Advanced Civilizations Could Build a Galactic Internet with Planetary Transits

Advanced Civilizations Could Build a Galactic Internet with Planetary Transits:

Decades after Enrico Fermi’s uttered his famous words – “Where is everybody?” – the Paradox that bears his name still haunts us. Despite repeated attempts to locate radio signals coming from space and our ongoing efforts to find visible indications of alien civilizations in distant star systems, the search extra-terrestrial intelligence (SETI) has yet to produce anything substantive.

But as history has taught us, failure has a way of stimulated new and interesting ideas. For example, in a recently-published paper, Dr. Duncan H. Forgan of St. Andrews University proposed that extra-terrestrial civilizations could be communicating with each other by creating artificial transits of their respective stars. This sort of “galactic internet” could be how advanced species are attempting to signal us right now.

Forgan’s paper, “Exoplanet Transits as the Foundation of an Interstellar Communications Network“, was recently published online. In addition to being a research fellow at the School of Physics and Astronomy and the Scottish Universities Physics Alliance at the University of St Andrews (Scotland’s oldest academic institution), he is also a member of the St Andrews Center for Exoplanet Science.



The paper begins by addressing the two fundamental problems associated with interstellar communication – timing and energy consumption. When it comes to things like radio transmissions, the amount of energy that would be needed to transmit a coherent message over interstellar distances is prohibitive. Optical communications (i.e. lasers) need less energy, but spotting them would require incredibly precise timing.

As such, neither method would be particularly reliable for establishing an interstellar communications system. Taking a cue from humanity’s recent exoplanet-hunting efforts, Forgan argues that a method where transits in front of a stars are a basis of communication would solve both problems. The reason for this is largely due to the fact that the Transit Method is currently one of the most popular and reliable ways of detecting exoplanets.

By monitoring a star for periodic dips in brightness, which are caused by a planet or object passing between the observer and the star, astronomers are able to determine if the star has a system of planets. The method is also useful for determining the presence and composition of atmospheres around exoplanet. As Forgan indicates in the paper, this method could therefore be used as a means of signalling other civilizations:

“An ETI ’A’ can communicate with ETI ’B’ if B is observing transiting planets in A’s star system, either by building structures to produce artificial transits observable by B, or by emitting signals at B during transit, at significantly lower energy consumption than typical electromagnetic transmission schemes.”

The Milky Way’s habitable zone. Credit: NASA/Caltech

In short, Forgan argued that within the Galactic Habitable Zone (GHZ) – the region of the Milky Way in which life is most likely develop – species may find that the best way to communicate with each other is by creating artificial megastructures to transit their star. These transits, which other civilizations will be looking for (looking for exoplanets, like us!) will lead them to conclude that an advanced civilization exists in another star system.

He even offers estimates on how often such transmissions could be made. As he put it:

“A message with a path of 20 kpc (the diameter of the GHZ) has a total travel time at lightspeed of just under 0.06 Myr. If we assume a relatively short timescale on which both ETIs remain in the transit zone of 100,000 years (which is approaching the timescale on which both secular evolution of planetary orbits and the star’s orbit become important), then a total of 30 exchanges can be made. This of course does not forbid a continuing conversation by other means.”

If this is starting to sound familiar, that’s probably because this is precisely what some theorists say is happening around KIC 8462852 (aka. Tabby’s Star). Back in May of 2015, astronomers noticed that the star had been undergoing considerable drops in brightness in the past few years. This behavior confounded natural explanations, which led some to argue that it could be the result of an alien megastructure passing in front of the star.

According to Forgan, such a possibility is hardly far-fetched, and would actually be a relatively economical means of communicating with other advanced species. Using graph theory, he estimated that civilizations within the GHZ could establish a fully connected network within a million years, where all civilizations are in communication with each other (either directly or via intermediate civilizations).

Artist’s concept of KIC 8462852, which has experienced unusual changes in luminosity over the past few years. Credit: NASA, JPL-Caltech

Not only would this network require far less energy to transmit data, but the range of any signal would be limited only by the extent of these civilizations themselves. Beyond saving energy and having greater range (assuming intermediate civilizations are able to pass messages along), this method presents other advantages. For one, a high level of technological sophistication would be required to pick up the transit of exoplanets.

