Posted on by Jason Major

Titan’s Gravity Indicates a Thicker, Uneven Icy Crust

Color composite of Titan and Dione made from Cassini images acquired in May 2011. (NASA/JPL/SSI/J. Major)

It’s long been speculated that Saturn’s moon Titan may be harboring a global subsurface ocean below an icy crust, based on measurements of its rotation and orbit by NASA’s Cassini spacecraft. Titan exhibits a density and shape that indicates a pliable liquid internal layer — an underground ocean — possibly composed of water mixed with ammonia, a combination that would help explain the consistent amount of methane found in its thick atmosphere.

Now, further analysis of Cassini gravity measurements by a Stanford University team has shown that Titan’s ice layer is thicker and less uniform than originally estimated, indicating a more complex internal structure — and a stronger external influences for its heat.

Titan’s liquid subsurface ocean was previously estimated to be in the neighborhood of 100 km (62 miles) thick, sandwiched between a rocky core below and an icy shell above. This was based on the behavior of Titan in its orbit — or, more precisely, how Titan’s shape changes along the course of its orbit, as measured by Cassini’s radar instrument.

Because Titan’s 16-day orbit is not perfectly circular the moon experiences a stronger gravitational pull from Saturn at certain points than at others. As a result it’s flattened at the poles and constantly changing shape slightly — an effect called tidal flexing. Along with the decay of radioactive materials in its core, this flexing generates the internal heat that helps keep a subsurface ocean liquid.

A team of researchers from Stanford University, led by Howard Zebker, professor of geophysics and electrical engineering, used recent Cassini measurements of Titan’s topography and gravity to determine that the icy layer between the moon’s surface and ocean is up to twice as thick as previously thought — and it’s considerably thicker at the equator than at the poles.

“The picture of Titan that we get has an icy, rocky core with a radius of a little over 2,000 kilometers, an ocean somewhere in the range of 225 to 300 kilometers thick and an ice layer that is 200 kilometers thick,” said Zebker.

Different thicknesses of Titan’s ice layer would mean that there’s less heat being generated internally by the decay of radioactive materials in Titan’s core, because that type of heat would be more or less globally uniform. Instead, tidal flexing caused by the gravitational interactions with Saturn and neighboring smaller moons must play a stronger role in heating Titan’s insides.

Read more: Titan’s Tides Suggest a Subsurface Sea

With Cassini’s new measurements of Titan’s gravity, Zebker and his team calculated that the icy layer below Titan’s flattened poles is 3,000 meters (about 1.8 miles) thinner than average, while at the equator it’s 3,000 meters thicker than average. Combined with the moon’s surface features, this makes the average global thickness of the ice layer to be more like 200 km, not 100.

Heat generated by tidal flexing — which is more strongly felt at the poles — is thought to be the cause of the thinner ice there. Thinner ice would mean there’s more liquid water beneath the poles, which is denser and thus would exert a stronger gravitational pull… exactly what’s been found in Cassini’s measurements.

The findings were announced Tuesday, Dec. 4 at the AGU convention in San Francisco. Read more on the Stanford University news page.

Posted on by Nancy Atkinson

Star Trek Teaser: “Into Darkness” Trailer Released

James T. Kirk and the crew of the Enterprise will be back for a second pre-quel of the young original Enterprise crew with next summer’s “Star Trek Into Darkness.” From this new teaser trailer just released today, it certainly looks dark, with lots of explosions, fight scenes, women screaming, Chris Pine’s Kirk having omnipresent cuts on his face, and what looks like a starship falling into an ocean.

The description of the film on the IMDb website:

After the crew of the Enterprise find an unstoppable force of terror from within their own organization, Captain Kirk leads a manhunt to a war-zone world to capture a one man weapon of mass destruction.

