The signal was like nothing Abel Méndez had ever seen. It had the same frequency as radio emissions from satellites, but it pulsed like it came from something much more distant. It appeared only when Mendez and his colleagues had their telescope pointed at a single star — an unassuming red dwarf called Ross 128 just 11 light-years away.

It presented a mystery within a mystery, said Méndez, a planetary astrobiologist at the University of Puerto Rico at Arecibo. First, did it originate in space, on the ground, or somewhere in near-Earth orbit? And second, wherever it came from, what could have produced it?

After spotting the strange signal in May, Méndez did what a good scientist always does: He took a closer look. He sought the advice of experts, asked other observatories to watch for the signal and applied for more telescope time in hopes of detecting the pulses again.

Here's what he didn't do: speculate that it's aliens. But after he described the signal in a brief blog post last week, “that's all anyone wants to know about,” Méndez said with an exasperated laugh. “I have that experience even with my family.”

The impulse to attribute any odd astronomical phenomena to extraterrestrial intelligence is so compelling it's practically its own law of physics. But jumping to “aliens” at the slightest mention of a strange signal kind of misses the point, Méndez said. Not everything has to come from aliens to be important.

On Friday, Méndez and his colleagues got confirmation that the emission — which they called the “Weird! signal” in tribute to the “Wow! signal” that's been unexplained since 1977 — was nothing out of the ordinary. Follow-up observations revealed that it most likely comes from a geostationary satellite — a craft with an orbit that matches the rotation of the Earth, so that it appears motionless in the sky.

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