In other words, civilizations would need to reach a certain level of development before they could hope to join the network. This would prevent any unfortunate “cultural contamination”, where less-advanced civilizations learned about the existence of aliens before they were ready. Second, once acquired, the transit network signals would be extremely predictable, with each transmission corresponding to a known orbital period.

That being said, there are some downsides that Forgan was sure to acknowledge. For starters, the periodicity of these signals would be a double edged sword, as signals could only be sent if and when the receiver begins to see the transit. And while a megastructure could be moved to alter the transit period, this poses problems in terms of synchronizing transmission and reception.

Addressing the limitations of the analysis, Forgan also acknowledges that the study relies on fixed stellar orbits. The orbits of stars are known to change over time, with stars passing in and out of the GHZ regularly on cosmic timescales. In addition, there is also the issue of how such a network would differ between denser regions in the galaxy – i.e. globular clusters – and areas populated by field stars. Binary stars are also not considered in the analysis.

Could alien megastructures be the key to interstellar communications? Credit: Kevin Gill

In addition, planetary orbits are known to change over time, due to perturbations caused by neighboring planets, companion stars, or close encounters with passing stars. As a result, the visibility of transiting planets can vary even more over cosmic timescales. Last, but not least, the study assumes that civilizations have a natural lifespan of about a billion years, which is not based in any concrete knowledge.

However, these considerations do not alter the overall conclusions reached by Forgan. Making allowances for the dynamic nature of stars and planets, and assuming that civilizations exist for only 1 million years, Forgan maintains that the creation of an interstellar network of this kind is still mathematically feasible. On top of that, an artificial object could continue to signal other species long after a civilization has gone extinct.

Addressing the Fermi Paradox, Forgan concludes that this sort of communication would take a long time to detect.As he summarizes in the paper (bold added for emphasis):

“I find that at any instant, only a few civilizations are correctly aligned to communicate via transits. However, we should expect the true network to be cumulative, where a “handshake” connection at any time guarantees connection in the future via e.g. electromagnetic signals. In all our simulations, the cumulative network connects all civilizations together in a complete network. If civilizations share knowledge of their network connections, the network can be fully complete on timescales of order a hundred thousand years. Once established, this network can connect any two civilizations either directly, or via intermediate civilizations, with a path much less than the dimensions of the GHZ.”

In short, the reason we haven’t heard from or found evidence of ETI could be an issue of timing. Or, it could be that we simply didn’t realize we were being communicated with. While such an analysis is subject to guess-work and perhaps a few anthropocentric assumptions, it is certainly fascinating because of the possibilities it presents. It also offers us a potential tool in the search for extra-terrestrial intelligence (SETI), one which we are already engaged in.

So many stars, so many planets. So many opportunities for connection! Credit: ESO/M. Kornmesser

And last, but not least, it offers a potential resolution to the Fermi Paradox, one which we may have already stumbled upon and are simply not yet aware of. For all we know, the observed drops in brightness coming from Tabby’s Star are evidence of an alien civilization (possibly an extinct one). Of course, the key word here is “perhaps”, as no evidence exists that could confirm this.

The possibilities raised by this paper are also exciting given that exoplanet-hunting is expected to ramp up in the coming years. With the deployment of next-generations missions like the James Webb Space Telescope and the Transiting Exoplanet Survey Satellite (TESS), we expect to be learning a great deal more about star systems both near and far.

Will we find more examples of unexplained drops in brightness? Who knows? The point is, if we do (and can’t find a natural cause for them) we have a possible explanation. Maybe its neighbors inviting us to “log on”!

Further Reading: arXiv

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Earth-Sized Planet Takes Just Four Hours to Orbit its Star

Earth-Sized Planet Takes Just Four Hours to Orbit its Star:

The Kepler space observatory has made some interesting finds since it began its mission back in March of 2009. Even after the mission suffered the loss of two reaction wheels, it has continued to make discoveries as part of its K2 mission. All told, the Kepler and K2 missions have detected a total of 5,106 planetary candidates, and confirmed the existence of 2,493 planets.