The bad guy (actor Benedict Cumberbatch) has a British accent (wasn’t that big in the 1960’s?) and rumors are starting to surface with Cumberbatch playing either a villain similar to the classic ‘Trek’ nemesis Gary Mitchell, who gains glassy eyes and superpowers and tries to take over the world in the second pilot episode “Where No Man Has Gone Before” for the 60’s TV series, or Khan, the genetically-engineered tyrant who first appeared in the original Trek TV series episode “Space Seed” but was killed in the “Star Trek II: Wrath of Khan” movie. So, in my mind, revisiting Khan would would cause the Trek world to get complicated.

But while the villain hasn’t yet been revealed, it is someone who “has returned,” so expect it to be a familiar name.

From the teaser, it appears all the main actors from the 2009 “Star Trek” film have returned, but does Spock have a new haircut?

A disclaimer: this was posted for all our Trek fans, so don’t complain that this isn’t space or astronomy news, because in our Trekkie minds it is space news.

Posted on by Nancy Atkinson

Moon’s Inner Crust Almost Completely Pulverized

This image shows a highly porous crust on the lunar surface, a consequence of fractures generated by billions of years of impact cratering. Credit: NASA/JPL-Caltech/ IPGP

From looking at the Moon’s surface, we know it has taken a beating from asteroids and comets pummeling its surface. But new details from the GRAIL mission reveal the lunar interior just below the surface has been walloped as well, and is almost completely pulverized. This surprising finding, along with the discovery of deep fractures, suggests that in its first billion years, the Moon may have endured a history of massive impacts, more than previously thought. By inference, this means Earth and other terrestrial planets in the Solar System endured huge early impacts, too.

“It was known that planets were battered by impacts, but nobody had envisioned that the [Moon’s] crust was so beaten up,” said Maria Zuber, Principal Investigator for the GRAIL mission. “This is a really big surprise, and is going to cause a lot of people to think about what this means for planetary evolution.”

The new GRAIL data agrees with recent studies that suggest that the Late Heavy Bombardment may have lasted much longer than originally estimated and well into the time when early life was forming on Earth. Additionally, this “late-late” period of impacts — 3.8 billion to 2.5 billion years ago — was not for the faint of heart. Various blasts may have rivaled those that produced some of the largest craters on the Moon, and could have been larger than the dinosaur-killing impact that created the Chicxulub crater 65 million years ago.

From GRAIL’s measurements, Zuber and her team have now stitched together a high-resolution map of the Moon’s gravity (read more about it in our previous article.)

But the resulting map also reveals an interior gravitational field consistent with an incredibly fractured lunar crust. Compared to the surface, the map of the interior looks extraordinarily smooth. Except for the large impact basins, the Moon’s upper crust largely lacks dense rock structures and is instead likely made of porous, pulverized material.

This moon map shows the gravity gradients calculated by NASA’s GRAIL mission. Red and blue correspond to stronger gravity gradients. Image credit: NASA/JPL-Caltech/CSM

GRAIL’s lunar gravity map has also revealed numerous structures on the Moon’s surface that were unresolved by previous gravity maps of any planet, including volcanic landforms, impact basin rings, and many simple, bowl-shaped craters. From GRAIL’s measurements, scientists have determined that the Moon’s crust, ranging in thickness from 34 to 43 kilometers, is much thinner than planetary geologists had previously suspected. The crust beneath some major basins is nearly nonexistent, indicating that early impacts may have excavated the lunar mantle, providing a window into the interior.

“If you look at surface of the Moon and how heavily cratered it is,” said Zuber during a press briefing on Wednesday from the American Geophysical Union conference, “that tells us that all terrestrial planets looked that way, but Earth’s history is not preserved because of atmospheric and erosional processes on our planet. So, if we want to study those early periods, we need to go somewhere else, and the Moon is the perfect place for that.”

Zuber said that from finding an incredible fracturing of the Moon’s upper crust, we now know the crust of other planets likely have these same fractures as well. “We have reason to believe that the fractures on the terrestrial planets are deeper, and perhaps as in case of the Moon, even into the mantle. This effects planetary evolution, such as how planets lose heat,” she said.

Fractures also provide a pathway for fluids.

