Tag: Alien Megastructures

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Scientists seek new ways to track technosignatures

Image: Alien megastructure
An artist’s conception shows a crumbling megastructure known as a Dyson sphere orbiting a distant star. Could such structures produce detectable technosignatures? (Danielle Futselaar Illustration)

Could extraterrestrial civilizations leave their fingerprints as chlorofluorocarbons in planetary atmospheres, or the waste heat generated by industrial processes, or artificial bursts of neutrinos or gravitational waves?

That’s what a vanguard of astronomers would like to find out, and they’re hoping to win more support for an approach that widens the nearly 60-year-old search for alien radio signals to include other alien indicators.

Those indicators — which could include anomalous chemicals in exoplanet atmospheres or readings that hint at the presence of alien megastructures — have come to be known collectively as technosignatures. It’s a term that originated with Jill Tarter, one of the pioneers in the search for extraterrestrial intelligence, or SETI.

“When the astrobiology people started talking about ‘biosignatures,’ it just seemed obvious,” Tarter told GeekWire this week at the American Astronomical Society’s winter meeting in Seattle.

Tarter said the term crystallizes the idea that scientists should look for a variety of technological traces potentially pointing to intelligent life beyond Earth.

“We’re really talking about more than just searching for radio signals or optical signals,” she said. “What is it that technology does to modify its environment in a way that we can detect over interstellar distances, and distinguish from what life does?”

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NASA turns to the search for technosignatures

Image: Alien megastructure
An artist’s representation  shows a megastructure known as a Dyson sphere capturing the energy from a distant star. Such a structure could create observable technosignatures pointing to the civilization behind its construction. (Credit: Danielle Futselaar / SETI International)

It’s been a quarter-century since Congress cut off NASA funding for the search for extraterrestrial intelligence, or SETI, but now the space agency is revisiting the topic under another name: technosignatures.

“I’m excited to announce that NASA is taking the 1st steps to explore ways to search for life advanced enough to create technosignatures: signs or signals, which if observed, would let us infer the existence of technological life elsewhere in the universe,” Thomas Zurbuchen, associate administrator for NASA’s Science Mission Directorate, said in a tweet today.

The search is the focus of a workshop taking place this week at the Lunar and Planetary Institute in Houston, with experts on the search for exoplanets, artificial radio signals and other potential pointers in attendance. House Science Committee Chairman Lamar Smith, R-Texas, is due to give a welcome message.

That’s a far cry from 1993, when a congressional effort spearheaded by Sen. Richard Bryan killed off NASA’s 10-year SETI program, which was known as the High Resolution Microwave Survey, or HRMS. “This hopefully will be the end of Martian hunting season at the taxpayer’s expense,” Bryan declared at the time.

Since then, much has changed.

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Alien megastructure? Forget about it, scientists say

Tabetha Boyajian
Astronomer Tabetha Boyajian discusses Tabby’s Star, “the most mysterious star in the universe,” during a TED talk in February 2016 in Vancouver, B.C. (TED via YouTube)

The astronomers who once speculated that an alien megastructure might be responsible for the weirdly fluctuating light from a distant star have now fully ruled out that way-out explanation.

Their conclusion, reported in a paper published today by Astrophysical Journal Letters, is based on a crowdfunded analysis of the light patterns in a wide range of wavelengths.

The authors of the paper include Louisiana State University’s Tabetha Boyajian, who led the discovery team for the star known as KIC 8462852 or “Tabby’s Star”; and Penn State’s Jason Wright, who first proposed the alien-megastructure hypothesis.

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Star’s weirdness ascribed to dust, not aliens

Tabby's Star
This illustration depicts a hypothetical uneven ring of dust orbiting KIC 8462852, also known as Boyajian’s Star or Tabby’s Star. (NASA / JPL-Caltech Illustration)

Are aliens building a huge energy-generating megastructure around a weirdly dimming star? That way-out hypothesis has suffered another blow, thanks to a study that draws upon infrared as well as ultraviolet observations.

