Join the Live Discussion: The Hunt for Other Worlds Heats Up

Artist’s impression of a massive asteroid belt in orbit around a star. Earth's water may not have all come from asteroids and comets, so maybe that's true for exoplanets. Credit: NASA-JPL / Caltech / T. Pyle (SSC)
Artist’s impression of a massive asteroid belt in orbit around a star. Earth's water may not have all come from asteroids and comets, so maybe that's true for exoplanets. Credit: NASA-JPL / Caltech / T. Pyle (SSC)

As readers of Universe Today know, exoplanets are one of the hottest topics in astronomy today. In just the past six months, astronomers have announced the discovery of more than 700 planets orbiting other stars, bringing the total to more than 1700. These discoveries include the first Earth-size planet found in what’s called the habitable zone of a star, where liquid water could exist; the oldest known planet that could support life; and the first rocky “mega-Earth,” a planet that’s much like Earth except that it’s 17 times more massive.

On July 9, at 19:00 UTC (3 pm EDT, 12:00 pm PDT), three exoplanet hunters will come together discuss the discovery boom, consider the next steps in the hunt for habitable worlds, and debate whether we’re likely to find alien life in the next decade.

You can watch live (or watch the webcast later) below:

The panel includes MIT’s Zachory Berta-Thompson, Stanford’s Bruce Macintosh and Université de Montréal’s Marie-Eve Naud) will come together discuss the recent discovery boom, consider the next steps in the hunt for habitable worlds, and ponder the odds of finding life on another planet. The discussion will be moderated by journalist Kelen Tuttle.

To submit questions ahead of time or during the webcast, send an email to [email protected] or post on Twitter with hashtag #KavliLive. You can find additional information about the webcast and the Kavli Foundation here.

A Brief History Of Gliese 581d and 581g, The Planets That May Not Be

Goldilocks Zone
Artists impression of Gliese 581g. Credit: Lynette Cook/NSF

Two potentially habitable planets in the Gliese 581 system are just false signals arising out of starstuff, a new study said. Gliese 581d and 581g are (study authors said) instead indications of the star’s activity and rotation. It’s the latest twist in a long tale about the system as astronomers struggle to understand how many planets could be orbiting the star.

“Our improved detection of the real planets in this system gives us confidence that we are now beginning to sufficiently eliminate Doppler signals from stellar activity to discover new, habitable exoplanets, even when they are hidden beneath stellar noise,” stated Paul Robertson, a postdoctoral fellow at Penn State University, in a press release.

“While it is unfortunate to find that two such promising planets do not exist, we feel that the results of this study will ultimately lead to more Earth-like planets.”

Planets were first announced around the system in 2007 (by a research team led by Geneva’s Stephane Udry) including Gliese 581d. The system has been under heavy scrutiny since a team led by Steven Vogt of the University of Santa Cruz announced Gliese 581g in September 2010. Both 581d and 581g were considered to be in the “habitable” region around the dwarf star they orbited, meaning the spot that’s not too far or close to the star for liquid water to exist.

Potentially habitable exoplanets and exoplanet candidates as of July 3, 2014. Gliese 581d and 581g are crossed off in the catalog. Click for larger version. Credit: PHL @ UPR Arecibo
Potentially habitable exoplanets and exoplanet candidates as of July 3, 2014. Gliese 581d and 581g are crossed off in the catalog. Click for larger version. Credit: PHL @ UPR Arecibo

About two weeks after the discovery, another team led by Geneva University’s Francesco Pepe said it could not find indications of Gliese 581g in data from HARPS (High Accuracy Radial Velocity Planet Searcher), a telescope instrument frequently used at the European Southern Observatory to confirm exoplanets. It also cast doubt on the existence of Gliese 581f, announced by a team led by Geneva’s Michel Mayor in 2009. Other researchers examined the system, too, with mixed results.

Two years later, Vogt led another research team saying that analysis of an “extended dataset” from HARPS did show Gliese 581g. But in a press release at the time from the Planetary Habitability Laboratory at the University of Puerto Rico at Arecibo, its director (Abel Mendez) said the discovery would continue to be controversial. At the time he added the planet to the list of potentially habitable exoplanets the laboratory maintains. As of yesterday, both 581d and 581g are crossed off.

