Solar system with Earth-size planet found

After six years of painstaking observations, astronomers have identified a distant solar system with at least five Neptune-class worlds orbiting within 130 million miles or so of the parent star--closer than Mars is to the sun. Two other planets are believed to be present, including one just 1.4 times as massive as Earth.

The presumed Earth-size planet orbits a scant 2 million miles from its star, completing a full orbit, or "year," every 1.18 days. If confirmed with additional observations, this hellish world would be the smallest yet discovered, additional proof that Earth-size planets are falling within the reach of current Earth-based instruments.

"We have probably found the system with the most planets known today, coming close to the solar system," Christophe Lovis of the University of Geneva, lead author of a paper reporting the discovery, told CNET in an e-mail exchange. "This means that we are now able to detect very complex systems of low-mass planets, which will help us a lot [in] understanding their diversity. This a step towards answering long-standing questions, such as, how common are habitable planets in the universe?"

As for the presumed Earth-size planet, Lovis said "it is probable that such a low-mass body cannot retain an atmosphere so close to its star. Most likely, this body is like a big melted-lava ball. Hard to imagine, since this is unknown in our solar system."

Over six years, Lovis and his colleagues used a sensitive spectrograph mounted on the European Southern Observatory's 3.6-meter (11.8-foot) telescope at La Silla, Chile, to measure subtle changes in the light from a sun-like star known as HD 10180 in the southern constellation Hydrus.

Located 127 light-years from Earth, HD 10180 wobbles ever so slightly, as it is tugged this way and that by the gravity of a retinue of unseen planets. Over the course of 190 observations, astronomers were able to confirm the presence of at least five Neptune-like planets between 13 and 25 times as massive as Earth.

All five worlds orbit HD 10180 at distances ranging from 0.06 and 1.4 times the distance between the Earth and the sun, out to about 130 million miles. The much smaller, yet-to-be-confirmed planet orbits inside the five Neptune-class worlds. A seventh Saturn-class planet is believed to be at a range of 3.4 times the Earth-sun distance, taking six Earth years to complete one orbit.

According to the Extrasolar Planets Encyclopaedia maintained by the Paris Observatory, 488 planets beyond Earth's solar system have been discovered to date. Some 15 solar systems feature at least three planets. A star known as 55 Cancri has five confirmed planets, including two Jupiter-class worlds.

The HD 10180 solar system is unique in that its planets circle the parent star in nearly circular orbits and seem to be positioned according to a relatively simple arithmetic rule that may be "a consequence of the various gravitational interactions that occur between the planets during their evolution," Lovis said.

"It is difficult to say at this point how significant this result is, but it will be very interesting to hear what our theoretician colleagues think of it," he added.

Surprisingly, perhaps, it appears the HD 10180 solar system is gravitationally stable over long time scales, despite the effects of five Neptune-class planets orbiting so close to their star.

"This was not an easy question, and answering it required in-depth dynamical analyses," Lovis said. "When modeling all major effects properly (including effects of general relativity), it turns out that the system is indeed stable over long time scales."

He said additional observations will be needed to pin down the orbit and mass of the innermost, Earth-class planet.

"We will dedicate some more telescope nights to observe the star...to improve the coverage of the 1.18-day period," he said of the smaller planet. "At the moment, we are suffering from the fact that we take one single data point per night, which makes it difficult to be sure about a 1.18-day period. I expect that we will make progress on this system within a year or so."

The observations are extremely difficult. The gravitational tug of the low-mass planet amounts to a 1.8 mph wobble in a star 127 light-years away, "which is hard to measure and, if confirmed, would represent a new record in precision," Lovis said.


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Dawn Team Members Check out Spacecraft

Dawn Mission Status Update

Mission managers for NASA's Dawn spacecraft are studying the spacecraft's ion propulsion system after Dawn experienced a loss of thrust on June 27. Dawn team members were able to trace the episode to an electronic circuit in the spacecraft's digital control and interface unit, a subsystem that houses the circuit and a computer that provides the "brains" to Dawn's ion propulsion system. That circuit appeared to lose an electronic signal. As a result, the valves controlling the flow of xenon fuel did not open properly. Dawn automatically put itself into a more basic configuration known as "safe-communications" mode, where the spacecraft stopped some activities and turned its high-gain antenna to Earth.

