August 26, 2006

Man, it seems, has always been interested in Mars which is full of surprises. In the pre-telescope era (before 1610 AD), and in many parts of the world even after telescope’s invention, man knew of only five planets. These were the “naked eye planets” — namely, Mercury, Venus, Mars, Jupiter and Saturn.

As for the Earth, it was ordained that the whole universe revolved around it. It was too holy to be regarded as just another planet. After all, that is how it looked like. The Sun went round the Earth, as did the Moon and stars. They all went round the Earth in an east-to-west direction, except for the Moon which went round the Earth just the same.

When it came to the planets, their movements were somewhat perplexing. But as the name suggests (planet means “wanderer”) their motion, considered as an aberration in the handiwork of gods, was “better understood” after these were worked out by the Greeks.

Today the ways in which these calculations were made cannot be regarded as accurate or even partially correct. The work of astronomers, beginning with Tycho Brahe and ending with Sir Isaac Newton and Sir Edmond Halley, made sure that all previous theories regarding planets met their demise.

While all planets were regarded as unique, the understanding and interpretation of each was done variously by our ancestors in the pre-telescope era. These included stargazers in Mesopotamia, Assyria, Greece, Rome, China and India.

Mercury being the fastest, as it is closest to the Sun, was named after the messenger of gods by that name whose job obviously was to deliver messages quickly. Venus — the brightest planet that hung majestically in the sky, now in the east and now in the west — was akin to an apparition of a beautiful woman, preoccupied with her appearance, holding a mirror to her face. Next – and that is where the buck stops – came the red planet, Mars. The Earth, lying between Venus and Mars, enjoyed a special status and did not belong to the “inferior” family of planets.

Mars’ coppery red colour distinguished it from all others and for that reason it came to acquire notoriety and was regarded as a symbol of war and aggression. The fact remains that Mars has stirred man’s imagination like no other planet. To the ancient people, its reddish glow was a celestial symbol of blood and it was seen as a harbinger of war and disaster, unless enough sacrifices were offered to appease and pacify it. Jupiter and Saturn were regarded as sedate and unassuming. Jupiter for its very large size, bright appearance and sedate gait was said to be the god of gods, better among equals. Finally, Saturn came to be associated with harvests and things of profit.

Meanwhile, the information that Mars is coming close to planet Earth has once again stoked the fires of interest in the Red Planet. Throughout this month Mars will glow tremendously because it is drawing close to Earth. But on Aug 27 it will shine extra brightly because on that day it will be closest to our planet.

This month, and the next, Earth will catch up with Mars in a rendezvous that will not only culminate in the closest approach between the two planets in recorded history, but the latter will appear at its brightest as it slowly moves away over the next four weeks.

On the evening of Aug 27, Mars will be at a hand-shaking distance of only 34,649,589 miles (roughly 35 million miles). The last time it came so close was about 5,000 years ago. The equations suggest that the next closest approach is about 60,000 years into the future.

Here is the question then: What is so unique about planet Mars coming close to Earth? Sure enough, Mars is not a rare sight. The Earth goes round the Sun once in 365.3 days and Mars does so in 687 days. This should bring the planets close at least twice in one Martian year, the two planets lying next to each other in their sequence in the solar system.

“Opposition” of the planet occurs every 780 days, when the Earth passes between the Sun and Mars. Opposition is the position of a planet opposite the Sun in the skies, which happens to be the most favourable spot for observing a superior planet. A superior planet is one that remains outside the orbit of Earth — that is, all planets except Mercury and Venus. These two are held to be inferior planets.

Because of the different shapes of the planets’ orbits, some oppositions are better for observation than others, based on the distance between them. Aug 27, 2007 is a rare occasion in that not only will the two planets in question come closer than ever but Mars will attain a magnitude of –2.9 and will have a size of 25.11 arc seconds width or diameter.

The sky (from east to west) comprises 180 degrees. One degree is divided into 60 minutes and each minute is further divided into 60 seconds (of an arc). The apparent diameter of both the Sun and the full Moon is half a degree or 30 minutes.

As stated above, Mars will attain a size of 25.11 seconds, which really means that it will be somewhat like 1/60th of the size that a full Moon has. Any talk of Mars being in equal in size to the full Moon, therefore, is nothing but ignorance. For planet Mars to equal the size of full Moon in the sky, it will have to be at a distance of 15 to 18 million miles from Earth and not at the current 35 million miles.

However, next to the Moon it will be the brightest object in the night sky. Observers on this occasion will do well to remember that despite its ominous size and brightness, Mars will not appear as a disc but only as a point of light, albeit very bright.Nowadays, Mars is rising in the sky late in the evening and remaining there until the wee hours, reaching its highest point in the sky at 1230am. It has been growing in size and brightness steadily.

In astronomy, magnitude refers to a celestial object’s brightness, especially that of a star. An object just about visible to the naked eye (without the aid of a binocular or telescope) is regarded as a magnitude 6 object. Then, the objects’ increasing brightness is taken into account so that an object at the magnitude scale of 5 is considerably brighter than the one calibrated at 6.

The scale allows for a magnitude 1 star to be exactly 100 times brighter than a star of magnitude 6. Stars brighter than magnitude 1 are given minus magnitudes — such as Sirius, the brightest of all stars, which has a magnitude of –1.4.Talking of stars fainter than magnitude 6, these are given larger positive magnitudes. The faintest objects so far seen in space are of about magnitude 24. On the magnitude scale the full Moon is –8 and the Sun a whopping –27.

You should never to look at the Sun, not even with an averted look. Its radiation most certainly will damage the eyes beyond repair, leading to permanent disability.

Back to Mars. Its closeness to Earth is a once-in-a-lifetime opportunity for us to observe the planet, study it and photograph it. This will motivate us into looking out for the so-called “god of war” on a sort of permanent basis. August 27 is the day (a few days earlier or later will not account for much).

A visit to a place away from city lights, smog and dust would provide an ideal opportunity to view it properly. Aided by some rain a couple of days or so before the outing and no clouds, one may be able to see the Martian polar caps and the opaque foggy portions in the part made visible by a good telescope.

So, go out and make a rendezvous with the Roman god of war. Good viewing!