A team of scientists has found what they claim is the oldest Earth-sized planet in the Milky Way, hinting at the possibility of ancient life elsewhere in our galaxy.
Dr. Tiago Campante, an Asteroseismology Research Fellow at the University of Birmingham (UK) who led the research team, presented their findings at a symposium in France earlier this year. The work centered on a system of five terrestrial-sized planets observed by the Kepler space telescope transiting the star KOI-3158, about 117 light years from us in the constellation Lyra.
KOI-3158 is actually part of what's called a hierarchical triple system including two smaller M dwarf stars. Kepler observed the five Earth-sized planets transiting the larger primary star, KOI-3158, which Campante says makes it the closest and brightest multi-planet system detected so far by Kepler.
But perhaps more interesting is the fact that the star system is estimated to be 11.2 billion years old, give or take 900 million years or so. "Which makes KOI-3158 the oldest known system of terrestrial-size planets," Campante told the symposium audience in the video below.
For some perspective, our own sun and solar system is believed to be less than 5 billion years old.
The planets circling KOI-3158 are also familiar in terms of their size, with the innermost being about the size of Mercury, followed by three Mars-sized intermediate planets and a fifth and largest planet that is bigger than the other four, but a bit smaller than Venus.
This system is far from being a total doppelganger for our own, however. It is super compact, with the planets' orbits around KOI-3158 as short as under 10 days. In fact, the orbits of all five planets would fall well within the orbit of Mercury around our own sun if you were to overlay the systems on top of each other.
Campante notes that KOI-3158 is an iron-poor star, and that stars hosting small planets tend to be more diverse in terms of their chemical composition than stars hosting giant planets, which tend to be metal-rich.
"That implies that Earth-sized planets may have readily formed at earlier epochs in the universe's history when metals were more scarce," he explains. "KOI-3158, a system of terrestrial-sized planets, formed when the universe was less than 20 percent of its current age, so that suggests that Earth-sized planets may have formed throughout most of the universe's history, leaving open the possibility for the existence of ancient life in the galaxy."
Of course, it's tough to say for sure what the odds are that the planets around KOI-3158 and others like them host life, without knowing more about their atmospheres and composition. But just knowing that planets of a similar size to Earth may have formed billions of years before our own sun changes the game a bit.
If the conditions for life exist on such ancient planets, those lifeforms may have had a few billion years headstart on us to become intelligent and even technologically advanced. They may have even had enough to time to evolve, develop advanced technology and wipe themselves out in a scenario fit for many an apocalyptic science fiction epic. Heck, they may have come and gone before our solar system was even born.
Upcoming advanced telescopes like NASA's Transiting Exoplanet Survey Satellite (TESS), the ESA's Planetary Transits and Oscillations of stars (PLATO) and others based on the ground may provide the needed observations to sketch out the history of ancient life in the galaxy, if it exists.
The findings from Campante and his team have been submitted for publication in The Astrophysical Journal. You can watch his full talk about KOI-3158 below.