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Closest ‘Alien Earth’ May Be 13 Light-Years Away

An Earth-like alien planet may reside right in our solar system’s backyard, just 13 light-years or so away, astronomers announced yesterday, Feb 6th.

Image: Artist’s Conception of Planets Orbiting Red Dwarf Star Credit: David A. Aguilar

That number is just an estimate, though, and not based on an exoplanet discovery.

The researchers used data from NASA’s prolific planet-hunting Kepler space telescope, which is staring at more than 150,000 stars simultaneously. Kepler detects planets by measuring the temporary brightness dips caused when the worlds pass in front of, or transit, their stars’ faces from the instrument’s perspective.

3,897 red dwarfs — stars dimmer and smaller than our own sun — and determined that Kepler has identified 95 exoplanet candidates circling them. Three of these candidates are roughly Earth-size and orbit within their stars’ “Goldilocks zone,” where liquid water (and possibly life as we know it) can exist.

Kepler isn’t able to detect every planet circling every star that it’s watching, researchers noted. Many worlds don’t orbit in the right plane for Kepler to observe transits, and the signals of others may be masked by brightness variations inherent to red dwarfs.

Taking this into account, about 6 percent of red dwarfs in the Milky Way galaxy should host Earth-like planets, the astronomers said.

Since about 75 percent of the galaxy’s 100 billion stars are red dwarfs, this translates to an estimated 4.5 billion “alien Earths” spread throughout the galaxy. The research team stressed, however, that this is a tentative figure because the distribution of stars varies widely.

Exoplanet Catalog Reveals 7 Possibly Habitable Worlds

A new catalog aims to list all the known planets in the galaxy that could potentially be habitable to life. The count is at seven so far, with many more to come, researchers said.

Image: More exoplanets than expected in the first year of the Habitable Exoplanets Catalog. Image released Dec. 6, 2012. Credit: PHL @ UPR Arecibo, ESA/Hubble, NASA

The online listing, called the Habitable Exoplanets Catalog, celebrated its first anniversary today (Dec. 5). When it was first released last year, it had two potential habitable planets to its name. According to lead researcher Abel Mendez, the team expected to add maybe one or two more in the catalog’s first year. The addition of five suspected new planets was wholly beyond anyone’s expectations.

“The main purpose is for research, but then I realized that also for the public, it was very important,” said Mendez, director of the University of Puerto Rico at Arecibo’s Planetary Habitability Laboratory.

European Satellite to Seek Nearby Super-Earth Planets in 2017

The European Space Agency will launch a new satellite in 2017 to study super-Earths and other large alien planets orbiting nearby stars, agency officials announced Friday (Oct. 19).

Image: Artist impression of Cheops Credit: University of Bern

The small CHaracterising ExOPlanets Satellite, called Cheops for short, will orbit the Earth at an altitude of about 500 miles (800 kilometers) and search for new exoplanets around nearby bright stars already known to harbor alien planets, ESA officials said.

“By concentrating on specific known exoplanet host stars, Cheops will enable scientists to conduct comparative studies of planets down to the mass of Earth with a precision that simply cannot be achieved from the ground,” Alvaro Giménez-Cañete, the ESA’s director of Science and Robotic Exploration, said in a statement.

Cheops’ high-precision monitoring will help scientist spot the telltale dips in the stars’ brightness that occur when a planet passes, or “transits,” in front of its star, according to a statement from the ESA. These observations promise to yield more accurate measurements of exoplanets, which could provide clues about their internal structure.

ESA officials said the mission will last run for about 3 1/2 years and is aimed at improving understanding the formation of alien planets ranging in size from so-called super-Earths (planets a few times the mass of the Earth) to giant Neptune-sized worlds. The mission is also designed to identify alien planets with significant atmospheres.

The Cheops mission was selected from a field of 26 different proposals from ESA’s Call for Small Missions in March, ESA officials said. It is the first of a potential new class of space missions for the European Space Agency’s science program, they added.

Since 1992, astronomers have discovered more than 800 confirmed alien planets using the transit method and other planet-hunting techniques, with the aid of ground and space-based telescopes.

