So, just what does the Venusian landscape look like? Normal photographs, like those sent to Russia, only show small portions, close-up "portraits" of the surrounding area: however, if Venus also has craters, mountains or volcanoes, the probes cannot show them. This is caused by the canopy of clouds and the distortions from the density of the atmosphere near the ground. Thus, a different type of instrument is needed, radiation that can "see" through the clouds. For this reason, in December of 1978, the Americans placed two special probes in orbit around Venus - Pioneer Venus 1 and 2: one had the job of hurling mini-capsules towards the planet to cross through the atmosphere and measure its characteristics; the other, instead, was equipped with complex instruments including special radar. The impulses emitted from the probe could pierce the mantle of clouds to reflect off the surface and return to the probe: from the time taken for the pulse to complete the round trip, it was possible to establish if the point that the pulse had been aimed at was higher or lower than the surrounding points. The result of this mission was the creation of the first "map" of the planet. In reality, this is still a rather approximate map, however it still enabled us to determine the true "topographical provinces". It was first discovered that Venus is, on the average, "flatter" than the Earth. Since there are no seas that can be used as a point of reference, zero altitude was determined by using the median radius - that has a length of 6 051 kilometers. It was found that only 16%, or one-sixth of the total is located under this level, unlike the Earth, where two-thirds of the surface is below sea level. What's more, 60% of the planet consists of a plain that reaches an average height of 500 meters, and only 5% exceeds 2 000 meters. Despite this great uniformity, there are mountains with a "mass" which are comparable to those on the Earth and plateaus similar to our continents. The most notable of these plateaus is called Ishtar, like the Babylonian goddess of love, and is located near the north pole of the planet. Slightly larger than the continental United States, it raises several kilometers above the median radius and descends rather steeply towards the surrounding lowlands. Its main characteristic consists of the largest and most unique formation on Venus, the Maxwell mountains. They are the only formation to have been given a masculine name in honor of the theoretical "father" of the radar, the English physicist James Clerk Maxwell. Probably of volcanic origin, they reach a height of 12 000 meters and are much higher than Mt. Everest, the tallest mountain on the Earth. In general, Ishtar does have the same structure as the Tibetan plateau, only that it is almost twice as big. What is considered to be an enormous crater, the largest on the planet, is located next to the Maxwell mountains: a circular formation one kilometer deep and one hundred kilometers wide. However, the largest "continent" is called Aphrodite. It covers a surface area that is about half of Africa and extends along the equator for more than 10 000 kilometers: more rugged and complex than Ishtar, it is crossed by massive linear fractures, some of which are 3 kilometers deep, one hundred kilometers wide and even one thousand kilometers long. Their origin is unknown, but they might be the result of enormous movements of the Venusian crust. So, no steaming jungles or little green men, but a world full of strange formations, like the "mini continents" of Alpha and Beta, the details of which the probe Pioneer Venus cannot decipher (in fact, it cannot distinguish details smaller than a kilometer). We need something more advanced to truly understand our fiery sister.
So, just what does the Venusian landscape look like? Normal photographs, like those sent to Russia, only show small portions, close-up "portraits" of the surrounding area: however, if Venus also has craters, mountains or volcanoes, the probes cannot show them. This is caused by the canopy of clouds and the distortions from the density of the atmosphere near the ground. Thus, a different type of instrument is needed, radiation that can "see" through the clouds. For this reason, in December of 1978, the Americans placed two special probes in orbit around Venus - Pioneer Venus 1 and 2: one had the job of hurling mini-capsules towards the planet to cross through the atmosphere and measure its characteristics; the other, instead, was equipped with complex instruments including special radar. The impulses emitted from the probe could pierce the mantle of clouds to reflect off the surface and return to the probe: from the time taken for the pulse to complete the round trip, it was possible to establish if the point that the pulse had been aimed at was higher or lower than the surrounding points. The result of this mission was the creation of the first "map" of the planet. In reality, this is still a rather approximate map, however it still enabled us to determine the true "topographical provinces". It was first discovered that Venus is, on the average, "flatter" than the Earth. Since there are no seas that can be used as a point of reference, zero altitude was determined by using the median radius - that has a length of 6 051 kilometers. It was found that only 16%, or one-sixth of the total is located under this level, unlike the Earth, where two-thirds of the surface is below sea level. What's more, 60% of the planet consists of a plain that reaches an average height of 500 meters, and only 5% exceeds 2 000 meters. Despite this great uniformity, there are mountains with a "mass" which are comparable to those on the Earth and plateaus similar to our continents. The most notable of these plateaus is called Ishtar, like the Babylonian goddess of love, and is located near the north pole of the planet. Slightly larger than the continental United States, it raises several kilometers above the median radius and descends rather steeply towards the surrounding lowlands. Its main characteristic consists of the largest and most unique formation on Venus, the Maxwell mountains. They are the only formation to have been given a masculine name in honor of the theoretical "father" of the radar, the English physicist James Clerk Maxwell. Probably of volcanic origin, they reach a height of 12 000 meters and are much higher than Mt. Everest, the tallest mountain on the Earth. In general, Ishtar does have the same structure as the Tibetan plateau, only that it is almost twice as big. What is considered to be an enormous crater, the largest on the planet, is located next to the Maxwell mountains: a circular formation one kilometer deep and one hundred kilometers wide. However, the largest "continent" is called Aphrodite. It covers a surface area that is about half of Africa and extends along the equator for more than 10 000 kilometers: more rugged and complex than Ishtar, it is crossed by massive linear fractures, some of which are 3 kilometers deep, one hundred kilometers wide and even one thousand kilometers long. Their origin is unknown, but they might be the result of enormous movements of the Venusian crust. So, no steaming jungles or little green men, but a world full of strange formations, like the "mini continents" of Alpha and Beta, the details of which the probe Pioneer Venus cannot decipher (in fact, it cannot distinguish details smaller than a kilometer). We need something more advanced to truly understand our fiery sister.