One of the latest finds made using Kepler is EPIC 228813918 b, a terrestrial (i.e. rocky) planet that orbits a red dwarf star some 264 to 355 light years from Earth. This discovery raises some interesting questions, as it is the second time that a planet with an ultra-short orbital period – it completes a single orbit in just 4 hours and 20 minutes – has been found orbiting a red dwarf star.

The study, which was recently published online, was conducted by an international team of scientists who hail from institutions ranging from the Massachusetts Institute of Technology (MIT), the California Institute of Technology (Caltech), the Tokyo Institute of Technology, and the Institute of Astrophysics of the Canary Islands (IAC) to observatories and universities from all around the world.

NASA’s Kepler space telescope was the first agency mission capable of detecting Earth-size planets. Credit: NASA/Wendy Stenzel

As the team indicated in their study, the detection of this exoplanet was made thanks to data collected by numerous instruments. This included spectrographic data from the 8.2-m Subaru telescope and the 10-m Keck I telescope (both of which are located on Mauna Kea, Hawaii) and the Nordic Optical Telescope (NOT) at the Roque de los Muchachos Observatory in La Palma, Spain.

This was combined with speckle imaging from the 3.5-m WIYN telescope at the Kitt Peak National Observatory in Arizona, photometry from the NASA’s K2 mission, and archival information of the star that goes back over 60 years. After eliminating any other possible explanations – such as an eclipsing binary (EB) – they not only confirmed the orbital period of the planet, but also provided constrains on its mass and size. As they wrote:

“Using a combination of archival images, AO imaging, RV measurements, and light curve modelling, we show that no plausible eclipsing binary scenario can explain the K2 light curve, and thus confirm the planetary nature of the system. The planet, whose radius we determine to be 0.89 ± 0.09 [Earth radii], and which must have a iron mass fraction greater than 0.45, orbits a star of mass 0.463 ± 0.052 M and radius 0.442 ± 0.044 R.”

This orbital period – four hours and 20 minutes – is the second shortest of any exoplanet discovered to date, being just 4 minutes longer than that of KOI 1843.03, which also orbits an M-type (red dwarf) star. It is also the latest in a long line of recently-discovered exoplanets that complete a single orbit of their stars in less than a day. Planets belonging to this group are known as ultra-short-period (USP) planets, of which Kepler has found a total of 106.

Archival images of the star EPIC 228813918, demonstrating its proper motion over nearly six decades – from (i) 1954, (ii) 1992, and (iii) 2012. Credit: Smith et al.

However, what is perhaps most surprising about this find is just how massive it is. Though they didn’t measure the planet’s mass directly, their constraints indicate that the exoplanet has an upper mass limit of 0.7 Jupiter masses – which works out to over 222 Earth masses. And yet, the planet manages to pack this gas giant-like mass into a radius that is 0.80 to 0.98 times that of Earth.

The reason for this, they indicate, has to do with the planet’s apparent composition, which is particularly metal-rich:

“This leads to a constraint on the composition, assuming an iron core and a silicate mantle. We determine the minimum iron mass fraction to be 0.525 ± 0.075 (cf. 0.7 for KOI 1843.03), which is greater than that of Earth, Venus or Mars, but smaller than that of Mercury (approximately 0.38, 0.35, 0.26, and 0.68, respectively; Reynolds & Summers 1969).”

Ultimately, the discovery of this planet is significant for a number of reasons. On the one hand, the team indicated that the constraints their study placed on the planet’s composition could prove useful in helping to understand how our own Solar planets came to be.

“Discovering and characterizing extreme systems, such as USP planets like EPIC 228813918 b, is important as they offer constraints for planet formation theories,” they conclude. “Furthermore, they allow us to begin to constrain their interior structure – and potentially that of longer-period planets too, if they are shown to be a single population of objects.”

