Looking up into all the stars in a dark sky will make you ponder that age-old question, "Are we alone in the universe?"

The answer to that question is probably no, based upon the sheer numbers involved.  

Astronomers estimate that there are about 50 billion galaxies in the visible universe, and each galaxy contains about 200 billion stars.

That means there is about one billion trillion stars, and if we assess the probability of life as one chance in a trillion, that gives us 20 billion stars that could support some form of life.

As I have stated before, the best way to find life in the universe is to listen for radio signals that might be broadcast through space.

The fastest rocket that we have launched would take about 80,000 years to reach the nearest stars and the costs would be staggering, so talk is cheap.

Our civilization has only been in the radio communication business for about 100 years, and for a long time we may not have had sufficiently sensitive radio equipment to detect incoming signals. But that may be about to change, thanks to two new projects that are getting started.

The first project is called the Allen Telescope Array, a joint project between the SETI Institute and the University of California at Berkley. This project is funded through private donations, with Microsoft cofounder Paul Allen being a major donor.

They currently have 42 dish antennas up and running at a location that is northeast of San Francisco. Each dish is 20 feet in diameter and operates in the microwave frequencies, and the plan is to bring the total number of dishes to 350.

The ATA will be able to listen to 100 million channels at one time. A favorite spot to contact extraterrestrial life is the cosmic water hole, which is between one and 10 GHz wavelength. At these wavelengths, you are not bothered by galactic noise or noise from the Earth.

Besides looking for signals from aliens, they will also be conducting research, looking for dark matter, trying to detect gravity waves, studying active galaxies, among other astronomical projects.

The second project is the Murchison Wide-Field Array, which is a collaboration between Harvard University, MIT and the Australia's Commonwealth and Industrial Research Organization.

The estimated time of completion will be in 2009, when the array of 8,192 micro wave antennae will be connected by computer to perform like a single 88,200 square-feet radio telescope in a radio quiet region of western Australia.

Besides looking for alien radio signals, the array will also study the sun, pulsars, supernovae and x-ray binaries. It has been calculated that the MWA could detect alien signals out 75 light years, an area that includes 1,000 of the nearest stars.

Computers and other electronic equipment have greatly improved, making the sensitivity of the radio telescopes much better, but it is still an iffy situation.

The extraterrestrials have to be broadcasting and we have to be listening to receive the message. The message could be a coded one such as pie (3.1415) or a series of pulses just to get our attention.

If we were to receive a message from a nearby star, say four light years away, it will take four years to send a message back, and they will have to be listening. This is what makes the communication with extraterrestrial so tough.

Just think, if we do receive a message, then it will be the greatest scientific feat, and we will never look at the sky the same way again, knowing that we will know we are not alone.

Jim Honeycutt is an instructor of astronomy at Oxford College of Emory University.