Engineers were able to return the spacecraft to a normal configuration and restart the spacecraft's thrusting on June 30 by switching to a second digital control and interface unit with equivalent capabilities. One set of images for navigation purposes was not obtained on June 28 because the spacecraft was in safe-communications mode, and one other set, on July 6, was not obtained to allow the spacecraft to spend the time thrusting. Other sets of navigation images have been and will be acquired as expected. The ion propulsion system is now functioning normally.

"Dawn is still on track to get into orbit around Vesta, and thanks to the flexibility provided by our use of ion propulsion, the time of orbit capture actually will move earlier by a little less than a day," said Marc Rayman, Dawn's chief engineer and mission manager. "More importantly, the rest of Dawn's schedule is unaffected, and science collection is expected to begin as scheduled in early August."

In an unrelated event, the visible and infrared mapping spectrometer on Dawn reset itself on June 29. At the time of the reset, the instrument was gathering calibration data during the spacecraft's approach to the giant asteroid Vesta. Some of its planned observations were completed successfully before automatic sensors turned the instrument off.

On June 30, Dawn team members were able to trace the reset to an internal error in the instrument's central processing unit, though they don't yet know why the internal error occurred. By temporarily turning the instrument back on, the Dawn team confirmed that the instrument is otherwise in a normal configuration. They powered the instrument back off, as originally planned for this time. Team members are working to determine when they will turn it back on again.

After arriving at Vesta, Dawn will spend about one year orbiting the asteroid, which is also known as a protoplanet because it is a large body that almost became a planet. Data collected at Vesta will help scientists understand the earliest chapter of our solar system's history.

The Dawn mission to Vesta and Ceres is managed by the Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, for NASA's Science Mission Directorate, Washington. Dawn is a project of the directorate's Discovery Program, managed by NASA's Marshall Space Flight Center in Huntsville, Ala. The University of California, Los Angeles, is responsible for overall Dawn mission science. Other scientific partners include Planetary Science Institute, Tucson, Ariz.; Max Planck Institute for Solar System Research, Katlenburg-Lindau, Germany; DLR Institute for Planetary Research, Berlin, Germany; Italian National Institute for Astrophysics, Rome; and the Italian Space Agency, Rome. Orbital Sciences Corporation of Dulles, Va., designed and built the Dawn spacecraft.

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NASA's Spitzer Finds Distant Galaxies Grazed on Gas

PASADENA, Calif. -- Galaxies once thought of as voracious tigers are more like grazing cows, according to a new study using NASA's Spitzer Space Telescope.

Astronomers have discovered that galaxies in the distant, early universe continuously ingested their star-making fuel over long periods of time. This goes against previous theories that the galaxies devoured their fuel in quick bursts after run-ins with other galaxies.

"Our study shows the merging of massive galaxies was not the dominant method of galaxy growth in the distant universe," said Ranga-Ram Chary of NASA's Spitzer Science Center at the California Institute of Technology in Pasadena, Calif. "We're finding this type of galactic cannibalism was rare. Instead, we are seeing evidence for a mechanism of galaxy growth in which a typical galaxy fed itself through a steady stream of gas, making stars at a much faster rate than previously thought."

Chary is the principal investigator of the research, appearing in the Aug. 1 issue of the Astrophysical Journal. According to his findings, these grazing galaxies fed steadily over periods of hundreds of millions of years and created an unusual amount of plump stars, up to 100 times the mass of our sun.

"This is the first time that we have identified galaxies that supersized themselves by grazing," said Hyunjin Shim, also of the Spitzer Science Center and lead author of the paper. "They have many more massive stars than our Milky Way galaxy."

Galaxies like our Milky Way are giant collections of stars, gas and dust. They grow in size by feeding off gas and converting it to new stars. A long-standing question in astronomy is: Where did distant galaxies that formed billions of years ago acquire this stellar fuel? The most favored theory was that galaxies grew by merging with other galaxies, feeding off gas stirred up in the collisions.

Chary and his team addressed this question by using Spitzer to survey more than 70 remote galaxies that existed 1 to 2 billion years after the Big Bang (our universe is approximately 13.7 billion years old). To their surprise, these galaxies were blazing with what is called H alpha, which is radiation from hydrogen gas that has been hit with ultraviolet light from stars. High levels of H alpha indicate stars are forming vigorously. Seventy percent of the surveyed galaxies show strong signs of H alpha. By contrast, only 0.1 percent of galaxies in our local universe possess this signature.