The uncertainty arises from the delicacy of looking for signals of small planets around much larger stars. Astronomers typically find planets through watching them pass across the face of a star, or measuring the tug that they exert on their parent star during their orbit. It is the nature of the tug on Gliese 581 that is so interesting astronomers.

Orbital Period
The orbits of planets in the Gliese 581 system are compared to those of our own solar system. The Gliese 581 star has about 30 percent the mass of our Sun, and the outermost planet is closer to its star than the Earth is to the Sun. The 4th planet, G, is a planet that could sustain life. Credit: Zina Deretsky, National Science Foundation

“These ‘Doppler shifts’ can result from subtle changes in the star’s velocity caused by the gravitational tugs of orbiting planets,” wrote Penn State in the press release yesterday.  “But Doppler shifts of a star’s ‘absorption lines’ also can result from magnetic events like sunspots originating within the star itself — giving false clues of a planet that does not actually exist.”

The researchers now say that only three planets exist around this star. It’s impossible to fully represent the debate in a single short news article, so we encourage you to look at some of the original literature. Here is a list of papers related to Gliese 581g and another for Gliese 581d. The new paper is available online in Science.

Also, here are some past Universe Today stories about the system:

Nearby Super-Earth is Best Habitable Candidate So Far, Astronomers Say

An artistic representation of Gliese 832 c against a stellar nebula background. A new paper says Gliese 832 might be home to another planet similar to this, but in the habitable zone. Credit: Planetary Habitability Laboratory at the University of Puerto Rico, Arecibo, NASA/Hubble, Stellarium.
An artistic representation of Gliese 832 c against a stellar nebula background. A new paper says Gliese 832 might be home to another planet similar to this, but in the habitable zone. Credit: Planetary Habitability Laboratory at the University of Puerto Rico, Arecibo, NASA/Hubble, Stellarium.

On a clear night, you might be able to spot the red dwarf star Gliese 832 through a backyard telescope, as it is just 16 light years away. Today, astronomers announced the discovery of super-Earth planet orbiting this nearby star and say it might be the best candidate yet for habitable world.

Gliese 832c was spotted by an international team of astronomers, led by Robert A. Wittenmyer from UNSW Australia. They used high-precision radial-velocity data from HARPS-TERRA, the Planet Finder Spectrograph and the UCLES echelle spectrograph. This star is already known to have one additional planet, a cold Jupiter-like planet, Gliese 832 b, discovered in 2009.

Orbital analysis of Gliese 832 c, a potentially habitable world around the nearby red-dwarf star Gliese 832. Gliese 832 c orbits near the inner edge of the conservative habitable zone. Its average equilibrium temperature (253 K) is similar to Earth (255 K) but with large shifts (up to 25K) due to its high eccentricity (assuming a similar 0.3 albedo). Credit: Planetary Habitability Laboratory.
Orbital analysis of Gliese 832 c, a potentially habitable world around the nearby red-dwarf star Gliese 832. Gliese 832 c orbits near the inner edge of the conservative habitable zone. Its average equilibrium temperature (253 K) is similar to Earth (255 K) but with large shifts (up to 25K) due to its high eccentricity (assuming a similar 0.3 albedo). Credit: Planetary Habitability Laboratory.

Since red dwarf stars shine dimly, the habitable zones around these stars would be very close in. Gliese 832c complies with an orbital period of 36 days (it’s orbital companion Gliese 832 b orbits the star in 9.4 years.)

The newly found super-Earth has a mass at least five times that of Earth’s and the astronomers estimate it receives about the same average energy as Earth does from the Sun. “The planet might have Earth-like temperatures, albeit with large seasonal shifts, given a similar terrestrial atmosphere,” says a press release from the Planetary Habitability Laboratory. “A denser atmosphere, something expected for Super-Earths, could easily make this planet too hot for life and a ‘Super-Venus’ instead.”

Using the Earth Similarity Index (ESI) — a measure of how physically similar a planetary mass object is to Earth, where 1 equals the same qualities as Earth — Gliese 832 c has an ESI of 0.81. This is comparable to Gliese 667C c (ESI = 0.84) and Kepler-62 e (ESI = 0.83).

“This makes Gliese 832c one of the top three most Earth-like planets according to the ESI (i.e. with respect to Earth’s stellar flux and mass) and the closest one to Earth of all three, a prime object for follow-up observations. However, other unknowns such as the bulk composition and atmosphere of the planet could make this world quite different to Earth and non-habitable.”

