Astronomers think our galaxy contains at least 100 billion stars, and perhaps as many as 400 billion.
Centaurus A is immense, perhaps 50 times larger than the Milky Way, home to the Earth and about 100 billion stars.
More than a billion stars blaze bright in a new photo of our Milky Way galaxy snapped by an international team of astronomers.
"Estimating carefully, there are 200 billion stars that host at least 50 billion planets, if not more, " Mikko Tuomi, of the University of Hertfordshire in England, told Space.com via email.
To be seen from the earth they would need to put out a billion times more power even than a supernova (a stellar explosion which, in turn, can outshine an entire galaxy of 100 billion stars).
Astronomers said Wednesday that each of the 100 billion stars in the Milky Way probably has at least one companion planet, on average, adding credence to the notion that planets are as common in the cosmos as grains of sand on the beach.
Mr. Scharf makes vivid the mind-boggling nature of the universe by noting, for instance, that the space between a star like the sun and its nearest neighbor is 30 million times the diameter of the sun itself and that there are 10 billion stars in the universe for every human being who has ever walked the Earth.
But could there be intelligent life in another planetary system, in orbit around one of the 100 billion other stars in our Milky Way galaxy?
The confirmation, based on analysis of 10 billion year-old dying RR Lyrae stars in the Gemini constellation, was done by an international team of astronomers who report their findings in The Astrophysical Journal.
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The cosmos was born in the Big Bang about 13.7 billion years ago, and the first stars in the universe are thought to have lit up about 100 million years afterward, when gas finally gathered in clumps dense enough to collapse under their own gravity and ignite nuclear fusion.
Yet, even roughly Earth-sized planets abound - more recent research suggests that one in six stars has a planet of about Earth's size in an orbit close to their host stars - making for at least 17 billion in our galaxy alone.
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But with a planetary history of over four billion years, the Earth has likely suffered the slings and arrows of exploding stars more than once in past eons.
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We call these stars supergiants and they are 20 times more massive than our own sun and so when these stars go supernova they expand to a radius of up to a billion miles, becoming the biggest and brightest star in the universe.
BBC: NASA's Swift satellite observes massive supernova stars
Science editor Alan Boyle's blog: A simulation based on data from NASA's planet-hunting Kepler mission has determined that about one out of every six stars has an Earth-sized planet, which would translate to at least 17 billion such worlds in our Milky Way galaxy.
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