Saturday, 29 June 2013

Search for Habitable Moons around Kepler-22b

Judith E. Braffman-Miller speculates in her recent blog about moons on Exoplanets and the search for habitable environments near Kepler-22b.
image from NASA
Moons are enchanting, mesmerizing objects dwelling in their orbits around planets both within and beyond our Solar System. Earth's own large Moon, a silver-golden world that shines in our starlit night sky with the reflected fires of our Star, the Sun, has long been the inspiration of haunting poems and tales of love, as well as myths of magic and madness. Most of the moons of our Sun's own bewitching family are glistening little icy worlds in orbit around the giant planets of the outer Solar System. In June 2013, astronomers announced their dedicated hunt for a habitable moon-world beyond our Sun's family, circling around the planet Kepler-22b, that dwells in the faraway family of a different star.
Moons can be found in a rich assortment of various sizes, shapes, and types. Although they are generally solid little worlds, a few of them are known to sport atmospheres. Indeed, the atmosphere of the second largest moon in our Solar System, Titan of Saturn, is so dense that it hides Titan's strange hydrocarbon-slashed surface beneath a thick orange veil.
Most of the moons dwelling in our Sun's family were probably born from primordial disks of dust and gas, orbiting around newly formed planets, when our Solar System was very young about 4.5 billion years ago. There are at least 150 moons circling the planets in our Solar System--and about 25 moons are currently awaiting official confirmation of their discovery.
Of the four terrestrial, rocky planets of the inner Solar System (Mercury, Venus, our Earth, and Mars), both Mercury and Venus are moonless. Earth possesses one lone Moon, but it is a very large one--the fifth largest moon in our entire Solar System, in fact. Mars, on the other hand, has two tiny misshapen moons that resemble rocky potatoes, and are lumpy and dark, as they travel in their nearly circular orbits close to the plane of the Martian equator. The Martian moons, Phobos and Deimos, are probably asteroids that were captured by Mars long ago.
The outer Solar System is more richly endowed with moons than the inner regions. The two enormous gas giant planets, Jupiter and Saturn, and the ice giant planets, Uranus and Neptune, have numerous moons of various sizes, shapes, and origins. As these enormous planets grew, during the early days of our Solar System, they were able to ensnare wandering objects with their mighty gravitational grips.
Jupiter, the largest planet in our Solar System, also has the largest moon--Ganymede. A large number of Jovian moons sport highly elliptical orbits and also circle backwards--that is, opposite to the spin of their planet. Saturn, Uranus, and Neptune also sport such so-called irregular moons, that orbit far from their respective parent planets.
Earth's bewitching large Moon was probably born as the result of an immense impact, when a Mars-size protoplanet named Theia smashed into Earth about 4.5 billion years ago. This cataclysmic collision is thought to have hurled a vast amount of Earth-stuff and Theia-stuff into orbit around our ancient planet. Debris from the two unfortunate bodies gradually accumulated to give birth to our Moon, as tumbling little newborn moonlets crashed into one another and melded together into one large object.
We have known since 1995 that our Solar System is far from unique in the Cosmic scheme of things, and that there are a vast number of planets that circle stars beyond our own Sun. Furthermore, some of these extrasolar planets probably have moons just like most of the planets in our Sun's family. These faraway exomoons are enticing little worlds of wonder and mystery--and possibly even life.
A Habitable Exomoon For Kepler-22b?
Kepler-22b is an extrasolar planet that circles Kepler-22, a G-type star that is situated about 600 light-years from our own planet in the constellation Cygnus. This intriguing new world, that resides beyond our Solar System, was first spotted by NASA's highly productive, though ill-fated, Kepler Space Telescope in 2011. Kepler-22b has the distinction of being the first known transiting extrasolar planet to reside within the so-calledhabitable zone of its star. The habitable zone is the term used to describe that Goldilocks region around a star where water can exist in its life-loving liquid state. Planets dwelling in this fortunate region are not too hot, not too cold, but just right for water and, hence, life to exist. A planet that circles its star in the habitable zone suggests that there is the possibility--though not the promise--of life as we know it to exist on that world.
Kepler-22b's initial transit in front of the face of its fiery star was seen by Kepler on its third day of scientific observations, back in May 2009. The third passage was spotted in late 2010. Still more confirming evidence was provided by the infrared Spitzer Space Telescope, as well as by ground-based 'scopes. The confirmation of the existence of this interesting extrasolar planet world was announced on December 5, 2011.
Kepler-22b sports an orbital period of approximately 200 days. Its inclination is about 90 degrees, and it transits in front of the face of its star as observed by Earth-based astronomers. The shape of Kepler-22b's orbit is unknown, but it is known that its average orbital distance is well within its parent star's habitable zone. Many extrasolar planets are known to sport highly elliptical (football-shaped) orbits, and if Kepler-22b also travels along such a path around its star, it would only spend a tiny fraction of its time within this Goldilocks zone. This would cause the planet to undergo such extreme variations in temperature that it would not be a pleasant place for delicate living things to evolve and flourish. Kepler-22b is approximately 2.4 times the radius of Earth.
With the discoveries of 132 confirmed extrasolar planets and more than three thousand planet candidates, the Kepler mission revolutionized scientific understanding of planets residing beyond our own Star. Much of the attention surrounding these discoveries has focused on identifying an Earth-analog--a planet about the size of our own world dwelling within the precious Goldilocks zone around its distant star. Now, for the first time, Dr. David M. Kipping of the Harvard-Smithsonian Center for Astrophysics (CfA) in Cambridge, Massachusetts, and his team, have started to hunt for a habitable moon around Kepler-22b!
Kepler-22b, with its radius almost two and a half times that of Earth, is too large to be considered a true Earth-analog. Nevertheless, if it possesses an Earth-sized moon, the planetary system could still host a habitable world like our own.
In order to spot such a remote exomoon, the authors of this new study, The Hunt for Exomoons with Kepler (HEK): III. The First Search for an Exomoon around a Habitable-Zone Planet, used a technique that models the dips and features of the parent star's light-curve (stellar brightness vs. time), which are caused by transits of the planet (and any accompanying moons) in front of the face of its star. This is a complicated and difficult endeavor because numerous and diverse models of planet-moon dynamics must be taken into consideration. Each one of these models possesses parameters that describe physical properties belonging to the planet or moon, as well as parameters describing the orbital system. The authors use what is termed Bayesian statistics to account for the fact that the true orbital model of this planetary system is still not known--and this enables them to calculate if a model with our without a moon fits the observed light-curve the best.
The team also considered whether it would be possible to determine, with an adequate degree of certainty, if a detected moon could bear life-loving liquid water. In their analysis, the "input" climate for the moon is habitable, which is identified with high probability. However, there still remains approximately a one in six failure rate.
With such intriguing results before them, the team of astronomers studied the data to determine if Kepler-22b actually has a moon. Unfortunately, their analysis reveals no evidence for the existence of an exomoon circling Kepler-22b. This non-detection suggests that the mass of any companion world around Kepler-22b must be less than 0.54 times the mass of our planet--with an impressive confidence rate of 95%! Therefore, it is very unlikely that Kepler-22b is circled by an Earth-like moon. Nevertheless, it is still too soon to give up hope. The Hunt for Exomoons with Kepler project has studied nine planetary systems in search of exomoons. Although none were detected, with the team's new results about the possibility of finding Earth-sized moons and the remaining treasure trove of Kepler data to sift through, large and possibly even habitable exomoons may start being spotted in the near future.
Judith E. Braffman-Miller is a writer and astronomer whose articles have been published since 1981 in various newspapers, magazines, and journals. Although she has written on a variety of topics, she particularly loves writing about astronomy because it gives her the opportunity to communicate to others the many wonders of her field. Her first book, "Wisps, Ashes, and Smoke," will be published soon.

