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Poison could have led to life

Artist's impression of a young planetary system

Organic molecules on Earth could have had their beginning in chemical reactions involving formaldehyde in the infant days of the Solar System.

FORMALDEHYDE, A POISON and a common molecule found throughout the universe, is likely the source of the Solar System’s organic carbon solids—abundant in both comets and asteroids—according to new research.

Scientists have long speculated about how organic, or carbon-containing, material became a part of the Solar System’s fabric.

Now new research from the Carnegie Institution’s George Cody, along with Conel Alexander and Larry Nittler, shows that these complex organic solids were likely converted from formaldehyde that existed in the primitive Solar System.

“We may owe our existence on this planet to interstellar formaldehyde,” Cody said. “And what’s ironic about it is that formaldehyde is poisonous to life on Earth.”

During the early period of the inner Solar System’s formation, much of the organic carbon that wasn’t trapped in primitive bodies like asteroids was lost into space, along with much of the water.

To find out where the organics came from, Cody, of Carnegie’s Geophysical Laboratory, along with Alexander and Nittler, of the Department of Terrestrial Magnetism, and the team decided to study primitive Solar System bodies using advanced methods.

Cross-section of a chondritic meteorite

Cross-section of a chondritic meteorite

What they discovered clearly pointed to a substance formed from formaldehyde.

They tested their conclusion with experiments that aimed to reproduce the type of organic matter found in carbonaceous chondrites—a type of organic-rich meteorite—starting with formaldehyde.

They found that their formaldehyde-synthesised organic material was not only similar to that found in carbonaceous chondrites, but also similar to organic material found in a comet named 81P/Wild 2, pieces of which were collected in space by NASA’s Stardust mission, as well as in interplanetary dust particles, or particles from space that likely originated from comets and asteroids.

They say their results make sense, because formaldehyde is relatively abundant throughout the galaxy and the conversion process would have been possible under the conditions prevailing in the primitive Solar System.

Their work was published online April 4 in the Proceedings of the National Academy of Sciences.

Adapted from information issued by the Carnegie Institution. Planetary system artwork courtesy ESA, NASA and L. Calçada (ESO).

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Solar System portrait, inside looking out

MESSENGER “family portrait” of our Solar System

The MESSENGER spacecraft collected a series of images (here split into two halves) to complete a “family portrait” of our Solar System as seen from the inside looking out. All of the planets are visible except for Uranus and Neptune, which at distances of 3.0 and 4.4 billion kilometres were too faint to detect. (Pluto, smaller and even farther away, would have been even more difficult to observe). Earth’s Moon and Jupiter’s Galilean satellites (Callisto, Ganymede, Europa, and Io) can be seen in the image insets. See the link in the main text below for a full-size version of the image.

NASA’s MESSENGER spacecraft has captured the first portrait of our Solar System from the inside looking out.

Comprised of 34 images, the mosaic provides a complement to the Solar System portrait—that one from the outside looking in—taken by Voyager 1 in 1990 (see below).

“Obtaining this portrait was a terrific feat by the MESSENGER team,” says MESSENGER Principal Investigator Sean Solomon, of the Carnegie Institution of Washington.

“This snapshot of our neighbourhood also reminds us that Earth is a member of a planetary family that was formed by common processes four and a half billion years ago,” he added.

“Our spacecraft is soon to orbit the innermost member of the family, one that holds many new answers to how Earth-like planets are assembled and evolve.”

MESSENGER’s Wide Angle Camera (WAC) captured the images on November 3 and 16, 2010. In the mosaic, all of the planets are visible except for Uranus and Neptune, which—at distances of 3.0 and 4.4 billion kilometres—were too faint to detect.

Earth’s Moon and Jupiter’s Galilean satellites (Callisto, Ganymede, Europa, and Io) can be seen in the NAC image insets. The Solar System’s perch on a spiral arm of the Milky Way galaxy also afforded a beautiful view of a portion of the galaxy in the bottom centre.

See the full-size image here.

Assembling this portrait was no easy feat, says Solomon. “It’s not easy to find a moment when many of the planets are within a single field of view from that perspective, and we have strong Sun-pointing constraints on our ability to image in some directions.”

