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First Discovery Of An Earth-Sized Planet In The Habitable Zone

Cosmic Diary Marchis - April 17, 2014

Source: SETI Institute Press-release

MOUNTAIN VIEW, CA – For the first time, an Earth-sized planet has been found in the habitable zone of its star. This discovery not only proves the existence of worlds that might be similar to our own, but will undoubtedly shape future investigations of exoplanets that could have terrestrial surface environments.

Artistic view of a Earth-sized planet in the habitable zone of its star. Credit: D. Futselaar/SETI Institute

The new-found body, orbiting the red dwarf star Kepler-186 and designated Kepler-186f, is the fifth – and outermost – world to be discovered in this system. The results are described in an article appearing in Science.

“This is the first definitive Earth-sized planet found in the habitable zone around another star,” says lead author Elisa Quintana of the SETI Institute at NASA Ames Research Center. “Finding such planets is a primary goal of the Kepler space telescope. The star is a main-sequence M-dwarf, a very common type. More than 70 percent of the hundreds of billions of stars in our galaxy are M-dwarfs.”

Of the nearly 1800 confirmed exoplanets found in the past two decades, approximately twenty orbit their host star in the habitable zone – a range of orbital distances at which surface water on a planet with an atmosphere would neither freeze nor boil. However, all of these previously discovered worlds are larger than Earth, and consequently their true nature – rocky or gaseous – is unknown. On the basis of the observed dimming of starlight from Kepler-186, the authors estimate that this newly discovered planet is roughly the same size as the Earth.

 

Thomas Barclay, a staff scientist for the Kepler mission affiliated with both NASA and the Bay Area Environmental Research Institute, notes that “theoretical models of how planets form suggest that those with diameters less than 1.5 times that of Earth are unlikely to be swathed in atmospheres of hydrogen and helium, the fate that’s befallen the gas giants of our own solar system. Consequently, Kepler-186f is likely a rocky world, and in that sense similar to Venus, Earth and Mars.”

The new planet orbits at a distance of 0.36 astronomical units from its star, or slightly closer than Mercury is to the Sun. Its orbital period is 130 days.

Traditionally, planets orbiting red dwarf stars were considered to be poor candidates for life. The objection was that star-hugging planets in the habitable zone would become tidally locked, and suffer a synchronous or pseudo-synchronous rotation that could make climate on these planets untenable. However, more recent modeling studies suggest that such worlds are not necessarily inhospitable, since atmospheric winds or ocean currents could even out extreme temperature variations . In addition, Kepler-186f is far enough away from its host star that it is unlikely to be locked. This greater distance also reduces the danger to any potential life forms posed by stellar flares, which are more common for dwarf stars.

 

Since 2012, the SETI Institute’s Allen Telescope Array has been observing Kepler

candidate exoplanets looking for signals that would indicate extraterrestrial intelligence. A search for emissions from Kepler-186f has been made over the very wide frequency range of 1 to 10 GHz, but none have so far been found. These observations will be repeated. Note that a detectable signal would require a transmitter approximately 10 to 20 times more powerful than the planetary radar system at Arecibo, in Puerto Rico.

 

According to Quintana, at 490 light-years Kepler-186f may be too dim for follow-up surveys to probe its atmosphere, even with next-generation telescopes. “However, our research tells us that we should be able to find planets around bright stars that will be ideal targets to observe with James Webb.” NASA’s Webb space-based telescope, now under construction, will be able to directly image planets around nearby dwarf stars, and use spectral analysis to characterize their atmospheres.

 

Finding Kepler-186f is a first, but “it’s not a record we wish to keep,” Quintana says. “We want to find more of these.”