An artist’s depiction of extra-solar planets transiting an M-type (red dwarf) star. Credit: NASA/ESA/STScl

On the other hand, the study raises some interesting questions about USP planets – for instance, why the two shortest-period planets were both found orbiting red dwarf stars. A possible explanations, they claim, is that short-period planets could have longer lifetimes around M-dwarfs since their orbital decay would likely be much slower. However, they are quick to caution against making any tentative conclusions before more research is conducted.

In the future, the team hopes to conduct measurements of the planet’s mass using the radial velocity method. This would likely involve a next-generation high-resolution spectrograph, like the Infrared Doppler (IFD) instrument or the CARMENES instrument – which are currently being built for the Subaru Telescope and the Calar Alto Observatory (respectively) to assist in the hunt for exoplanets around red dwarf stars.

One thing is clear though. This latest find is just another indication that red dwarf stars are where exoplanet-hunters will need to be focusing their efforts in the coming years and decades. These low mass, ultra-cool and low-luminosity stars are where some of the most interesting and extreme finds are being made. And what we stand to learn by studying them promises to be most profound!

Further Reading: arXiv

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IC 1396: Emission Nebula in Cepheus

C 1396: Emission Nebula in Cepheus:

Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

2017 July 20

IC 1396: Emission Nebula in Cepheus

Image Credit & Copyright: César Blanco González


Explanation: Stunning emission nebula IC 1396 mixes glowing cosmic gas and dark dust clouds in the high and far off constellation of Cepheus. Energized by the bright central star seen here, this star forming region sprawls across hundreds of light-years, spanning over three degrees on the sky while nearly 3,000 light-years from planet Earth. Among the intriguing dark shapes within IC 1396, the winding Elephant's Trunk nebula lies just below center. Stars could still be forming inside the dark shapes by gravitational collapse. But as the denser clouds are eroded away by powerful stellar winds and radiation, any forming stars will ultimately be cutoff from the reservoir of star stuff. The gorgeous color view is a composition of image data from narrowband filters, mapping emission from the nebula's atomic oxygen, hydrogen, and sulfur into blue, green, and red hues.

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July 14 Solar Flare and a Coronal Mass Ejection

July 14 Solar Flare and a Coronal Mass Ejection: A medium-sized (M2) solar flare and a coronal mass ejection erupted from the same, large active region of the sun on July 14, 2017. The flare lasted almost two hours, quite a long duration. The coils arcing over this active region are particles spiraling along magnetic field lines.

Original enclosures:

Strange Radio Signals Detected from a Nearby Star

Strange Radio Signals Detected from a Nearby Star:

Astronomers have been listening to radio waves from space for decades. In addition to being a proven means of studying stars, galaxies, quasars and other celestial objects, radio astronomy is one of the main ways in which scientists have searched for signs of extra-terrestrial intelligence (ETI). And while nothing definitive has been found to date, there have been a number of incidents that have raised hopes of finding an “alien signal”.

In the most recent case, scientists from the Arecido Observatory recently announced the detection of a strange radio signal coming from Ross 128 – a red dwarf star system located just 11 light-years from Earth. As always, this has fueled speculation that the signal could be evidence of an extra-terrestrial civilization, while the scientific community has urged the public not to get their hopes up.

The discovery was part of a campaign being conducted by Abel Méndez – the director of the Planetary Habitability Laboratory (PHL) in Peurto Rico – and Jorge Zuluaga of the Faculty of Exact and Natural Sciences at the University of Antioquia, Colombia. Inspired by the recent discoveries around Proxima Centauri and TRAPPIST-1, the GJ 436 campaign relied on data from Arecibo Observatory to look for signs of exoplanets around nearby red dwarf stars.