Outside looking in

On February 14, 1990, NASA’s Voyager 1 spacecraft had sailed beyond the outermost planet in our Solar System and turned its camera inward to snap a series of final images that would be its parting valentine to the string of planets it called home.

Mercury was too close to the Sun to see, Mars showed only a thin crescent of sunlight, and Pluto was too dim, but Voyager was able to capture cameos of Neptune, Uranus, Saturn, Jupiter, Earth and Venus from its unique vantage point. These images, later arranged in a large-scale mosaic, make up the first family portrait of our planets arrayed about the Sun.

Voyager portrait of the Solar System

The cameras of Voyager 1 on February 14, 1990, pointed back toward the Sun and took a series of pictures of the Sun and the planets, making the first ever "portrait" of our Solar System as seen from the outside. See the link in the main text for a full-size version of the image.

See the full-size image here.

Candy Hansen, a planetary scientist based at NASA’s Jet Propulsion Laboratory, who worked with the Voyager imaging team at the time, remembers combing through the images and finally finding the image of Earth. She had seen so many pictures over the years that she could distinguish dust on the lens from the black dots imprinted on the lens for geometric correction.

There was our planet, a bright speck sitting in a kind of spotlight of sunlight scattered by the camera. Hansen still gets chills thinking about it.

“I was struck by how special Earth was, as I saw it shining in a ray of sunlight,” she said. “It also made me think about how vulnerable our tiny planet is.”

This was the image that inspired Carl Sagan, the Voyager imaging team member who had suggested taking this portrait, to call our home planet “a pale blue dot.”

Voyager images of six planets

These six narrow-angle colour images were made from the first ever 'portrait' of the Solar System taken by Voyager 1 in 1990, when it was more than 6 billion kilometres from Earth. Left to right and top to bottom are: Venus, Earth, Jupiter, and Saturn, Uranus, Neptune. The background features in the images are artefacts resulting from the magnification.

As he wrote in a book by that name, “That’s here. That’s home. That’s us. On it everyone you love, everyone you know, everyone you ever heard of, every human being who ever was, lived out their lives. … There is perhaps no better demonstration of the folly of human conceits than this distant image of our tiny world.”

MESSENGER (MErcury Surface, Space ENvironment, GEochemistry, and Ranging) is a NASA-sponsored scientific investigation of the planet Mercury and the first space mission designed to orbit the planet closest to the Sun.

MESSENGER was launched on August 3, 2004, and—having completed flybys of Earth, Venus, and Mercury—will start a yearlong study of its target planet in March 2011.

Adapted from information issued by NASA / JPL-Caltech. Image credits: (MESSENGER) NASA / JHU APL / Carnegie; (Voyager) NASA / JPL.

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Fourth planet found in Solar System look-alike

An artist's impression of one of the planets in the HR 8799 system.

An artist's impression of one of the planets in the HR 8799 system. Credit: NASA, ESA, and G. Bacon (STScI).

  • Fourth planet found in system with three previously known planets
  • The planetary system resembles a supersized version of our Solar System
  • Origin of the four giant planets remains a puzzle

An international team of astronomers has discovered and imaged a fourth giant planet outside our Solar System, a discovery that further strengthens the remarkable resemblances between a distant planetary system and our own.

In a new paper in the journal Nature, the astronomers say the planetary system resembles a supersized version of our Solar System.

“Besides having four giant planets, both systems also contain two ‘debris belts’ composed of small rocky or icy objects, along with lots of tiny dust particles,” said Benjamin Zuckerman, a UCLA professor of physics and astronomy and co-author of the Nature paper.

Our giant planets are Jupiter, Saturn, Uranus and Neptune, and our debris belts include the asteroid belt between the orbits of Mars and Jupiter and the Kuiper Belt, beyond Neptune’s orbit.

The newly discovered fourth planet (known as HR 8799e) orbits a bright star called HR 8799, which lies some 129 light years from Earth and is faintly visible to the naked eye. The mass of the HR 8799 planetary system is much greater than our own.

Astronomers estimate that the combined mass of the four giant planets may be 20 times greater than the mass of all the planets in our Solar System, and the debris belt counterparts also contain much more mass than our own.

