Chaos in cosmos: System of two stars with three planet-forming discs of gas

A star with a ring of planets orbiting around it -- that is the picture we know from our own solar system and from many of the thousands of exoplanets observed in recent years. But now researchers from the Niels Bohr Institute have discovered a system consisting of two stars with three rotating planet-forming accretion discs around them. It is a binary star where each star has its own planet-forming disc and in addition, there is one large shared disc. All three planet-forming discs are misaligned in relation to one another. The spectacular results are published in the scientific journal, Astrophysical Journal Letters.

A solar system is formed by a large cloud of gas and dust. The cloud of gas and dust condenses and eventually becomes so compact that it collapses into a ball of gas in the centre. Here the pressure heats up the matter and creates a glowing ball of gas, a star. The remainder of the gas and dust cloud rotates as a disc around the newly formed star. In this rotating disc of gas and dust, the material begins to accumulate and form larger and larger clumps, which finally become planets.

Often it is not just one, but two stars that are formed in the dense cloud of gas and dust. This is called a binary star and they are held together by their mutual gravity and orbit in a path around each other. About half of all stars are binary stars and they can each have a rotating disc of gas and dust.

Never before seen

But now the researchers have observed something highly unusual: a binary star with not just two, but three rotating gas discs.

"The two newly formed stars are both the size of our sun and they each have a rotating disc of gas and dust similar to the size of our solar system. In addition, they have a shared disc that is much larger and crosses over the other two discs. All three discs are staggered and this breaks with everything we have seen so far," says Christian Brinch, assistant professor in the research group Astrophysics and Planetary Science and the Niels Bohr International Academy at the Niels Bohr Institute, University of Copenhagen.

The stars were observed with the large international telescope, the Atacama Large Millimeter Array (ALMA) in northern Chile by an international team of researchers from Denmark, England and the Netherlands. The stars are about 400 light years away from the Earth. The stars are about 100-200,000 years old and planet formation may already have started. They cannot see this. But when they can see the accretion discs, it is because they are still mostly made up of gases.

Tumble around

"What we can observe is the gas itself, because the molecules are excited by the heat from the stars and therefore emit light in the infrared and microwave range. By studying the wavelength of the light you can see whether the light source is moving farther away or is getting closer. If the light shifts towards red wavelengths it is moving farther away, while blue shift light is moving closer and thus we can see that the three planet-forming discs are almost 'tumbling around' and are skewed relative to each other," explains Christian Brinch.

The researchers do not know why it is not a 'nice' system where the rotating discs of gas lie flat in relation to each other. Perhaps the formation occurred in a particularly turbulent manner.

"We will use computer simulations to try to understand the physics of the formation process. Perhaps it is a dynamic process of formation, which happens often and then it corrects itself later on. We will try to clarify this. We will also apply for more observation time on the ALMA telescope to study the planet-forming discs in even higher resolution to get more detailed information about their chemical composition," says Jes Jørgensen, associate professor in the research group Astrophysics and Planetary Science at the Niels Bohr Institute and Centre for Star and Planet Formation, University of Copenhagen.

Hubble sees Nova Remnant with spiral arms

The two spiral arms winding towards the bright centre might deceive you into thinking you are looking at a galaxy a bit like our Milky Way. But the object starring in this image is of a different nature: PK 329-02.2 is a ‘planetary nebula’ within our home galaxy.

Location:

RA 16h 14 m 32.42 DEC -54 57’ 04.2”

Despite the name, this isn’t a planet either. Planetary nebula is a misnomer that came about because of how much nebulas resembled giant, gaseous planets when looked through a telescope in the 1700s. Rather, what we see in this image is the last breath of a dying star.

When stars like the Sun are nearing the end of their lives, they let go of their gaseous outermost layers. As these clouds of stellar material move away from the central star they can acquire irregular and complex shapes. This complexity is evident in the faint scattered gas you see at the centre of the image. But there is also beautiful symmetry in PK 329-02.2, as the two bright blue spiral arms perfectly align with the two stars at the centre of the nebula.

It may look like the spiral arms are connected, but it is the stars that are companions. They are part of a visual binary, though only the one at the upper right gave rise to the nebula. While the stars will continue to orbit each other for millions or billions of years, the nebula – and its spiral arms – will spread out from the centre and eventually fade away over the next few thousands of years.

This planetary nebula with spiral arms is also known as Menzel 2, after the US astronomer Donald Menzel who discovered it in the 1920s. It is located in Norma, a constellation in the Southern celestial hemisphere where you can also find Menzel 1 and 3, two ‘bipolar planetary nebulas’ (shaped like butterflies or hourglasses).

Hubble’s Wide Field and Planetary Camera 2 captured this image, which was processed using green, blue, red and infrared filters. Astrophotography-enthusiast Serge Meunier entered a version of this image into the 2012 Hubble’s Hidden Treasures image processing competition.

Blustery dust storm to shroud Mars in a few weeks

THE PLANET MARS arrives at Perihelion on 29 October, and remains visible in the evening sky during the remainder of this year. Shining at Mag +0.4, It is rather low in the sky lying in the constellation of Sagittarius at the moment, then Mars moves into Capricorn on 8 November, and  into Aquarius on 16 December.

Its apparent size is getting smaller from 8.1” on 15 October to 5.66” at the end of the year. Its elongation from the Sun decreases from 79 degrees to 57 during the same period.

NASA is predicting a new significant dust storm will happen on Mars in a weeks ahead, a big one should strike in the next few weeks or months, lending weight to a Martian dust storm forecasting system.

A 2015 study in Icarus by James Shirley, a planetary scientist at NASA's Jet Propulsion Laboratory in Pasadena, California, found Mars' dust storm season midpoint is the end of October.  Which is when ESA’s  ExoMars arrives at the red planet, and the small Schiaparelli lander descends onto the Martian surface.

"Based on the historical pattern we found, we believe it is very likely that a global dust storm will begin within a few weeks or months of this date," Shirley says.

The most recent Martian global dust storm blew up in 2007. The rovers Spirit and Opportunity were starved of solar power.

So how do these global storms arise?

Dust storms are part of everyday life on the red planet. Local eddies and whirls can join forces to become bigger storms – perhaps producing lightning – that can cover entire regions.

These tend to arise during the southern hemisphere's spring and summer, when Mars is closest to the sun.

Shirley calculated that the effects other planets have on Mars' momentum as it orbits the sun, along with its orbital motion, contribute to the frequency and severity of the storms.

