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This is a Golden Age of astronomy

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This article, written by Penn State astronomer Jason Wright, originally appeared in the Centre Daily Times (CDT) on 13 April 2012 in the bimonthly "Focus on Research" column, which highlights different research projects being conducted at Penn State.
This is a Golden Age of astronomy

Artist's concept of a red dwarf and its three planets discovered by NASA's Kepler mission. Credit: NASA/JPL-Caltech

Did the universe have a beginning? When was it, and what was it like? What are the stars? How distant are they? Why do they shine? How and when did the Earth form? Are there other worlds like Earth in the universe? Do they, too, have life?

We are living in a Golden Age of astronomy, where some of the oldest and most profound questions of philosophy -- long thought unanswerable -- are finding resolution.

The Apollo era created new interest and capabilities to answer these questions, and our next forays into the solar system led us to Venus, Mars and Jupiter's moon, Europa. Our searches there have led to a scientific bounty, but also mild philosophical disappointment: so far, there is no sign of life on these worlds, or even conditions where much life from Earth could thrive.

Astronomers have not given up on these nearby bodies as potential hosts for life, but in 1992 a new avenue of discovery opened when Alexander Wolszczan, now an Evan Pugh professor of astronomy and astrophysics at Penn State, discovered planets orbiting the distant corpse of a burnt-out star -- the first "exoplanets" ever found outside our own solar system. Three years later, a Swiss team led by Michel Mayor, an astrophysicist and professor emeritus at the University of Geneva, discovered a giant gas planet like Jupiter orbiting scorchingly close to a nearby star. The methods that professors Wolszczan and Mayor helped to pioneer rapidly led to the discovery of many more of these distant planets. Over the next five years, the number of known exoplanets would approach 40 and astronomers would begin to measure the sizes and compositions of these alien worlds.

The promise of research for finding Earth-like exoplanets has been realized rapidly over the past decade. Ever-smaller and balmier exoplanets have been continuously discovered in systems reminiscent of our own solar system. The past few years have been especially exciting, as the first exoplanets have been directly imaged, and exoplanets not much larger than Earth have been detected around the nearest stars.

The Kepler spacecraft has discovered thousands of exoplanets throughout our galaxy. As astronomers pore over this bounty they hope, and cautiously expect, to find the sort of exoplanet Kepler was specifically designed to reveal: an Earth-sized body (a "terrestrial planet") around a sun-like star with an orbital distance implying a surface temperature compatible with liquid water ("within the habitable zone"). This discovery may be only months away.

And what of life? The search for extraterrestrial intelligence has been scouring the skies for radio and other signals for decades, but so far has not found, or at least not recognized, anything resembling alien intelligence.

Astronomers will not be able to image the surfaces of the newly discovered exoplanets for decades, so they cannot search for signs of civilizations, but most astronomers don•t expect alien life to necessarily be technological. After all, it took intelligent, space-faring life on Earth -- us -- more than 4 billion years to evolve from single-celled organisms, and for all we know that lucky accident could have been an extraordinarily unlikely one. Intelligent, space-faring aliens may be rare in our galaxy, but alien "slimes" or "molds" may be common -- and perhaps they are as close as under some Martian rocks or in the under-ice seas of Europa.

So astronomers and biologists also have been attacking the problem from the other end, joining forces in the field of astrobiology. Astrobiologists study the most primitive lifeforms and biochemistries on Earth to determine the parameters and materials required for the genesis of life as we know it. They then apply this understanding to what we can learn of bodies in our solar system and the known exoplanets, and to the search for the signatures and conditions of primitive life there. If "slime" is common, astrobiologists will tell us how to detect it.

Whatever the next 20 years of astrobiology and exoplanetary science brings, it likely will come at an even faster pace, and with even more profound philosophical implications, than what we have learned since those first, strange objects were discovered by Wolszczan 20 years ago. Stay tuned.

Jason Wright, shown in 2009Jason Wright is an assistant professor of astronomy and astrophysics at Penn State. His blog, AstroWright, can be found here.

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