Artistic representation of the potentially habitable exoplanet Gliese 832 c as compared with Earth. Gliese 832 c is represented here as a temperate world covered in clouds. The relative size of the planet in the figure assumes a rocky composition but could be larger for a ice/gas composition. Credit: Planetary Habitability Laboratory.
Artistic representation of the potentially habitable exoplanet Gliese 832 c as compared with Earth. Gliese 832 c is represented here as a temperate world covered in clouds. The relative size of the planet in the figure assumes a rocky composition but could be larger for a ice/gas composition. Credit: Planetary Habitability Laboratory.

In their paper, Wittenmyer and his colleagues noted that while Solar Systems like our own appear — so far — to be rare, the Gliese 832 system is like a scaled-down version of our own Solar System, with an inner potentially Earth-like planet and an outer Jupiter-like giant planet. They added that the giant outer planet may have played a similar dynamical role in the Gliese 832 system to that played by Jupiter in our Solar System.

Certainly, astronomers will be attempting to observe this system further to see if any additional planets can be found.

If you’re interested in trying to see this star, here’s our guide on red dwarf stars that are visible in backyard telescopes.

Space Seed: How To Spread Earth’s Life Across The Universe

A 'Blue Marble' image of the Earth taken from the VIIRS instrument aboard NASA's most recently launched Earth-observing satellite - Suomi NPP. This composite image uses a number of swaths of the Earth's surface taken on January 4, 2012. Credit: NASA/NOAA/GSFC/Suomi NPP/VIIRS/Norman Kuring.

Earth’s lifespan for life is finite. In about five billion years, our Sun will transform into a red giant and make our planet uninhabitable, to put it lightly, as our closest star gets bigger and swallows up Mercury and Venus. But perhaps there is a way to help our life colonize other spots in the universe.

One researcher’s vision would see microbes from our planet being sent to distant planetary systems in formation and seeding the area with exports from Earth.

The idea is of course highly theoretical and requires careful thought of the ethics (what if our life destroys others?) and technology (how to get the microbes out there)? But it’s something that Michael Mautner, a chemistry researcher at the Virginia Commonwealth University College of Humanities and Sciences, is considering.

“I suggest we give life a chance,” he said in an interview with Universe Today.

These are the steps that Mautner suggests for those considering his method of spreading life into the universe.

Artist’s impression of a baby star still surrounded by a protoplanetary disc in which planets are forming.  Credit: ESO
Artist’s impression of a baby star still surrounded by a protoplanetary disc in which planets are forming. Credit: ESO

1. Think long-term. Many planets or systems are under formation, dozens if not hundreds of light-years away from us. We can send hardy microorganisms to start new life there, but travelling will take many thousands of years. This new life can then take millions or perhaps billions of years to evolve, some to intelligent life that can spread life further in the galaxy. Planning on such time-scales is key to our cosmological future.

2. Find a habitable system. One idea could be to look for a habitable planet; he observed that the Kepler space telescope has made great strides in showing us potentially habitable worlds from afar. As telescope technology improves, finding these worlds will be easier. That said, there’s a risk that any Earth-borne life could obliterate any native life there. His solution is to find star systems under formation instead: “There hasn’t been enough time for life, especially advanced life-forms, to start there,” he says.

Kepler-62f, an exoplanet that is about 40% larger than Earth. It's located about 1,200 light-years from our solar system in the constellation Lyra. Credit: NASA/Ames/JPL-Caltech
Kepler-62f, an exoplanet that is about 40% larger than Earth. It’s located about 1,200 light-years from our solar system in the constellation Lyra. Credit: NASA/Ames/JPL-Caltech

3. Aim carefully. A planet would take a very precise aiming system, he acknowledges, but aiming for larger star-forming interstellar clouds where a planetary systems are being formed, would be easier for current technology.

4. Freeze the microbes. Transit in cold interstellar space will put the microbes into deep hibernation and also make them more radiation-resistant: “the challenge is to maybe be able to bio- engineer microbes that can survive for that period,” Mautner points out. He added that there are plenty of examples on Earth of extremophiles surviving harsh environments, such as outside in satellites in or in hot vents near the bottom of the ocean. And microbes are also capable of hibernating. They could then be woken up when they get to a region near planetary systems that allows for liquid water, in conditions that could let them grow.