NASA's Mars Reconnaissance Orbiter's colour camera will keep an eye on the planet, though – we'll know if Shirley's predictions come true soon enough.

China to upgrade geological probe on moon, Mars

China has unveiled its new space probe that they will send to the Moon & Mars in the near future.

China has resolved to advance its geological research in Earth's polar regions, the moon, Mars and other planets In a blueprint issued recently by the Ministry of Land and Resources, the ministry placed emphasis on studying the chemical composition of the moon and Mars, as well as their evolution and remote sensing measurements.

A survey of lunar gravity and magnetism as well as probes into the moon's deep interior structure will also be carried out in the next five years. Other ambitious projects described in the blueprint include constructing terrestrial analogues to the moon and Mars, and carrying out their geological mapping.

A staff member from China Geological Survey said that, as the moon is Earth's only permanent natural satellite, and Mars is a rocky planet somewhat similar to Earth, research relating to both celestial bodies contributes to the study of Earth and its geodiversity.

Another focus of upcoming research is Earth's polar regions. The ministry plans to further its study of polar geophysical prospecting, glacier movement and deformation, polar environmental changes, polar energy and ecological resources, ice drilling technology, and microbiology using ice core samples.

By 2020, the Ministry of Land and Resources is expected to launch 21 operational satellites and six research satellites, which will form an advanced satellite observation system. The department has also vowed to upgrade the application efficacy of the satellites, which will increase their capabilities in marine management, mapping and disaster prevention.

Protostars make waves first, planets later

Astronomers thought it likely they would find a spiral of particles hidden in the cloudy disks that orbit and feed new-born stars. They have now found one, even though they weren’t looking for it.

A project initiated by Rice University astronomer Andrea Isella years ago bore fruit with the first observation of a pair of symmetrical spiral density waves around a protostar, one still gathering mass from its gaseous cloud.

The report in Science co-authored by Isella and led by his former California Institute of Technology colleague, Laura Pérez of the Max Planck Institute for Radio Astronomy, details the discovery around Elias 2-27 that could help explain why and how planetary systems form. Elias 2-27 is in a nebula within the Southern constellation Ophiuchus, about 450 light years from Earth, and was already known to host an unusually massive disk.

Astronomers have seen spirals on the surface of protoplanetary disks, but this is the first time they have detected a spiral density wave in a disk’s midplane, where planets are expected to form. They believe disks around these Protostars, which both feed the star and send material into the far reaches, are susceptible to gravitational instability caused by the large amount of gas and dust orbiting the star.

This instability prompts the material to coalesce into spiral-like arms in the flow of material around the star. Over time, they believe the material in these dense arms become the seeds of planetary systems. Gravitational instability not only suggests how spiral arms might form, but also how planets begin to take shape far from the warmth of their sun.

“We don’t completely understand how planets form,” said Isella, an assistant professor of physics and astronomy, “but we suspect there are two ways: Either small particles stick together until they form something like the Earth or Mars, or accreting gas forms a planet like Saturn or Jupiter.

“But this process works only very close to the star, within a few astronomical units (roughly the distance from the sun to the Earth), because that’s where all the material is, and it has to have enough density.”

Planets forming farther out, at 20-30 astronomical units, need material too, but the core accretion process is less likely, the researchers noted. “If a disk is massive enough to be gravitationally unstable, a spiral will form naturally,” Isella said. Material spiralling into the cold depths may collapse under its own gravity and form the seed of a new planet.

Andrea Isella (Credit: Jeff Fitlow/Rice University)

Large exoplanets have been observed far from their host stars, but how they got there has been a mystery, he said. “If we can measure the mass of the disk and say, well, there is a lot of material, and we see this feature, it’s a direct demonstration that this process might work,” Isella said.

He said the greater resolution provided by the world’s newest and largest radio telescope, the Atacama Large Millimeter/submillimetre Array (ALMA) in the high desert of Chile, made the discovery possible. For the first time, astronomers were able to see through a disk-shaped cloud of dust and gas around the protostar to the denser mid-disk region.

Based on their initial work on disks in 2010 and 2013, Perez proposed a close-up of Elias 2-27 in 2013, about the time ALMA came online. “As often happens, you find things you don’t expect to see. This spiralling feature was completely unexpected,” Isella said.

“When the project started, we wanted to see how the dust grain in these disks evolve with time,” Isella said. “Planets start to form from micro-sized particles that stick together, and Laura and I thought we might be able to measure the size of the dust particles based on their distance from the star.

“If you look at two or three different wavelengths of light from the disk, then you can measure grain sizes as a function of radius,” he said. “But when we got the data, we got this beautiful spiral.”

Collaborators in the U.S., Germany, Chile, the Netherlands, Italy, South Korea and the United Kingdom contributed to the paper, and many will be part of the next effort at ALMA to gather information from 20 known Protostars with similar properties.

New Hubble Photo Shows Center of Spiral Galaxy NGC 247

NGC 247 is a spiral galaxy approximately 11.5 million light-years from Earth in the southern constellation Cetus.

Otherwise known as ESO 540-22, LEDA 2758 or UGCA 11, this galaxy is a member of the Sculptor Group, a collection of galaxies that also contains the more famous Sculptor Galaxy (NGC 253).

NGC 247’s nucleus is visible in this Hubble image as a bright, whitish patch, surrounded by a mixture of stars, gas and dust.

The dust forms dark patches and filaments that are silhouetted against the background of stars, while the gas has formed into bright knots known as H II regions, mostly scattered throughout the galaxy’s arms and outer areas.

NGC 247 displays one unusual feature — it is not visible in this image, but can be seen clearly in wider views of the galaxy.

The northern part of the galaxy’s disc hosts an apparent void, a gap in the usual swarm of stars and H II regions that spans almost a third of the galaxy’s total length.

There are stars within this void, but they are quite different from those around it. They are significantly older, and as a result much fainter and redder.

This indicates that the star formation taking place across most of the disc of NGC 247 has somehow been arrested in the void region, and has not taken place for around one billion years.

Although astronomers are still unsure how the void formed, recent studies suggest it might have been caused by gravitational interactions with part of another galaxy.

This colour image of NGC 247 (hi-res version) is a composite of separate exposures taken in the visible and infrared regions of the spectrum with Hubble’s Advanced Camera for Surveys (ACS).

Three filters (the blue filter F475W, the broad V-band filter F606W and the near-infrared filter F814W) were used to sample various wavelengths.

