Earthlings could make contact with extraterrestrial beings by the year 2025, two astronomers predict in a new book.
The universe is indeed vast. In 1924 astronomer Edwin Hubble showed that there are galaxies beyond our own. “More than a half century later, the Hubble telescope has shown that there are at least 100 billion such galaxies,” said Shostak. Our galaxy, the Milky Way, is home to at least 100 billion stars.
Planets are also plentiful. Since 1995, when the first Jupiter-sized planet outside of our solar system was found, astronomers have been able to identify about 100 more planets, all of them around 300 times more massive than Earth.
“Planets really are as common as phone poles,” said Shostak. “Right now, we know that there are planets out there [orbiting] ten or twenty percent of the stars we look at. So far, only huge planets have been found, but it would be a big surprise if there were only big ones. I don’t think anyone expects that to be the case.”
Until now, the search for intelligent life has been somewhat hampered by inadequate technology—too few stars surveyed at too low a sensitivity by Earth and space-based telescopes.
But in 2007, habitable zone: the distance from a star where liquid water can exist on the planet’s surface.
Projects like the Kepler Mission and the new Allen Telescope Array, located near Mount Lassen, California, which will enable astronomers to survey 100,000 stars by 2015, should increase the odds of finding a radio signal broadcast by alien life, say the astronomers.
“The bottom line is that there is an enormous amount of real estate, and there doesn’t seem to be anything particularly special about our neighborhood. The star that’s our sun is nothing special. The Earth is just a rock,” said Shostak. “To think anything else is to once again put ourselves at the center of the universe, and