NASA’s exoplanet hunting Kepler space telescope has encountered a few problems as of late, but there’s still a mountain of data for astronomers to dig through from the last four years. Astronomers analyzing Kepler data recently uncovered something unusual — a solar system about 117 light years away in the direction of Lyra called Kepler-444 with at least five Earth-sized planets. That would be unusual enough, but this planetary system is also extraordinarily ancient at roughly 11.2 billion years.
Astronomers are intrigued by this discovery for several reasons. First, that’s a lot of small rocky planets. Kepler detects alien worlds by the transit method. It watches distant suns for slight dips in brightness that indicate a planet has passed between it and the telescope. These events can be used to calculate the characteristics of the planet, but it works best for larger worlds (super Earths and gas giants). Spotting five planets between the size of Mercury and Venus (basically a little smaller than Earth) is unusual.
Artistic Depiction of Kepler 444 with its Star
The age of Kepler-444 is also something to note. At 11.2 billion years old, the planets orbiting this star were already older than Earth is now when our sun ignited 4.5 billion years ago. The universe itself is only 13.8 billion or so years old, making Kepler-444 one of the oldest stars in the Milky Way. It would have been from the first generation of stars that dotted the sky. Kepler-444 is still very sun-like because it’s 25% smaller and cooler. That means it burns through its nuclear fuel more slowly.
Finding small rocky planets that are billions of years older than Earth suggests that advanced life may have existed in the universe for a very long time. Life on Earth might be very new by comparison. Just think, planets similar to Earth were forming more than 7 billion years before Earth formed, and some of them could have supported life. If other first-generation stars like Kepler-444 have planets, uncountable civilizations could have come into being eons before the first single-cell life appeared on Earth.
The planets orbiting Kepler-444 themselves are not able to support life as we know it. All five planets are packed very close to the parent star with orbits closer than that of Mercury in our solar system. With solar years less than 10 Earth days, they definitely stood out in the Kepler data. The surfaces of these worlds have been baked by the intense heat, reducing any organic material to cinders.
Kepler-444 isn’t a bastion of alien life, but it improves our understanding of planetary formation and points us in a new direction. Astronomers are anxious to find other ancient stars with rocky planets in hopes they might prove more hospitable to life. What if there was still something alive on one of these ancient worlds? That might sound like science fiction right now, but maybe it won’t always be — there’s still a lot of data from Kepler, and future telescopes will improve our ability to spy distant exoplanets.