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Imagination can change what we hear and see: spooky?

It appears what you see or hear isn't always what you get!  I wonder if this contributes more widely to 'spooky' experiences.
A study from the Swedish Karolinska Institutet shows, that our imagination may affect how we experience the world more than we perhaps think. What we imagine hearing or seeing 'in our head' can change our actual perception. The study, which is published in the scientific journal Current Biology, sheds new light on a classic question in psychology and neuroscience - about how our brains combine information from the different senses.
Henrik Ehrsson and Christopher Berger. Photo: Stefan Zimmerman
"We often think about the things we imagine and the things we perceive as being clearly dissociable," says Christopher Berger, doctoral student at the Department of Neuroscience and lead author of the study. "However, what this study shows is that our imagination of a sound or a shape changes how we perceive the world around us in the same way actually hearing that sound or seeing that shape does. Specifically, we found that what we imagine hearing can change what we actually see, and what we imagine seeing can change what we actually hear."
The study consists of a series of experiments that make use of illusions in which sensory information from one sense changes or distorts one's perception of another sense. Ninety-six healthy volunteers participated in total. In the first experiment, participants experienced the illusion that two passing objects collided rather than passed by one-another when they imagined a sound at the moment the two objects met. In a second experiment, the participants' spatial perception of a sound was biased towards a location where they imagined seeing the brief appearance of a white circle. In the third experiment, the participants' perception of what a person was saying was changed by their imagination of a particular sound.
Illusion of colliding objects.
According to the scientists, the results of the current study may be useful in understanding the mechanisms by which the brain fails to distinguish between thought and reality in certain psychiatric disorders such as schizophrenia. Another area of use could be research on brain computer interfaces, where paralyzed individuals' imagination is used to control virtual and artificial devices.
"This is the first set of experiments to definitively establish that the sensory signals generated by one's imagination are strong enough to change one's real-world perception of a different sensory modality", says Professor Henrik Ehrsson, the principle investigator behind the study.
This study was funded by the European Research Council, the Swedish Foundation for Strategic Research, the James S. McDonnell Foundation, the Swedish Research Council, and the Söderberg Foundation.
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Friday, 28 June 2013