The colour results from assigning different hues to each grayscale image associated with an individual filter.

Modular Space Telescope Could Be Assembled By Robot

 

Seeing deep into space requires large telescopes. The larger the telescope, the more light it collects, and the sharper the image it provides.

For example, NASA’s Kepler space observatory, with a mirror diameter of under one meter, is searching for exoplanets orbiting stars up to 3,000 light-years away. By contrast, the Hubble Space Telescope, with a 2.4-meter mirror, has studied stars more than 10 billion light-years away.

Now Caltech’s Sergio Pellegrino and colleagues are proposing a space observatory that would have a primary mirror with a diameter of 100 meters — 40 times larger than Hubble’s. Space telescopes, which provide some of the clearest images of the universe, are typically limited in size due to the difficulty and expense of sending large items into space. Pellegrino’s team would circumvent that issue by shipping the mirror up as separate components that would be assembled, in space, by robots.

Their design calls for the use of more than 300 deployable truss modules that could be unfolded to form a scaffolding upon which a commensurate number of small mirror plates could be placed to create a large segmented mirror. The assembly of the scaffolding and the attachment of the many mirrors is a task well-suited to robots, Pellegrino and his colleagues say.

In their concept, a spider-like, six-armed “hexbot” would assemble the trusswork and then crawl across the structure to build the mirror atop it. It was modeled on the JPL RoboSimian system, which in 2015 completed the DARPA Robotics Challenge, a federal competition aimed at spurring the development of robots that could perform complicated tasks that would be dangerous for humans. The hexbot would run on electrical power from the telescope’s solar grid. It would use four of its arms to walk—with one leg moving at any given time, while the three others remain securely attached to the structure. The two remaining arms would be free to assemble the trusses and mirrors.

The team opted to pursue an ambitious 100-meter design. “We wanted to study how different kinds of architectures perform as the diameter is increased,” says Pellegrino, Joyce and Kent Kresa Professor of Aeronautics and Professor of Civil Engineering in Caltech’s Division of Engineering and Applied Science, and Jet Propulsion Laboratory Senior Research Scientist. “We found that far away from the Earth, a structurally connected telescope is much heavier than an architecture based on separate spacecraft for the primary mirror, the optics, and the instrumentation.”

The realization of such an assembly is still decades away. However, Pellegrino and his colleagues are already working on the various technologies that will be needed to make it possible.

The entire space observatory would be composed of the fully assembled mirror-and-truss structure and three other parts, flying in formation. An optics and instrumentation unit would be located about 400 meters from the mirror; a control unit, stationed about 400 meters beyond that, would align the system and keep it working properly; and a thin shade, roughly 20 meters in diameter, would shield the mirror from the sun to keep its temperature stable and consistent across its diameter.

The four-part assembly would be stationed at one of the sun–earth Lagrange points—locations between the sun and the earth where the pull of gravity from two bodies locks a satellite into orbit with them, allowing it to maintain a stable position. There, the space observatory could peer deep into space without drifting out of place.

Pellegrino collaborated with Joel Burdick, Nicolas Lee, and Kristina Hogstrom of Caltech, as well as Paul Backes, Christine Fuller, Brett Kennedy, Junggon Kim, Rudranarayan Mukherjee, Carl Seubert, and Yen-Hung Wu of JPL. A paper about the work, titled “Architecture for in-space robotic assembly of a modular space telescope,” was published by the Journal of Astronomical Telescopes, Instruments, and Systems. This research was supported by NASA and the W. M. Keck Institute for Space Studies.

Great balls of fire --- Variable star V Hydra Surprises Astronomers

Great balls of fire! NASA's Hubble Space Telescope has detected superhot blobs of gas, each twice as massive as the planet Mars, being ejected near a dying star. The plasma balls are zooming so fast through space it would take only 30 minutes for them to travel from Earth to the moon. This stellar "cannon fire" has continued once every 8.5 years for at least the past 400 years, astronomers estimate.

The fireballs present a puzzle to astronomers, because the ejected material could not have been shot out by the host star, called V Hydrae. The star is a bloated red giant, residing 1,200 light-years away, which has probably shed at least half of its mass into space during its death throes. Red giants are dying stars in the late stages of life that are exhausting their nuclear fuel that makes them shine. They have expanded in size and are shedding their outer layers into space.

The current best explanation suggests the plasma balls were launched by an unseen companion star. According to this theory, the companion would have to be in an elliptical orbit that carries it close to the red giant's puffed-up atmosphere every 8.5 years. As the companion enters the bloated star's outer atmosphere, it gobbles up material. This material then settles into a disk around the companion, and serves as the launching pad for blobs of plasma, which travel at roughly a half-million miles per hour.

This star system could be the archetype to explain a dazzling variety of glowing shapes uncovered by Hubble that are seen around dying stars, called planetary nebulae, researchers say. A planetary nebula is an expanding shell of glowing gas expelled by a star late in its life.

"We knew this object had a high-speed outflow from previous data, but this is the first time we are seeing this process in action," said Raghvendra Sahai of NASA's Jet Propulsion Laboratory in Pasadena, California, lead author of the study. "We suggest that these gaseous blobs produced during this late phase of a star's life help make the structures seen in planetary nebulae."

Hubble observations over the past two decades have revealed an enormous complexity and diversity of structure in planetary nebulae. The telescope's high resolution captured knots of material in the glowing gas clouds surrounding the dying stars. Astronomers speculated that these knots were actually jets ejected by disks of material around companion stars that were not visible in the Hubble images. Most stars in our Milky Way galaxy are members of binary systems. But the details of how these jets were produced remained a mystery.

"We want to identify the process that causes these amazing transformations from a puffed-up red giant to a beautiful, glowing planetary nebula," Sahai said. "These dramatic changes occur over roughly 200 to 1,000 years, which is the blink of an eye in cosmic time."

V Hydra:  Right ascension 10h 51m 37.3s  Declination -21° 15' 0"

Sahai's team used Hubble's Space Telescope Imaging Spectrograph (STIS) to conduct observations of V Hydrae and its surrounding region over an 11-year period, first from 2002 to 2004, and then from 2011 to 2013. Spectroscopy decodes light from an object, revealing information on its velocity, temperature, location, and motion.

The data showed a string of monstrous, super-hot blobs, each with a temperature of more than 17,000 degrees Fahrenheit - almost twice as hot as the surface of the sun.

