Looking for ET 
Four planets form an arc across the sky as twilight begins to fall right now. Brilliant Venus and Jupiter dazzle in the west, with brighter Venus standing higher in the sky. Ruddy Mars is high in the southeast, with golden Saturn just climbing skyward in the east.
So far, there’s no evidence that anything has ever lived on any of these worlds or their moons. Yet we’re just beginning the search, so we don’t know what we’ll find in the decades or centuries ahead.
We also haven’t found any evidence of probes from other civilizations. But two scientists from Penn State say that could simply mean we haven’t been looking hard enough.
The researchers looked at how thoroughly different parts of the solar system have been studied. From that, they calculated whether we can rule out the possibility of any “non-terrestrial artifacts” -- objects like robotic probes sent to study the solar system.
For Earth, the odds are good. We’ve scoured the planet pretty thoroughly, and Internet rumors aside, no ETs have turned up. The Moon is likely to be artifact-clean, too, and so is Mars. Beyond that, however, it’s hard to say -- we haven’t found anything, but we haven’t looked at any world or region of space very closely.
The researchers don’t suggest that we undertake a search for evidence of alien visitors. But they do suggest that while we’re studying the solar system, we keep our eyes open -- just in case.
More about advanced civilizations tomorrow.
Script by Damond Benningfield, Copyright 2012