Previous studies using ultraviolet-light telescopes found about six times less star formation than Spitzer, which sees infrared light. Scientists think this may be due to large amounts of obscuring dust, through which infrared light can sneak. Spitzer opened a new window onto the galaxies by taking very long-exposure infrared images of a patch of sky called the GOODS fields, for Great Observatories Origins Deep Survey.

Further analyses showed that these galaxies furiously formed stars up to 100 times faster than the current star-formation rate of our Milky Way. What's more, the star formation took place over a long period of time, hundreds of millions of years. This tells astronomers that the galaxies did not grow due to mergers, or collisions, which happen on shorter timescales. While such smash-ups are common in the universe -- for example, our Milky Way will merge with the Andromeda galaxy in about 5 billion years -- the new study shows that large mergers were not the main cause of galaxy growth. Instead, the results show that distant, giant galaxies bulked up by feeding off a steady supply of gas that probably streamed in from filaments of dark matter.

Chary said, "If you could visit a planet in one of these galaxies, the sky would be a crazy place, with tons of bright stars, and fairly frequent supernova explosions."

NASA's Jet Propulsion Laboratory in Pasadena, Calif., manages the Spitzer Space Telescope mission for the agency's Science Mission Directorate in Washington. Science operations are conducted at the Spitzer Science Center at Caltech. Caltech manages JPL for NASA.

New Animation Depicts Next Mars Rover in Action

Although NASA's Mars Science Laboratory will not leave Earth until late this year nor land on Mars until August 2012, anyone can watch those dramatic events now in a new animation of the mission.

The full, 11-minute animation shows sequences such as the spacecraft separating from its launch vehicle near Earth and the mission's rover, Curiosity, zapping rocks with a laser and examining samples of powdered rock on Mars.

Curiosity's landing will use a different method than any previous Mars landing, with the rover suspended on tethers from a rocket-backpack "sky crane."

The new animation combines detailed views of the spacecraft with scenes of real places on Mars, based on stereo images taken by earlier missions.

"It is a treat for the 2,000 or more people who have worked on the Mars Science Laboratory during the past eight years to watch these action scenes of the hardware the project has developed and assembled," said Mars Science Laboratory Project Manager Pete Theisinger at NASA's Jet Propulsion Laboratory, Pasadena, Calif. "The animation also provides an exciting view of this mission for any fan of adventure and exploration."

JPL manages the Mars Science Laboratory project for the NASA Science Mission Directorate, Washington. The rover and other parts of the spacecraft have been delivered to NASA Kennedy Space Center in Florida for launch during the period of Nov. 25 to Dec. 18, 2011. In August 2012, Curiosity will land on Mars for a two-year mission to examine whether conditions in the landing area have been favorable for microbial life and for preserving evidence about whether life has existed there. JPL is a division of the California Institute of Technology, Pasadena.

NASA SAYS SUN AND PLANETS CONSTRUCTED DIFFERENTLY

PASADENA, Calif. - Researchers analyzing samples returned by NASA's 2004 Genesis mission have discovered that our sun and its inner planets may have formed differently than previously thought.

Data revealed differences between the sun and planets in oxygen and nitrogen, which are two of the most abundant elements in our solar system. Although the difference is slight, the implications could help determine how our solar system evolved.

"We found that Earth, the moon, as well as Martian and other meteorites which are samples of asteroids, have a lower concentration of the O-16 than does the sun," said Kevin McKeegan, a Genesis co-investigator from UCLA, and the lead author of one of two Science papers published this week. "The implication is that we did not form out of the same solar nebula materials that created the sun -- just how and why remains to be discovered."

The air on Earth contains three different kinds of oxygen atoms which are differentiated by the number of neutrons they contain. Nearly 100 percent of oxygen atoms in the solar system are composed of O-16, but there are also tiny amounts of more exotic oxygen isotopes called O-17 and O-18. Researchers studying the oxygen of Genesis samples found that the percentage of O-16 in the sun is slightly higher than on Earth or on other terrestrial planets. The other isotopes' percentages were slightly lower.

Another paper detailed differences between the sun and planets in the element nitrogen. Like oxygen, nitrogen has one isotope, N-14, that makes up nearly 100 percent of the atoms in the solar system, but there is also a tiny amount of N-15. Researchers studying the same samples saw that when compared to Earth's atmosphere, nitrogen in the sun and Jupiter has slightly more N-14, but 40 percent less N-15. Both the sun and Jupiter appear to have the same nitrogen composition. As is the case for oxygen, Earth and the rest of the inner solar system are very different in nitrogen.

