Tag: SETI

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SETI Institute searches for red-dwarf aliens

Image: Red dwarf planetary system
An artist’s conception shows a planetary system around a red dwarf star. (Credit: ESO)

The SETI Institute is shifting the focus of its search for extraterrestrial intelligence to places that could harbor life that’s not as we know it: 20,000 red-dwarf star systems.

“Red dwarfs – the dim bulbs of the cosmos – have received scant attention by SETI scientists in the past,” SETI Institute engineer Jon Richard said today in a news release announcing the initiative. “That’s because researchers made the seemingly reasonable assumption that other intelligent species would be on planets orbiting stars similar to the sun.”

Red dwarfs are nothing like the sun: The brightest of the breed are a tenth as luminous as the sun, and some are just 0.01 percent as bright. But astronomers say they account for three-quarters of all stars.

The star that’s closest to our sun, Proxima Centauri, is a red dwarf. A variety of observing efforts, including the Pale Red Dot initiative, are looking for planets around Proxima Centauri.

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Look for places where aliens are looking for us

Image: Earth transit
When Earth passes in front of the sun, it blocks a small part of the sun’s light. Potential observers outside our solar system might be able to detect the resulting dimming of the sun and study Earth’s atmosphere. (Credit: Axel Quetz / MPIA / NASA)

The past decade has brought about a revolution in astronomers’ ability to detect potentially habitable planets, and there’s much, much more to come. The problem will be identifying the likeliest places for life to lurk, and two newly published studies address that problem from two dramatically different perspectives.

One study takes an inward-looking perspective: If we were the aliens, how would we know about Earth?

The best planet-detection method that’s currently available to earthly astronomers looks for the telltale dimming of light as a planet crosses the disk of its parent star. But that dimming, known as a planetary transit, can be seen only when the planet and the alien star are lined up with Earth.

That suggests that Earth is most likely to be detected by observers on alien planets in a narrow strip of the sky where our planet can be seen crossing the sun.

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Bad news and good news about the SETI quest

Image: Jill Tarter
SETI pioneer Jill Tarter pays a visit to the Allen Telescope Array in California, one of the prime sites for the search for extraterrestrial intelligence. (Credit: SETI Institute)

t’s a question that goes back decades: If other civilizations have arisen beyond Earth over the course of billions of years, why haven’t we heard from them? Two kinds of answers have recently come into the spotlight – one kind that’s disheartening, and another kind that’s challenging.

First, the bad news: Researchers from the Australian National University say climate change could have killed off E.T. and his ilk.

In a paper published last month in the journal Astrobiology, Aditya Chopra and Charles Lineweaver suggest that habitable Earthlike planets eventually fall prey either to runaway global warming, as in the case of Venus; or runaway global cooling, as in the case of Mars.

Their model proposes that if life ever does arise on an alien world, it would go extinct in most cases after just 1.5 billion years of the planet’s existence, without getting past the microbial stage.

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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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Those weird spots on Ceres? Probably water ice

Image: Ceres' Occator Crater
This color-coded representation of Ceres’ Occator Crater shows differences in surface composition, highlight bright patches inside the crater. (Credit: NASA / JPL-Caltech / UCLA / MPS / DLR / IDA)

For months, scientists have puzzled over weirdly bright spots of material shining on the asteroid Ceres, but now they say the spots are probably made of salty ice.

That determination, based on a detailed analysis of spectral data from NASA’s Dawn orbiter, comes in a paper published today by the journal Nature. Dawn’s images highlight one particular patch in a 106-mile-wide impact basin known as Occator Crater, but other spots are spread across the surface of the 590-mile-wide dwarf planet.

“The global nature of Ceres’ bright spots suggests that this world has a subsurface layer that contains briny water-ice,” the study’s principal author, Andreas Nathues of the Max Planck Institute for Solar System Research, said in a NASA statement. He and his co-authors suggest that cosmic impacts dig up enough surface material to expose the shiny ice.

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Is it aliens? SETI telescope targets mystery star

Image: Allen Telescope Array
The antennas of the Allen Telescope Array in California is collecting signals from a strange star known as KIC 8462852. (Credit: SETI Institute)

One of the premier telescope arrays in the search for extraterrestrial intelligence, or SETI, is focusing its antennas on an anomalously blinking star, thanks in part to speculation that the star called KIC 8462852 could harbor a network of alien megastructures.

The Allen Telescope Array, a complex of 42 radio dishes in Northern California that was funded in part by Seattle billionaire Paul Allen, has been collecting data about the star since Thursday evening, SETI Institute researcher Doug Vakoch said.

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