Bringing the Universe to Classrooms
and Homes Around the World!

Thursday, November 24, 2016

Pluto: Secrets Of The Heart

Far away in the semi-darkness of perpetual dusk, there is a frigid domain in our Solar System's outer fringes where our Sun can shine with only a frail, faint fire. Here, in this region of icy, dancing bodies, there resides a little world with a big heart. The dwarf planet Pluto, a denizen of the Kuiper Belt--the home of a swarming sea of frozen comet nuclei--has, ever since its discovery, captured the imagination and affection of humanity. Perhaps this is because it is so remote from Earth and the golden, melting heat of our brilliant Star. On July 14, 2015, NASA's New Horizons spacecraft, at last, reached this strange world, circled by an extraordinary quintet of moons, and began to uncover some of the very well-kept secrets of this icy world. In November 2016, planetary scientists announced that their new research reveals fascinating clues about Pluto, indicating that this frozen sphere at the outer limits of our Solar System is much more active than anyone had ever imagined--and may harbor a subsurface ocean beneath its secretive big heart.

Pluto's heart holds clues about an underwater ocean on the dwarf planet. Credit: NASA/JHUAPL/SwRI.
Pluto's heart holds clues about an underwater ocean on the dwarf planet. Credit: NASA/JHUAPL/SwRI.

Indeed, the presence of a liquid ocean situated deep beneath Pluto's frozen, icy surface is the best explanation for certain mysterious features unveiled by New Horizons, according to two new studies. The possibility that Pluto contains a subsurface ocean is not a new idea, but this research provides the most detailed investigation offered yet of its possible starring role in the evolution of certain important and unexplained features on Pluto--such as its low-lying, vast plain named Sputnik Planitia (Sputnik Planum).

Sputnik Planitia is a 1,000-kilometer-wide basin located within a big heart-shaped feature observed on Pluto's surface, and the new research suggests that it could be in its current location because the accumulation of ice made the ice dwarf planet that is Pluto rollover, thus forming cracks and tensions in the crust that suggest the possible presence of a liquid subsurface ocean.

Sputnik Planitia, which forms one side of Pluto's famous big heart-shaped feature observed in the first New Horizons images, is mysteriously well-aligned with Pluto's tidal axis. The probability that this is a mere chance occurrence is only about 5%. Hence, the alignment indicates that extra mass in that particular location interacted with tidal forces between Pluto and its largest moon Charon to reorient Pluto. This reorientation placed Sputnik Planitia directly opposite the side facing Charon. However, a deep basin seems unlikely to provide the additional mass necessary to result in that particular kind of reorientation.

"It's a big, elliptical hole in the ground, so the extra weight must be hiding somewhere beneath the surface. And an ocean is a natural way to get that," commented Dr. Francis Nimmo on November 16, 2016, University of California, Santa Cruz Press Release. Dr. Nimmo is a professor of Earth and Planetary Sciences at UC Santa Cruz and first author of a paper on the new findings published in the November 16, 2016 issue of the journal Nature. A second paper, appearing in the same issue of Nature, led by Mr. James Keane at the University of Arizona in Tucson, also proposes that this reorientation occurred and points to fractures on Pluto as evidence that this happened.

Dancing In The Dark

Where Pluto resides in our Solar System's deep freeze, our Sun appears in its murky sky as if it were just an especially large Star floating around in a strange sea of starlight. Mystery tickles the imagination, and Pluto has been an intriguing mystery for almost a century. Situated as it is, far from our Sun, Pluto remained unexplored until the New Horizons spacecraft successfully accomplished its historic closest approach to Pluto, at about 7,750 miles above its secretive surface--about the same distance that it is from Mumbai, India to New York City--making it the first space mission to finally explore this brave new world so far from Earth.