"These findings show that all solar system objects including the terrestrial planets, meteorites and comets are anomalous compared to the initial composition of the nebula from which the solar system formed," said Bernard Marty, a Genesis co-investigator from Centre de Recherches Pétrographiques et Géochimiques and the lead author of the other new Science paper. "Understanding the cause of such a heterogeneity will impact our view on the formation of the solar system."

Data were obtained from analysis of samples Genesis collected from the solar wind, or material ejected from the outer portion of the sun. This material can be thought of as a fossil of our nebula because the preponderance of scientific evidence suggests that the outer layer of our sun has not changed measurably for billions of years.

"The sun houses more than 99 percent of the material currently in our solar system, so it's a good idea to get to know it better," said Genesis Principal Investigator Don Burnett of the California Institute of Technology, Pasadena, Calif. "While it was more challenging than expected, we have answered some important questions, and like all successful missions, generated plenty more."

Genesis launched in August 2000. The spacecraft traveled to Earth's L1 Lagrange Point about 1 million miles from Earth, where it remained for 886 days between 2001 and 2004, passively collecting solar-wind samples.

On Sept. 8, 2004, the spacecraft released a sample return capsule, which entered Earth's atmosphere. Although the capsule made a hard landing as a result of a failed parachute in the Utah Test and Training Range in Dugway, Utah, it marked NASA's first sample return since the final Apollo lunar mission in 1972, and the first material collected beyond the moon. NASA's Johnson Space Center in Houston curates the samples and supports analysis and sample allocation.

The Jet Propulsion Laboratory, Pasadena, Calif., managed the Genesis mission for NASA's Science Mission Directorate, Washington. The Genesis mission was part of the Discovery Program managed at NASA's Marshall Space Flight Center in Huntsville, Ala. Lockheed Martin Space Systems, Denver, developed and operated the spacecraft. Analysis at the Centre de Recherches Pétrographiques et Géochimiques, Nancy, France, was supported by the Centre National d'Etudes Spatiales, Paris, and the Centre National de la Recherche Scientifique, Paris, France.

Astronomers Find Newly Discovered Asteroid Is Earth's Companion

Astronomers from the Armagh Observatory in Northern Ireland have found that a recently discovered asteroid has been following Earth in its motion around the Sun for at least the past 250,000 years, and may be intimately related to the origin of our planet.

The asteroid first caught the eye of the scientists, Apostolos "Tolis" Christou and David Asher, two months after it was found by the WISE infrared survey satellite, launched in 2009 by the United States. "Its average distance from the Sun is identical to that of the Earth,", "but what really impressed me at the time was how Earth-like its orbit was." Most near-Earth Asteroids -- NEAs for short -- have very eccentric, or egg-shaped, orbits that take the asteroid right through the inner solar system. But the new object, designated 2010 SO16, is different. Its orbit is almost circular so that it cannot come close to any other planet in the solar system except Earth.

The researchers set out to investigate how stable this orbit is and how long the asteroid has occupied it. To do that, they first had to take into account the current uncertainty in the asteroid's orbit. "Not knowing precisely the location of a newly-discovered NEA is quite common," explained Dr Asher. "The only way to eliminate the uncertainty is to keep tracking the asteroid for as long as possible, usually months or years." But the two scientists overcame that problem by creating virtual "clones" of the asteroid for every possible orbit that it could conceivably occupy. They then simulated the evolution of these clones under the gravity of the Sun and the planets for two million years into the past and in the future.

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Comet Elenin: Preview of a Coming Attraction

Comet Elenin, was first detected on Dec. 10, 2010 by Leonid Elenin, an observer in Lyubertsy, Russia, who made the discovery "remotely" using the ISON-NM observatory near Mayhill, New Mexico. At the time of the discovery, the comet was about 647 million kilometers from Earth. Over the past four-and-a-half months, the comet has - as comets do - closed the distance to Earth's vicinity as it makes its way closer to perihelion. As of May 4, Elenin's distance is about 274 million kilometers.

"That is what happens with these long-period comets that come in from way outside our planetary system," said Don Yeomans of NASA's Near-Earth Object Program Office at NASA's Jet Propulsion Laboratory in Pasadena, Calif. "They make these long, majestic, speedy arcs through our solar system, and sometimes they put on a great show. But not Elenin. Right now that comet looks kind of wimpy."