“Mars has been theorized to have an ancient ocean, and we wonder where it went,” said Zuber. “The ocean could well be underground, and we’ve seen evidence of water underground on Mars. If there were ever microbes on the surface of Mars, they could have gone very deep, so this finding opens up possibilities like that, and really opens a window to the early stages of our Solar System and just how violent a place it was.”

In addition to GRAIL’s discoveries, Zuber said another major accomplishment has been the performance of the spacecraft themselves. To achieve the mission’s science goals, the two probes, which can travel more than 200 kilometers apart, needed to be able to measure changes in the distance between them to within a few tenths of a micron per second. But GRAIL actually outperformed its measurement requirements by about a factor of five, resolving changes in spacecraft distance to several hundredths of a micron per second.

“On this mission, with two spacecraft, everything had to go perfectly twice,” Zuber says, adding proudly, “Imagine you’re a parent raising a twins, and your children sit down at the piano and play a duet perfectly. That’s how it feels.”

See an image gallery from the GRAIL mission here.

Sources: GRAIL press conference from AGU, MIT, JPL

Posted on by Jason Major

Pale Blue Dot: an Animated Contemplation

Every now and then, someone takes Carl Sagan’s wonderful reading of his iconic “Pale Blue Dot” narrative and turns it into an animated presentation, usually combining images and video footage of space exploration and Earthly vistas to create something undeniably spellbinding (Sagan’s narratives do have a tendency to have that effect!) Artist Adam Winnik went a slightly different route, however, creating an illustrated animation to go along with Sagan’s reading for his thesis project in 2011. The result is no less poignant… check it out above.

See more of Adam’s work on his website here.

Video: Adam Winnik. Music: Hans Zimmer “You’re So Cool”

Posted on by Nancy Atkinson

GRAIL First Results Provide Most Precise Lunar Gravity Map Yet

This map shows the gravity field of the moon as measured by NASA’s GRAIL mission. Image credit: NASA/ARC/MIT

The first science results from NASA’s twin GRAIL lunar orbiters provide incredible detail of the Moon’s interior and the highest resolution gravity field map of any celestial body, including Earth.

The Gravity Recovery and Interior Laboratory (GRAIL) data shows ancient internal structures that were previously unknown, provides details that are up to five orders of magnitude better than previous studies of the Moon, and delivers unprecedented information about the Moon’s surface and gravity field.

The twin spacecraft, nicknamed Ebb and Flow, send radio signals to each other and any changes in distance between the two as they circle the Moon are measured, down to changes as small as 50 nanometers per second. “That’s 1/ 20,000th the velocity that a snail moves,” said Maria Zuber, GRAIL Principal Investigator, speaking at the American Geophysical Union conference today.

The new gravity maps reveals an abundance of features such as tectonic structures, volcanic landforms, basin rings, crater central peaks and numerous simple, bowl-shaped craters. Data also show the moon’s gravity field is unlike that of any terrestrial planet in our solar system.

The instruments on the GRAIL spacecraft can probe inside the planet. Incredible videos released today shows an abundance of detail that the team said they are only just beginning to study.

Subtracting away the gravity from surface features provides what is called a Bouguer gravity map. What remains is a view of mass anomalies inside the Moon due to either variations in crustal thickness or mantle density. In the video above, the prominent nearside circular highs (in red) indicate the well-known mass concentrations or ‘mascons,’ but many similar newfound far-side features are also visible.

“Ninety-eight percent of local gravity is associated with topography, while 2 percent are other gravitational features,” said Zuber. “You can see bull’s-eyes of the lunar mascons, but otherwise we see a smooth inner surface. The only way this could happen is if impacts to the early Moon shattered the inner surface.”

These maps of the moon show the “Bouguer” gravity anomalies as measured by NASA’s GRAIL mission. Image credit: NASA/JPL-Caltech/CSM

The Bougeur gravity map also revealed evidence for ancient volcanic activity under the surface of the Moon and strange linear gravitational anomalies.

“In the gradients of Bouguer gravity map, saw features we didn’t expect,” said Jeff Andrews-Hanna, GRAIL co-investigator. “We identified a large population of linear gravitational anomalies. We don’t see any expression of them on topography maps, so we infer that these are an ancient internal structures.”

