This artist's illustration represents the variety of planets being detected by NASA's Kepler spacecraft. Scientists now say that one in six stars hosts an Earth-size planet.

Are we alone in the universe? The ultimate question of life beyond Earth and the solar system takes center stage in a science conference led by the Vatican Observatory and a University of Arizona this week.

Nearly 200 scientists are attending the conference, called "The Search for Life Beyond the Solar System: Exoplanets, Biosignature & Instruments," which runs from March 16 through 21 in Tucson, Ariz. The Vatican Observatory is co-hosting the conference with the University of Arizona's Steward Observatory.

"Finding life beyond Earth is one of the great challenges of modern science and we are excited to have the world leaders in this field together in Tucson," said event co-chair Daniel Apai, assistant professor of astronomy and planetary sciences at the UA Steward Observatory, in a statement. "But reaching such an ambitious goal takes planning and time. The goal of this meeting is to discuss how we can find life among the stars within the next two decades." [9 Exoplanets That Could Host Alien Life]

According to the organizers, the conference will cover the technical challenges of finding and imaging exoplanets and identifying biosignatures in the atmospheres of far-flung worlds. Other presentations will discuss the study of life forms that live in extreme environments on Earth, which could be apt analogs for life on other planets.

The Habitable Exoplanets Catalog now list a dozen object of interest as potentially habitable worlds with the addition of two planets, Gliese 667C e and f (Gliese 667C c was known since early 2012). Image released June 25, 2013. (Image credit: PHL @ UPR Arecibo)

The conference is not open to the public, but NASA's Astrobiology Institute will broadcast a live feed of the sessions. You can learn more about the conference via its website: http://www.ebi2014.org/

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