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Space Topics

Extrasolar Planets


Humans are a planetary race. All of human history took place upon our home planet, and all of human knowledge - religious, philosophical and scientific alike - has been based on our experiences on Earth. Since the dawn of human consciousness, our planet had encompassed the limits of our universe, the boundary of all that we could ever hope to know or have.

But is our world unique? Is it the only one in existence, or are there others – perhaps many others – out there? Do other beings – maybe even intelligent ones – call these worlds their home, and live out their lives completely unbeknownst to us? The questions have been asked repeatedly and persistently through the centuries, but apart from philosophical speculation, no answer was forthcoming.

Then, in 1995, something changed: A group of astronomers headed by Michel Mayor of the Geneva Observatory announced that they had detected a planet orbiting the star 51 Pegasi. For the first time in history, scientists had discovered a new world in the wide expanses of space. Suddenly, the question "are there other worlds out there?" was transformed from a topic for philosophical speculation, to the subject of intense scientific study.

The planet around 51 Pegasi turned out to be a Gas Giant, much like our own neighbor, Jupiter. Indeed most of the "extrasolar" planets discovered since 1995 have been Gas Giants, for the simple reason that the more massive a planet is, the easier it is to detect. Gradually, however, astronomers have found smaller and smaller planets, including icy "Neptunes" and even, possibly, terrestrial-sized planets. Slowly but surely astronomers are closing in on the holy grail of extrasolar planet research: the discovery of another Earth orbiting a distant star.