The researchers compiled a detailed map of the blobs' location, allowing them to trace the first behemoth clumps back to 1986. "The observations show the blobs moving over time," Sahai said. "The STIS data show blobs that have just been ejected, blobs that have moved a little farther away, and blobs that are even farther away." STIS detected the giant structures as far away as 37 billion miles away from V Hydrae, more than eight times farther away than the Kuiper Belt of icy debris at the edge of our solar system is from the sun.

The blobs expand and cool as they move farther away, and are then not detectable in visible light. But observations taken at longer sub-millimetre wavelengths in 2004, by the Submillimeter Array in Hawaii, revealed fuzzy, knotty structures that may be blobs launched 400 years ago, the researchers said.

Based on the observations, Sahai and his colleagues Mark Morris of the University of California, Los Angeles, and Samantha Scibelli of the State University of New York at Stony Brook developed a model of a companion star with an accretion disk to explain the ejection process.

"This model provides the most plausible explanation because we know that the engines that produce jets are accretion disks," Sahai explained. "Red giants don't have accretion disks, but many most likely have companion stars, which presumably have lower masses because they are evolving more slowly. The model we propose can help explain the presence of bipolar planetary nebulae, the presence of knotty jet-like structures in many of these objects, and even multipolar planetary nebulae. We think this model has very wide applicability."

A surprise from the STIS observation was that the disk does not fire the monster clumps in exactly the same direction every 8.5 years. The direction flip-flops slightly from side-to-side to back-and-forth due to a possible wobble in the accretion disk. "This discovery was quite surprising, but it is very pleasing as well because it helped explain some other mysterious things that had been observed about this star by others," Sahai said.

Astronomers have noted that V Hydrae is obscured every 17 years, as if something is blocking its light. Sahai and his colleagues suggest that due to the back-and-forth wobble of the jet direction, the blobs alternate between passing behind and in front of V Hydrae. When a blob passes in front of V Hydrae, it shields the red giant from view.

"This accretion disk engine is very stable because it has been able to launch these structures for hundreds of years without falling apart," Sahai said. "In many of these systems, the gravitational attraction can cause the companion to actually spiral into the core of the red giant star. Eventually, though, the orbit of V Hydrae's companion will continue to decay because it is losing energy in this frictional interaction. However, we do not know the ultimate fate of this companion."

The team hopes to use Hubble to conduct further observations of the V Hydrae system, including the most recent blob ejected in 2011. The astronomers also plan to use the Atacama Large Millimeter/submillimetre Array (ALMA) in Chile to study blobs launched over the past few hundred years that are now too cool to be detected with Hubble.

The team's results appeared in the August 20, 2016, issue of The Astrophysical Journal.

Planet in star system nearest our Sun 'may have oceans'

A rocky planet discovered in the "habitable" zone of the star nearest our Sun may be covered with oceans, researchers at France's CNRS research institute said Thursday.

A team including CNRS astrophysicists have calculated the size and surface properties of the planet dubbed Proxima b, and concluded it may be an "ocean planet" similar to Earth.

Scientists announced Proxima b's discovery in August, and said it may be the first exoplanet -- planet outside our Solar System -- to one day be visited by robots from Earth.

The planet orbits within a "temperate" zone from its host star Proxima Centauri, some four light years from us.

It is estimated to have a mass about 1.3 times that of Earth, and orbits about 7.5 million kilometres (4.6 million miles) from its star -- about a tenth the distance of innermost planet Mercury from the Sun.

"Contrary to what one might expect, such proximity does not necessarily mean that Proxima b's surface is too hot" for water to exist in liquid form, said a CNRS statement.

Proxima Centauri is smaller and 1,000 times weaker than our Sun, which means Proxima b is at exactly the right distance for conditions to be potentially habitable.

"The planet may very well host liquid water on its surface, and therefore also some forms of life," the statement said.

The size of exoplanets are generally calculated by measuring how much light they block out, from Earth's perspective, when they pass in front of their host star.

But no such transit of Proxima b has yet been observed, so the team had to rely on simulations to estimate the planet's composition and radius.

They calculated the radius was between 0.94 and 1.4 times that of Earth, which is 6,371 kilometres on average.

Assuming a minimum radius of 5,990 km, the planet would be very dense, with a metallic core making up two-thirds of the entire planet's mass, surrounded by a rocky mantle.

If there is surface water, it would not contribute more than 0.05 percent to the planet's total mass, the team said -- similar to Earth, where it is about 0.02 percent.

In the larger planet scenario, with a radius of 8,920 km, Proxima b's mass would be split 50-50 between a rocky centre and surrounding water.

"In this case, Proxima b would be covered by a single, liquid ocean 200 km deep," said the CNRS.

"In both cases, a thin, gassy atmosphere could surround the planet, like on Earth, rendering Proxima b potentially habitable," it concluded.

A Natural Law for Rotating Galaxies… What Does This Mean for Dark Matter?

An image of the nearby galaxy Messier 81, created with data from NASA's Spitzer Space Telescope.

Distant galaxies, black holes, exotics worlds…these are not just the stuff of science fiction; they are also the stuff that makes up our reality. Our quest to understand the universe is thrilling, challenging, and often confusing. Even the basic question “What is the universe made of?” isn’t easy to answer.

Adding new pieces to this puzzle, researchers from Case Western Reserve University and the University of Oregon recently discovered a natural law for rotating galaxies. Their surprising result is the subject of a new paper coming out later this week in Physical Review Letters that could have serious implications for the theory of dark matter.

The planets in our solar system rotate around the sun because of gravity. In the early 1600s, astronomer Johannes Kepler worked out a mathematical relationship between a planet’s distance from the sun and its orbital period, the time it takes to go completely around the sun. This is known as Kepler’s third law of planetary motion, and it reveals that planets farther from the sun travel around it with slower speeds. Isaac Newton later generalized Kepler’s law for all orbital systems.

There’s a problem though. The law doesn’t appear to hold for stars orbiting the centre of their galaxy. Astronomer Vera Rubin highlighted this discrepancy in the 1970s and since then, astronomers have verified time and again that stars on the outskirts of a galaxy rotate around the centre at the same speed as stars closer the centre. This result gave rise to the idea that galaxies have a halo of dark matter. If this is the case, stars do follow Newton’s law once the missing mass, made up of dark matter, is accounted for.

