Strange star observations still a mystery to astronomers

This illustration shows a star behind a shattered comet. This is likely what astronomers were observing with the star KIC 8462852. NASA/JPL-Caltech

Do you remember in October when a mysterious star had scientists talking about “aliens”? The star erratically dimmed in ways that astronomers hadn’t before seen, which lead some to entertain the idea that perhaps it was not a natural occurrence, but rather a manufactured one.

Well, it turns out the explanation for the bizarre observations is indeed more astronomical in nature: a swarm of comets.

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Originally, astronomers were perplexed by the strange light curve the star was emitting. When looking for exoplanets — planets orbiting other stars — one method scientists use is to watch a star to see if anything causes its light to dim (this is an extremely small measurement — unseen to the human eye). Typically, if there is a planet passing in front of a star, it does this on a regular basis.

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A example of a Dyson ring, similar to a Dyson sphere, which could collect energy from a star. Wikimedia Commons/Vedexent

But for star KIC 8462852, astronomers were puzzled by the irregularity and strength of the dimming. Typically a large, Jupiter-sized planet dims a star by about one per cent. The light of this star was dimmed by some 20 per cent.

Using the break-up of a comet as a theory, astronomers used NASA’s Wide-Field Infrared Survey Explorer (WISE) to search for any heat signature given off in the way of infrared light — but found none (collisions give off heat in this manner).

While more measured reasons were considered — such as a family of comets, asteroids or even a planet — another possibility that was thrown into the mix was that it was something similar to a Dyson sphere that could be constructed to collect the energy of a star, ie. aliens.

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Recently, NASA turned its Spitzer Space Telescope to the star to once again search for this infrared emission, but failed to find anything significant.

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One theory is that the dip in light emission is due to a family of cold comets that have a very long eccentric orbit. And at the end of that trail would be something very large which caused the original observation in 2011. Then, in 2013, the rest of the debris would follow, once again causing the dip.

While it’s fun to entertain the idea of an alien civilization out there, scientists still believe there is a high probability that it’s something natural we simply haven’t seen before, noting that pulsars — rapidly rotating stars that give off regular radio impulses — were once considered to be caused by aliens. When the first one was discovered, it garnered the name LGM-1 — as in “Little Green Men-1.”