Pluto, Charon, and the other four relatively small moons belonging to the Pluto system reside in the frigid Kuiper Belt--a dimly lit and distant domain beyond the beautiful dark blue ice giant planet Neptune, the outermost of the eight major planets orbiting our Sun. In this previously unknown and unexplored region of our Solar System, a dazzling and icy host of tiny worldlets do a mesmerizing ballet around our distant Star. Pluto is a relatively large denizen of the Kuiper Belt, and it was originally classified as the ninth major planet from our Sun soon after its discovery in 1930. However, a better understanding of the true nature of the Kuiper Belt, and its heavy population of icy inhabitants forced astronomers to come to the realization that Pluto--a beloved, frozen, small "oddball"--is only one of the at least several large denizens of the Kuiper Belt. This realization prompted the International Astronomical Union (IAU) to formally define the term "planet" in 2006--and, as a result, poor Pluto was unceremoniously booted out of the pantheon of major planets, and re-classified as a mere dwarf planet--specifically, an ice dwarf due to its frozen nature. Nevertheless, Pluto still remains a small world of mystery and affection--and debate, since its re-classification as an ice dwarf is not universally accepted among astronomers.

The Pluto saga began when a young farmer's son from Kansas, the astronomer Clyde Tombaugh (1906-1997) had bestowed upon him the difficult task of hunting for the elusive and possibly non-existent Planet X. According to theory, Planet X is an elusive giant planet that keeps itself well-hidden from the prying eyes of curious astronomers, where it lurks in the cold twilight zone of our Solar System's outer limits. Tombaugh, who used a telescope in Flagstaff, Arizona, did indeed discover a faint tiny pinpoint of light. However, in one of the many instances of scientific serendipity, Tombaugh did not find what he was looking for. He found something else. What Tombaugh found was not Planet X--it was the little world now known as Pluto!

Like the other Kuiper Belt Objects (KBOs), Pluto is primarily made up of ice and rock. A small world, sporting only about 1/6 the mass of Earth's Moon and about 1/3 its volume, Pluto displays a highly inclined and eccentric orbit that takes it from 30 to 49 astronomical units (AU) from our Sun. One AU is equivalent to the average distance between our Earth and the Sun, which amounts to about 93,000,000 miles. Pluto periodically wanders inward towards our Star at a closer distance than Neptune. However, luck prevails, and orbital resonance with Neptune prevents the two worlds from blasting into each other with catastrophic results.

The Kuiper Belt is very far from us, orbiting our Sun well beyond the realm of the four majestic gaseous outer planets. The Belt itself extends from Neptune's orbit to approximately 50 AU. Neptune's average distance from our Sun is about 30.1 AU--its perihelion (when it closest to our Star) is 29.8 AU, while its aphelion (when it is furthest from our Star) is 30.4 AU

The ice dwarf Pluto was named for the Roman god of the underworld. Pluto's largest moon, Charon, was discovered in 1978 by the American astronomer James Christy. Some astronomers have suggested that Charon is really an enormous chunk of Pluto. According to this theory, Charon was once a part of Pluto that had been blasted off as a result of a violent collision between Pluto and some unidentified small world that was making a destructive rampage through the Kuiper Belt. The mess occurred when the doomed object met up with Pluto and crashed into it. Charon is the result of this ancient collision.

During most of the 20th century, astronomers thought that Pluto was a solitary small world, situated in the frigid outer limits of our Solar System. However, in 1992, the very first KBO (other than Pluto and Charon) was spotted, and astronomers came to the realization that Pluto is far from alone. The realization that Pluto is just another constituent of the madding crowd of icy KBOs, resulted in its removal from the pantheon of major planets, and its reclassification as an ice dwarf.

Launched on January 19, 2006, New Horizons successfully completed a five-month-long reconnaissance flyby of the Pluto system and is now en route to our Solar System's frozen fringes in order to study more distant small worlds inhabiting the Kuiper Belt, as part of its extended mission. New Horizons will help shed new light on the mysterious and very remote worldlets lingering in our Solar System's deep freeze. The Kuiper Belt is actually a lingering relic of our Solar System's ancient birth, and the population of frozen objects residing there has preserved in their frozen hearts some very important long-lost secrets of its past. New Horizons promises to uncover the amazing story about the origins of our Sun and its family of objects.

