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Catching a Glimpse of Alien Worlds
Since the first exoplanet was discovered in 1992 astronomers have found thousands of planets around nearby stars. These planets take a variety of forms, from gas giants bigger than Jupiter to rocky worlds that may be similar to Earth. Our knowledge of many of these planets remains limited, but over the next decade a series of newly constructed space telescopes will start to reveal their secrets.
An exoplanet is defined as any planet that is not one of the eight planets orbiting our own Sun. The small size of most planets, together with the vast distance to other stars, makes exoplanets very hard to detect. Despite centuries of speculation, the first exoplanet discovery was not confirmed until the early 1990s. Techniques for finding exoplanets have been refined since that first discovery, and nowadays the detection of exoplanets has become almost routine, with more than 4000 exoplanets now catalogued, and many thousands of potential discoveries waiting to be confirmed.
The first exoplanets to be found belonged to a class that became known as “Hot Jupiters”. These gas giants are many times larger than the biggest planet in our own Solar System, Jupiter, but orbit extremely closely to their stars. No life could possibly exist on these boiling worlds, but their gigantic sizes, and rapid orbits, makes them easy to detect.