A linear gravity anomaly intersecting the Crisium basin on the nearside of the moon has been revealed by NASA’s GRAIL mission. The GRAIL gravity gradient data are shown at left, with the location of the anomaly indicated. Red and blue correspond to stronger gravity gradients. Topography data over the same region from NASA’s Lunar Reconnaissance Orbiter’s Lunar Orbiter Laser Altimeter are shown at right; these data show no sign of the gravity anomaly. Credit: NASA/JPL-Caltech/CSM

For example, this image of Crisium Basin, which forms one of the ‘man on moon’s’ eyes, the gravity maps shows a linear feature crossing the basin while topography maps show no such correlating feature. “This tells us the gravity anomaly formed before the impacts,” Andrews-Hanna said.

These maps of the near and far side of the moon show the gravity gradients as measured by NASA’s GRAIL mission, highlighting a population of linear gravity anomalies. Image credit: NASA/JPL-Caltech/CSM

Additional data reveal that the Moon’s inner crust in almost completely pulverized. Read more about it in our second article on the new GRAIL results.

Other data reveal the crust of the Moon is thinner than previously thought.

“Using GRAIL gravity data, we found the average thickness of the crust is 32-34 kilometers which is about 10 km less than previous studies,” said Mark Wieczorek, GRAIL Co-Investigator. “We found the bulk abundance of aluminum on Moon is nearly the same as that of the Earth. This is consistent with a recent hypothesis that the Moon is derived of materials from the Earth when it was formed during a giant impact event.”

NASA’s GRAIL mission took this flyover video above the Mare Orientale basin of Earth’s moon. It was collected by the MoonKAM aboard GRAIL’s Ebb spacecraft on April 7 and 8, 2012. Movie credit: NASA/JPL-Caltech/Sally Ride Science

During its prime mission, the two GRAIL spacecraft orbited just 55 km above the Moon’s surface. This close distance is why GRAIL is producing the best gravity field data for any planet, including Earth.

“GRACE is still collecting great data about Earth’s gravity field, but because Earth has an atmosphere, GRACE has to orbit at 500 km,” said Zuber. “Nothing beats going low.”

Zuber said the GRAIL team learned from GRACE and were able to make “some judicious improvements.” She also suggested this technology should be used for every planetary body in the solar system, and threw out an enticing idea: “Imagine mapping currents beneath the surface of Europa,” she said.

GRAIL finishes the primary science mission in May and are currently working in an extended mission where the spacrafts’ altitude was lowered to just 23 km above the surface. “We are opening another window interms of geophysics, and so you’ll be hearing results from the new data sets soon,” said Sami Asmar, GRAIL team member.

At a AGU conference session later in the day, Zuber revealed that tomorrow, December 6, 2012, the team will lower the GRAIL spacecraft down to just 11 km above the lunar surface.

Artist concept of GRAIL mission, with two twin spacecraft in tandem orbits around the moon to measure its gravity field in unprecedented detail. Image credit: NASA/JPL

The extended mission will end soon, in mid-December, and soon after that, the two spacecraft will be crashed intentionally onto the lunar surface. The team said today that they are still formulating ideas for the impact scenario, and looking at the possibility of aiming the crashes so they are within the field-of-view of instruments on NASA’s Lunar Reconnaissance Orbiter.

Posted on by Nancy Atkinson

The Black Marble: Stunning New Orbital Views of Earth at Night

This image of Asia and Australia at night is a composite assembled from data acquired by the Suomi NPP satellite in April and October 2012. Credit: NASA, NOAA, and the Department of Defense.

Two months of night-time imagery gathered by the Suomi NPP satellite have resulted in a stunning new look at Earth at night, appropriately nicknamed the Black Marble.

The nighttime views were made possible by the new satellite’s “day-night band” of the Visible Infrared Imaging Radiometer Suite. VIIRS detects light in a range of wavelengths from green to near-infrared and uses filtering techniques to observe dim signals such as city lights, gas flares, auroras, wildfires, and reflected moonlight. In this case, auroras, fires, and other stray light have been removed to emphasize the city lights.

