E.T., Are You Home?

Astronomy has a long history of supposed sightings of space aliens. In the late 19th century, American astronomer Percival Lowell reported seeing canals on Mars and concluded that intelligent extraterrestrials must’ve dug them. In 1967, when British researchers spotted a powerful, pulsating source of radio waves, they speculated that it was a beacon from an alien civilization. They even dubbed the source LGM-1, for Little Green Men. Within months, though, the researchers discovered a second pulsating signal and realized it was a natural phenomenon, a rapidly rotating remnant of a dead star. It was renamed the pulsar.

Now astronomers have focused on a new mystery, a strangely behaving F-type star — slightly larger and hotter than our sun — that has revived speculations about extraterrestrial intelligence. Known by its formal designation KIC 8462852, the star is located almost 1,500 light-years from Earth. It’s one of the more than 100,000 stars observed by the Kepler Space Telescope, the NASA probe that measured the intensity of their light from 2009 to 2013 to see if any planets orbited them. If a planet passes directly in front of a star, it blocks a small fraction of the star’s light, enabling scientists to estimate the size of the planet and its orbit. Scientists are still analyzing Kepler’s observations, but they’ve already confirmed the presence of more than a thousand distant planets, including some that might harbor liquid water — and perhaps life.

Last fall, however, a team of researchers led by Tabetha Boyajian of Yale University found that KIC 8462852 was dramatically different from all the other stars monitored by Kepler. The intensity of its starlight plummeted several times over the four years of observations, dropping 15 percent at one point and 22 percent at another. These stellar brownouts were far more severe than —> Read More

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