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Mars Express Sees Deep Fractures on Mars

Newly released images from the European Space Agency's Mars Express show Nili Fossae, a system of deep fractures around the giant Isidis impact basin. Some of these incisions into the martian crust are up to 500 m deep and probably formed at the same time as the basin.

Nili Fossae is a 'graben' system on Mars, northeast of the Syrtis Major volcanic province, on the northwestern edge of the giant Isidis impact basin. Graben refers to the lowered terrain between two parallel faults or fractures in the rocks that collapses when tectonic forces pull the area apart. The Nili Fossae system contains numerous graben concentrically oriented around the edges of the basin.

It is thought that flooding of the basin with basaltic lava after the impact that created it resulted in subsidence of the basin floor, adding stress to the planet's crust, which was released by the formation of the fractures.

A strongly eroded impact crater is visible to the bottom right of the image. It measures about 12 km across and exhibits an ejecta blanket, usually formed by material thrown out during the impact. Two landslides have taken place to the west of the crater. Whether they were a direct result of the impact or occurred later is unknown.

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Mars Tribute Marks Memories of Shepard's Flight

The team exploring Mars via NASA's Opportunity rover for the past seven years has informally named a Martian crater for the Mercury spacecraft that astronaut Alan Shepard christened Freedom 7. On May 5, 1961, Shepard piloted Freedom 7 in America's first human spaceflight.

The team is using Opportunity this week to acquire images covering a cluster of small, relatively young craters along the rover's route toward a long-term destination. The cluster's largest crater, spanning about 25 meters , is the one called "Freedom 7." The diameter of Freedom 7 crater, about 25 meters, happens to be equivalent to the height of the Redstone rocket that launched Shepard's flight.

"Many of the people currently involved with the robotic investigations of Mars were first inspired by the astronauts of the Mercury Project who paved the way for the exploration of our solar system," said Scott McLennan of the State University of New York at Stony Brook, who is this week's long-term planning leader for the rover science team. Shepard's flight was the first of six Project Mercury missions piloted by solo astronauts.

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Dawn Reaches Milestone Approaching Asteroid Vesta

NASA's Dawn spacecraft has reached its official approach phase to the asteroid Vesta and will begin using cameras for the first time to aid navigation for an expected July 16 orbital encounter. The large asteroid is known as a protoplanet – a celestial body that almost formed into a planet.

At the start of this three-month final approach to this massive body in the asteroid belt, Dawn is 1.21 million kilometers (752,000 miles) from Vesta, or about three times the distance between Earth and the moon. During the approach phase, the spacecraft's main activity will be thrusting with a special, hyper-efficient ion engine that uses electricity to ionize and accelerate xenon. The 12-inch-wide ion thrusters provide less thrust than conventional engines, but will provide propulsion for years during the mission and provide far greater capability to change velocity. "We feel a little like Columbus approaching the shores of the New World," said Christopher Russell, Dawn principal investigator, based at the University of California in Los Angeles (UCLA). "The Dawn team can't wait to start mapping this Terra Incognita."

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Plasmoids and Sheaths Mean Success or Failure for Solar Eruptions

Our Sun experiences regular eruptions of material into space, but solar physicists still have difficulty in explaining why these dramatic events take place. Now a group of scientists from the University of St Andrews think they have the answer: clouds of plasma constrained by magnetic fields and known as 'plasmoids' that struggle to break free of the Sun's magnetic field.

Active regions on the solar surface are often the site of eruptions. These are associated with magnetic fields from the solar interior rising to the surface and gradually expanding into the Sun's outer atmosphere, the corona, in a process known as magnetic flux emergence. The St Andrews team developed 3D computer models of these phenomena, revealing that the emergence of magnetic flux naturally leads to the formation and expulsion of plasmoids that adopt a twisted tube configuration.

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NASA's Swift and Hubble Probe Asteroid Collision Debris

Data from NASA's Swift satellite and Hubble Space Telescope showed these changes likely occurred after Scheila was struck by a much smaller asteroid. "Collisions between asteroids create rock fragments, from fine dust to huge boulders, that impact planets and their moons," said Dennis Bodewits, an astronomer at the University of Maryland in College Park and lead author of the Swift study. "Yet this is the first time we've been able to catch one just weeks after the smash-up, long before the evidence fades away."