In this new research, work by astronomers Stacy McGaugh and Federico Lelli (Case Western) and Jim Schombert (Oregon) reveals that galaxies obey a natural law just like planets. It’s just not the same one.

The missing mass problem is the result of a difference in how we expect stars within a galaxy to behave and the way that they actually behave. Instead of assuming that these two should match, McGaugh, Lelli, and Schombert compared the observed orbital speed of stars within a galaxy (described by their radial velocity) to the predicted value that assumes what you see is what you get—no dark matter. Then they looked at the relationship between these results for a large number of galaxies.

Their work relied on data from NASA’s Spitzer Space Telescope, a space-based observatory that studies objects in infrared light. Over the years Spitzer has observed many types of galaxies, collecting information on how gas and stars are distributed within them. This information can be used to estimate the visible mass of a galaxy, which can be used to predict the radial velocity of its stars. Using 2,693 data points from 153 very different galaxies, the researchers modelled the radial velocity based on the visible mass of each galaxy.

Next, the scientists graphed these results against observed, published results of radial velocity for the same galaxies. When they got to that point, says McGaugh, “There was the result on the screen: Far better than we had ever hoped. It just fell right out.” There was a clear mathematical relationship between the observed radial velocity of a star in a galaxy to the distribution of visible matter.

If dark matter ultimately dominates the mass of galaxies, as many scientists think, then there’s no reason to assume that the amount of visible matter should be directly related to the amount of dark matter. But that’s just what this work implies. If two galaxies with very different properties have the same distribution of visible mass, the observed radial acceleration is the same. If you know one, you know the other. Not only is this surprising, it’s a big deal.

The authors suggest that their result can be explained in three ways.

1.It represents the end product of galaxy formation.
2.It represents new "dark sector" physics.
3.It is the result of new dynamical laws rather than dark matter.

None of these explanations are completely satisfying, say the authors. Their paper doesn’t go into the details, but it falls right in the middle of an ongoing discussion about the validity of the dark matter model. This work demonstrates a regularity in the data, says McGaugh. “How you interpret that is a whole 'nother can o' worms.” There’s no doubt that scientists will be elbow deep in that can before long.

—Kendra Redmond

NASA-funded science rocket discovers mysterious X-ray emissions in space

It’s a new mystery for astronomers: About a quarter of the high-energy X-rays picked up by the NASA-funded DXL sounding rocket on its most recent 15-minute flight must have come from somewhere else, and we don’t know where that somewhere might be.

Let’s step back and explain what’s going on first. A sounding rocket (also called a research rocket) is a rocket designed to take measurements and perform experiments in sub-orbital flights. DXL is short for Diffuse X-ray emission from the Local galaxy, which is exactly what the rocket was sent to measure. On this run, the instrument solved a longstanding question about the origins of the dim X-ray fog blanketing the entire sky. Evidence it collected confirms predictions that our solar system is moving through a region called the Local Hot Bubble, which may have been blasted clear by supernova explosions during the past 20 million years.

In addition to confirming the LHB, the rocket’s readings show the relative contribution of the solar wind and the LHB to the sum total of X-rays in the fog: about 40% of the observed X-rays come from the solar wind, and we find those mostly along the ecliptic. The LHB accounts for most of the rest. But DXL also found some high-energy X-band photons whose origins are still unexplained.

“We think that around 10 million years ago, a supernova exploded and ionized the gas of the Local Hot Bubble,” said study co-author Massimiliano Galeazzi. “But one supernova wouldn’t be enough to create such a large cavity and reach these temperatures — so it was probably two or three supernova over time, one inside the other.”

The high-energy X-rays, though, are too high-energy to have come from either the solar wind or the LHB, even in the wake of double or triple supernovae. “These sources contribute less than a quarter of the X-ray emission,” said lead author Youaraj Uprety. “So there’s an unknown source of X-rays in this energy range.”

To get the best readings on solar wind versus interstellar helium, DXL waited to launch this mission until Earth was passing through the sun’s helium-focusing cone. The helium-focusing cone is comparable with the sun’s wake: a region of space “behind” the sun, with respect to its axis of travel, where neutral helium from the LHB is much denser than in the rest of the inner solar system.

“The solar system is moving through interstellar space at about 15 miles per second,” said Uprety. “This space is filled with hydrogen and helium. The helium is a little heavier, so it carves around the sun to form a tail.” DXL flew right into that tail and took readings to figure out just where the X-rays it picked up had come from. Our galaxy has lots of neutral gas that would absorb X-rays coming from distant sources — meaning that these X-rays must originate somewhere near our solar system. At the same time, there’s nothing nearby that looks responsible; the LHB just isn’t hot enough to produce X-ray emissions at those energies, said Uprety.

“So we’re left with an open question on the source of these X-rays,” he said.

ESO's dust buster reveals hidden stars

In this new image of the nebula Messier 78, young stars cast a bluish pall over their surroundings, while red fledgling stars peer out from their cocoons of cosmic dust. To our eyes, most of these stars would be hidden behind the dust, but ESO's Visible and Infrared Survey Telescope for Astronomy (VISTA) sees near-infrared light, which passes right through dust. The telescope is like a giant dust buster that lets astronomers probe deep into the heart of the stellar environment.

Click on the images to enlarge

Messier 78, or M78, is a well-studied example of a reflection nebula. It is located approximately 1600 light-years away in the constellation of Orion (The Hunter), just to the upper left of the three stars that make up the belt of this familiar landmark in the sky. In this image, Messier 78 is the central, bluish haze in the centre; the other reflection nebula towards the right goes by the name of NGC 2071. The French astronomer Pierre Méchain is credited with discovering Messier 78 in 1780. However, it is today more commonly known as the 78th entry in French astronomer Charles Messier's catalogue, added to it in December of 1780.

M78 RA:  00h 00m 51.6s   DEC:+00° 05'  36"    Magnitude +8.3

When observed with visible light instruments, like ESO's Wide Field Imager at the La Silla Observatory, Messier 78 appears as a glowing, azure expanse surrounded by dark ribbons (see eso1105). Cosmic dust reflects and scatters the light streaming from the young, bluish stars in Messier 78's heart, the reason it is known as a reflection nebula.

The dark ribbons are thick clouds of dust that block the visible light originating behind them. These dense, cold regions are prime locations for the formation of new stars. When Messier 78 and its neighbours are observed in the submillimetre light between radio waves and infrared light, for example with the Atacama Pathfinder Experiment (APEX) telescope, they reveal the glow of dust grains in pockets just barely warmer than their extremely cold surroundings (see eso1219). Eventually new stars will form out of these pockets as gravity causes them to shrink and heat up.

