With Mars closer to Earth than it has been since prehistoric times, scientists hope to learn if there is (or ever was) life on Mars. They once assumed that the hostile environment of Venus meant there was never life on that planet, but now they've changed their minds. Since finding life in incredibly harsh places here on Earth, they now think we'll eventually find signs of life on Venus as well. If life turns out to be fairly common, there's a much greater chance we'll meet another highly-developed form of it one day.
David L. Chandler writes in New Scientist that the harsh climate of Venus may be a fairly recent development, in planetary terms. Pleasant, Earth-like conditions probably existed for two billion years after the planet's birth, which is plenty of time for life to develop. Scientists think life may have developed in better times on Mars too, and it may now be hiding in liquid water under the ice. Could life still exist somewhere on Venus as well?
Today Venus has temperatures that are hot enough to melt lead. There is a continuous drizzle of concentrated sulfuric acid and thick clouds block out the Sun. But it once had a climate like ours, complete with large oceans. It lost its water due to a runaway greenhouse effect, but it's not known if this happened before life had a chance to get started there.
Geologist Jeffrey Kargel thinks the climate of Venus changed four billion years ago, just 600 million years after the Solar System's birth. That wouldn?t be enough time for life to take hold. But David Grinspoon thinks things changed much later, and says Kargel didn?t take into account the cooling effects of the clouds.
About 700 million years ago, the entire surface of Venus actually melted and reformed. Could life have survived and it still be hiding there?
Who are these extraterrestrials that people seem to be communicating with and where do they come from? When you find out what really happens to witnesses, you'll understand why it's so hard to find the answers.
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