Thursday, January 29, 2015

Life in the universe may be very old, as rocky planets existed much earlier than thought

Did they enjoy that summer 4.6 billion years ago?
Kepler 444, a newly discovered star, and its five rocky planets are 11.2 billion years old. For comparison, the Universe was born at the Big Bang 13.8 billion years ago while our Sun and Earth are around 4.6 billion years old. The solid planets orbiting Kepler 444 are proof that this type of planets were already there in the very early days of the universe. Extraterrestrial life may, therefore, be much more ancient as it had more time to try to emerge and evolve on suitable planets. Consequently, civilizations might have already existed billions of years before our species' appearance in East Africa 200,000 years ago. Where will humanity be in another 200,000 years? In 11.2 billion years...?

The Old Ones were already ancient when the Earth was born. Five small planets orbit an 11.2 billion-year-old star, making them about 80 per cent as old as the universe itself. That means our galaxy started building rocky planets earlier than we thought.

"Now that we know that these planets can be twice as old as Earth, this opens the possibility for the existence of ancient life in the galaxy," says Tiago Campante at the University of Birmingham in the UK.

NASA's Kepler space telescope spotted the planets around an orange dwarf star called Kepler 444, which is 117 light years away and about 25 per cent smaller than the sun.

Orange dwarfs are considered good candidates for hosting alien life because they can stay stable for up to 30 billion years, compared to the sun's 10 billion years, the time it takes these stars to consume all their hydrogen. For context, the universe is currently 13.8 billion years old.
"These planets mean it only took the universe a couple billion years to figure out how to build rocky planets, and they've been around for a really long time," says Travis Metcalfe at the Space Science Institute in Boulder, Colorado. While Kepler 444's planets are too hot for life, its age suggests there might be cooler, older worlds elsewhere. "If life needs a long time to develop or lots of places to try to develop, having rocky planets this early in the history of the galaxy means planets with advanced civilisations should be everywhere."

"These are all little bits of good news," says Andrew Howard at the University of Hawaii at Manoa. "There are still a lot of other hurdles life would have to overcome, but now we're seeing evidence that small planets are common, and here we have one from when the Milky Way was a kid and it was already forming probably rocky planets."

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