In between visible and submillimetre light lies the near-infrared part of the spectrum, where the Visible and Infrared Survey Telescope for Astronomy (VISTA) provides astronomers with crucial information. Beyond dusty reflections and through thinner portions of obscuring material, the luminous stellar sources within Messier 78 are visible to VISTA's eyes. In the centre of this image, two blue supergiant stars, called HD 38563A and HD 38563B, shine brightly. Towards the right of the image, the supergiant star illuminating NGC 2071, called HD 290861, is also seen.

Besides big, blue, hot stars, VISTA can also see many stars that are just forming within the cosmic dust strewn about this region, their reddish and yellow colours shown clearly in this image. These colourful fledgling stars can be found in the dust bands around NGC 2071 and along the trail of dust running towards the left of the image. Some of these are T Tauri stars. Although relatively bright, they are not yet hot enough for nuclear fusion reactions to have commenced in their cores. In several tens of millions of years, they will attain full "star hood," and will take their place alongside their stellar brethren lighting up the Messier 78 region.

Hubble Spots Water Plumes Erupting on Jupiter's Moon Europa

Astronomers using NASA's Hubble Space Telescope have imaged what may be water vapour plumes erupting off the surface of Jupiter's moon Europa. This finding bolsters other Hubble observations suggesting the icy moon erupts with high-altitude water vapour plumes.

The observation increases the possibility that missions to Europa may be able to sample Europa's ocean without having to drill through miles of ice.

"Europa's ocean is considered to be one of the most promising places that could potentially harbour life in the solar system," said Geoff Yoder, acting associate administrator for NASA's Science Mission Directorate in Washington, D.C.. "These plumes, if they do indeed exist, may provide another way to sample Europa's subsurface."

The plumes are estimated to rise about 125 miles (200 kilometres) before, presumably, raining material back down onto Europa's surface. Europa has a huge global ocean containing twice as much water as Earth's oceans, but it is protected by a layer of extremely cold and hard ice of unknown thickness. The plumes provide a tantalizing opportunity to gather samples originating from under the surface without having to land or drill through the ice.

The team, led by William Sparks of the Space Telescope Science Institute (STScI) in Baltimore, Maryland, observed these finger-like projections while viewing Europa's limb as the moon passed in front of Jupiter.

The original goal of the team's observing proposal was to determine whether Europa has a thin, extended atmosphere, or exosphere. Using the same observing method that detects atmospheres around planets orbiting other stars, the team also realized if there was water vapour venting from Europa's surface, this observation would be an excellent way to see it.

"The atmosphere of an extrasolar planet blocks some of the starlight that is behind it," Sparks explained. "If there is a thin atmosphere around Europa, it has the potential to block some of the light of Jupiter, and we could see it as a silhouette. And so we were looking for absorption features around the limb of Europa as it transited the smooth face of Jupiter."

In 10 separate occurrences spanning 15 months, the team observed Europa passing in front of Jupiter. They saw what could be plumes erupting on three of these occasions.

This work provides supporting evidence for water plumes on Europa. In 2012, a team led by Lorenz Roth of Southwest Research Institute in San Antonio, Texas, detected evidence for water vapour erupting from the frigid south polar region of Europa and reaching more than 100 miles (160 kilometres) into space. Although both teams used Hubble's Space Telescope Imaging Spectrograph (STIS) instrument, each used a totally independent method to arrive at the same conclusion.

"When we calculate in a completely different way the amount of material that would be needed to create these absorption features, it's pretty similar to what Roth and his team found," Sparks said. "The estimates for the mass are similar, the estimates for the height of the plumes are similar. The latitude of two of the plume candidates we see corresponds to their earlier work."

But as of yet, the two teams have not simultaneously detected the plumes using their independent techniques. Observations thus far have suggested the plumes could be highly variable, meaning that they may sporadically erupt for some time and then die down. For example, observations by Roth's team within a week of one of the detections by Sparks' team failed to detect any plumes.

If confirmed, Europa would be the second moon in the solar system known to have water vapour plumes. In 2005, NASA's Cassini orbiter detected jets of water vapour and dust spewing off the surface of Saturn's moon Enceladus.

Scientists may use the infrared vision of the James Webb Space Telescope, which is scheduled to launch in 2018, to confirm venting or plume activity on Europa. NASA also is formulating a mission to Europa with a payload that could confirm the presence of plumes and study them from close range during multiple flybys.

"Hubble's unique capabilities enabled it to capture these plumes, once again demonstrating Hubble's ability to make observations it was never designed to make," said Paul Hertz, director of the Astrophysics Division at NASA Headquarters in Washington, D.C. "This observation opens up a world of possibilities, and we look forward to future missions — such as the James Webb Space Telescope — to follow-up on this exciting discovery."

The work by Sparks and his colleagues will be published in the Sept. 29 issue of The Astrophysical Journal.

The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency (ESA). NASA's Goddard Space Flight Center in Greenbelt, Maryland, manages the telescope. The Space Telescope Science Institute (STScI) in Baltimore, Maryland, conducts Hubble science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy in Washington, D.C.

Astronomers shed light on different galaxy types

In research published today, Australian scientists have taken a critical step towards understanding why different types of galaxies exist throughout the Universe.

The research, made possible by cutting-edge AAO instrumentation, means that astronomers can now classify galaxies according to their physical properties rather than human interpretation of a galaxy’s appearance.

For the past 200 years, telescopes have been capable of observing galaxies beyond our own galaxy, the Milky Way.

Only a few were visible to begin with but as telescopes became more powerful, more galaxies were discovered, making it crucial for astronomers to come up with a way to consistently group different types of galaxies together.

In 1926, the famous American astronomer Edwin Hubble refined a system that classified galaxies into categories of spiral, elliptical, lenticular or irregular shape. This system, known as the Hubble sequence, is the most common way of classifying galaxies to this day.

Despite its success, the criteria on which the Hubble scheme is based are subjective, and only indirectly related to the physical properties of galaxies. This has significantly hampered attempts to identify the evolutionary pathways followed by different types of galaxies as they slowly change over billions of years. 

Dr Luca Cortese, from The University of Western Australia node of the International Centre for Radio Astronomy Research (ICRAR), said the world’s premier astronomical facilities are now producing surveys consisting of hundreds of thousands of galaxies rather than the hundreds that Hubble and his contemporaries were working with.