Pluto: Secrets Of The Heart

Like other large basins in our Solar System, Sputnik Planitia likely formed as the result of a catastrophic impact by a large crashing meteorite, which would have blasted away an enormous amount of Pluto's icy crust. If a subsurface ocean had been present, this would result in an upwelling of water pushing up against the weak, thin, and fragile shell of crustal ice. Because water is denser than ice, at equilibrium, that would still leave a rather deep basin with a slender crust of ice covering the upwelled mass of water.

"At that point, there is no extra mass at Sputnik Planitia. What happens then is the ice shell gets cold and strong, and the basin fills with nitrogen ice. That nitrogen represents the excess mass," Dr. Nimmo explained in the November 16, 2016, UC Santa Cruz Press Release.

Dr. Nimmo and his team also considered whether the extra mass could be provided by just a deep crater that is filled with nitrogen ice, in the absence of upwelling of a subsurface ocean. However, their calculations indicated that this particular scenario would demand an unrealistically deep layer of nitrogen--more than 25 miles thick! The astronomers found that a nitrogen layer approximately 4 miles thick blanketing a subsurface ocean provides sufficient mass to form a "positive gravity anomaly."

"We tried to think of other ways to get a positive gravity anomaly, and none of them looks as likely as a subsurface ocean," Dr. Nimmo continued to explain.

Dr. Douglas Hamilton, who is of the University of Maryland in College Park, and a co-author of the study, formulated the reorientation scenario, while Dr. Nimmo came up with the subsurface ocean hypothesis. The subsurface ocean hypothesis proposes a scenario that is similar to what occurred on Earth's Moon, where positive gravity anomalies have been precisely measured for several large impact basins. However, instead of a subsurface ocean, the dense mantle material buried beneath the lunar crust pushed up against the thin crust of the impact basins. Lava flows then gushed up and flooded the basins, thus providing the extra mass. Icy Pluto, however, experienced this sort of scenario with a different ingredient. Instead of lava, the basin on Pluto filled with frozen nitrogen.

"There's plenty of nitrogen in Pluto's atmosphere, and either it preferentially freezes out in this low basin, or it freezes out in the high areas surrounding the basin and flows down as glaciers," Dr. Nimmo noted in the UC Santa Cruz Press Release. Indeed, the images obtained from New Horizons reveal what appear to be nitrogen glaciers flowing out of mountainous terrain surrounding Sputnik Planitia.

In reference to a subsurface ocean, Dr. Nimmo added that he suspects it is composed mostly of water with some unidentified antifreeze added to the mixture--which would most likely be ammonia. The slow refreezing of the ocean would cause stress on the icy shell. This stress would cause fractures that are consistent with features seen in the New Horizons images.

Pluto is not alone where it resides in the Kuiper Belt. There are other large kindred bodies dwelling in the Kuiper Belt that resemble Pluto both in size and density, and Dr. Nimmo noted that these other objects likely also contain subsurface oceans. "When we look at these other objects, they may be equally interesting, not just frozen snowballs," he added.

In a second study also appearing in the November 17, 2016 issue of the journal Nature, Dr Isamu Matsuyama and his doctoral student Mr. James Keane, of the University of Arizona's Lunar and Planetary Laboratory cite evidence of frozen nitrogen pileup that threw all of Pluto out of kilter, in a process termed true polar wander. This has been compared to a spinning top with a wad of gum stuck to it.

"There are two ways to change the spin of a planet. The first--and the one we're all most familiar with--is a change in the planet's obliquity, where the spin axis of the planet is reorienting with respect to the rest of the Solar System. The second way is through true polar wander, where the spin axis remains fixed with respect to the rest of the Solar System, but the planet reorients beneath it," Mr. Keane explained in a November 16, 2016, University of Arizona Press Release.

