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    Science in Mind

    Earth-sized planets really not that rare, team finds

    An artist’s rendering illustrates a variety of planets detected by NASA. A new analysis determined that one in six stars hosts an Earth-sized planet within the Milky Way.
    An artist’s rendering illustrates a variety of planets detected by NASA. A new analysis determined that one in six stars hosts an Earth-sized planet within the Milky Way.

    It was a major feat last year when a team of astronomers announced it had detected two Earth-sized planets circling very close to a star called Kepler-20, which is 950 light-years away. Now, scientists say that such planets are not uncommon at all — one in every six stars has an Earth-sized world.

    A team from the Harvard-Smithsonian Center for Astrophysics announced the new result last Monday at the meeting of the American Astronomical Society in Long Beach, Calif. The 17 billion Earth-sized worlds scientists say are lurking in the Milky Way are so close to their stars that they would be far too sweltering for life, at least as we know it.

    The data may also fuel just a little bit of wonder for anyone gazing up at night, because the scientists predicted that at least 70 percent of stars have a planet, whether it is a small rocky planet or a gas giant.


    “Every time you look at the night sky, [virtually] each star you’re looking at has a planet. It will have a planetary system,” said Francois Fressin, a Harvard astronomer who led the new study. “It’s quite amazing.”

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    Scientists use NASA’s Kepler telescope to detect planetary transits — a momentary dimming in a star’s light as as a planet passes between the star and the telescope.

    But each wink of light is not necessarily a planet, so scientists must confirm observations by study.

    Fressin did scientific simulations of the kinds of astrophysical phenomenon that could give rise to false signals when seen by Kepler to see how many false detections were likely, and found false signals could account for only a small fraction — 10 percent — of the signals.

    In the next few years, Fressin said, scientists will begin to get enough data to detect Earth-sized planets in orbits around their stars. That means they are inching closer to “Goldilocks” worlds that would be not too hot, not too cold, and just the right size for life.

    Responsive polymer has lots of potential


    The goal was to build a material that could be used to stimulate muscles if a person’s nerves were damaged or lost. It was one part of a broader effort in the large Massachusetts Institute of Technology laboratory run by Robert Langer to engineer devices and tissues that could be useful in biomedical applications.

    But science doesn’t always follow directions.

    In April 2011, Mingming Ma, a postdoctoral researcher, picked up a a thin, black film that he had just synthesized to take a closer look. To his surprise, it started writhing around.

    Ma had accidentally designed a polymer that changed shape when exposed to trace amounts of moisture, such as a sweaty palm.

    Ma walked into Langer’s office, moistened a small patch of the black film, and placed it in Langer’s hand. It proceeded to do the equivalent of a gymnastics routine.


    “It started doing somersaults and stuff like that,” Langer said. “We knew this was something very different.”

    The team reported Thursday in the journal Science the details of its water-responsive film, which curves, buckles, and backflips as it absorbs water, which then evaporates.

    Although the researchers freely admit they don’t exactly know how such a material could ultimately be useful, they put forth all kinds of possibilities.

    In the paper, they use a circuit that converts mechanical energy (such as a polymer that squirms) into electricity to create a possible power source for miniature devices.

    They also think it could be used as a sensor that detects water, or to do mechanical work, like an artificial muscle.

    Christian Santangelo, a physicist at the University of Massachusetts Amherst who has worked on designing polymers that change shape, said this sort of behavior used to be seen as imperfections.

    “Most people think of that kind of process as being the gunk you get on the edge of a sample. It wrinkles, the shape changes at the edge of a sample, and people haven’t been focusing on it,” Santangelo said. “It turns out that polymer chemistry has advanced to a point where we can control how the growth happens and use that to actually tune the shape of the stuff you get.”

    Langer said that although his laboratory has demonstrated using the polymer as a way of producing electricity, he’s not sure that would be the best use. He’s looking forward to seeing what people who read his paper propose.

    “I doubt that we have figured out the best application,” Langer said. “When people read it, they’ll think of other applications.”

    What’s laboratory life really like? Check out Twitter

    Over the past week, a Twitter science hashtag has gone viral: #overlyhonestmethods.

    Twitter trends are hard to predict, but who would have guessed that a sort of silly, sort of cynical, sort of hilarious riff on how science is actually practiced in a lab would take off?

    For those who don’t work behind the bench, the Methods section of a scientific paper is supposed to describe how a study was done. But these descriptions are often a pat, perfect version of events that may tell little.

    I rounded up a few Tweets tagged #overlyhonestmethods from people who self-identify on Twitter as being from New England. Enjoy!

    @NAChristakis (Twitter handle of Dr. Nicholas Christakis, the well-known Harvard researcher whose highly-publicized and sometimes controversial work suggests traits such as obesity, smoking, and happiness are contagious) writes: “We added needless extra math to our paper because this impresses people.”

    @p_maverick_b, a synthetic biologist based in Boston, tweets: “Scientists are pressured to sugarcoat our methods because we value career advancement over reproducibility #overlyhonestmethods #buzzkill.”

    @boldtetrahymena, a molecular biologist in Cambridge, wrote: “The research in our lab is supported by NIH and Mary’s grandmother who donated a microwave” #overlyhonestmethods.”

    Carolyn Y. Johnson can be reached at Follow her on Twitter @carolynyjohnson.