Are we alone?
It’s a question that humanity has asked itself for hundreds of years, perhaps thousands.
Look up at the night sky at a dark location and you’ll see millions of stars. Those are millions of suns that could possibly be shedding their life-giving light on other planets.
On June 25, the European Southern Observatory (ESO) revealed that the star Gliese 667C — a star that is part of a triple-star system 22 light-years away in the constellation Scorpius — had a six-planet system. Three of these planets orbited in the habitable zone, an area that astronomers believe is the most conducive to life.
Previous studies of the star found that only three planets orbited the star. However, a team of astronomers re-examined the system, adding data from other observations, the ESO’s Very Large Telescope, the Keck Observatory, and the Magellan Telescopes.
“We knew that the star had three planets from previous studies, so we wanted to see whether there were any more,” said astronomer Mikko Tuomi, of the University of Hertfordshire, United Kingdom. “By adding some new observations and revisiting existing data we were able to confirm these three and confidently reveal several more. Finding three low-mass planets in the star’s habitable zone is very exciting!”
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But does that mean that there are other people looking back at us?
In this case, maybe.
The habitable zone surrounding a star has been deemed the “Goldilocks zone”: it is the ideal place for water and therefore life to develop. (It should be added that this is life as we know it, as there could be other forms of life unknown to us.)
To date there have been almost 900 confirmed planets around almost 700 stars. There are still 3,216 more Kepler candidates and confirmed planets (named for the Kepler mission that scans for possible exoplanets) and almost 3 million others to be confirmed.
So what’s the big deal about Gliese 667C?
What makes the planets surrounding Gliese 667C so exciting is that these planets that orbit in the Goldilocks zone are super-Earths, planets more massive than Earth, but less massive than Uranus and Neptune. The planets around Gliese 667C orbit much closer to the star than we do to the sun — almost at Mercury’s orbit. It may seem like life on a planet that orbits so close to a star would be unlikely to hold water, what we believe to be necessary to life. However, Gliese 667C is much cooler and dimmer than our sun.
This makes Gliese 667C the first system where such a low-mass star could host rocky planets in the habitable zone.
Though there are potentially millions of planets which lie in the Goldilocks zone surrounding stars, not all of them hold the promise of having water or life. And even if they do hold that potential, it would be hundreds or perhaps thousands of years before we could send and receive a signal to any other intelligent life that may exist. In the case of Gliese 667, however, that message time is cut down to just 22 years one-way. But, that, of course, begs the question: Would we want to?
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