In 2018, something remarkable happened. The Kepler Space Telescope, a veteran observer of the cosmos, captured data that unveiled the presence of three exoplanets. It may come as a surprise that these celestial bodies remained hidden until now, long after the telescope had retired from its mission.
The Kepler Space Telescope was launched in 2009 with a crucial objective in mind: to seek out new worlds. Over its impressive nine-year lifespan, Kepler detected more than 2,600 exoplanets, some of which exist within the “Goldilocks Zone.” This special region around a star provides conditions that might be suitable for supporting life.
Unfortunately, in October 2018, Kepler’s fuel ran out, and its mission came to an end. However, the treasure trove of data collected by the telescope still holds cosmic secrets. Just recently, a team of astronomers announced their discovery of three planets that were observed by Kepler right before it was retired. Their findings were published in the Monthly Notices of the Royal Astronomical Society.
These planets were observed during the final series of observations known as K2 Campaign 19. As Kepler reached the end of its journey, it became increasingly unstable, making it challenging to obtain clear data from its targets. Despite this, a week of high-quality data was obtained during K2 Campaign 19, proving the value of continuing Kepler’s mission until the very end. The research team stated in their paper that “these discoveries demonstrate Kepler’s exoplanet detection power, even when it was literally running on fumes.”
The team received assistance from the Visual Survey Group, a dedicated community of citizen scientists who meticulously examined the light curves from stars observed by Kepler during the campaign. Variations or dips in the light curve are often indicative of a passing celestial body, such as an exoplanet. Other space missions, like the TESS spacecraft, employ a similar method to hunt for exoplanets.
It’s important to note that Kepler did not directly observe the planets themselves, at least not with great detail. Instead, the astronomers noted three stars that experienced temporary dimming from Kepler’s perspective, suggesting that they had been transited by orbiting bodies. Two of these bodies were confirmed to be exoplanets, while the third is still under consideration as a potential exoplanet.
The confirmed planets are described as “hot mini-Neptunes” by MIT News, meaning they are a few times larger than Earth and orbit very close to their host stars. These worlds reside approximately 400 light-years away from us. The candidate planet, which is larger than Earth by almost four times, is situated at a more distant location, approximately 1,200 light-years away.
“These are the last planets observed chronologically by Kepler, but every bit of the telescope’s data is incredibly valuable,” said Elyse Incha, lead author of the study from the University of Wisconsin at Madison. “We want to make sure none of that data goes to waste because there are still many discoveries to be made.”
As Kepler bids farewell, its legacy lives on through the James Webb Space Telescope. Continuing the search for exoplanets near and far, this successor to Kepler is poised to deepen our understanding of the diversity and prevalence of worlds beyond our solar system. The quest for habitable worlds remains a top priority for scientific exploration, as emphasized in the latest decadal survey by The National Academies of Sciences, Engineering, and Medicine.
In the vastness of space, Kepler’s final days shed light on hidden treasures. These newfound exoplanets remind us that the pursuit of knowledge knows no bounds, and there are countless wonders waiting to be discovered beyond our own celestial neighborhood.