Scientists have discovered over five thousand planets outside our solar system and they are unlike any of the planets we have come to know.
While we are small organisms living on planet Earth, we may not consider the other planets beyond our system. Scientists have discovered over five thousand planets outside our solar system and they are unlike any of the planets we have come to know.
What are Exoplanets?
Short for “extrasolar planets,” exoplanets are planets that are located outside our solar system. Exoplanets vary in size and most tend to be gas giants that are larger than Jupiter, or small, rocky planets that are relatively similar to Mars. On the contrary, many exoplanets have their own terrain characteristics that make them stand out from other planets. Temperatures range from a hot climate, hot enough to boil metal, or stuck in a deep freeze. A great percentage of exoplanets could be very similar to our planet, Earth, as well. With rocky surfaces and liquid water, these exoplanets may be able to support life.
Many exoplanets uniquely stand out on their own. Some of the most common exoplanets that scientists study are “mini-Neptunes,” worlds slightly smaller than Neptune, and “super-Earths,” which are rocky planets larger than the size of Earth. Exoplanets that originally formed around a star and got thrown out of the orbit to drift alone in space, are called “rogue planets.” When exoplanets orbit their star, a “year” can range from a few days to a few decades.
Why do we Study Exoplanets?
For decades, humans have become increasingly curious about life outside of the solar system. Are we truly alone? Or is there life beyond Earth? Before exoplanets were discovered, our perspective towards planets was limited to the eight planets that are present in our solar system. Once scientists discovered that we are only a small fraction of the entire universe, we began to question existence beyond what we know.
The first exoplanet to have a worldly stage, orbiting a star similar to our Sun, was called 51 Pegasi b. It was a “hot Jupiter” planet, orbiting its sun 50 light-years away. Hot-Jupiter exoplanets are giant planets that orbit closely to their star. Since 51 Pegasi b, thousands of exoplanets have been discovered by scientists, revolutionizing our interpretation of the universe. These new “alien” worlds have drastically altered how we think about planets, from how planets are born to how they can potentially host life of their own. With ongoing advancements in technology, we may find an exoplanet that hosts life outside our solar system after all.
Discovering Exoplanets & Looking for Life
Exoplanets can be difficult to see or detect if they have a bright star nearby, but scientists use many techniques to look for signs that the star may have a planet around it. The radial velocity method, used to discover the first exoplanets around Sun-like stars, senses planets indirectly by monitoring the movements of the parent star through the Doppler Effect. This method is a powerful technique that is still widely used by scientists today. In 2009, advancements in technology increased with the launch of NASA’s Kepler space telescope. By using the transit method, which measures a star's brightness over time to see if it has been eclipsed by an orbiting planet, Kepler discovered roughly 3,000 exoplanets.
Since a large number of exoplanets have been discovered, scientists raise the question of their abilities to harbor life, much like our own planet Earth. Earth-like planets could be much larger than our planet, or much smaller, but they hold similar traits of liquid water, rocky surfaces, and an atmosphere that could support life. For a planet to be in its habitable zone, the range of orbits around a star must be a distance where liquid water can exist. If the planet is too far from its star, the water will freeze, and being too close, the water will evaporate. The geology and atmosphere of the planets are significant in harboring life as well, but the rocky terrain tells us a lot about the planets.
In conclusion, scientists at NASA and the European Space Agency (ESA) continue to look for exoplanets that may be able to harbor a life of its own, and some may already have life present. Do you believe there is life beyond our solar system? Based on the research made on exoplanets, a large number have the potential to harbor life as we know it.
The study of exoplanets has transformed our understanding of the universe and has revealed a shocking diversity of worlds beyond our solar system. With increasing technology and knowledge, scientists are moving closer to answering the most profound question in the universe: Are we truly alone?