Arecibo Observatory, the world’s biggest single dish radio telescope, was and is still being used to image comet 45P/H-M-P. Courtesy of the NAIC – Arecibo Observatory, a facility of the NSF

In the course of looking at data from stars systems like Gliese 436, Ross 128, Wolf 359, HD 95735, BD +202465, V* RY Sex, and K2-18 – which was gathered between April and May of 2017 – they noticed something rather interesting. Basically, the data indicated that an unexplained radio signal was coming from Ross 128. As Dr. Abel Mendez described in a blog post on the PHL website:

“Two weeks after these observations, we realized that there were some very peculiar signals in the 10-minute dynamic spectrum that we obtained from Ross 128 (GJ 447), observed May 12 at 8:53 PM AST (2017/05/13 00:53:55 UTC). The signals consisted of broadband quasi-periodic non-polarized pulses with very strong dispersion-like features. We believe that the signals are not local radio frequency interferences (RFI) since they are unique to Ross 128 and observations of other stars immediately before and after did not show anything similar.”

After first noticing this signal on Saturday, May 13th at 8:53 p.m., scientists from the Arecibo Observatory and astronomers from the Search for Extra-Terrestrial Intelligence (SETI) Institute teamed up to conduct a follow-up study of the star. This was performed on Sunday, July 16th, using SETI’s Allen Telescope Array and the National Radio Astronomy Observatory‘s (NRAO) Green Bank Telescope.

They also conducted observations of Barnard’s star on that same day to see if they could note similar behavior coming from this star system. This was done in collaboration with the Red Dots project, a European Southern Observatory (ESO) campaign that is also committed to finding exoplanets around red dwarf stars. This program is the successor to the ESO’s Pale Red Dot campaign, which was responsible for discovering Proxima b last summer.

Images of the star systems examined by the GJ 436 Campaign. Credit: PHL/Abel Méndez 

As of Monday night (July 17th), Méndez updated his PHL blog post to announced that with the help of SETI Berkeley with the Green Bank Telescope, that they had successfully observed Ross 128 for the second time. The data from these observatories is currently being collected and processed, and the results are expected to be announced by the end of the week.

In the meantime, scientists have come up with several possible explanations for what might be causing the signal. As Méndez indicated, there are three major possibilities that he and his colleagues are considering:

“[T]hey could be (1) emissions from Ross 128 similar to Type II solar flares, (2) emissions from another object in the field of view of Ross 128, or just (3) burst from a high orbit satellite since low orbit satellites are quick to move out of the field of view. The signals are probably too dim for other radio telescopes in the world and FAST is currently under calibration.”

Unfortunately, each of these possibilities have their own drawbacks. In the case of a Type II solar flare, these are known to occur at much lower frequencies, and the dispersion of this signal appears to be inconsistent with this kind of activity. In the case of it possibly coming from another object, no objects (planets or satellites) have been detected within Ross 128’s field of view to date, thus making this unlikely as well.

The stars currently being examined as part of the GJ 436 campaign. Credit: PHL/Abel Méndez

Hence, the team has something of a mystery on their hands, and hopes that further observations will allow them to place further constrains on what the cause of the signal could be. “[W]e might clarify soon the nature of its radio emissions, but there are no guarantees,” wrote Méndez. “Results from our observations will be presented later that week. I have a Piña Colada ready to celebrate if the signals result to be astronomical in nature.”

And just to be fair, Méndez also addressed the possibility that the signal could be artificial in nature – i.e. evidence of an alien civilization. “In case you are wondering,” he wrote, “the recurrent aliens hypothesis is at the bottom of many other better explanations.” Sorry, alien-hunters. Like the rest of us, you’ll just have to wait and see what can be made of this signal.

Further Reading: AFP, PHL

The post Strange Radio Signals Detected from a Nearby Star appeared first on Universe Today.

Ancient Impacts Shaped the Structure of the Milky Way

Ancient Impacts Shaped the Structure of the Milky Way:

Understanding how the Universe came to be is one of the greater challenges of being an astrophysicist. Given the observable Universe’s sheer size (46.6 billion light years) and staggering age (13.8 billion years), this is no easy task. Nevertheless, ongoing observations, calculations and computer simulations have allowed astrophysicists to learn a great deal about how galaxies and larger structures have changed over time.

