THE EARTH’S TWIN

Venus is named after the Roman goddess of love and beauty and is the only planet named after a female. Venus may have been named after the most beautiful deity of the pantheon because it shone as the brightest among the five planets known to ancient astronomers. Venus is the planet closest to the earth, and is 7700 miles in diameter, which is 20 miles less than the earth’s.

Venus has been called Earth’s twin. However the size of Venus is a little smaller than our home planet, with a mass that’s about 80% of Earth’s.

Venus conjures up visions of beautiful hills and the green valleys, though no one has seen the surface of the planet as Venus is completely covered in a layer of dense bright cloud. But Venus is indeed a beautiful sight in the morning or evening sky when she shines with a brilliant silvery hue. At her brightest Venus is the brightest object in the sky besides the sun and moon.

She is known by many as the Morning Star or the Evening Star. In ancient times, Venus was often thought to be two different stars–that is, one that appeared at sunrise and another at sunset. In Latin, they were respectively known as Vesper and Lucifer. In Christian times, Lucifer, or “light-bringer,” became known as the name of Satan before his fall. Observations of Venus in the space age show a very hellish environment. This makes Venus a very difficult planet to observe from up close, because spacecraft do not survive long on its surface.

One peculiar fact about Venus is that a “day” on Venus is longer than “a Venusian year”. The situation arises as Venus revolves faster around the Sun than it rotates on its own axis, the former period being 24 days and the latter 243 days. Thus Venus appears to rotate backwards with respect to the sun and so the sun would appear from Venus to rise in West and set in the East.

One other mystery which has puzzled astronomers for several decades, is the so called “Ashen Light” seen on Venus.

If you observe our Moon circling the Earth, you can often see the unlighted side faintly shining. ‘This should not cause a surprise for there is nothing mysterious about this phenom­enon. The glow is caused by light reflected from the Earth to the Moon, a fact understood even by the great Italian painter and scientist Leonardo da Vinci. However, through the telescope, the same sort of radiance has been noticed on the planet Venus and it has been generally known by the term “Ashen Light” as mentioned above. On Venus it is not so easy to explain this. Venus has no Moon, and the Earth does not illuminate it perceptibly.

A German astronomer of the previous century who had a rather vivid imagination put forward a theory to explain the so called “Ashen Light” (he discovered what he believed to be an artificial structure on the Moon, which he went on to describe as a collection of gigantic ramparts—a work of art. Unfortu­nately it is now known that there’s nothing there but a few haphazard ridges. He noted that the light on Venus had been observed in 1759 and again in 1806, after an interval of 76 Venusian years (equivalent to 47 terrestrial years). According to him, if we estimate that the ordinary life of an inhabitant of Venus (assuming it is inhabited) lasts 130 Venusian years which amounts to 80 terrestrial years, the reign of an emperor of Venus might well last for 76 Venusian years. Hence, according to him, it is possible that the appearance of light is the result of a general festival illumination of Venus in honour of the ascension of a new emperor to the throne of the planet. Since the theory was not backed by any evidence and did not find favour with many of his sober contemporaries, this German astronomer put forward a second theory to explain the phe­nomenon. He wondered whether the light might be due to the burning of large stretches of the jungles on Venus to produce new farmland. He added that in this way perhaps large migrations of people were being prevented on that planet with a view to avoiding possible wars by abolishing the main reason for them. Thus, whatever race existed on Venus could be kept united by its benevolent Emperor.

However, both the theories remained essentially specula­tive with no scientific proof to support the ideas. The “Ashen Light” phenomenon remained one of the unsolved mysteries of Astronomy, though some astronomers were inclined to dismiss it as a mere effect of contrast.

However to see the “Ashen Light” properly one has to fit a special “occulting bar” into the telescope’s eyepiece to hide the bright crescent of the planet. And of course, one can never see Venus well against a really black sky because it is always too low over the horizon.

Among possible explanations over the “Ashen Light” seen on Venus, astronomers have suggested florescence in the planet’s seas, or auroras or lightning flashes. It now appears as though the lightning theory maybe correct. The nature of the surface of Venus still remains a mystery although some space probes shed light on the matter.

Much of what we now know about Venus comes from results of space probes which include landings. Many strange surface features have now become known. Most notable is a huge rift valley five kilometres deep, 280 kilometres wide and stretching at least 1440 kilometres apparently with no sudden beginning or an end. This remarkable valley not only dwarfs the Valles Marineris on Mars but also makes Grand Canyon seem like a mere mud crack.

Just as interesting as the discovery of the valley itself is the revelation that on Venus there is continuous lighting up to 32 kilometres above ground-level. Space probes have detected as many as 325 discharges per second. An observer of Venus would be able to see what appears to be a continuous eerie glow and would hear ceaseless thunder.

There is also a second glow thought to be cause by chemi­cal reactions in the super-heated atmosphere close to the planet’s surface. This glow seems to start about 16 kilometres above the ground level and it may well combine with the lightning to make up the “Ashen Light”, an effect that has been seen by nearly all serious Venus watchers. About less than three decades ago it seemed probable that Venus was covered by oceans with a surface temperature we could find quite tolerable. By December, 1978 astronomers were resigned to finding a carbon dioxide atmosphere about ninety times as dense as the Earth’s, clouds containing sulphuric acid and a surface temperature above 450° C. (The carbon dioxide is believed to trap much of the sun’s heat). One astronomer has gone so far as to suggest that the atmosphere is so dense that light rays would be bent all the way round the planet so that an observer on the surface could see a distorted image of the back of his own head.

The new findings make Venus even more peculiar than astronomers expected. Any traveller careless enough to step outside his spaceship to view the landscape on the planet would be simultaneously corroded, fried, squashed and poi­soned. It now seems that he might also be deafened by the thunder claps on Venus which must be vastly louder than anything we hear on Earth.

Venus was the first planet to be explored by a spacecraft – NASA’s Mariner 2 successfully flew by and scanned the cloud-covered world on Dec. 14, 1962. Since then, numerous spacecraft from the U.S. and other space agencies have explored Venus, including NASA’S MAGELLAN which mapped the planet’s surface with radar. The former Soviet Union is the only nation to land a spacecraft on the surface of Venus to date, though it did not survive long in the harsh environment.

Maybe in this century astronomers would be able to send probes that stay on the planet undamaged for much longer periods for the instruments to collect useful information.

Over the years many people have suggested that we “seed” the atmosphere of Venus with bacteria to break up the carbon dioxide molecules and release free oxygen in order to prepare that planet for colonisation in the future. It now seems unlikely that such plans will ever be practicable. Venus has been a disappointment as far as space colonisation is concerned though it remains one of the most fascinating bodies in our solar system especially to astronomers who will never stop studying its strange features.