NASA's Voyager 1 Explores Final Frontier

Data from Voyager 1, now more than 11 billion miles (18 billion kilometers) from the sun, suggest the spacecraft is closer to becoming the first human-made object to reach interstellar space.

Research using Voyager 1 data and published in the journal Science today provides new detail on the last region the spacecraft will cross before it leaves the heliosphere, or the bubble around our sun, and enters interstellar space. Three papers describe how Voyager 1's entry into a region called the magnetic highway resulted in simultaneous observations of the highest rate so far of charged particles from outside heliosphere and the disappearance of charged particles from inside the heliosphere.
Scientists have seen two of the three signs of interstellar arrival they expected to see: charged particles disappearing as they zoom out along the solar magnetic field, and cosmic rays from far outside zooming in. Scientists have not yet seen the third sign, an abrupt change in the direction of the magnetic field, which would indicate the presence of the interstellar magnetic field.
"This strange, last region before interstellar space is coming into focus, thanks to Voyager 1, humankind's most distant scout," said Ed Stone, Voyager project scientist at the California Institute of Technology in Pasadena. "If you looked at the cosmic ray and energetic particle data in isolation, you might think Voyager had reached interstellar space, but the team feels Voyager 1 has not yet gotten there because we are still within the domain of the sun's magnetic field."
Scientists do not know exactly how far Voyager 1 has to go to reach interstellar space. They estimate it could take several more months, or even years, to get there. The heliosphere extends at least 8 billion miles (13 billion kilometers) beyond all the planets in our solar system. It is dominated by the sun's magnetic field and an ionized wind expanding outward from the sun. Outside the heliosphere, interstellar space is filled with matter from other stars and the magnetic field present in the nearby region of the Milky Way.
Voyager 1 and its twin spacecraft, Voyager 2, were launched in 1977. They toured Jupiter, Saturn, Uranus and Neptune before embarking on their interstellar mission in 1990. They now aim to leave the heliosphere. Measuring the size of the heliosphere is part of the Voyagers' mission.
The Science papers focus on observations made from May to September 2012 by Voyager 1's cosmic ray, low-energy charged particle and magnetometer instruments, with some additional charged particle data obtained through April of this year.
Voyager 2 is about 9 billion miles (15 billion kilometers) from the sun and still inside the heliosphere. Voyager 1 was about 11 billion miles (18 billion kilometers) from the sun Aug. 25 when it reached the magnetic highway, also known as the depletion region, and a connection to interstellar space. This region allows charged particles to travel into and out of the heliosphere along a smooth magnetic field line, instead of bouncing around in all directions as if trapped on local roads. For the first time in this region, scientists could detect low-energy cosmic rays that originate from dying stars.
"We saw a dramatic and rapid disappearance of the solar-originating particles. They decreased in intensity by more than 1,000 times, as if there was a huge vacuum pump at the entrance ramp onto the magnetic highway," said Stamatios Krimigis, the low-energy charged particle instrument's principal investigator at the Johns Hopkins University Applied Physics Laboratory in Laurel, Md. "We have never witnessed such a decrease before, except when Voyager 1 exited the giant magnetosphere of Jupiter, some 34 years ago."
Other charged particle behavior observed by Voyager 1 also indicates the spacecraft still is in a region of transition to the interstellar medium. While crossing into the new region, the charged particles originating from the heliosphere that decreased most quickly were those shooting straightest along solar magnetic field lines. Particles moving perpendicular to the magnetic field did not decrease as quickly. However, cosmic rays moving along the field lines in the magnetic highway region were somewhat more populous than those moving perpendicular to the field. In interstellar space, the direction of the moving charged particles is not expected to matter.
In the span of about 24 hours, the magnetic field originating from the sun also began piling up, like cars backed up on a freeway exit ramp. But scientists were able to quantify that the magnetic field barely changed direction -- by no more than 2 degrees.
"A day made such a difference in this region with the magnetic field suddenly doubling and becoming extraordinarily smooth," said Leonard Burlaga, the lead author of one of the papers, and based at NASA's Goddard Space Flight Center in Greenbelt, Md. "But since there was no significant change in the magnetic field direction, we're still observing the field lines originating at the sun."
NASA's Jet Propulsion Laboratory, in Pasadena, Calif., built and operates the Voyager spacecraft. California Institute of Technology in Pasadena manages JPL for NASA. The Voyager missions are a part of NASA's Heliophysics System Observatory, sponsored by the Heliophysics Division of the Science Mission Directorate at NASA Headquarters in Washington.