Asteroids are rocky fragments thought to be debris from the formation and evolution of the solar system approximately 4.6 billion years ago. Millions of them orbit the sun between Mars and Jupiter in the main asteroid belt. Scheila is approximately 70 miles across and orbits the sun every five years."The Hubble data are most simply explained by the impact, at 11,000 mph, of a previously unknown asteroid about 100 feet in diameter," said Hubble team leader David Jewitt at the University of California in Los Angeles. Hubble did not see any discrete collision fragments, unlike its 2009 observations of P/2010 A2, the first identified asteroid collision.

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Voyager Probes Set to Enter Interstellar Space

NASA's twin Voyager probes are now at the edge of the solar system. Not only that, they're still working. And with each passing day they are beaming back a message that, to scientists, is both unsettling and thrilling. "It's uncanny," says Ed Stone of the California Institute of Technology in Pasadena, Voyager Project Scientist since 1972. "Voyager 1 and 2 have a knack for making discoveries." Today, April 28, 2011, NASA held a live briefing to reflect on what the Voyager mission has accomplished--and to preview what lies ahead as the probes prepare to enter the realm of interstellar space in our Milky Way galaxy.

The adventure began in the late 1970s when the probes took advantage of a rare alignment of outer planets for an unprecedented Grand Tour. Voyager 1 visited Jupiter and Saturn, while Voyager 2 flew past Jupiter, Saturn, Uranus and Neptune.

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Austrian Space Forum Successfully Tests Mars Suit ‘Aouda.X’ in Spain

A team from the Austrian Space Forum is arriving back in Austria April 25, 2011 following a week testing its analogue space suit 'Aouda.X' in the semi-desert of Rio Tinto in Spain. This suit has been developed by the Austrian Space Forum over three years and is one of the best models of its kind worldwide.

The European Space Agency (ESA) also participated in this mission with the Mars rover 'Eurobot'. This 1.5 million Euro prototype was been transported from the Netherlands to Spain and passed its first test under field conditions on April 19. Valuable scientific and technical data have been collected between during the tests, which ran from April 18 to 21. Aouda.X and Eurobot completed several activities together, demonstrating it was possible to test the man-machine-interface, which will play a vital role in a real Mars mission.

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Huge Dry Ice Deposit on Mars: NASA Orbiter Reveals Big Changes in Red Planet's Atmosphere

NASA's Mars Reconnaissance Orbiter has discovered the total amount of atmosphere on Mars changes dramatically as the tilt of the planet's axis varies. This process can affect the stability of liquid water, if it exists on the Martian surface, and increase the frequency and severity of Martian dust storms.

Researchers using the orbiter's ground-penetrating radar identified a large, buried deposit of frozen carbon dioxide, or dry ice, at the Red Planet's south pole. The scientists suspect that much of this carbon dioxide enters the planet's atmosphere and swells the atmosphere's mass when Mars' tilt increases. The findings are published in the journal Science.

The newly found deposit has a volume similar to Lake Superior's nearly 3,000 cubic miles. The deposit holds up to 80 percent as much carbon dioxide as today's Martian atmosphere. Collapse pits caused by dry ice sublimation and other clues suggest the deposit is in a dissipating phase, adding gas to the atmosphere each year. Mars' atmosphere is about 95 percent carbon dioxide, in contrast to Earth's much thicker atmosphere, which is less than .04 percent carbon dioxide.

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Beams of Electrons Link Saturn With Its Moon Enceladus

Data from NASA's Cassini spacecraft have revealed that Enceladus, one of Saturn's diminutive moons, is linked to Saturn by powerful electrical currents -- beams of electrons that flow back and forth between the planet and moon. one of the instruments on board Cassini which made the electron beam discovery, includes a electron sensor called CAPS-ELS -- led by UCL (University College London).

Since Cassini's arrival at Saturn in 2004 it has passed 500km-wide Enceladus 14 times, gradually discovering more of its secrets on each visit. Research has found that jets of gas and icy grains emanate from the south pole of Enceladus, which become electrically charged and form an ionosphere. The motion of Enceladus and its ionosphere through the magnetic bubble that surrounds Saturn acts like a dynamo, setting up the newly-discovered current system.

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Astronomers Can Tune in to Radio Auroras to Find Exoplanets

scientists at the University of Leicester have shown that emissions from the radio aurora of planets like Jupiter should be detectable by radio telescopes such as LOFAR, which will be completed later this year. Dr Jonathan Nichols will present results at the RAS National Astronomy Meeting in Llandudno, Wales, on April 18.