“We really need a way to classify galaxies consistently using instruments that measure physical properties rather than a time consuming and subjective technique involving human interpretation,” he said.

In a study led by Dr Cortese, a team of astronomers has used a technique known as Integral Field Spectroscopy to quantify how gas and stars move within galaxies and reinterpret the Hubble sequence as a physically based two-dimensional classification system.

“Thanks to the development of new technologies, we can map in great detail the distribution and velocity of different components of galaxies. Then, using this information we’re able to determine the overall angular momentum of a galaxy, which is the key physical quantity affecting how the galaxy will evolve over billions of years.

“Remarkably, the galaxy types described by the Hubble scheme appear to be determined by two primary properties of galaxies–mass and angular momentum. This provides us with a physical interpretation for the well known Hubble sequence whilst removing the subjectiveness and bias of a visual classification based on human perception rather than actual measurement.”

The new study involved 488 galaxies observed by the 3.9m Anglo Australian Telescope in New South Wales and an instrument attached to the telescope called the Sydney-AAO Multi-object Integral-field spectrograph or ‘SAMI’.

The SAMI project, led by the University of Sydney and the ARC Centre of Excellence for All-sky Astrophysics (CAASTRO), aims to create one of the first large-scale resolved survey of galaxies, measuring the velocity and distribution of gas and stars of different ages in thousands of systems.

“Australia has a lot of expertise with this type of astronomy and is really at the forefront of what’s being done,” said Professor Warrick Couch, Director of the Australian Astronomical Observatory and CAASTRO Partner Investigator.

“For the SAMI instrument we succeeded in putting 61 optical fibres within a distance that’s less than half the width of a human hair.

“That’s no small feat, it’s making this type of work possible and attracting interest from astronomers and observatories from around the world.”

Future upgrades of the instrument are planned that will allow astronomers to obtain even sharper maps of galaxies and further their understanding of the physical processes shaping the Hubble sequence.

“As we get better at doing this and the instruments we’re using are upgraded, we should be able to look for the physical triggers that cause one type of galaxy to evolve into another—that’s really exciting stuff,” Dr Cortese said.

OSIRIS REx NASA’s mission to Bennu

Running time: 35 minutes

Acknowledgements: Damian Peach for his image of Saturn; NASA JPL the European Southern Observatory for their kind permission to use images & graphics in this month’s program.

OSIRIS REx is due to launch on 8 September to Bennu, an asteroid that is possibly on a collision course with Earth. This is NASA’s first sample return mission to study a Near Earth Asteroid.

In this month’s program we examine the European Southern Observatory’s remarkable discovery of an Earth-like planet in orbit around Proxima Centauri, our nearest star. Take a detailed look at the OSIRIS spacecraft along with its mission, and asteroids in general.

Historic first image of Pluto in X-rays

The first detection of Pluto in X-rays has been made using NASA's Chandra X-ray Observatory in conjunction with observations from NASA's New Horizons spacecraft.

As New Horizons approached Pluto in late 2014 and then flew by the planet during the summer of 2015, Chandra obtained data during four separate observations. During each observation, Chandra detected low-energy X-rays from the small planet. The main panel in this graphic is an optical image taken from New Horizons on its approach to Pluto, while the inset shows an image of Pluto in X-rays from Chandra.

There is a significant difference in scale between the optical and X-ray images. New Horizons made a close flyby of Pluto but Chandra is located near the Earth, so the level of detail visible in the two images is very different. The Chandra image is 180,000 miles across at the distance of Pluto, but the planet is only 1,500 miles across. Pluto is detected in the X-ray image as a point source, showing the sharpest level of detail available for Chandra or any other X-ray observatory. This means that details over scales that are smaller than the X-ray source cannot be seen here.

Detecting X-rays from Pluto is a somewhat surprising result given that Pluto - a cold, rocky world without a magnetic field - has no natural mechanism for emitting X-rays. However, scientists knew from previous observations of comets that the interaction between the gases surrounding such planetary bodies and the solar wind - the constant streams of charged particles from the sun that speed throughout the solar system -- can create X-rays.

The researchers were particularly interested in learning more about the interaction between the gases in Pluto's atmosphere and the solar wind. The New Horizon spacecraft carries an instrument designed to measure that activity up-close -- Solar Wind Around Pluto (SWAP) -- and scientists examined that data and proposed that Pluto contains a very mild, close-in bow shock, where the solar wind first "meets" Pluto (similar to a shock wave that forms ahead of a supersonic aircraft) and a small wake or tail behind the planet.

The immediate mystery is that Chandra's readings on the brightness of the X-rays are much higher than expected from the solar wind interacting with Pluto's atmosphere. The Chandra detection is also surprising since New Horizons discovered Pluto's atmosphere was much more stable than the rapidly escaping, "comet-like" atmosphere that many scientists expected before the spacecraft flew past in July 2015. In fact, New Horizons found that Pluto's interaction with the solar wind is much more like the interaction of the solar wind with Mars, than with a comet. While Pluto is releasing enough gas from its atmosphere to make the observed X-rays, there isn't enough solar wind flowing directly at Pluto at its great distance from the Sun to make them according to certain theoretical models.

There are several suggested possibilities for the enhanced X-ray emission from Pluto. These include a much wider and longer tail of gases trailing Pluto than New Horizons detected using its SWAP instrument. Because Pluto is so small compared to the size of a Chandra point source, scientists may be unable to detect such a tail in X-rays. Other possibilities are that interplanetary magnetic fields are focusing more particles than expected from the solar wind into the region around Pluto, or the low density of the solar wind in the outer solar system at the distance of Pluto could allow for the formation of a doughnut, or torus, of neutral gas cantered around Pluto's orbit. It will take deeper and higher resolution images of X-rays from Pluto's environment than we currently have from Chandra to distinguish between these possibilities. 

Image Credit:

NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Center/Chandra X-Ray Center

 

Ed Beshore's Rocket Ride Into the Sunset

 

 

 

 

 

 

 

 

 

 

 

With the OSIRIS-REx spacecraft successfully launched and bound for the asteroid Bennu, the deputy principal investigator of the UA-led mission will retire in three weeks, and Heather Enos will take over as second in command to Dante Lauretta.