Representation of HR 8799 planetary system and Solar System

A 3D representation of the HR 8799 planetary system (left) and our Solar System (right). All orbital diameters are greatly exaggerated in order to make them visible. (Background Milky Way image credit: Atlas image courtesy of 2MASS / Umass / IPAC-Caltech / NASA / NSF.)

Planets’ long-term fate uncertain

The new planet joins three previously discovered planets that were the subjects of a 2008 paper in the journal Science reporting the first-ever images of a planetary family orbiting a star other than our sun. Four of the co-authors of the new Nature paper, including Zuckerman, were also co-authors on that Science paper.

“This is the fourth imaged planet in this planetary system, and only a tiny percentage of known exoplanets (planets outside our Solar System) have been imaged; none has been imaged in multiple-planet systems other than those of HR 8799,” Zuckerman said.

All four planets orbiting HR 8799 are similar in size, likely between five and seven times the mass of Jupiter. The newly discovered planet orbits HR 8799 more closely than the other three. If it were in orbit around our Sun, astronomers say, it would lie between the orbits of Saturn and Uranus.

The astronomers used the Keck II telescope at Hawaii’s W.M. Keck Observatory to obtain images of the fourth planet. Zuckerman’s colleagues are from Canada’s National Research Council (NRC), Lawrence Livermore National Laboratory (LLNL) in California, and Lowell Observatory in Arizona.

“The images of this new inner planet are the culmination of 10 years’ worth of innovation, making steady progress to optimise every aspect of observation and analysis,” said Christian Marois, an NRC astronomer and lead author of the Nature paper. “This allows us to detect planets located ever closer to their stars and ever further from our own Solar System.”

HR 8799 planetary system

Actual image showing the three earlier planets (b, c, and d) and the newly discovered planet "e". Arrows show the next 10 years of motion. 20 AU is 20 times the distance from the Earth to the Sun. (Credit: NRC-HIA, C. Marois, and Keck Observatory)

“The four massive planets pull on each other gravitationally,” said co-author Quinn Konopacky, a postdoctoral researcher at LLNL. “We don’t yet know if the system will last for billions of years or fall apart in a few million more.”

“As astronomers carefully follow the HR 8799 planets during the coming decades, the question of the stability of their orbits could become much clearer.”

New instrument will help with future studies

The origin of these four giant planets remains a puzzle; neither of the two main models of planet formation can account for all four.

“There’s no simple model that can form all four planets at their current location,” said co-author Bruce Macintosh of LLNL. “It’s going to be a challenge for our theoretical colleagues.”

It is entirely plausible that this planetary system contains additional planets closer to the star than these four planets, quite possibly rocky, Earth-like planets, Zuckerman said. But such interior planets are far more difficult to detect, he added.

“Images like these bring the exoplanet field, which studies planets outside our Solar System, into an era of exoplanet characterisation,” said co-author Travis Barman, a Lowell Observatory exoplanet theorist.

“Astronomers can now directly examine the atmospheric properties of four giant exoplanets that are all the same young age and that formed from the same building materials.”

Detailed study of the properties of HR 8799e will be challenging due to the planet’s relative faintness and its proximity to its star. To overcome those limitations, Macintosh is leading an effort to build an advanced exoplanet imager, called the Gemini Planet Imager, for the Gemini Observatory.

This new instrument will physically block the starlight and allow quick detection and detailed characterisation of planets similar to HR 8799e. UCLA and the NRC are also contributing to Gemini Planet Imager.

Adapted from information issued by Stuart Wolpert, UCLA.

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Second Solar System found?

Artist’s impression of planetary system of the star HD 10180

This artist’s impression shows the remarkable planetary system around the Sun-like star HD 10180. Observations have revealed the definite presence of five planets and evidence for two more. This system is similar to the Solar System in terms of number of planets and the presence of a regular pattern in the sizes of the orbits.

  • Star 127 light-years away has five confirmed planets
  • May also have an extra two planets
  • Orbits and sizes are similar to those of our Solar System

Astronomers have discovered a planetary system containing at least five planets, orbiting the Sun-like star known only as HD 10180, 127 light-years away.