“This is not your father’s low light sensor!” said Steve Miller, senior research scientist and deputy director of the Cooperative Institute for Research in the Atmosphere (CIRA), Colorado State University, speaking at the American Geophysical Union conference this week.

See more views and a video presentation of the VIIRS data below:

The new satellite is providing a much higher resolution across a greater band of light than previous night-light gathering satellites.

Originally developed for meteorologists to be able to look at nighttime clouds, the VIIRS data is providing a wide variety of information. “We are getting as much mileage from these data sets as we can,” said Chris Elvidge, who leads the Earth Observation Group at NOAA’s National Geophysical Data Center.

Elvidge and Miller said the data is being used to model population distribution, fossil fuel and CO2 emissions, and other information that can be gleaned from nighttime lights such finding power outages, determining astronomical viewing conditions, providing site selection for astronomical observatories, and looking at impacts of artificial lights on humans and animals.

The difference between electrical lights and fires, and night glow and auroras can even be determined by VIIRS.

North and South America at night is a composite assembled from data acquired by the Suomi NPP satellite in April and October 2012. Credit: NASA, NOAA, and the Department of Defense.

Europe, Africa, and the Middle East at night is a composite assembled from data acquired by the Suomi NPP satellite in April and October 2012. Credit: NASA, NOAA, and the Department of Defense.

Named for satellite meteorology pioneer Verner Suomi, NPP flies over any given point on Earth’s surface twice each day at roughly 1:30 a.m. and p.m. The polar-orbiting satellite flies 824 kilometers (512 miles) above the surface, sending its data once per orbit to a ground station in Svalbard, Norway, and continuously to local direct broadcast users distributed around the world,
.

See more imagery and get additional information about the night-time VIIRS Data at the NASA Earth Observatory website.

Posted on by Nancy Atkinson

Other Solar Systems Might Be More Habitable Than Ours

This artist’s impression shows the planetary system around the sun-like star HD 10180. Credit: ESO/L. Calçada

Our Earth feels like a warm and welcoming place for us life forms, but beyond our little planet, the majority of the solar system is too cold for us to live comfortably. A new study suggests that planets in other solar systems might be more habitable than our own because, on the whole, they would be warmer — up to 25 % warmer. This would make them more geologically active and more likely to retain enough liquid water to support life, at least in its microbial form. In turn, the “Goldilocks Zone” around other stars — the habitable region — would be bigger than the Zone in our own Solar System.

This new study comes from geologists and astronomers at Ohio State University who have teamed up to search for alien life in a new way.

They studied eight “solar twins” of our Sun—stars that very closely match the Sun in size, age, and overall composition—in order to measure the amounts of radioactive elements they contain. Those stars came from a dataset recorded by the High Accuracy Radial Velocity Planet Searcher spectrometer at the European Southern Observatory in Chile.

They searched the solar twins for elements such as thorium and uranium, which are essential to Earth’s plate tectonics because they warm our planet’s interior. Plate tectonics helps maintain water on the surface of the Earth, so the existence of plate tectonics is sometimes taken as an indicator of a planet’s hospitality to life.

Of the eight solar twins the team has studied so far, seven appear to contain much more thorium than our Sun—which suggests that any planets orbiting those stars probably contain more thorium, too. That means that the interior of the planets are probably warmer than ours.

For example, one star in the survey contains 2.5 times more thorium than our Sun, according to team member and Ohio State doctoral student Cayman Unterborn. He says that terrestrial planets that formed around that star probably generate 25 percent more internal heat than Earth does, allowing for plate tectonics to persist longer through a planet’s history, giving more time for live to arise.

“If it turns out that these planets are warmer than we previously thought, then we can effectively increase the size of the habitable zone around these stars by pushing the habitable zone farther from the host star, and consider more of those planets hospitable to microbial life,” said Unterborn, who presented the results at the American Geophysical Union meeting in San Francisco this week.

“If it turns out that these planets are warmer than we previously thought, then we can effectively increase the size of the habitable zone around these stars.”