The star, known as KIC 8462852 or Tabby’s Star, first came to attention two years ago when citizen scientists sifting through data from NASA’s Kepler space telescope noticed some unusually drastic dips in its brightness. The star’s nickname comes from Tabetha “Tabby” Boyajian, the Yale astronomer who oversaw those observations.

Another astronomer, Penn State’s Jason Wright, mused that the data could be explained by the construction of a huge orbital structure known as a Dyson sphere — although he cautioned that “aliens should always be the very last hypothesis you consider.”

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‘Alien megastructure’ star caught in the act

Image: Comets and star
his illustration shows a star behind a shattered comet. (Credit: NASA / JPL-Caltech)

Tabby’s Star – also known as KIC 8462852 or the “alien megastructure” star – is at it again. And this time the world is watching. The star in the constellation Cygnus has intrigued astronomers for a year and a half because they can’t quite explain why it periodically dims. One hypothesis is that aliens are building an energy-generating Dyson sphere around the star, but less way-out possibilities include cometary storms or blobs of circumstellar material. This week, a team on the Canary Islands detected unusual readings from Tabby’s Star, just in time to alert fellow astronomers around the world to turn their telescopes toward it.

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Unusual suspects for ‘alien megastructure’ star

Image: Comets and star
This illustration shows a star behind a shattered comet. (Credit: NASA / JPL-Caltech)

That mysterious “alien megastructure” star is still a mystery, but the most plausible explanations appear to be dense patches of interstellar gas or dust that just happened to pass in front of the star.

That’s the upshot of analyses conducted by the astronomer who first raised the idea of an extraterrestrial construction project a year ago.

In the Astrophysical Journal Letters, Penn State’s Jason Wright and a co-author, Steinn Sigurdsson, run through a wide range of hypotheses for the behavior of a star called KIC 8462852, also known as Boyajian’s Star or Tabby’s Star.

Not even the alien hypothesis is ignored.

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‘Alien megastructure’ star’s mystery deepens

Image: KIC 8462852
This illustration shows a star behind a shattered comet. Astronomers say it’s possible that such a phenomenon could explain some aspects of the dimming pattern for a mysterious star called KIC 8462852, but not all aspects. (Credit: NASA / JPL-Caltech)

It’s been almost a year since astronomers first speculated that a strangely dimming star called KIC 8462852 might harbor an alien megastructure, and newly reported observations are making the case even stranger.

KIC 8462852 is also known as Tabby’s Star, because Yale astronomer Tabetha Boyajian first brought the case to light, based on observations that were collected by NASA’s Kepler space telescope and analyzed by the Planet Hunters project. The somewhat sunlike star lies about 1,500 light-years from Earth in the constellation Cygnus.

Kepler’s data revealed an erratic pattern in the intensity of KIC 8462852’s starlight, including periods when the light dimmed as much as 20 percent. Penn State astronomer Jason Wright noted that the dimming could theoretically be caused by shifts in an alien megastructure surrounding the star – something like a giant energy-generating Dyson sphere.

Thus was an Internet phenomenon born.

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‘Alien megastructure’ star poses new puzzle

Image: Alien megastructure
An artist’s speculative representation shows a crumbling megastructure known as a Dyson sphere orbiting KIC 8462852. (Credit: Danielle Futselaar / SETI International)

He’s not saying it’s aliens – but an astronomer has raised new questions about KIC 8462852, the strange star that stirred up a debate about “alien megastructures” months ago.

In a paper submitted to Astrophysical Journal Letters, Lousiana State University’s Bradley Schaefer reviews archival photographic plates that show KIC 8462852 at various times going back to 1890. He reports that the star, which is 1,500 light-years away in the constellation Cygnus, faded by about 20 percent between the 1890s and the 1980s.

“This century-long dimming is completely unprecedented for any F-type main sequence star,” Schaefer writes.

KIC 8462852’s dimming was already worthy of note, due to observations by NASA’s Kepler space telescope that revealed unusual episodes during which the star faded by as much as 20 percent. That led Penn State astronomer Jason Wright to observe that such a pattern was consistent with what you’d expect if aliens were building an energy-generating megastructure known as a “Dyson sphere” around the star.

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