科学美国人60秒:Five Rocky Planets Found In Ancient Distant Solar System @sciam Space podcast by @ClaraMosk

Like Dr. Evil in the Austin Powers movies, our solar system appears to have its own mini-me. Astronomers have discovered that the sun-like star Kepler-444 has five rocky planets orbiting it that range from about Mercury’s size to that of Venus. The planets are bunched in close to their star, making it a miniature version of our solar system—and one that’s much, much older. The finding is in the Astrophysical Journal. [T.L. Campante et al, An Ancient Extrasolar System with Five Sub-Earth-size Planets]
 
Kepler-444 and its planets formed some 11.2 billion years ago, when the universe was less than one-fifth its current age. That date makes this system the oldest group of terrestrial worlds known.
 
The discovery tells scientists that rocky, Earth-like planets were forming very early in the history of the universe, and under conditions quite different than when the sun and its planets were born just 4.6 billion years ago.
 
Astronomers detected the planets using the Kepler telescope, which measures the slight dimming of a star’s light caused by orbiting planets passing in front of it. A second technique called asteroseismology—the measurement of tiny oscillations in the star’s brightness—revealed Kepler-444’s size, mass and impressive age, which researchers say provides billions of more years for ancient extraterrestrial life to have taken hold somewhere out there.
 
—Clara Moskowitz
 
(The above text is a transcript of this podcast)