The Kepler space telescope has detected the first distant solar system containing more than one planet. One of these five Earth-sized planets orbits inside a habitable zone, meaning that liquid water could exist on its surface and potentially support life.
This discovery is consistent with the Kepler telescope’s mission since its launch in 2009: to search for Earth-like planets throughout the universe. After suffering a mechanical breakdown in 2013, technicians repurposed the satellite and continued its use. According to NASA, it performs its work by scanning the stars and measuring their light levels every few hours, searching for signs of habitable planets. In 2014, the satellite discovered the most Earth-like planet yet found, and this recent discovery has put the orbital telescope back in the news.
These planets orbit the star named Kepler 444, which lies 177 light-years from Earth. By measuring the light pulses from the star, researchers concluded that the star is about 11.2 billion years old, making it one of the oldest stars in the entire galaxy and the oldest known solar system. According to the Astrophysics Journal article in which this research was published, this shows “that Earth-size planets have formed throughout most of the universe’s 13.8-billion-year history, leaving open the possibility for the existence of ancient life in the galaxy.”
Charles Sobeck, the project manager for NASA’s Ames Research Center added, “We are delighted to see the enthusiastic response for [the mission]. The mission has extended the telescope’s search capability to a new part of the sky, marking the first … exoplanet discovery less than a month ago, and now the possible discovery of the first … multiple-planet system.”
Kepler 444 and its planetary system differ in important respects from our home solar system. For instance, the star is only 3/4 the size of the sun, and the planets observed compare in size to Mercury and Venus. Size is not the only difference; Kepler 444’s surface temperature is around 700 degrees Celsius lower than that of our sun. Despite that, the discovered planets are much closer to Kepler 444 than Mercury is to our sun, meaning they are all much warmer than the Earth. According to Ian Sample of The Guardian, each planet has a year that is shorter than 10 Earth days.
The implications of this discovery are difficult to judge but simple to define. Though none of this new information necessarily implies the existence of extraterrestrial life, the increasing evidence of Earth-like planets beyond our solar system points to its likelihood being much higher than commonly supposed. As Christopher Crocket of Science News reports, “Because planets form at the same time as the stars they orbit, the discovery implies that the universe has been churning out rocky planets throughout its entire history, providing ample time for alien life to develop and perhaps flourish.” As Kepler’s mission continues, scientists continue to probe these issues looking for evidence of life beyond our Earth.