For example, a recent study by a team from the University of Kentucky (UK) has challenged previously-held notions about how our galaxy has evolved to become what we see today. Based on observations made of the Milky Way’s stellar disk, which was previously thought to be smooth, the team found evidence of asymmetric ripples. This indicates that in the past, our galaxy may have been shaped by ancient impacts.

The study, titled “Milky Way Tomography with K and M Dwarf Stars: The Vertical Structure of the Galactic Disk“, recently appeared in the The Astrophysical Journal. Led by Deborah Ferguson, a 2016 UK graduate, the team consisted of Professor Susan Gardner – from the UK College of Arts and Sciences – and Brian Yanny, an astrophysicist from the Fermilab Center for Particle Astrophysics (FCPA).



This study evolved from Ferguson’s senior thesis, which was overseen by Prof. Gardner. At the time, Ferguson sought to expand on previous research by Gardner and Yanny, which also sought to understand the presence of ripples in our galaxy’s stellar disk. For the sake of this new study, the team relied on data obtained by the Sloan Digital Sky Survey‘s (SDSS) 2.5m Telescope, located at the Apache Point Observatory in New Mexico.

This allowed the team to examine the spatial distribution of 3.6 million stars in the Milky Way Galaxy, from which they confirmed the presence of asymmetric ripples. These, they claim, can be interpreted as evidence of the Milky Way’s ancient impacts – in other words, that these ripples resulted from our galaxy coming into contact with other galaxies in the past.

These could include a merger between the Milky Way and the Sagittarius dwarf galaxy roughly 0.85 billion years ago, as well as our galaxy’s current merger with the Canis Major dwarf galaxy. As Prof. Gardner explained in a recent UK press release:

“These impacts are thought to have been the ‘architects’ of the Milky Way’s central bar and spiral arms. Just as the ripples on the surface of a smooth lake suggest the passing of a distant speed boat, we search for departures from the symmetries we would expect in the distributions of the stars to find evidence of ancient impacts. We have found extensive evidence for the breaking of all these symmetries and thus build the case for the role of ancient impacts in forming the structure of our Milky Way.”

Illustration showing a stage in the predicted merger between our Milky Way galaxy and the neighboring Andromeda galaxy, as it will unfold over the next several billion years. Credit: NASA; ESA; Z. Levay and R. van der Marel, STScI; T. Hallas; and A. Mellinger

As noted, Gardner’s previous work also indicated that when it came to north/south symmetry of stars in the Milky Way’s disk, there was a vertical “ripple”. In other words, the number of stars that lay above or below the stellar disk would increase from one sampling to the next the farther they looked from the center of the galactic disk. But thanks to the most recent data obtained by the SDSS, the team had a much larger sample to base their conclusions on.

And ultimately, these findings confirmed the observations made by Ferguson and Lally, and also turned up evidence of an asymmetry in the plane of the galactic disk as well. As Ferguson explained:

“Having access to millions of stars from the SDSS allowed us to study galactic structure in an entirely new way by breaking the sky up into smaller regions without loss of statistics. It has been incredible watching this project evolve and the results emerge as we plotted the stellar densities and saw intriguing patterns across the footprint. As more studies are being done in this field, I am excited to see what we can learn about the structure of our galaxy and the forces that helped to shape it.”

Understanding how our galaxy evolved and what role ancient impact played is essential to understanding the history and evolution of the Universe as a whole. And in addition to helping us confirm (or update) our current cosmological models, studies like this one can also tell us much about what lies in store for our galaxy billions of years from now.

For decades, astronomers have been of the opinion that in roughly 4 billion years, the Milky Way will collide with Andromeda. This event is likely to have tremendous repercussions, leading to the merger of both galaxy’s supermassive black holes, stellar collisions, and stars being ejected. While it’s doubtful humanity will be around for this event, it would still be worthwhile to know how this process will shape our galaxy and the local Universe.

https://upload.wikimedia.org/wikipedia/commons/transcoded/d/da/Andromeda_and_Milky_Way_collision.ogv/Andromeda_and_Milky_Way_collision.ogv.480p.webm

Further Reading: University of Kentucky, The Astrophysical Journal

The post Ancient Impacts Shaped the Structure of the Milky Way appeared first on Universe Today.

