New idea for finding extraterrestrial intelligence in the galaxy

There was an interesting article yesterday on spaceref.com about a new proposed method for finding extraterrestrial civilizations. It's based on how other civilizations might attempt to send signals to Earth if they were to discover the presence of our planet and come to the conclusion that life might exist here:

(I've bolded the most important parts)

They propose to use new Allen Telescope Array, operated as a partnership between the SETI Institute in Mountain View, Calif., and the Radio Astronomy Laboratory at the University of California, Berkeley.

Comprising hundreds of specially produced small dishes that marry modern, miniaturized electronics and innovative technologies with computer processing, the ATA provides researchers with the capability to search for possible signals from technologically advanced civilizations elsewhere in our galaxy - if, in fact, such civilizations exist and are transmitting in this direction.

Employing this new equipment in a unique, targeted search for possible civilizations enhances the chances of finding one, in the same way that a search for a needle in a haystack is made easier if one knows at least approximately where the needle was dropped, said Henry, who is speaking about the proposal at the American Astronomical Society annual meeting in St. Louis.

According to the researchers, the critical place to look is in the ecliptic, a great circle around the sky that represents the plane of Earth's orbit. The sun, as viewed from Earth, appears annually to pass along this circle. Any civilization that lies within a fraction of a degree of the ecliptic could annually detect Earth passing in front of the sun. This ecliptic band comprises only about 3 percent of the sky.

"If those civilizations are out there - and we don't know that they are - those that inhabit star systems that lie close to the plane of the Earth's orbit around the sun will be the most motivated to send communications signals toward Earth," Henry said, "because those civilizations will surely have detected our annual transit across the face of the sun, telling them that Earth lies in a habitable zone, where liquid water is stable. Through spectroscopic analysis of our atmosphere, they will know that Earth likely bears life.

"Knowing where to look tremendously reduces the amount of radio telescope time we will need to conduct the search," he said.

Most of the 100 billion stars in our Milky Way galaxy are located in the galactic plane, forming another great circle around the sky.

and:

"The crucial implication is that this targeted search in a favored part of the sky -- the ecliptic stripe, if you will - may provide us with significantly better prospects for detecting extraterrestrials than has any previous search effort," Kilston said.

Ray Villard of the Space Telescope Science Institute, who will join the team in its observations, said that in November 2001, STScI publicized Hubble Space Telescope observations of a transiting planet and "it occurred to me that alien civilizations along the ecliptic would likely be doing similar observations to Earth."

"Once they had determined Earth to be habitable, they might initiate sending signals," Villard said.