Ancient Planets

Kepler 444 is an old star, of spectral class K0, 117 light years away in the constellation Lyra. Recently researchers determined it has a planetary system. The five planets are between Mercury and Venus in size. All are closer to Kepler 444 than Mercury is to our sun, so they're too hot to be habitable. Nevertheless it's interesting that such an ancient, metal poor star has such a retinue. Kepler 444 is around 11.2 billion years old. Generally, it was thought that stars of that age, known as Population II, are too lacking in heavy elements to have terrestrial planets.

Of the five planets, the four nearest their star, known as Kepler 444b, c, d and e, are roughly Mars-sized. Kepler 444b is the smallest, with about 40% the diameter of Earth. Kepler 444c is slightly larger--.497%. Kepler 444d is slightly over half (.53) Earth's diameter. Kepler 444e is around the same size as d--.546.

These worlds are almost certainly bereft of volatiles. The only exception may be polar ice, in perpetually shaded craters. Inasmuch as Mars, with 53% Earth's diameter, can barely retain an atmosphere even at 1.5 AU from the sun, all Keplerian planets probably resemble the moon or Mercury.

Kepler 444f is the largest, with a radius about 74% that of Earth. It is smaller than Venus (95% Earth's diameter) and essentially as desolate as the others. Nevertheless, it might've been habitable had it been orbiting its star at a greater distance.

A key lesson of the Keplerian system is that rocky planets of reasonably large size had already begun forming just 2.5 billion years after the Universe began. Kepler 444 and its planets are 80% the age of the Universe. Conceivably, a habitable planet already existed 11 billion years ago. If life began that early, by now it could be six billion years ahead of us. We should assume contact will be made by them, via technological means we can scarcely grasp. The UFO phenomenon is precisely what the latest knowledge predicts. SETI, not UFOlogy, should be disparaged. The probable existence of ancient Earths should lead us to expect aliens arriving here, exhibiting the most astonishing capabilities. For several decades, this has in fact been observed.

Most Keplerian planets are diminutive like Mars, above. But remarkably, one approaches Earth's size even though it's 11 billion years old.