“At this point, all we can say for sure is that there is some natural variation in the amount of radioactive elements inside stars like ours,” he added. “With only nine samples including the sun, we can’t say much about the full extent of that variation throughout the galaxy. But from what we know about planet formation, we do know that the planets around those stars probably exhibit the same variation, which has implications for the possibility of life.”

His advisor, Wendy Panero, associate professor in the School of Earth Sciences at Ohio State, explained that radioactive elements such as thorium, uranium, and potassium are present within Earth’s mantle. These elements heat the planet from the inside, in a way that is completely separate from the heat emanating from Earth’s core.

“The core is hot because it started out hot,” Panero said. “But the core isn’t our only heat source. A comparable contributor is the slow radioactive decay of elements that were here when the Earth formed. Without radioactivity, there wouldn’t be enough heat to drive the plate tectonics that maintains surface oceans on Earth.”

The relationship between plate tectonics and surface water is complex and not completely understood. Panero called it “one of the great mysteries in the geosciences.” But researchers are beginning to suspect that the same forces of heat convection in the mantle that move Earth’s crust somehow regulate the amount of water in the oceans, too.

“It seems that if a planet is to retain an ocean over geologic timescales, it needs some kind of crust ‘recycling system,’ and for us that’s mantle convection,” Unterborn said.

In particular, microbial life on Earth benefits from subsurface heat. Scores of microbes known as archaea do not rely on the sun for energy, but instead live directly off of heat arising from deep inside the Earth.

On Earth, most of the heat from radioactive decay comes from uranium. Planets rich in thorium, which is more energetic than uranium and has a longer half-life, would “run” hotter and remain hot longer, he said, which gives them more time to develop life.

As to why our solar system has less thorium, Unterborn said it’s likely the luck of the draw.

“It all starts with supernovae. The elements created in a supernova determine the materials that are available for new stars and planets to form. The solar twins we studied are scattered around the galaxy, so they all formed from different supernovae. It just so happens that they had more thorium available when they formed than we did.”

Jennifer Johnson, associate professor of astronomy at Ohio State and co-author of the study, cautioned that the results are preliminary. “All signs are pointing to yes—that there is a difference in the abundance of radioactive elements in these stars, but we need to see how robust the result is,” she said.

To continue this research, the team wants to do a detailed statistical analysis of noise in the HARPS data to improve the accuracy of his computer models. Then he will seek telescope time to look for more solar twins.

Source: The Ohio State University

Posted on by Nancy Atkinson

Stunning Gallery of Previously Unpublished Images from “Hubble’s Universe”

Distant star-forming region NGC 2467. Credit: NASA/ESA, Courtesy of “Hubble’s Universe.”

The new book, Hubble’s Universe: Greatest Discoveries and Latest Images includes several previously unpublished images from the Hubble Space Telescope, and author Terence Dickinson has graciously shared a few of those images with Universe Today. All images are courtesy of NASA, ESA, and “Hubble’s Universe.”

Find out how you can win a copy of “Hubble’s Universe” here.

Read our full review of this book here.

Above is NGC 2467, a nebula similar to the Orion Nebula, but 11 times farther away, in the southern constellation Puppis. A churning foam of strangely shaped dust clouds forms the backdrop to the newborn blue stars emerging from the gas and dust. Most of the radiation that is eating away at the cloud is being emitted by the single brilliant massive star near the center of the image. Its fierce radiation has cleared the surrounding area, and some of the next generation of stars are forming in the denser regions around the edge.

See more beautiful Hubble images below:

The star cluster NGC2060 contains a supernova that exploded about 10,000 years ago, blowing out gas surrounding the cluster.

A celestial shell of interstellar gas being shocked by the blast wave from a supernova, the Ornament Nebula was imaged by the Hubble Space Telescope and combined with X-ray images from NASA’s Chandra X-ray Observatory. The supernova – the explosive destruction of a star – occurred nearly 400 years ago and is 23 light-years across. The nebula is expanding at the rate of the Earth-to-Moon distance every minute.