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Discovery! Earth-Size Alien Planet at Alpha Centauri Is Closest Ever Seen

The star system closest to our own sun hosts a planet with roughly Earth’s mass and may harbor other alien worlds as well, a new study reports.

This artist’s concept shows the newfound alien planet Alpha Centauri Bb, found in a three-star system just 4.3 light-years from Earth. Credit: ESO/L. Calçada

Astronomers detected the alien planet around the sunlike star Alpha Centauri B, which is part of a three-star system just 4.3 light-years away from us. The newfound world is about as massive as Earth, but it’s no Earth twin; its heat-blasted surface may be covered with molten rock, researchers said.

The mere existence of the planet, known as Alpha Centauri Bb, suggests that undiscovered worlds may lurk farther away from its star — perhaps in the habitable zone, that just-right range of distances where liquid water can exist.

Tiniest Alien Solar System Discovered: 5 Packed Planets

The most crowded alien planetary system found yet possesses five worlds all orbiting a star at least 12 times closer than Earth does the sun, researchers say.

Image: Kepler observatory spots five planets in close formation around KOI-500, 1,100 light-years from Earth Credit: Illustration by Karl Tate, SPACE.com

Investigators discovered these exoplanets using NASA’s pioneering Kepler space observatory. The orbiting telescope has detected more than 2,300 potential alien worlds since its March 2009 launch. It searches for these planets by observing more than 160,000 stars simultaneously, looking for small dips in stars’ brightness due to orbiting worlds passing in front of them.

The researchers used Kepler to analyze the planetary system around the star KOI-500, a star about the mass of the sun but only about three-quarters its diameter and only about 1 billion years old, less than one-quarter the sun’s age. KOI-500 is approximately 1,100 light-years away in the constellation Lyra, the harp.

10 Billion Earth-Like Planets May Exist in Our Galaxy

About 40 percent of red dwarf stars may have Earth-sized planets orbiting them that have the right conditions for life.

Red dwarfs – which are smaller and cooler than our sun – are extremely common, making up 80 percent of stars in the galaxy. Their ubiquity suggests that there are tens of billions of possible places to look for life beyond Earth, with at least 100 such planets located nearby.

The new estimate comes from a team of astronomers using the European Southern Observatory’s HARPS planet-hunting telescope to look at a sample of 102 nearby red dwarfs over a six-year period. The telescope checked for a characteristic wobble from the star, indicating that at least one planet was tugging on it while orbiting around.

The search found nine planets with between one and 10 Earth masses, including two in the habitable zone, possibly giving them the right temperature to have liquid water. Because red dwarfs don’t produce as much heat as our sun, their habitable zones occur much closer to the star.

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Nomad Alien Planets May Fill Our Milky Way Galaxy

Illustration: An artistic rendition of a nomad object wandering through the interstellar medium. The object is intentionally blurry to represent uncertainty about whether it has an atmosphere. Credit: Greg Stewart / SLAC National Accelerator Laboratory

Our Milky Way galaxy may be teeming with rogue planets that ramble through space instead of being locked in orbit around a star, a new study suggests.

These “nomad planets” could be surprisingly common in our bustling galaxy, according to researchers at the Kavli Institute for Particle Astrophysics and Cosmology (KIPAC), a joint institute of Stanford University and the SLAC National Accelerator Laboratory. The study predicts that there may be 100,000 times more of these wandering, homeless planets than stars in the Milky Way.

If this is the case, these intriguing cosmic bodies would belong to a whole new class of alien worlds, shaking up existing theories of planet formation. These free-flying planets may also raise new and tantalizing questions in the search for life beyond Earth.

“If any of these nomad planets are big enough to have a thick atmosphere, they could have trapped enough heat for bacterial life to exist,” study leader Louis Strigari said in a statement.

How Scattered Light May Reveal Alien Planet Atmospheres

Image: Extrasolar planet Upsilon Andromedae d lies in the habitable zone and if sufficiently large moons of Upsilon Andromedae d exist, they may be able to support liquid water, as the image shows.

On the horizon of this hypothetical moon can be seen Upsilon Andromedae d, possibly a class II planet (Sudarsky classification): since it is too warm to form ammonia clouds this ones are made up of water vapor, white in colour instead of the caracteristic yellow-reddish clouds of Jupiter and Saturn. Credit: Lucianomendez

The light scattered off distant worlds could help reveal details about their atmospheres that no other method could uncover, scientists find.

Nearly all the information astronomers have of the atmospheres of alien planets or exoplanets comes from worlds whose orbits happen to be precisely aligned from our vantage point.

Once per orbit, these exoplanets go in front of (transit) their host stars from our point of view, and the light from these stars passes through the atmospheres of these planets on its way to Earth.

The molecules in these alien atmospheres absorb some of this starlight, resulting in patterns known as spectra that allow scientists to identify what they are.

However, “we know of many other planets that do not transit their host stars, and we therefore know almost nothing about those atmospheres,” said astronomer Sloane Wiktorowicz at University of California, Santa Cruz. Indeed, “less than 10 percent of the known exoplanets have had their atmospheres detected. This is because planets are at least a thousand times fainter than their host stars.”

Instead of looking at starlight that has passed through alien atmospheres on its way to Earth, Wiktorowicz and his colleagues aim to look for light that has scattered off alien atmospheres. This strategy should work equally well for exoplanets in both transiting and non-transiting orbits, “which will open up many previously unstudied planets for exploration,” he explained.

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Astronomers Use Kepler Spacecraft to Search for Exomoons

Illustration: Concept rendering of a Jupiter-like planet is seen orbiting from the perspective of a life abundant exomoon.

We’ve been reassured time and again on the presence of ‘Exoplanets’ and the possibilities they hold, but like our very own planet Earth, could they too hold a moon of their own? If so could these ‘Exomoons’ potentially harbor conditions favorable to life? Take Jupiter’s own moon Europa for instance, a moon shown to possibly hold oceans underneath its icy crust. Were we to send our manned tools to Europa and dig enough could we find life underneath? In this article SciAm talks with renowned Exomoon hunter David Kipping to lend his expertise on the subject of such Extra solar moons and how they might go about spotting them:

Astronomers have discovered a trove of exoplanets—more than 700 worlds in orbit around distant stars, with leads on thousands of additional suspects. So now, naturally, they’re beginning to ask: What moons might be in orbit about these planets?

It is a reasonable question. Most of the planets in our solar system host sizable natural satellites. And in some planetary systems, the moons of an extrasolar planet could themselves be favorable habitats for extraterrestrial life.

To answer it, a team of astronomers is now digging through publicly available data from Kepler, NASA’s prolific exoplanet-finding spacecraft, in hopes of detecting the faint signal of the first known exomoon.

“It’s something that I’ve been very passionate about for a long time,” says David Kipping, who wrote his PhD thesis at University College London last year on exomoons. Now a postdoctoral scholar at the Harvard–Smithsonian Center for Astrophysics (CfA), Kipping is leading the Hunt for Exomoons with Kepler project, or HEK. He and his colleagues described the HEK campaign in a recent study posted to the preprint Web site arXiv.org that has been submitted to The Astrophysical Journal.

“When I first started this, I was just seeing what was possible,” Kipping says. “As I went on with this, I realized that it wasn’t just a crazy idea.” He and his colleagues calculated that if large moons are common in the galaxy, Kepler might be sensitive enough to find them.

Since 2009, the Kepler spacecraft has trailed Earth in orbit around the sun, doggedly pursuing a deceptively simple mission. With a giant digital camera, Kepler keeps watch on a field of more than 150,000 stars near the constellation Cygnus. It watches those stars for so-called transits—instances where a planet passes in front of its host star, which slightly and temporarily diminishes the star’s apparent brightness. So far, the mission has been incredibly productive; Kepler scientists have discovered more than 60 new exoplanets and have identified more than 2,000 likely candidates that await confirmation.

Some 50 of those candidates fall in the so-called habitable zone, the region around a star where temperatures would allow for the presence of liquid water and perhaps the emergence of life. A gas-giant planet in the habitable zone, akin to a warmer Jupiter or Saturn, would lack a solid surface and hence would not be an ideal habitat for life—but its moons might be. “There could be a lot of habitable moons out there, and we want to know about them,” Kipping says.

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