One. More. Month: Our Guide to the Total Solar Eclipse

One. More. Month: Our Guide to the Total Solar Eclipse:

Totality! An incredible moment from the March 29th, 2006 total solar eclipse. Credit and copyright: Alan Dyer/Amazing Sky Photography

Have you heard?

I remember, getting into astronomy as a kid back in the 1970s, building a pinhole projector in a shoe box and watching the partial solar eclipse of February 26^th, 1979 from our living room in northern Maine. I had no Learjet, no magic carpet to whisk me off to that thin thread of a path of totality way out west along the Pacific coast. As I settled for the 66% partial solar eclipse, I remember news reports stating that a total solar eclipse won’t cross the United States again until… August 21^st, 2017.

That date is almost upon us now, only one month from this coming Friday.

An animation of the August 21st eclipse. Credit: NASA/GSFC/AT Sinclair

This total solar eclipse is one for the ages, THE big ticket event for 2017. Umbraphiles (those who chase eclipses) have been planning for this one for decades, and it’s already hard to find a room along the path. Fear not, as you only need to be within striking distance the day of the eclipse to reach totality, though expect the roads to be congested that Monday morn.

The eclipse is indeed the first time totality touches the contiguous (“lower 48”) United States since 1979, and the first total solar eclipse to cross the United States since almost a century ago on June 8^th 1918. A total solar eclipse did cross Hawaii on July 11^th, 1991.

The path of the August 21st eclipse over the U.S. Credit: Michael Zeiler/Eclipse-Maps.

Partial phases for the eclipse begin at 15:47 Universal Time (UT) and span 5 hours and 18 minutes until 21:04 UT. The partial aspect of the eclipse touches all continents except Antarctica and Australia. The 115 kilometer wide shadow of Earth’s moon (known as the umbra) first makes landfall over the Oregon coast at 17:16 UT /10:16 Pacific Daylight Saving time (PDT) and races eastward at 3,900 kilometers per second. The shadow touches 14 states, just briefly nicking Montana and Iowa. Maximum totality of 2 minutes, 40 seconds occurs near Carbondale, Illinois.

Seen a partial solar eclipse before and wonder what the big deal is? You really need to get to the path of totality for the full eclipse experience. Millions live in the path of the August 21^st eclipse, and millions more within an easy day drive. We witnessed the May 10^th, 1994 annular eclipse from the shores of Lake Erie in Sandusky, Ohio, and can attest that 1% of the Sun at midday is still pretty darned bright.

A partial eclipse rising over the Vehicle Assembly Building at the Kennedy Space Center. Credit: Dave Dickinson

Action really gets interesting moments before totality sweeps over the landscape. Be sure to keep an eye out for shadow bands flitting across the ground, an effect notoriously hard to photograph. It’s safe to drop those glasses moments before totality, when you’ll see those final rays of sunlight streaming through the valleys along the limb of the Moon, creating what’s known as Baily’s Beads or the Diamond Ring Effect. You’re now in the realm of the shadow of the Moon, an ethereal shadow world turned on its head. I dare you to blink. Looking sunward, you’ll see the pearly corona of the Sun, a white halo about as bright as a Full Moon spied only during totality.

Think about it: you knew this moment was coming, perhaps you’d been planning for it for years… but would you think as an average citizen thousands or millions of years ago if you were suddenly confronted with such as strange sky?

And all too soon, it’s over.

Be sure to keep an eye out for planets and bright stars during the eclipse. Totality is a late morning affair out west, and an early afternoon event for the US East Coast. All naked eye planets except Saturn are above the horizon during totality, covering a span of about 80 degrees from Jupiter to Venus. Look just one degree from the eclipsed Sun and you might just spy the star Regulus occulted by the Moon shortly after the eclipse.

The orientation of the planets and bright stars during totality. Credit: Stellarium.

