By Caroline Binley
92,955,807 miles above Earth, the Kepler Space Telescope orbits our planet and observes light from close to 150,000 stars. Astronomers turn data from Kepler into graphs of light given off by celestial bodies over time. These graphs are called light curves.
For a better understanding of light curves, give the NASA graph (left) a glance. Position one shows a planet before it passes the star it orbits. In this position, Kepler observes the star’s normal brightness. In position two, the planet stars to pass between Kepler and the star. As a result, Kepler perceives less of the star’s light. In position three, the planet blocks as much of the star’s light as it can, and the lightcurve dips even further. Scientists work backwards from the low points they see on these graphs in order to identify exoplanets.
Exoplanets are planets outside our solar system. They either orbit other stars or travel the universe without a host star. So far, we’ve only confirmed 1,827 exoplanets, but astronomers have thousands more candidates to consider.
Zooniverse — a portal to citizen science projects ranging from physics to humanities — hosts Planet Hunters, which allows users to help find exoplanets through lightcurve analysis. But why do we care about finding these planets?
If nothing else, it’s cool. From dreaming up constellations to watching “Star Trek,” humanity has demonstrated its stargazing curiosity countless ways. Now we’re finally able to explore — at least from a distance — the worlds we’ve so long dreamed of. That’s my first, unabashedly geeky answer.
But of course, not everyone is so easily fascinated by these planets. Beyond wow factor, exoplanets are key to our understanding of how our Earth and solar system function. The eight planets that orbit the Sun make up a small datapool. As a result, there’s knowledge we have to look beyond our solar system to gather.
Exoplanets are often at different stages in their life cycles than Earth, and the solar systems they make up have different characteristics than our own. This diversity has taught us how our solar system could have looked. Some stars host larger planets, some have their planets distributed differently, and yet others have planets with more distinctly elliptical orbits. This diversity also teaches us about solar system formation. For example, solar systems with Jupiter-sized (big) exoplanets near host stars confirmed the theory that planets move during formation.
And, of course, exoplanets propel us towards answering what many consider the ultimate question: are we alone in the universe? We don’t yet have the technology to search for exoplanetary life, but that that doesn’t mean that life isn’t out there. As we start to measure which planets are habitable (since we don’t have a better way to define “habitable,” I just mean Earth-like) our search will narrow, and we might even be able to answer that ever-looming question.