For more information about the Voyager spacecraft mission, visit: and .


Jia-Rui C. Cook 818-354-0850
Jet Propulsion Laboratory, Pasadena, Calif.

Steve Cole 202-358-0918
NASA Headquarters, Washington 

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Tuesday, 18 June 2013

Cassini Probe to Take Photo of Earth From Deep Space

NASA's Cassini spacecraft, now exploring Saturn, will take a picture of our home planet from a distance of hundreds of millions of miles on July 19. NASA is inviting the public to help acknowledge the historic interplanetary portrait as it is being taken. 

This simulated view from NASA's Cassini spacecraft shows the expected positions of Saturn and Earth on July 19, 2013, around the time Cassini will take Earth's picture. Cassini will be about 898 million miles (1.44 billion kilometers) away from Earth at the time. That distance is nearly 10 times the distance from the sun to Earth. Image credit: NASA/JPL-Caltech 

Earth will appear as a small, pale blue dot between the rings of Saturn in the image, which will be part of a mosaic, or multi-image portrait, of the Saturn system Cassini is composing.

"While Earth will be only about a pixel in size from Cassini's vantage point 898 million [1.44 billion kilometers] away, the team is looking forward to giving the world a chance to see what their home looks like from Saturn," said Linda Spilker, Cassini project scientist at NASA's Jet Propulsion Laboratory in Pasadena, Calif. "We hope you'll join us in waving at Saturn from Earth, so we can commemorate this special opportunity."

Cassini will start obtaining the Earth part of the mosaic at 2:27 p.m. PDT (5:27 p.m. EDT or 21:27 UTC) and end about 15 minutes later, all while Saturn is eclipsing the sun from Cassini's point of view. The spacecraft's unique vantage point in Saturn's shadow will provide a special scientific opportunity to look at the planet's rings. At the time of the photo, North America and part of the Atlantic Ocean will be in sunlight.

Unlike two previous Cassini eclipse mosaics of the Saturn system in 2006, which captured Earth, and another in 2012, the July 19 image will be the first to capture the Saturn system with Earth in natural color, as human eyes would see it. It also will be the first to capture Earth and its moon with Cassini's highest-resolution camera. The probe's position will allow it to turn its cameras in the direction of the sun, where Earth will be, without damaging the spacecraft's sensitive detectors.

"Ever since we caught sight of the Earth among the rings of Saturn in September 2006 in a mosaic that has become one of Cassini's most beloved images, I have wanted to do it all over again, only better," said Carolyn Porco, Cassini imaging team lead at the Space Science Institute in Boulder, Colo. "This time, I wanted to turn the entire event into an opportunity for everyone around the globe to savor the uniqueness of our planet and the preciousness of the life on it."

Porco and her imaging team associates examined Cassini's planned flight path for the remainder of its Saturn mission in search of a time when Earth would not be obstructed by Saturn or its rings. Working with other Cassini team members, they found the July 19 opportunity would permit the spacecraft to spend time in Saturn's shadow to duplicate the views from earlier in the mission to collect both visible and infrared imagery of the planet and its ring system.

"Looking back towards the sun through the rings highlights the tiniest of ring particles, whose width is comparable to the thickness of hair and which are difficult to see from ground-based telescopes," said Matt Hedman, a Cassini science team member based at Cornell University in Ithaca, N.Y., and a member of the rings working group. "We're particularly interested in seeing the structures within Saturn's dusty E ring, which is sculpted by the activity of the geysers on the moon Enceladus, Saturn's magnetic field and even solar radiation pressure."

This latest image will continue a NASA legacy of space-based images of our fragile home, including the 1968 "Earthrise" image taken by the Apollo 8 moon mission from about 240,000 miles (380,000 kilometers) away and the 1990 "Pale Blue Dot" image taken by Voyager 1 from about 4 billion miles (6 billion kilometers) away.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. JPL manages the Cassini-Huygens mission for NASA's Science Mission Directorate in Washington, and designed, developed and assembled the Cassini orbiter and its two onboard cameras. The imaging team consists of scientists from the United States, the United Kingdom, France and Germany. The imaging operations center is based at the Space Science Institute in Boulder, Colo.

To learn more about the public outreach activities associated with the taking of the image, visit: .

For more information about Cassini, visit and .

Jia-Rui C. Cook 818-354-0850
Jet Propulsion Laboratory, Pasadena, Calif.

Dwayne Brown 202-358-1726
NASA Headquarters, Washington 
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