Transcript: The truth about Mars began to emerge in the 1960s and 1970s. In 1965 the Mariner IV space probe became the first probe to reach the red planet. It took a few close-up photographs as it zipped by the surface revealing an impact cratered surface looking much like the Moon. In 1976...

Transcript: Radar mapping of the surface of Venus has given us some clues as to the volcanic history of our sister planet. Venus has huge volcanoes ranging in size up to 5 to 6 miles high. There is evidence that the entire surface of Venus was re-surfaced by volcanoes and magma 500 to 800...

Transcript: Venus, second planet out from the Sun, is the sister planet to the Earth, closest among all the planets to the Earth in size and mass. Its atmosphere is composed of 96 percent carbon dioxide and 4 percent nitrogen with very small amounts of water vapor, argon, sulfur dioxide, and...