Could humans follow in their wake? Mautner says he would be happy for humans to go, but it could take thousands of years or more to make the journey. He doesn’t rule out the possibility of cryogenics making that trip more possible, and says there is a “fair chance” that it could work.

For more information on Mautner’s research and related concepts, consult this research paper, the Interstellar Panspermia Society, this page on “Astro Ecology” and this Q&A with Mautner at Victoria College’s website.

What do you think of the concept? Let us know in the comments.

Discovered: Two New Planets for Kapteyn’s Star

An artist's conception of the planets orbiting Kapteyn's Star (inset) and the stream of stars associated with an ancient galaxy merger. Credit: image courtesy of Victor Robles, James Bullock, and Miguel Rocha at University of California Irvine and Joel Primack at University of California Santa Cruz.

The exoplanet discoveries have been coming fast and furious this week, as astronomers announced a new set of curious worlds this past Monday at the ongoing American Astronomical Society’s 224th Meeting being held in Boston, Massachusetts.

Now, chalk up two more worlds for a famous red dwarf star in our own galactic neck of the woods. An international team of astronomers including five researchers from the Carnegie Institution announced the discovery this week of two exoplanets orbiting Kapteyn’s Star, about 13 light years distant. The discovery was made utilizing data from the HIRES spectrometer at the Keck Observatory in Hawaii, as well as the Planet Finding Spectrometer at the Magellan/Las Campanas Observatory and the European Southern Observatory’s La Silla facility, both located in Chile.

The Carnegie Institution astronomers involved in the discovery were Pamela Arriagada, Ian Thompson, Jeff Crane, Steve Shectman, and Paul Butler. The planets were discerned using radial velocity measurements, a planet-hunting technique which looks for tiny periodic changes in the motion of a star caused by the gravitational tugging of an unseen companion.

“That we can make such precise measurements of such subtle effects is a real technological marvel,” said Jeff Crane of the Carnegie Observatories.

Kapteyn’s Star (pronounced Kapt-I-ne’s Star) was discovered by Dutch astronomer Jacobus Kapteyn during a photographic survey of the southern hemisphere sky in 1898. At the time, it had the highest proper motion of any star known at over 8” arc seconds a year — Kapteyn’s Star moves the diameter of a Full Moon across the sky every 225 years — and held this distinction until the discovery of Barnard’s Star in 1916. About a third the mass of our Sun, Kapteyn’s Star is an M-type red dwarf and is the closest halo star to our own solar system. Such stars are thought to be remnants of an ancient elliptical galaxy that was shredded and subsequently absorbed by our own Milky Way galaxy early on in its history. Its high relative velocity and retrograde orbit identify Kapteyn’s Star as a member of a remnant moving group of stars, the core of which may have been the glorious Omega Centauri star cluster.

The worlds of Kapteyn’s Star are proving to be curious in their own right as well.

“We were surprised to find planets orbiting Kapteyn’s Star,” said lead author Dr. Guillem Anglada-Escude, a former Carnegie post-doc now with the Queen Mary University at London. “Previous data showed some irregular motion, so we were looking for very short period planets when the new signals showed up loud and clear.”

The location of Kapteyn's Star in teh constellation Pictor. Created using Stellarium.
The location of Kapteyn’s Star in the constellation Pictor. Created using Stellarium.

It’s curious that nearby stars such as Kapteyn’s, Teegarden’s and Barnard’s star, though the site of many early controversial claims of exoplanets pre-1990’s, have never joined the ranks of known worlds which currently sits at 1,794 and counting until the discoveries of Kapteyn B and C. Kapteyn’s star is the 25th closest to our own and is located in the southern constellation Pictor. And if the name sounds familiar, that’s because it made our recent list of red dwarf stars for backyard telescopes. Shining at magnitude +8.9, Kapteyn’s star is visible from latitude 40 degrees north southward.

Kapteyn B and C are both suspected to be rocky super-Earths, at a minimum mass of 4.5 and 7 times that of Earth respectively. Kapteyn B orbits its primary once every 48.6 days at 0.168 A.U.s distant (about 40% of Mercury’s distance from our Sun) and Kapteyn C orbits once every 122 days at 0.3 A.U.s distant.