Glorious Saturn. This exquisite Hubble portrait of Saturn shows the famous rings nearly edge-on. Some of the larger of Saturn’s more than five dozen moons are seen, including most prominently Titan, the largest, casting its inky shadow on the planet. The rings are composed of trillions of icy particles that probably originated with the collision of large moons aeons ago.

Egg Nebula. Concentric dust layers extend over one-tenth of a light-year from this dying sun. Running almost vertically through the image, a thick dust belt blocks the light of the central star. Twin beams of light radiate from the hidden star, illuminating the pitch-black dust like a flashlight shining in a smoky room. The nebula was photographed through polarizing filters to measure how the dust reflects light.

NGC6384. Star birth in this relatively quiescent middle-aged galaxy has declined. Noticeably missing are pinkish nebulas that are the sites of new star formation. Radiation and stellar winds from superhot, young blue stars have cleared out the remaining gas, shutting down any further production of stars. A bright concentration of starlight marks the galaxy’s center. Spiraling outward, dust lanes are silhouetted against the population of whitish middle-aged stars. Much younger blue stars trace the spiral arms.

ARP 273. A cosmic waltz between two galaxies is the result of gravitational tidal distortion from their close proximity to each other. Despite the fact that they are separated by tens of thousands of light-years, a tenuous tidal bridge of material stretches between the pair. The swath of blue across the top is the combined light from clusters of bright, hot, young blue stars, The smaller, nearly edge-on companion galaxy shows intense star formation at its nucleus, which was probably triggered by the interactions. More close encounters and an eventual merger are the likely future of this galaxy duo.

Stephan’s Quintet. One of the most famous examples of interacting galaxies is Stephan’s Quintet. Three of the galaxies have distorted shapes, elongated spiral arms and long, gaseous tidal tails containing myriad star clusters. The interactions among the galaxies have sparked a frenzy of star birth in the pair of intertwined galaxies just above center. This drama is being played out against a rich background of far more distant galaxies. The galaxy at lower left is in the foreground and not part of the grouping. It is 40 million light-years from Earth, while the remaining members of the quintet reside 290 million light-years away.

Galaxy Panorama. This is just 1 of 10 photos of that create a panorama of distant galaxies. Perhaps better than anything else in this book, these images open a window on the universe of galaxies – arguably, the Hubble Space Telescopes’ greatest gift so far. The image reveals a rich tapestry of thousands of galaxies stretching back through most of the universe’s history. The closest galaxies in the foreground emitted their observed light about a billion years ago. The most distant galaxies, a few of the very faint red specks, are seen as they appeared more than 13 billion years ago. The image combines a broad range of colors, from the ultraviolet, through visible light and into the near infrared. Such a detailed view of the deep universe in this combination of color, clarity, accuracy and depth has never before been assembled. The panorama shows galaxy shapes that, at each earlier epoch, appear increasingly chaotic as galaxies grew through accretion, collisions and mergers. The galaxies range from the mature spirals and elliptical in the foreground to smaller, fainter, irregularly shaped galaxies, most of which are farther away and, therefore, existed further back in time. The smaller galaxies are considered the building blocks of the large galaxies we see today.

Ants in space? Designated Menzel 3 (Mz 3), and called the Ant Nebula, this member of Hubble’s celestial menagerie resembles the head and thorax of a garden ant. The central star in Mz3 might have a closely orbiting companion that is exerting strong gravitational tidal forces which are shaping the outflowing gas. The very massive young star Eta Carinae shows a similar outflow pattern to that of Mz3.

The Hubble Space Telescope captured this image of the 86-kilometer-wide lunar impact crater Tycho. Because the Moon has been mapped in great detail by lunar orbiting spacecraft, there is relatively little call for Hubble’s intense gaze to be turned toward the Earth’s natural satellite.

This image was published earlier this year, and shows the dazzling globular star cluster Messier 9, or simply M9, contains hordes of stars swarming in a spherical cloud about 25,000 light-years from Earth. It is too faint to be seen with the naked eye, and when it was discovered by French astronomer Charles Messier in 1764, he observed it only as a faint smudge in his small telescope. He classified the cluster as a nebula (“cloud” in Latin). This Hubble Space Telescope portrait, the best image yet of M9, reveals 250,000 individual stars.