One week post-launch, NASA’s Origins, Spectral Interpretation, Resource Identification, Security-Regolith Explorer (OSIRIS-REx) spacecraft remains healthy and is on track for its two-year journey to the asteroid Bennu.  As of noon EDT Thursday, the spacecraft was approximately 2 million miles (3.2 million kilometres) from Earth, traveling at approximately 12,300 miles per hour (19,800 kilometres per hour) relative to Earth.  All of the spacecraft’s subsystems are operating as expected.

This is the first image from the OSIRIS-REx star tracker taken on Monday, Sept. 12. Similar to the way early sailors used the stars to navigate, the star tracker on OSIRIS-REx takes images of the stars and compares them to an on-board catalogue, which then tells the spacecraft navigation systems its attitude, or which way it is pointing. Credits: NASA

The OSIRIS-REx spacecraft is designed to rendezvous with, study, and return a sample of Bennu to Earth. This sample of a primitive asteroid will help scientists understand the formation of our solar system more than 4.5 billion years ago.

After lift-off at 7:05 p.m. EDT on Sept. 8, the United Launch Alliance Atlas V rocket performed flawlessly and positioned the OSIRIS-REx spacecraft exactly where the mission’s navigation team expected it to be. By 1:30 p.m. EDT on Sept. 9, approximately 18 1/2 hours after launch, the OSIRIS-REx spacecraft had crossed the orbital path of the moon at 240,000 miles (386,500 kilometres). By that evening, the spacecraft transitioned from launch operations into its outbound cruise phase.

On Sept. 12, OSIRIS-REx took its first image from it star tracker navigational camera, proving the system is functioning properly.  The star tracker takes images of the stars and compares them to an on-board catalogue, which then tells the spacecraft navigation systems its attitude, or which way it is pointing.

Next week, the engineers controlling the OSIRIS-REx spacecraft will conduct checkouts of the science instruments on board the spacecraft.

Goddard Space Flight Center provides overall mission management, systems engineering and the safety and mission assurance for OSIRIS-REx. Dante Lauretta of the University of Arizona, Tucson, is the principal investigator. Lockheed Martin Space Systems in Denver built the spacecraft. OSIRIS-REx is the third mission in NASA’s New Frontiers Program. NASA’s Marshall Space Flight Center in Huntsville, Alabama, manages the agency’s New Frontiers Program for its Science Mission Directorate in Washington.

New spacecraft Proba-3 is set to study the Sun’s Corona

By converging in orbit, a pair of small satellites will open a new view on the source of the largest structure in the Solar System: the Sun’s ghostly atmosphere, extending millions of kilometres out into space.

The two satellites together are called Proba-3, set for launch in late 2019. Through precise formation flying, one will cast a shadow across the second to open up an unimpeded view of the inner area of the ‘corona’, which is a million times fainter than the blindingly brilliant solar disc.

“When I first heard of the idea I said ‘Wow! That’s just what we need’,” said Andrei Zhukov of the Royal Observatory of Belgium, serving as Principal Investigator for Proba-3’s solar instrument.

“The best way to observe the corona from the ground is during a solar eclipse, although we still have to cope with stray light – we cannot correct for the influence of Earth’s atmosphere. 

“The next best method is by using ‘coronagraphs’ to create an artificial eclipse, either on ground telescopes or inside Sun-watching satellites such as SOHO and Stereo.

“The problem is that stray light bending around the edge of the occulting disc limits our view of the most important inner portion of the corona. SOHO’s coronagraph, for instance, can observe no closer in than 1.1 Sun-diameters. Others can see closer, but with strong stray light making detailed observation impossible.

“With Proba-3 we aim to see extremely close to the solar surface in visible light, by flying the occulted and coronagraph on separate satellites some 150 m apart.

“This should give us a ringside seat on the most interesting segment of the corona, where a lot of interesting physics is going on, where the solar wind is born and ‘coronal mass ejections’ originate – gigantic solar eruptions with the potential to affect our terrestrial infrastructure.”

While the Sun’s surface is a comparatively cool 6000ºC, the corona averages a sizzling million degrees. The mystery is how energy travels from the cool Sun to the hot corona, in apparent defiance of the laws of thermodynamics.

“By mapping the fine structure of the inner corona for a prolonged time – we are targeting around six hours – our hope is that we gain insight into the kind of energy flows that are taking place,” notes Dr Zhukov. 

“Our standard observing mode will be once per minute, but we could speed that up to a few seconds within a selected field of view, for instance when tracing the rapid evolution of a mass ejection.

“The ultimate goal is to be able to solve the physics of space weather, in order to forecast coronal mass ejections, which are known to have dramatic effects on terrestrial electricity grids and other infrastructure.”

Proba-3 is first and foremost a technology demonstration, exploring the potential of precise formation flying in orbit, but achieving meaningful scientific results will also help to prove its approach works.     

Saturn, Approaching Northern Summer

Since NASA's Cassini spacecraft arrived at Saturn in mid-2004, the planet's appearance has changed greatly. The shifting angle of sunlight as the seasons march forward has illuminated the giant hexagon-shaped jet stream around the north polar region, and the subtle bluish hues seen earlier in the mission have continued to fade. Earlier views obtained in 2004 and 2009 (see PIA06077 and PIA11667) demonstrate how drastically the illumination has changed.

This view shows Saturn's northern hemisphere in 2016, as that part of the planet nears its northern hemisphere summer solstice in May 2017. Saturn's year is nearly 30 Earth years long, and during its long time there, Cassini has observed winter and spring in the north, and summer and fall in the south. The spacecraft will complete its mission just after northern summer solstice, having observed long-term changes in the planet's winds, temperatures, clouds and chemistry.

Cassini scanned across the planet and its rings on April 25, 2016, capturing three sets of red, green and blue images to cover this entire scene showing the planet and the main rings. The images were obtained using Cassini's wide-angle camera at a distance of approximately 1.9 million miles (3 million kilometres) from Saturn and at an elevation of about 30 degrees above the ring plane. The view looks toward the sunlit side of the rings from a sun-Saturn-spacecraft angle, or phase angle, of 55 degrees. Image scale on Saturn is about 111 miles (178 kilometres) per pixel.

Image Credit: NASA/JPL-Caltech/Space Science Institute

Picture postcards from Jupiter sent by NASA’s Juno probe

 

 

 

 

 

 

Please click on these images to enlarge

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

On 27 August the JUNO spacecraft made its first close approach to giant Jupiter, and JUNO CAM captured all these images released by NASA during the course of 2 September 2016 with more to follow.