Planets usually spin in a way that minimizes energy. This means that planets tend to reorient in order to move extra mass closer to the equator while moving any mass deficit closer to the pole. In order to visualize this, if a large volcano were to grow in San Francisco, our planet would reorient to move San Francisco to the Earth's equator.

But, in order to visualize how polar wander works on Pluto, it first needs to be realized that unlike Earth, whose spin axis is only slightly tilted so that the regions around the equator are gifted with most of the sunlight, Pluto is more like a "spinning top that is lying on its side." This means that the dwarf planet's poles receive most of the sunlight. Depending on the season, it is either one or the other. Furthermore, Pluto's equatorial regions remain extremely frigid all the time.

Pluto is almost 40 times farther from our Star than Earth. This means that it takes the distant icy little world 248 Earth-years to complete one Pluto-year. At Pluto's lower latitudes close to its equator, temperatures are bitterly cold at minus 400 degrees Fahrenheit. At this almost unimaginably frigid temperature, nitrogen turns into a frozen solid.

Nitrogen and other exotic gases, over the span of a Pluto-year, condense on its dark side that is kept in perpetual shadow. Eventually, as Pluto circles around our Sun, our Star's melting heat causes the nitrogen and other substances to become gaseous again and re-condense on the other side of the little world. This results in seasonal "snowfall" on Sputnik Planitia.

"Each time Pluto goes around the Sun, a bit of nitrogen accumulates in the heart. And once enough ice has piled up, maybe a hundred meters thick, it starts to overwhelm the planet's shape, which dictates the planet's orientation. And if you have an excess of mass in one spot on the planet, it wants to go to the equator. Eventually, over millions of years, it will drag the whole planet over," Mr. Keane said in the November 16, 2016, University of Arizona Press Release.

"I think this idea of a whole planet being dragged around by the cycling of volatiles is not something many people had really thought about," Mr. Keane added.

The two University of Arizona researches used observations made during New Horizons' flyby and combined them with supercomputer models that enabled them to take a surface feature such as Sputnik Planitia, shift it around on Pluto's surface and observe how it alters the ice dwarf's spin axis.

As a result, in the computer models, the geographic location of Sputnik Planitia wound up intriguingly close to where one would expect it to be.

If Sputnik Planitia were a large positive mass anomaly--possibly as a result of loading of nitrogen ice--it would migrate to Pluto's tidal axis with respect to Charon, as it approaches a minimum energy state. Therefore, the massive building up of ice would wind up where it would cause the least wobble in Pluto's spin axis.

In addition, the supercomputer simulations and calculations predicted that the accumulation of frozen volatiles in Pluto's big heart would result in cracks and faults in the planet's surface in precisely the same locations where New Horizons spotted them.

The presence of tectonic faults on Pluto suggests the existence of a subsurface ocean at some point in Pluto's history, Mr. Keane noted. He added that "Before New Horizons, people usually only thought of volatiles in terms of a thin frost veneer, a surface effect that might change the color, or affect local or regional geology. That the movement of volatiles and shifting ice around a planet could have a dramatic, planet-moving effect is not something anyone would have predicted."

Judith E Braffman-Miller

Article Source: Pluto: Secrets Of The Heart
Read More

Sunday, November 20, 2016

Deep Sky Image Database - M81 and M82 Galaxies

As the crew of Insight Observatory works on getting the Astronomical Telescope for Educational Outreach (ATEO) ready for first light in 2017, it is now time to start compiling databases of deep-sky images as well as designing a curriculum for teaching deep-sky imaging using remote robotic telescopes. As the Insight Observatory deep-sky image database accumulates, it will be available for educational purposes as well as material for software publications. 