The researchers also have tantalising evidence that two other planets may be present, one of which would have the lowest mass ever found.

This would make the system similar to our Solar System in terms of the number of planets (seven as compared to the Solar System’s eight planets).

Furthermore, the team also found evidence that the distances of the planets from their star follow a regular pattern, as also seen in our Solar System.

“We have found what is most likely the system with the most planets yet discovered,” says Christophe Lovis, lead author of the paper reporting the result.

“This remarkable discovery also highlights the fact that we are now entering a new era in exoplanet research: the study of complex planetary systems and not just of individual planets.”

“Studies of planetary motions in the new system reveal complex gravitational interactions between the planets and give us insights into the long-term evolution of the system.”

Close-up image of the star HD 10180

Close-up image of the star HD 10180. The blue and orange halos around the star, and the eight spikes of light, are artifacts of the imaging process and are not real. The remarkable planetary system around this star is far too faint and close in to be visible in this image.

Smallest exoplanet ever found?

The team of astronomers used the HARPS spectrograph, attached to European Southern Observatory’s (ESO) 3.6-metre telescope at La Silla, Chile, for a six-year-long study of HD 10180).

HARPS is an instrument with great measurement stability and precision and is the world’s most successful exoplanet hunter.

Thanks to the HARPS measurements, the astronomers detected the tiny back and forth motions of the star caused by the complex gravitational attractions from five or more planets.

The five strongest “signals” correspond to planets with Neptune-like masses—between 13 and 25 the mass of Earth—which orbit the star with periods ranging from about 6 to 600 Earth days.

These planets are spread out between just 0.06 and 1.4 times the Earth–Sun distance from their central star.

“We also have good reasons to believe that two other planets are present,” says Lovis. One would be a Saturn-like planet (with a minimum mass of 65 Earth masses) orbiting in 2200 days.

The other would be the least massive exoplanet ever discovered, with a mass of about 1.4 times that of the Earth. It is very close to its host star, at just 2 percent of the Earth–Sun distance. One “year” on this planet would last only 1.18 Earth-days.

“This object causes a wobble of its star of only about 3 km/hour—slower than walking speed—and this motion is very hard to measure,” says team member Damien Ségransan.

If confirmed, this object would be another example of a hot rocky planet, similar to Corot-7b.

Artist's impression of Corot-7b

One of the possible planets could orbit very close to its star, a bit like another explanet, Corot-7b, depicted in this artist's impression.

Similar to our own Solar System?

The newly discovered system of planets around HD 10180 is unique in several respects. First of all, with at least five Neptune-like planets lying within a distance equivalent to the orbit of Mars, this system is more populated than our Solar System in its inner region, and has many more massive planets there.

Furthermore, the system probably has no Jupiter-like gas giant planet. In addition, all the planets seem to have almost circular orbits.

So far, astronomers know of fifteen systems with at least three planets. The last record-holder was 55 Cancri, which contains five planets, two of them being giant planets.

“Systems of low-mass planets like the one around HD 10180 appear to be quite common, but their formation history remains a puzzle,” says Lovis.

Using the new discovery as well as data for other planetary systems, the astronomers found an equivalent of the Titius–Bode law that exists in our Solar System—the orbital distances of the planets from their star seem to follow a regular pattern.

“This could be a signature of the formation process of these planetary systems,” says team member Michel Mayor.

The Titius–Bode law states that the distances of the planets from the Sun follow a simple pattern. For the outer planets, each planet is predicted to be roughly twice as far away from the Sun as the previous object. The hypothesis correctly predicted the orbits of Ceres and Uranus, but failed as a predictor of Neptune’s orbit.

Another important result found by the astronomers while studying these systems is that there is a relationship between the mass of a planetary system and the mass and chemical content of its host star.

All very massive planetary systems are found around massive and “metal-rich” stars (elements heavier than hydrogen and helium), while the four lowest-mass systems are found around lower-mass and metal-poor stars. Such properties confirm current theoretical models.

Adapted from information issued by ESO / L. Calçada / Digitized Sky Survey 2 / Davide De Martin.

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