We all see a clearly visible bright object in the sky after the sun and the moon. Due to its bright appearance it looks like a star in the evening and also in the morning. Often it is called as the ‘Evening Star’ or ‘Morning Star’ as it is usually visible only during these times. However, it is not a star but a planet, called Venus, the nearest planet of our Earth. It is the second planet from the sun and it looks like our moon through telescope. We can get a full view of it when it is very far from us. Venus is the brightest of all planets and is also the hottest of them though it is relatively far away from the Sun in comparison to Mercury, the nearest planet to the Sun.
Venus and our Earth are called twin brothers in the Solar System as both of them have some common striking similarities in their size and density. Yet, both of them differ in various grounds. Many new facts about Venus have come to light by space probes. In the exploration of Venus, former USSR trailed behind the USA. Its chain-flights of Venera (Venus) carried out many significant scientific researches. Venera-8, a spacecraft of Venera Series reached the proximity of the brilliantly shining planet Venus in 117 days after covering an enormous distance of 300 million kms. When the spacecraft entered in the Venusian atmosphere, its capsule, loaded with highly sophisticated instruments was detached from it. On 22 July 1972, at 3 pm, IST the capsule landed on the surface of Venus with the help of parachutes. Many scientific experiments were carried out on the atmosphere and soil of Venus for 50 minutes. The findings of these experiments were transmitted to the laboratories of earth with the help of radio waves.
During this experiment, the amount of radiation around Venus and the ratio of hydrogen and heavy hydrogen were found. For the first time, the intensity of light on the Venusian surface, its atmosphere, atmospheric pressure and temperature were measured. Various data were also collected of the rock pieces and dust particles, about their nature. The Sun light, on its way to the surface of Venus becomes dim because of thick clouds. The kind of murkiness, which we generally notice on our earth on a cloudy evening, an almost similar murkiness always persists on the surface of Venus. Former Soviet Union again launched Venera-9 and Venera-10 in 1975, and then Venera-11 and Venera-12 to unravel many unresolved mysteries of Venus.
These flights transmitted data that the surface temperature in Venus is 480 degree Celsius; hot enough to melt zinc and tin. Our Earth’s normal temperature is 30 degree Celsius, and water boils at 100 degree Celsius. The studies revealed that the atmospheric pressure on the Venusian surface is 100 times than that of our Earth’s surface. Even 95 kms above the surface of the Venus the atmosphere reaches 138 degrees Centigrade in daytime, and then cools to 77 degrees Centigrade at night.
Venus has very thick clouds, which reach upto a height of 55 kms where as our Earth’s cloud are visible at a height of 10-12 kms. The Venusian clouds act like a blanket. The bright appearance of Venus is due to its cloudy atmosphere, which reflects almost three-fourth of the sunlight falling on it. It is speculated that the clouds of Venus like terrestrial clouds possess water and snow. The atmosphere of Venus also contains 90 to 95 percent of carbon dioxide. Some hydrogen and water vapour are also present in this hot planet. Accordingly, the solar heat reaching the Venusian soil is absorbed by the enormous carbon dioxide and a minute quantity of water vapour. As both of them stop the reradiation of solar heat, so the temperature and pressure of these gases increase. No astronaut can survive in the atmosphere of Venus, nor can tolerate its excessive heat.
Sulphur, mercury, iodine and bromine are likely to be found in the Venusian clouds. Each of these elements might be turning into liquid before reaching upto the height of 55 kms. Scientists speculate that Venus had oceans about 4000 million years ago and water evaporated due to the extreme temperature or warming phenomenon. The sharp ultraviolet rays of the sun split water into its original elements hydrogen and oxygen. Being lighter, the hydrogen gas rises up and disappears in the space while the oxygen, being heavier is absorbed by the rocks on its surface. Hence the splitting of these two gases differently creates scantiness of water in this planet.
Radio waves have indicated that there are mountains and valleys in Venus. The Sun rises in the west and sets in the east in this planet. A day on Venus equals about 243 earth days and the year for Venus is only 224.7 earth days.