Discovery of exoplanets-the planets orbiting the stars outside our solar system-one of the biggest revolutions we have had over the last couple of decades, in our understanding of the universe. The first confirmed exoplanet was observed in 1995, and thousands more have been detected since then, significantly expanding our knowledge of planetary systems.
Exoplanets are small, often very different in size and composition, and can be located at many different distances from their parent stars. Others are gas giants like Jupiter; others are rocky, just like Earth. It is a matter of great importance that the Kepler Space Telescope has been the primary tool in these studies, using the transit method where a telescope measures the amount of light dimmed through a star when the planet passes through it. To date, the number of confirmed exoplanets stands at more than 2,300; many more remain candidates waiting to be confirmed.
Possibly the most interesting application of exoplanet research to date is the search for habitable worlds. The habitable zone is often called the "Goldilocks zone" because it represents that region around the star where conditions might be just right for liquid water to exist-presumably a very important component in life. Potentially habitable exoplanets, like Proxima Centauri b, circling our nearest star neighbor have sparked much interest among astronomers and the community in general.
The field of exoplanets as much serves for the purpose of the search for life as that of studying planetary formation and its evolution. Astronomers can know what these distant worlds are made of and what kind of weather they endure through the analysis of their atmospheres using advanced techniques such as spectroscopy. Some exoplanets have very striking features, including extreme temperatures and bizarre manifestations of weather. For instance, WASP-121b is a gas giant, but the atmosphere is too hot to vaporize metals. Some other features of environments in exoplanets would exhibit a diversity of planetary systems.
The implications of exoplanet research go beyond intellectual curiosity: they can also inform the search for extraterrestrial intelligence, SETI. The James Webb Space Telescope will return unprecedented types of insights on distant exoplanets' atmospheres that could reveal biosignatures-changes in chemical composition indicating life.
There are, however, challenges remaining. Since the distances between the stars are so great, even the nearest exoplanets are light years away, and so can never be accessed directly by current technology. Still, with advancing observational techniques, so too does the possibility of unearthing the hidden secrets that these distant worlds hold.
This exoplanet journey can be taken as a new frontier in understanding astronomy and compelling us to imagine some pretty profound questions and elevate our station in the universe. Every finding adds one more knowledge into our repository of the planet system as well as life possibly beyond the Earth. Advancement in technology means that we're going to explore more interesting worlds and further spark our imagination as we continue the pursuit of centuries-old inquiry about the cosmos.
