should become very prominent at this time, provided there is no dust cloud obscuring the view. Mars changes in apparent diameter dramatically - from Conjunction (when it appears close to the Sun in the sky) to Opposition.

Compared to that dramatic change - the change in its apparent diameter may not be so dramatic from Opposition to Opposition - so, do not look for dramatic changes in its appearance compared to some of its favourable oppositions in the recent past - it would not be very different from the views of 1956 or 1988. But, still, a record is a record - Mars will be closer to us than any of these favourable oppositions in recent history - the last time it had been this close was in 57,538 BC.

Of course, the views through ordinary amateur telescopes would be much less dramatic - be aware of that!

Written by - Dr. N. Rathnasree, Director, Nehru Planetarium, New Delhi.