Seeing that the ATEO will be hosted in the mountains of New Mexico, we thought it would be a good idea to start the deep-sky image database using the remote robotic telescopes on the iTelescope network hosted at their Mayhill, New Mexico facility. Their dark-sky site is very comparable to the site the ATEO will be hosted at the SkyPi Remote Observatory located in Pie Town, New Mexico.

M81 (left) and M82 (right) imaged on T20 by Insight Observatory
M81 (left) and M82 (right) imaged on T20 by Insight Observatory.

On the morning of November 10, 2016, we compiled raw data of the galaxy pair of M81 and M82 located in the constellation of Ursa Major. The two objects were nearly perfectly placed at the meridian when the images were acquired. The telescope system that was used is known as T20 on the iTelescope network. The instrument is a very wide-field telescope, typically used for wide-field RGB / Narrowband Imaging, but also carries a Photometric V filter.
T20 is a great platform for wide-angle imaging and can also do valuable scientific research with its photometric V filter. This small Takahashi FSQ could also serve as a tool for scanning for asteroids and working on variable stars. Nothing can match its very wide field portraits and its performance on the sky's larger extended objects such as large nebula, clusters, bright comets and even catching fast-moving Near-Earth Objects.

T20 - iTelescope.net
T20 - iTelescope.net.

After the raw data was taken on T20, it was then stacked and processed using a CCD imaging software package called PixInsight. The images of M81 and M82 that were stacked consisted of five Luminance (clear) images at 300 seconds, four Red filtered images at 180 seconds, four Green filtered images at 180 seconds and four Blue filtered images at 180 seconds. After the images were processed in PixInsight, the final image was then post-processed using Photoshop CS6.

A few Facts about M81 and M82:
  • Messier 81 was first discovered by Johann Elert Bode on December 31, 1774. Consequently, the galaxy is sometimes referred to as "Bode's Galaxy". In 1779, Pierre M├ęchain and Charles Messier reidentified Bode's object, which was subsequently listed in the Messier Catalogue.

  • Only one supernova has been detected in Messier 81. The supernova, named SN 1993J, was discovered on 28 March 1993 by F. Garcia in Spain. At the time, it was the second brightest supernova observed in the 20th century.

  • Messier 81 is located approximately 10° northwest of Alpha Ursae Majoris along with several other galaxies in the Messier 81 Group. Messier 81 and Messier 82 can both be viewed easily using binoculars and small telescopes. The two objects are generally not observable to the unaided eye, although highly experienced amateur astronomers may be able to see Messier 81 under exceptional observing conditions with a very dark sky. Telescopes with apertures of 8 inches (20 cm) or larger are needed to distinguish structures in the galaxy. Its far northern declination makes it generally visible for observers in the northern hemisphere. It is not visible to most observers in the southern hemisphere, except those in a narrow latitude range immediately south of the equator.

  • Messier 82 (also known as NGC 3034, Cigar Galaxy or M82) is a starburst galaxy about 12 million light-years away in the constellation Ursa Major. A member of the M81 Group, it is about five times more luminous than the whole Milky Way and has a center one hundred times more luminous than our galaxy's center. The starburst activity is thought to have been triggered by interaction with neighboring galaxy M81. As the closest starburst galaxy to our own, M82 is the prototypical example of this galaxy type. SN 2014J, a Type Ia supernova, was discovered in the galaxy on January 21, 2014.  In 2014, in studying M82, scientists discovered the brightest pulsar yet known, designated M82 X-2.

  • Messier 82 was previously believed to be an irregular galaxy. In 2005, however, two symmetric spiral arms were discovered in near-infrared (NIR) images of M82. The arms were detected by subtracting an axisymmetric exponential disk from the NIR images. Even though the arms were detected in NIR images, they are bluer than the disk. The arms were previously missed due to M82's high disk surface brightness, our nearly edge-on view of this galaxy (~80°), and obscuration by a complex network of dusty filaments in its optical images. These arms emanate from the ends of the NIR bar and can be followed for the length of 3 disc scales. Assuming that the northern part of M82 is nearer to us, as most of the literature does, the observed sense of rotation implies trailing arms.

