Perimenopause Age. There is not a set age for perimenopause to start; however, most women report the first symptoms in their early 40s. Since that is only an average, beginning perimenopause at an older or younger age signifies nothing.here is not a set age for perimenopause to start; however, most women report the first symptoms in their early 40s. Since that is only an average, beginning perimenopause at an older or younger age signifies nothing.
The surface of Venus is covered by a dense atmosphere and presents clear evidence of former violent volcanic activity. It has shield and composite volcanoes similar to those found on Earth. Relative to the Moon, Mars or Mercury, Venus has few small impact craters.fter the Moon, Venus was the second object in the Solar System to be explored by radar from the Earth. The first studies were carried out in 1961 at NASA 's Goldstone Observatory, part of the Deep Space Network.
Photos showed mountains, craters, and plains and that most of the rock is basalt which is typical of volcanism. The most extensive radar imaging was obtained from the Magellan orbiter in a 4-year period in the early 1990s. As a consequence, we now have a detailed radar picture of the surface of Venus. The adjacent animation shows the topography of the surface as determined using the Magellan synthetic aperture radar (black areas are regions not examined by Magellan). An MPEG movie (303 kB) of this animation is also available.