"This is the first study to predict the radio emissions by exoplanetary systems similar to those we find at Jupiter or Saturn. At both planets, we see radio waves associated with auroras generated by interactions with ionised gas escaping from the volcanic moons, Io and Enceladus. Our study shows that we could detect emissions from radio auroras from Jupiter-like systems orbiting at distances as far out as Pluto," said Nichols.

Of the hundreds of exoplanets that have been detected to date, less than 10% orbit at distances where we find the outer planets in our own Solar System. Most exoplanets have been found by the transit method, which detects a dimming in light as a planet moves in front of a star, or by looking for a wobble as a star is tugged by the gravity of an orbiting planet. With both these techniques, it is easiest to detect planets close in to the star and moving very quickly.

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Solar Activity Heats Up: Sunspots Finally Return

If you've ever stood in front of a hot stove, watching a pot of water and waiting impatiently for it to boil, you know what it feels like to be a solar physicist. Back in 2008, the solar cycle plunged into the deepest minimum in nearly a century. Sunspots all but vanished, solar flares subsided, and the sun was eerily quiet.

"Ever since, we've been waiting for solar activity to pick up," says Richard Fisher, head of the Heliophysics Division at NASA Headquarters in Washington DC. "It's been three long years." Quiet spells on the sun are nothing new. They come along every 11 years or so, it's a natural part of the solar cycle. This particular solar minimum, however, was lasting longer than usual, prompting some researchers to wonder if it would ever end.

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Fast-Rotating Asteroid Winks For Astronomer's Camera

Video imaging of newly discovered asteroid 2011 GP59 shows the object appearing to blink on and off about once every four minutes. Amateur astronomers, including Nick James of Chelmsford, Essex, England, have captured video of the interesting object. James generated this video of GP59 on the night of Monday, April 11. The video, captured with an 11-inch Schmidt-Cassegrain telescope, is a compilation of 137 individual frames, each requiring 30 seconds of exposure. At the time, the asteroid was approximately 3,356,000 kilometers distant.

"Usually, when we see an asteroid strobe on and off like that, it means that the body is elongated and we are viewing it broadside along its long axis first, and then on its narrow end as it rotates ," said Don Yeomans, manager of NASA's Near-Earth Object Program Office at the Jet Propulsion Laboratory in Pasadena, Calif. "GP59 is approximately 50 meters [240 feet] long, and we think its period of rotation is about seven-and-a-half minutes. This makes the object's brightness change every four minutes or so." 2011 GP59 was discovered the night of April 8/9 by astronomers with the Observatorio Astronomico de Mallorca in Andalusia, Spain. It will make its closest approach to Earth on April 15 at 19:09 UTC (12:09 p.m. PDT) at a distance just beyond the moon's orbit - about 533,000 kilometers.

Mars Rover's 'Gagarin' Moment Applauded Exploration

A flat, light-toned rock on Mars visited by NASA's Mars Exploration Rover in 2005 informally bears the name of the first human in space, Yuri Gagarin, who rode into orbit in the Soviet Union's Vostok-1 spacecraft on April 12, 1961. The team using Opportunity to explore the Meridiani Planum region of Mars since 2004 chose "Gagarin" for what they would call the rock that the rover examined beside "Vostok" crater. A target for close-up examination on Gagarin is called "Yuri." To commemorate Gagarin's flight, a color image of the rock on Mars has been posted, here. The image combines frames taken through three different filters by Opportunity's panoramic camera. Early accomplishments in the Space Age inspired many of the researchers exploring other planets robotically today, who hope their work can, in turn, help inspire the next generation.

"The 50th anniversary of mankind's first fledgling foray into the cosmos should serve as an important reminder of the spirit of adventure and exploration that has propelled mankind throughout history," said Mars rover science team member James Rice of NASA Goddard Space Flight Center, Greenbelt, Md. "We are a species of explorers; it is encoded into our very DNA. Half a century ago Yuri Gagarin was lofted into a totally unknown, remote and hostile environment and in doing so opened up a new limitless frontier of possibilities for mankind. A mere 23 days later another brave human, Alan Shepard, climbed aboard a rocket and ventured into the starry abyss. Their courage and vision continue to inspire and lead us into the unknown. Hopefully, one day in the not too distant future it will lead humanity on a voyage to Mars."

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