Sources: Wikipedia M81 and M82
Read More

Monday, November 7, 2016

The Great Attractor

The large galaxy in this, artist's, computer-generated image, is the Milky Way galaxy.

All of the other galaxies shown, are either being swallowed by it or are hidden by it. They were revealed using the CSIRO's Parkes radio telescope by non-visible radio imaging, by the University of Western Australia's ICRAR (International Center for Radio Astronomy Research) program and lie in a region of space known to astronomers, as, the "Zone of Avoidance" (well, yeah, for obvious reasons!).

Artist's computer-generated image of the Milky Way Galaxy
Artist's computer-generated image of the Milky Way Galaxy.

The Milky Way galaxy, itself, was not formed by standard galaxy formation theory; rather, it is an aggregation of interacting (no one is yet sure how many), formerly individual galaxies.

Dale Alan Bryant
Senior Contributing Science Writer
Read More

Saturday, November 5, 2016

ETI Signals Would Look Like This

Well, the answer to the age-old question, "Are We Alone?" - might, very well, soon be answered. And if the current, apparent, scenario is confirmed by two other teams of astronomers, that answer will be: "No. We Are Not." - for better or for worse.

Ermanno F. Borra and F. Trottier, two astronomers from Quebec's, Laval University have published a paper in the Astronomical Journal, announcing that they have received signals, from an area of space which contains 234 stars of near-Solar spectral type, that, after having ruled out all of the 3 other possible causes, exactly correspond to an ETI communications hypothesis published prior to their most recent submission.

Graph from the Astronomical Journal of December 2012.
Graph from the Astronomical Journal of December 2012.

Astronomers, generally, have an idea of what would likely be expected in an intentional beacon signal, broadcast by an extraterrestrial civilization to the stars. It might be a signal generated in the radio portion of the electromagnetic spectrum, or, the more recently favored optical window near to, or including, the visible light band. A signal generated from the latter would be visually detectable by humans, and interestingly, I think, by any ET species which had evolved on a planet of a star in the F-G-M spectral range. Our star, of course, is type G2V yellow dwarf star, "Sol", or, the Sun. They would want to direct their signals at stars similar to their parent star, for this reason.

Borra and Trottier's paper shows signals, embedded in the SDSS (Sloan Digital Sky Survey), spectra which conform to these expectations, in the form of nano-bursts, or, pulses, which include varied and repeating time intervals in between, which were outlined in Borra's previous work and which are, "so unusual that it can only be artificial. A most unusual signal would be made of a spectral modulation of the spectrum that is so unusual that it warrants more observations, which will then reveal that it is artificial." Borra and Trottier make it clear that the signals confirm "exactly" as outlined in the paper of 16 OCT 2016 to the Astronomical Journal. Current technology allows humans, to send such signals out to at least 1,000 light-years, without any significant degradation, using a spectroscope and a 10-meter optical telescope, at an energetic 15,000 photons per 3 nanoseconds.

Any signal by an ETI located at a distance of 1,000 light-years from Earth, means that the signal had to have been sent at least 1,000 years ago. Considering the current level of human technology, and ETI technology, which was the rough equivalent of humans 1,000 years ago must be wildly advanced by present-day standards.

The commonality here is the EMS. It's available to anyone, anywhere, and obeys the same physical laws bestowed upon Earthlings. It would be the universally agreed-upon method of trying to get the attention of any other sentient beings that may exist in the galaxy.

The ETI hypothesis as a source for the signals is the only hypothesis that was not ruled out by Borra and Trottier but it needs confirmation by at least two other teams, trying to find natural reasons for the signals.

So - the answer to that age-old question - is still ways off, for now.

Dale Alan Bryant
Senior Contributing Science Writer
Read More