This is really intriguing, as Kapteyn B sits in the habitable zone of its host star. Though cooler than our Sun, the habitable zone of a red dwarf sits much closer in than what we enjoy in our own solar system. And although such worlds may have to contend with world-sterilizing flares, recent studies suggest that atmospheric convection coupled with tidal locking may allow for liquid water to exist on such worlds inside the “snow line”.

And add to this the fact that Kapteyn’s Star is estimated to be 11.5 billion years old, compared with the age of the universe at 13.7 billion years and our own Sun at 4.6 billion years. Miserly red dwarfs measure their future life spans in the trillions of years, far older than the present age of the universe.

A comparison of habitable zones of Sol-like versus Red dwarf stars. Credit: Chewie/Ignacio Javier under a Wikimedia Commons 3.0 license).
A comparison of habitable zones of Sol-like versus red dwarf stars. Credit: Chewie/Ignacio Javier under a Wikimedia Commons 3.0 license).

“Finding a stable planetary system with a potentially habitable planet orbiting one of the very nearest stars in the sky is mind blowing,” said second author and Carnegie postdoctoral researcher Pamela Arriagada. “This is one more piece of evidence that nearly all stars have planets, and that potentially habitable planets in our galaxy are as common as grains of sand on the beach.”

Of course, radial velocity measurements only give you lower mass constraints, as we don’t know the inclination of the orbits of the planets with respect to our line of sight. Still, this exciting discovery could potentially rank as the oldest habitable super-Earth yet discovered, and would make a great follow-up target for the direct imaging efforts or the TESS space telescope set to launch in 2017.

“It does make you wonder what kind of life could have evolved on those planets over such a long time,” added Dr Anglada-Escude. And certainly, the worlds of Kapteyn’s Star have had a much longer span of time for evolution to have taken hold than Earth… an exciting prospect, indeed!

-Read author Alastair Reynolds’ short science fiction piece Sad Kapteyn accompanying this week’s announcement.

‘Mega-Earth’ And Doomed Planets Top Today’s Exoplanet Finds

Artist's impression of "mega-Earth" Kepler 10c. Credit: David A. Aguilar (CfA)

Can you imagine a world that is 17 times as massive as Earth, but still rocky? Or two planets that are doomed to be swallowed up by their parent star in just a blink of astronomical time?

While these scenarios sound like science fiction, these are real-life finds released today (June 2) at the American Astronomical Association meeting in Boston.

Here’s a rundown of the finds about these planets in our ever-more-amazing universe.

‘Mega-Earth’ Kepler-10c

Spinning around its star every 45 days is Kepler-10c, which is about 2.3 times as large as Earth but a heavyweight, at 17 times more massive. The planet was discovered by the prolific NASA Kepler space telescope (which was sidelined after a reaction wheel failed last year, but now has been tasked with a new planet-hunting mandate.)

While initially astronomers thought Kepler-10c was a “mini-Neptune”, or a world that is similar to that planet in our solar system, its mass measured by the HARPS-North instrument on the Galileo National Telescope showed it was a rocky world. What’s more, astronomers believe the planet did not “let go” of any atmosphere over time, which implies the planet’s past is similar to what it was today.

Here’s the other neat thing: astronomers found that the system was 11 billion years old, at a time when the universe was young (it was formed 13.7 billion years ago) and the elements needed to make rocky planets were scarce. This implies that rocky planets could have formed earlier than previously thought.

“I was wrong that old stars do not have rocky planets, which has consequences about the Fermi Paradox,” the Harvard-Smithsonian Center for Astrophysics’s (CfA) Dimitar Sasselov said in a webcast press conference today (June 2).  The Fermi Paradox, simply put, refers to the question of why we can’t see civilizations since they are assumed to have spread quite a ways since the universe was formed.

Artist's impression of Kepler-56b being torn apart by its star about 130 million years from today. Its sibling planet, Kepler-56c, will last until 155 million years from now. Credit: David A. Aguilar (CfA)
Artist’s impression of Kepler-56b being torn apart by its star about 130 million years from today. Its sibling planet, Kepler-56c, will last until 155 million years from now. Credit: David A. Aguilar (CfA)

‘We’re doomed!’ Kepler-56b and Kepler-56c

If there was anybody in the vicinity of these two planets, you’d want to move out of the way fairly quickly — at least when talking about astronomical time. Both of these planets, whose orbits are within the equivalent distance of Mercury to the sun, are expected to be swallowed up by their star in 130 million years (for Kepler-56b) and 155 million years (Kepler-56c). It’s the first time two doomed planets have been found in a single system.

“Possibly the core of planet will be left behind and you [will] see this dead corpse floating behind in the universe,” said CfA’s Gongjie Li in the press conference.

There are two factors behind this: the size of the star will enlarge as it gets older (which is typical among stars) and the tidal forces between the planets and their star will also cause them to slow down in their orbits and rip apart. Interestingly enough, another gas giant planet called Kepler-56d will remain safe from most of the chaos since its orbit is equivalent to the asteroid belt in our own solar system.

“Looking at this system is like foreseeing our own solar system,” added Li, referring to the fact that in another five billion years or so our sun will enlarge and swallow Mercury and Venus at the least, boiling off all the oceans on our planet and killing anything left.

Artist's conception of an exoplanet orbiting a red dwarf star. Credit: David A. Aguilar (CfA)
Artist’s conception of an exoplanet orbiting a red dwarf star. Credit: David A. Aguilar (CfA)

Windy City: Why living near a red dwarf might be a bad idea

One fertile ground for exoplanet discoveries — particularly when looking for planets about Earth’s size in the habitable zone — is red dwarfs, because they are smaller and therefore have less light to obscure any rocky worlds orbiting nearby. A new study warns that they could be less friendly to life than previously believed.

CfA’s Ofer Cohen said that red dwarfs can have intense stellar winds, when looking at the model of a known red dwarf with three planets around it: KOI 1422.02, KOI 2626.01, KOI 584.01. Even a magnetic field the size of Earth would not be able to protect the planet from being stripped of its atmosphere assuming a certain intensity of stellar flares.

A member of the audience pointed out that the red dwarf star under study likely has stronger winds than 95% of all red dwarfs, however. Cohen acknowledged that, but added “the main effect is not the stellar activity, but these giants are close to the star.” All the same, this could require a more nuanced understanding of the habitable zone around these stars, he added.

Artist's impression of exoplanets. Credit: J. Jauch
Artist’s impression of exoplanets. Credit: J. Jauch

Heavy metal: Figuring out how much planets have

In astronomical terms, any elements heavier than hydrogen and helium are considered to be “metallic”. Past research found that metal-rich stars tend to have hot Jupiter exoplanets, while the smaller planets have a larger span of metal possibilities.

A team led by CfA’s Lars Buchhave surveyed more than 400 stars with 600 exoplanets, and found that planets smaller than 1.7 times the size of Earth are more likely to be rocky, while those than are 3.9 times the size of Earth or larger are likely gassy.

In between is a zone called “gas dwarfs”, which are planets 1.7 and 3.9 times the size of Earth that likely have hydrogen and helium atmospheres blanketing their surface.

Also intriguing: the researchers discovered that planets far away from their stars can get larger before picking up a lot of gas and becoming a “gas dwarf”, presumably because there isn’t as much gas material out there.

The team also discovered that stars with smaller, Earth-like worlds metallicities like our sun, while stars with “gas dwarfs” have more metals, and stars with gas giants have even more metals. But bear in mind these are for planets close to their host star, which are easiest for Kepler to find. Buchhave plans to do work for planets further away.

The papers for these findings are on arVix: Kepler 10b, habitable planets orbiting M-dwarfs, exoplanets around metal-rich stars.

There Might Be 100 Million Planets In The Galaxy With Complex Life

Artist's impression of complex life on other worlds. Credit: PHL @ UPR Arecibo, NASA, Richard Wheeler @Zephyris

What a multitude of worlds! A new study suggests that the Milky Way could host 100 million planets with complex life, leaving no lack of choice for astronomers to look for organisms beyond Earth. The challenge is, however, that these worlds might be too far away from us to do much yet.

“On the one hand, it seems highly unlikely that we are alone,” stated Louis Irwin, lead author of the study and professor emeritus at the University of Texas at El Paso. “On the other hand, we are likely so far away from life at our level of complexity, that a meeting with such alien forms is extremely improbable for the foreseeable future.”

The figure came from studying a list of more than 1,000 exoplanets for metrics such as their density, temperature, chemistry, age and distance from the parent star. From this, Irwin’s team formulated a “biological complexity index” that ranges between 0 and 1.0. The index is rated on “the number and degree of characteristics assumed to be important for supporting multiple forms of multicellular life,” the research team stated.

Assuming that Europa (a moon of Jupiter believed to have an ocean below its ice) is a good candiate for life, the team estimated that 1% to 2% of exoplanets would have a BCI that is even higher than that. So to translate that into some estimates: 10 billion stars in the Milky Way, averaging one planet a star, which brings us to 100 million planets minimum.

Goldilocks Zone
Artists impression of Gliese 581g. Credit: Lynette Cook/NSF

So what does this metric mean? There’s of course no guarantee that complex life exists in any of these places — just that the conditions could be conducive to life. Also, the researchers added, don’t assume that any life in this category would be intelligent life, but more life that is more complex than a microbe. And the known planets with higher BCIs tend to be pretty far away from us. (One of the closest is the Gliese 581 system, which is 20 light-years away.)

Read more about the research in the journal Challenges. Recall that a few years ago, this group also wrote about an “Earth Similarity Index” rating exoplanets on how close they are to our own.

“Planets with the highest BCI values tend to be larger, warmer, and older than Earth,” added Irwin, “so any search for complex or intelligent life that is restricted just to Earth-like planets, or to life as we know it on Earth, will probably be too restrictive.”

Source: Planetary Habitability Laboratory at the University of Puerto Rico at Arecibo

How Much Can Titan’s Sunsets Teach Us About Alien Planets?

An illustration of a Titanic lake by Ron Miller. All rights reserved. Used with permission.

Titan — that smoggy, orangy moon circling Saturn — is of great interest to exobiologists because its chemistry could be good for life. It has a thick atmosphere of nitrogen and methane and likely has lakes filled with liquid hydrocarbons, and scientists believe there is enough light filtering down into the atmosphere to drive chemical reactions.

It turns out the moon could also be a good analog to help us understand the atmospheres of exoplanets far beyond our solar system. From looking at sunsets on the moon, scientists led by NASA believe that a thick atmosphere could influence how we perceive a planet from afar.

First, a bit of information about how scientists learn about planet atmospheres in the first place. When a distant planet passes in front of its parent star, the light from the star passes through the atmosphere and gets distorted.

The spectra that telescopes pick up can then tell scientists information about what the atmosphere is made of, what temperature it is, and how it is structured. (This science, it should be noted, is in its very early stages and works best on very large exoplanets that are relatively close to Earth, since the planets are so small and far away.)

“Previously, it was unclear exactly how hazes were affecting observations of transiting exoplanets,” stated Tyler Robinson, a postdoctoral research fellow at NASA’s Ames Research Center who led the research. “So we turned to Titan, a hazy world in our own solar system that has been extensively studied by Cassini.”

Titan's surface is almost completely hidden from view by its thick orange "smog" (NASA/JPL-Caltech/SSI. Composite by J. Major)
Titan’s surface is almost completely hidden from view by its thick orange “smog” (NASA/JPL-Caltech/SSI. Composite by J. Major)

To do this, Robinson’s team used data from the Cassini spacecraft during four solar occultations, or times when Titan passed in front of our own sun from the perspective of the spacecraft. They found out that the moon’s hazy atmosphere makes it difficult to figure out what is in its spectra.

“The observations might be able to glean information only from a planet’s upper atmosphere,” NASA stated. “On Titan, that corresponds to about 90 to 190 miles (150 to 300 kilometers) above the moon’s surface, high above the bulk of its dense and complex atmosphere.”

The haze is even more powerful in the shorter (bluer) wavelengths of light, which contradicts previous studies assuming that all wavelengths of light would have the same distortions. Models of exoplanet atmospheres usually have simplified spectra because hazes are complex to model, requiring a lot of computer power.

Researchers hope to take these observations of Titan and then use them to better inform how exoplanet models are created.

The research was published May 26 in the Proceedings of the National Academy of Science.

Source: NASA

Will We Find Alien Life Within 20 Years? You Can Bet On It.

SETI's Allen Telescope Array monitor the stars for signs of intelligent life (SETI.org)

During a hearing last week before the U.S. House Science and Technology Committee SETI scientists Seth Shostak and Dan Werthimer asserted that solid evidence for extraterrestrial life in our galaxy — or, at the very least, solid evidence for a definitive lack of it — will come within the next two decades. It’s a bold claim for scientists to make on public record, but one that Shostak has made many times before (and he’s not particularly off-schedule either.) And with SETI’s Allen Telescope Array (ATA) continually scanning the sky for any signals that appear intentional, exoplanets being discovered en masse, and new technology on deck that can further investigate a select few of their (hopefully) Earth-like atmospheres, the chances that alien life — if it’s out there — will be found are getting better and better each year.

Would you put your bet on E.T. being out there? Actually, you can.

Thanks to the internet and the apparently incorrigible human need to compete you can actually place a wager on when alien life will be discovered, via an Irish online betting site.

Illustration of Kepler-186f, a recently-discovered, possibly Earthlike exoplanet that could be a host to life. (NASA Ames, SETI Institute, JPL-Caltech, T. Pyle)
Illustration of Kepler-186f, a recently-discovered, possibly Earthlike exoplanet that could be a host to life. (NASA Ames, SETI Institute, JPL-Caltech, T. Pyle)

Typically focused on the results of international sporting matches, PaddyPower.com has also included the announcement of extraterrestrial life in its novelty bet section, hinging on “the sitting President of the USA making a statement confirming without doubt the existence of alternative life beings from another planet.” The odds of such an announcement being made in the years 2015-2018 are currently listed at 100 to one. After that they drop significantly… probably because by then the JWST will be in operation and we will “have the technology.” Stranieri.com also has offered a chance for Italian players of chance to bet on the sitting president discussing life from other planets, with betting open until 2025 for long-term gamblers!

Of course, whether you personally would place a wager on such things is purely personal preference, and neither I nor Universe Today condones or supports gambling, for aliens or otherwise. (And the legalities of doing so and any and all results thereof are the sole responsibility of the reader.) But it is interesting that we now live in a time when wagering on the discovery of alien life sits just a click away from the results of the Kentucky Derby, French Open, or World Cup.

Now if you really want to support the science that will make such a discovery possible — maybe even within our own Solar System — you can “stand up for space” and write your representatives to tell them you want NASA’s planetary science budget to be funded, and rather than gamble your money you can make a donation to support SETI’s ongoing mission here (or even help out yourself via SETI@home.)

And even if all else fails, you could end up with a free coffee courtesy of Dr. Shostak…

Learn more about SETI and how the ATA works here, and read Dan Werthimer’s May 21 statement to the House Committee here.

Source/ht: FloridaToday Space and The Independent

“Two possibilities exist: either we are alone in the Universe or we are not. Both are equally terrifying.”

– Arthur C. Clarke

Kepler Space Telescope Gets A New Exoplanet-Hunting Mission

Artist's conception of the Kepler Space Telescope. Credit: NASA/JPL-Caltech

After several months with their telescope on the sidelines, the Kepler space telescope team has happy news to report: the exoplanet hunter is going to do a new mission that will compensate for the failure that stopped its original work.

Kepler’s exoplanet days were halted last year when the second of its four reaction wheels (pointing devices) failed, which meant the telescope could not gaze at its “field” of stars in the Cygnus constellation for signs of exoplanets transiting their stars.

Results of a NASA Senior Review today, however, showed that the telescope will receive the funding for the K2 mission, which allows for some exoplanet hunting, among other tasks. The telescope will essentially change positions several times a year to do its new mission, which is funded through 2016.

“The approval provides two years of funding for the K2 mission to continue exoplanet discovery, and introduces new scientific observation opportunities to observe notable star clusters, young and old stars, active galaxies and supernovae,” wrote Charlie Sobeck, the mission manager for Kepler, in a mission update today (May 16).

Artist’s rendering of the Earth-sized Kepler-186f (Credit: NASA Ames/SETI Institute/Caltech)
Artist’s rendering of the Earth-sized Kepler-186f (Credit: NASA Ames/SETI Institute/Caltech)

“The team is currently finishing up an end-to-end shakedown of this approach with a full-length campaign (Campaign 0), and is preparing for Campaign 1, the first K2 science observation run, scheduled to begin May 30.”

While Kepler itself was not being used for planet hunting, scientific discoveries continue because the telescope has a legacy of observations stretching between 2009 and 2013. One notable find: 715 exoplanets were announced in one swoop earlier this year using a new technique called “verification by multiplicity”, which is useful in multiple-planet systems.

Kepler also spotted the first known Earth-sized planet in a habitable zone outside of our solar system, which achieves the mission’s stated goal of finding extrasolar Earths.

Read more about NASA’s 2014 senior science review at this website.