Posted on by Nancy Atkinson

Win a Copy of “Hubble’s Universe: Greatest Discoveries and Latest Images”

A beautiful new book, “Hubble’s Universe: Greatest Discoveries and Latest Images” provides the history of the iconic Hubble Space Telescope, explaining some of the greatest discoveries in astronomy. But it’s also a stunning picture book, including some stunning, previously unpublished images from HST. You can see a gallery of some of those images here, and read our full review of the book here.

Thanks to Firefly Books, Universe Today has a copy of this book to giveaway!

In order to be entered into the giveaway drawing, just put your email address into the box below before Monday, December 10, 2012. We’ll send you a confirmation email, so you’ll need to click that to be entered into the draw.

This giveaway is now closed.

We’re only going to use these email addresses for Universe Today giveaways/contests and announcements. We won’t be using them for any other purpose, and we definitely won’t be selling the addresses to anyone else. Once you’re on the giveaway notification list, you’ll be able to unsubscribe any time you like.

Posted on by Evan Gough

Book Review: “Hubble’s Universe: Greatest Discoveries and Latest Images”

The Hubble Space Telescope has been the subject of several books and articles, and certainly much more will be written about it in the future, as its status as the world’s most successful science experiment will guarantee that. And though breathtaking images are what hooks many people on the telescope, the Hubble was designed and built to do more than just take pretty pictures. The Hubble was planned and built to shed light on several different issues in astronomy and cosmology.

A new book, “Hubble’s Universe: Greatest Discoveries and Latest Images,” by Terence Dickinson, explains the important contributions Hubble has made in the areas of galactic evolution, dark matter and dark energy, and the expansion rate of the Universe. After a quick recounting of the Hubble’s launch and its well-documented initial problems, the author spells out Hubble’s top discoveries, including Hubble’s contribution to our understanding of the super-massive black holes at the centre of galaxies and our first looks at the atmospheres of extra-solar planets.

But the book is more than just clear and readable explanations of discoveries in astronomy. It’s a stunning picture book, equally at home in the living room as it is in the study. The array of pictures is simply awesome, and as Universe Today readers know, astronomy photos can suck anyone in.

See a gallery of new images from the book here.

Find out how you can win a copy of this book here.
The Hubble Space Telescope and the people that work with it are responsible for the images in this book, but it takes a special person to put a book like this together. The author, Terence Dickinson, is well-known in astronomy circles. If you don’t know who he is, you should. He’s the author of the top-selling star-gazing guide in the world, “NightWatch: A Practical Guide to Viewing the Universe,” as well as 14 other books. He’s won numerous awards for science-writing and for the popularization of science. An accomplished astro-photographer, one of his photos of the Moon has been on a U.S. postage stamp. He’s even been awarded the Order of Canada, the country’s second highest honour for merit. Terence Dickinson has a healthy passion for science, and has spent his life igniting that passion in others.

“Hubble’s Universe” is loaded with hundreds of photos of the kind we’ve become used to from Hubble, and some in the book have never before been published (see some of them here). The beauty of glowing gas clouds, the rich luminescence of filaments of gas and dust in distant nebulae, the beauty of the planets in our own solar system. This book is basically a feast of astrophotography.

While many books have been written about Hubble, this one will stack up against any of them. All Hubble books have stunning images in them, but what makes this one special is Dickinson’s ability for explanation. The writing is very accessible while still doing an outstanding job of handling some difficult subjects. If you’ve ever struggled with explanations of things like Dark Matter and Dark Energy, “Hubble’s Universe” will bring clarity, without any dumbing down of the subject matter.

You won’t regret buying this book, for yourself or perhaps for someone else. It’s destined to be a staple in libraries and astronomy collections. I’ll be bold and go a little further. “Hubble’s Universe” is destined to be a classic much like some of Dickinson’s other books.

Here’s a video of Dickinson discussing Hubble and his new book: