Venus (the Goddess of Love) is the planet second closest to the Sun.  From looking at most of the facts, Venus seems pretty similar to Earth, but in reality it's completely different.  OK, so it might be just 652 km smaller, have similar composition, mass and position, but for a start, Venus' surface temperature is 484^oC, secondly it has no oceans and thirdly it's surface pressure is akin to that of an ocean bed.  This pressure has pulverized and crushed surface rocks.  Venus is strange also in that it spins in the opposite direction to Earth (the Sun rises in the West instead of the East).  Venus has a persistent layer of Sulphuric Acid clouds on top of it which produces lethal Sulphuric Acid rain.  Venus is visible in the night sky a few hours before sunrise or after sunset at certain times of the year and it looks like a brilliant blue-white star. 

Pioneer mapped 98% of it's surface in 1978-80 and later, it was visited by the Magellan space probe, which mapped it in greater detail, revealing volcanoes and craters.  They found that at least 85% of Venus is covered by volcanic rock - mostly lava flows form the planet's vast plains.

In 1962 the Mariner 2 space probe flew by Venus followed in 1970 by the Russian Venera 7 which landed on Venus but lasted just 23 minutes before being burnt like toast and disintegrating.  In 1972 Venera 8 also landed on Venus followed in 1975 by Venera 9.  Then an American probe, the Pioneer Venus Orbiter mapped Venus and the Pioneer Venus Multiprobe dropped four probes on Venus.   Following that, Veneras 15 and 16 mapped Venus followed by the also Russian Vegas 1 & 2 in 1984 which also dropped landers. Four years later, in 1990, Magellan arrived at Venus, mapping it in great detail to reveal craters and Volcanoes we never knew existed.