 

Tidally locked planet around an M-type star (credit: Seth Shostak/SETI Institute)

Contacts:

 

Elisa Quintana

SETI Institute

E-mail: elisa.quintana@nasa.gov

Tel: +1 650 604-2467

 

Thomas Barclay
E-mail: thomas.barclay@nasa.gov

Tel: +1 650 604-3560

 

Karen Randall, Media Contact
SETI Institute
E-mail: krandall@seti.org
Tel: +1 650 960-4537

 

 

About the SETI Institute:

The mission of the SETI Institute is to explore, understand and explain the origin, nature and prevalence of life in the universe. The Institute is a private, nonprofit organization dedicated to scientific research, education and public outreach. It comprises three centers, the Center for SETI Research, the Carl Sagan Center for the Study of Life in the Universe and the Center for Education and Public Outreach. Founded in November 1984, the SETI Institute today employs over 150 scientists, educators and support staff. For more information, www.seti.org 650-961-6633.

 

That's Containment!

ENCORE We all crave power: to run laptops, charge cell phones, and play Angry Birds. But if generating energy is easy, storing it is not. Remember when your computer conked out during that cross-country flight? Why can’t someone build a better battery?

Discover why battery design is stuck in the 1800s, and why updating it is key to future green transportation (not to mention more juice for your smartphone). Also, how to build a new type of solar cell that can turn sunlight directly into fuel at the pump.

Plus, force fields, fat cells and other storage systems. And: Shock lobster! Energy from crustaceans?

Guests:
  • Dan Lankford – Former CEO of three battery technology companies, and a managing director at Wavepoint Ventures
  • Jackie Stephens – Biochemist at Louisiana State University
  • Kevin MacVittie – Graduate student of chemistry, Clarkson University, New York
  • Nate Lewis – Chemist, California Institute of Technology
  • Alex Filippenko – Astronomer, University of California, Berkeley
  • Peter Williams – Physicist, San Francisco Bay Area

Descripción en español

First released February 4, 2103.

Since Sliced Bread

Happy Birthday, World Wide Web! The 25-year-old Web, along with the Internet and the personal computer, are among mankind’s greatest inventions. But back then, who knew?

A techno-writer reminisces about the early days of the WWW and says he didn’t think it would ever catch on.

Also, meet an inventor who claims his innovation will leave your laptop in the dust. Has quantum computing finally arrived?

Plus, why these inventions are not as transformative as other creative biggies of history: The plow. The printing press. And… the knot?

And, why scientific discoveries may beat out technology as the most revolutionary developments of all. A new result about the Big Bang may prove as important as germ theory and the double helix.

Guests:

Descripción en español

Nooks and crannies

Cosmic Diary by Lori Fenton - April 04, 2014

A piece of Mars: This 521×391 m (1709×1283 ft) scene shows a rocky plain with many small impact craters (the bigger ones are ~45 m, or 148 ft across). Dark rippled sand fills the floors of the craters. Why? Once it blows in, it’s hard for the sand to get out. It gets caught in the nooks and crannies of the terrain. The same way it gets caught in your bathing suit and towel at the beach. (ESP_035164_1655, NASA/JPL/Univ. of Arizona)

When Mars gets weird

Cosmic Diary by Lori Fenton - March 31, 2014

A piece of Mars: Mars can be a strange place. This is actually a sand dune on Mars not far from the north pole. Here it’s imaged in the springtime when the dunes are still covered in  bright CO2 frost, which is in turn overlain by yellowish dust that has fallen out of the atmosphere. The dark patch is a spot where the sunlight has penetrated the ice cover enough to allow some defrosting to begin — the dark line in the middle is close to the true color of ice-free sand. (HiRISE ESP_025126_2640, NASA/JPL/Univ. of Arizona)

Skeptic Check: Evolutionary Arms Race

It’s hard to imagine the twists and turns of evolution that gave rise to Homo Sapiens. After all, it required geologic time, and the existence of many long-gone species that were once close relatives. That may be one reason why – according to a recent poll – one-third of all Americans reject the theory of evolution. They prefer to believe that humans and other living organisms have existed in their current form since the beginning of time.

But if you’ve ever been sick, you’ve been the victim of evolution on a very observable time scale. Nasty viruses and bacteria take full advantage of evolutionary forces to adapt to new hosts. And they can do it quickly.

Discover how comparing the deadly 1918 flu virus with variants today may help us prevent the next pandemic. Also, while antibiotic resistance is threatening to become a major health crisis, better understanding of how bacteria evolve their defenses against our drugs may help us out.

And the geneticist who sequenced the Neanderthal genome says yes, our hirsute neighbors co-mingled with humans.

It’s Skeptic Check … but don’t take our word for it!

Guests:

Descripción en español

Surprising discovery: a ring around an asteroid

Cosmic Diary Marchis - March 26, 2014

Some may say that our universe is full of beauty, others argue that it is our solar system that surprises us the most, but ultimately I will say that it is the world of small solar system bodies which is strikingly full of diversity. Today’s announcement of the discovery of rings around the Centaur Chariklo by an international team of astronomers is a vivid proof that small solar system bodies have not yet revealed all their secrets.

 My recent work has made me realize that asteroids (also called small solar system bodies or minor planets) are in fact real mini-geological worlds. Planetary scientists found out about their complexity very recently after visiting them with robotic spacecraft that took snapshots of their surfaces. These images showed the presence of geological activity on their surface (craters & landslides) and morphological features (ponds of dust, and pebbles). More recently, studies based on powerful observations with large ground-based telescopes, revealed that several asteroids have moons. The follow-up of their moons’ orbits revealed a complex interior for these asteroids that is possibly differentiated, similarly to the major planets.

The announcement of a ring around a Centaur is, without doubt, another step ahead in blurring the differences between minor and major planets.

Orbit of the Centaur Asteroid Chariklo (credit: JPL)

Centaur asteroids are a special population of minor bodies which orbit among the giant planets. They possess the characteristics of comets, since some of them have shown cometary activity, and can also look like asteroids. They are most likely made of a mixture of ices and rocks.  They were discovered quite recently and because they are far away from us, we don’t know much about them beyond their orbits around the sun, the colors of their surfaces, and the average size for the largest ones.

One Centaur named Chariklo, or asteroid number 10199, was discovered in 1997 by the Spacewatch survey. It has never been the target of the Hubble Space Telescope because time on this telescope is extremely difficult to obtain, due to the high competition with other programs. Also, to my knowledge, none of the 8-10m class telescopes equipped with adaptive optics has also observed it, most likely because of its faintness (V~18.3 in visible).  Consequently, we didn’t know much about this asteroid, with the exception of its average size of 260 km.

A team of astronomers designed a clever way to study distant asteroids, like Centaur asteroids.  Since their orbits are well-known after several years of observations, they can predict when a Centaur asteroid will hide the light of a bright star and where and when this event will happen.    On 3 June 2013, Chariklo passed in front of a star and the path of this occultation crossed South America. Based on this prediction, seven telescopes observed the disappearance of this star that lasted a few seconds. But what really stunned the astronomers was that the star also vanished a few seconds before and after the main occultation.

After putting together those occultation chords, they derived the size and shape of Chariklo, and realized that these secondary occultations could be best explained by assuming that Chariklo is surrounding by a dense ring of dust.  Using data from the largest telescope involved in these observations (the 1.54m Danish telescope located at La Silla Observatory in Chile), they found out that there are in fact 2 rings around Chariklo.

This is not a direct image per se, but their work, which is based on multiple chords taken from a wide variety of instruments and different observers, is quite reliable.

The structures in the disk around Chariklo suggest that the system is quite complex. We can assume that its rings are shepherded by a system of moons, not yet detected, like the F ring of Saturn is shepherded by Pandora and Prometheus.

Two of Saturn’s shepherd moons keep the planet’s F ring in check. Image Credit: NASA/JPL

The team also discussed the consistency of their results with previous observations of Chariklo. Between 1997-2008, they calculated that the system was seen edge-on, so the ring of dust was occulting the primary and should have dimmed its brightness significantly. This attenuation of Chariklo’s brightness was reported in the literature and no explanation had been found at the time. Additionally, spectroscopic variations of Chariklo were seen during the same period. The disappearance of these absorption bands, when the ring was edge-on, could be explained by assuming that it is made of ices and organics.

How did such a system form?” is the bonus question of this study. The presence of those signatures of ices in the spectrum of the Chariklo system implies that the system is young, so how are we so extremely lucky to see it? The team discussed a collisional origin but other scenarios could be considered. I hypothesize that the system has a complex moon system and the rings are replenished by cometary activity from the surface of the primary.

This centaur asteroid will be a great target for extremely large telescopes. The rings are 0.040″ away from the primary so will be difficult to detect with current 8-10m class telescopes, which can only marginally reach this angular resolution. Extremely large telescopes, like the future TMT, E-ELT or GMT, would be capable of imaging the system and revealing those moons.

I wonder how many of these asteroid ring systems will be found in the future thanks to the development of large aperture telescopes on the ground and in space. The development of instrumentation has revealed how common moons are around asteroids, so we can extrapolate that asteroid ring systems may be common in the distant and cold regions of our solar system.

Chariklo’s ring system, and those that remain to be found, are not only a curiosity for astronomers, they are also a time-capsule that allow us to peek into the collisional history of our solar system. Their study could also help us understand the composition of the asteroid itself.

One simple question that came to my mind when I read the article is why we found this ring system around a centaur asteroid? It would have been easier to find it around an asteroid in the main-belt since they are closer to us and we observe the larger ones quite often with large ground-based telescopes. I suspect that this is related to the composition of centaur asteroids and that the ring is indeed a secondary product of their surface activity.

I am done speculating for the moment, and will simply enjoy this rare moment when a new sub-field of research in planetary science is being born.

Clear skies

Franck Marchis

The millipede, rewritten

Cosmic Diary by Lori Fenton - March 24, 2014

A piece of Mars: Looks like a millipede, doesn’t it? It’s something much larger and much less poisonous. It’s an ancient dune (or maybe a ripple) on Mars, that once stretched ~285 m (935 ft) from lower left to middle right. Since then it’s been nearly rewritten twice. The first time, a different wind direction made smaller ripples (the millipede’s “feet”) that nearly erased the original shape. The second time, a cluster of craters formed, punching holes in the millipede. Maybe it was martian pest control. (HiIRSE ESP_034942_1615, NASA/JPL/Univ. of Arizona).

Do the Math

ENCORE One plus one is two. But what’s the square root of 64, divided by 6 over 12?* Wait, don’t run for the hills! Math isn’t scary. It helps us describe and design our world, and can be easier to grasp than the straight edge of a protractor.

Discover how to walk through the city and number-crunch simultaneously using easy tips for estimating the number of bricks in a building or squirrels in the park. Plus, why our brains are wired for finger-counting … whether aliens would have calculators … and history’s most famous mathematical equations (after e=mc2).

*The answer is 16

Guests:

Descripción en español

Ribbons on Mars

Cosmic Diary by Lori Fenton - March 17, 2014

A piece of Mars: Bet you didn’t know there were ribbons on Mars. Long, sweeping, velvety lines, delicately frayed at the ends. These are actually ancient ripples, formed by a wind blowing from right to left. Stripes on the ripples and on the ground between them show the ancient ripple interiors, exposed by erosion. The long ripple in left center is 175 m (574 ft) long. (HiRISE ESP_016136_1525, NASA/JPL/Univ. of Arizona)

You Think; You're So Smart

Sure you have a big brain; it’s the hallmark of Homo sapiens. But that doesn’t mean that you’ve cornered the market on intelligence. Admittedly, it’s difficult to say, since the very definition of the term is elusive. Depending on what we mean by intelligence, a certain aquatic mammal is not as smart as we thought (hint: rhymes with “caulpin”) … and your rhododendron may be a photosynthesizing Einstein.

And what I.Q. means for A.I. We may be building our brilliant successors.

Guests:

Descripción en español

Lighting effects

Cosmic Diary by Lori Fenton - March 10, 2014

A piece of Mars: It’s winter in the southern hemisphere, and dunes like these are covered in bright white CO2 frost. The sun is near the horizon (shining from the top of the image), so it creates stark shadows. That can make doing science tough, but it’s the best way to show off the beauty of the dunes. Can you tell which way is up here, which way is down, and when you’re looking at a inherent change in the surface color vs. sun and shadows? (ESP_034922_1385, NASA/JPL/Univ. of Arizona)

We Heart Robots

ENCORE The machines are coming! Meet the prototypes of your future robot buddies and discover how you may come to love a hunk of hardware. From telerobots that are your mechanical avatars … to automated systems for the disabled … and artificial hands that can diffuse bombs.

Plus, the ethics of advanced robotics: should life-or-death decisions be automated?

And, a biologist uses robo-fish to understand evolution.

Guests:

Descripción en español

First released January 21, 2013

Swoosh

Cosmic Diary by Lori Fenton - March 05, 2014

A piece of Mars: What is this big swoosh? It’s a big dark dune. The dark/light striping across it is found in all of the dunes in this area, but what is it? We’re probably seeing the inside of the dune: the wind may so strong here that it erodes the highest point of the dune, showing off the interior structure. (HiRISE ESP_034909_1744, NASA/JPL/Univ. of Arizona)

There’s ripples and then there’s ripples

Cosmic Diary by Lori Fenton - March 03, 2014

A piece of Mars: On the floor of a crater in the southern midlatitudes, there’s a field of ripples. But wait, there are big ones that are very sinuous and small ones that are not. Why? Both are ripples, but they’re different kinds of ripples. The smaller ones (~3 m, or ~10 ft) are probably made entirely of sand, while the larger ones (~15 m, or 50 ft) are older and they’re probably made of a mixture of different grain sizes. (ESP_034801_1300, NASA/JPL/Univ. of Arizona).

Space for Everyone

Is space the place for you? With a hefty amount of moolah, a trip there and back can be all yours. But when the price comes down, traffic into space may make the L.A. freeway look like a back-country lane.

Space is more accessible than it once was, from the development of private commercial flights … to a radical new telescope that makes everyone an astronomer … to mining asteroids for their metals and water to keep humanity humming for a long time.

Plus, move over Russia and America: Why the next words you hear from space may be in Mandarin.

Guests:
  • Leonard David – Space journalist, writer for SPACE.com
  • Mario Juric – Astronomer working on data processing for the LSST – the Large Synoptic Survey Telescope
  • John Lewis – Chemist, professor emeritus of planetary sciences, University of Arizona, chief scientist, Deep Space Industries
  • Philip Lubin – Professor of physics, University of California, Santa Barbara
  • James Oberg – Retired NASA rocket scientist, space historian, and a self-described space nut

Descripción en español

Before the Big Bang

Big Picture Science Latest Shows - February 24, 2014

ENCORE It’s one of the biggest questions you can ask: has the universe existed forever? The Big Bang is supposedly the moment it all began. But now scientists wonder if there isn’t an earlier chapter to our origin story. And maybe chapters before that! What happened before the Big Bang? It’s the ultimate prequel.

Plus – the Big Bang as scientific story: nail biter or snoozer?

Guests

Descripción en español

First released December 17, 2102

HiRISE image caption for Curiosity

Cosmic Diary by Lori Fenton - February 17, 2014


A piece of Mars: Last week I wrote an image caption for Curiosity, showing both the HiRISE perspective and Curiosity’s image of the ripple crossing Dingo Gap. Read more on the HiRISE image page.

Skeptic Check: Paleo Diet

Big Picture Science Latest Shows - February 17, 2014

What’s for dinner? Meat, acorns, tubers, and fruit. Followers of the Paleo diet say we should eat what our ancestors ate 10,000 years ago, when our genes were perfectly in synch with the environment.

We investigate the reasoning behind going paleo with the movement’s pioneer, as well as with an evolutionary biologist. Is it true that our genes haven’t changed much since our hunter-gatherer days?

Plus, a surprising dental discovery is nothing for cavemen to smile about.

And another fad diet that has a historical root: the monastic tradition of 5:2 – five days of eating and two days of fasting.

It’s our monthly look at critical thinking, Skeptic Check … but don’t take our word for it.

Guests:

Descripción en español

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