Perhaps you’re planning on aiming a battery of cameras skyward during the eclipse, or maybe, you’re simply planning on simply enjoying the moment, then photographing the next one. The Eclipse MegaMovie project is planning on capturing the scene down the eclipse path. NASA will also be flying overhead with converted WB-57F aircraft, looking to capture high definition video in the visible and infrared wavelengths during the eclipse.

Preparing for the eclipse. Credit: Dave Dickinson

You need to take the same safety precautions observing the partial phases of the eclipse as you would during ordinary solar observing. Use only a filtered telescope designed to look at the Sun, or solar eclipse glasses with an ISO 12312-2 rating. Make sure that filter fits snugly over the aperture of the telescope and cannot be removed by curious prying hands or high winds, and that all finder-scopes are removed, stowed and/or covered. Also, don’t try and use one of those old screw-on eyepiece solar filters that came with old department store 60mm refractors, as they can heat up and crack. Likewise, be careful when projecting the Sun through a telescope onto a piece of paper, as it can heat up and damage the optics.

If you don’t think the danger is real, read this amazing recent interview with an optometrist on Space.com, where he states you can actually see the crescent Sun burned into the backs of patient’s eyes who stared too long at a partial solar eclipse (!) It’s a permanent souvenir you don’t want to have. Don’t be like 18th century psychologist Gustav Fechner who blinded himself staring at the Sun, mesmerized by the glare of lingering afterimages.

Seen on the streets of Paducah, Kentucky… a harbinger of things to come? Credit: Dave Dickinson

And though we can predict eclipses centuries out, there’s one thing we won’t know eclipse day: what the weather plans on doing. Best bets are for clear skies out west, though you only need a gap in the clouds to see the Sun. We’ll be running a final post on Universe Today just days prior to the eclipse looking at weather prospects, solar activity and prospects for transits of the International Space Station and possible views from space.

The umbra of the Moon on Earth as seen from Mir in 1999. Credit: NASA/Roscosmos.

The second eclipse season for 2017 begins with a partial lunar eclipse favoring on August 7th… we’ve got you covered on that as well. And us? We’ll be watching the event from the Pisgah Astronomical Research Institute (PARI) in Smoky Mountains just outside of Asheville, North Carolina for a glorious 107 seconds of totality.

And after that? Well, totality visits that same living room in northern Maine on April 8th, 2024… I think I know where I’ll be then.

The path of the 2017 and 2024 eclipses. Credit: Michael Zeiler/Eclipse Maps.

A request- observing the eclipse from the path of totality? I’m planning on doing a state-by-state roundup post eclipse, perhaps with a paragraph of personal impressions from each observer. Let us know what your plans are!

-Read more about the August 21^st total solar eclipse, plus the true tale of Edison’s Chickens and the 1878 total solar eclipse in out free e-guide to 101 Astronomical Events for 2017.

-Eclipse… fiction? Read our original eclipse-fueled sci-fi tales Exeligmos, Peak Season, Shadowfall and more!

The post One. More. Month: Our Guide to the Total Solar Eclipse appeared first on Universe Today.

Hey Map Collectors, Here’s a New Map of Pluto!

Hey Map Collectors, Here’s a New Map of Pluto!:

On July 14th, 2015, the New Horizons mission made history when it became the first spacecraft to conduct a flyby of Pluto and its moons. In the course of making its way through this system, the probe gathered volumes of data on Pluto and its many satellites using a sophisticated suite of instruments. These included the first detailed images of what Pluto and its largest moon (Charon) look like up close.

And while scientists are still analyzing the volumes of data that the probe has sent home (and probably will be for years to come), the New Horizons mission team has given us plenty of discoveries to mull over in the meantime. For instance, using the many images taken by the mission, they recently created a series of high-quality, highly-detailed global maps of Pluto and Charon.

The maps were created thanks to the plethora of images that were taken by New Horizons’ Long-Range Reconnaissance Imager (LORRI) and its Multispectral Visible Imaging Camera (MVIC). Whereas LORRI is a telescopic camera that was responsible for obtaining encounter and high-resolution geologic data of Pluto at long distances, the MVIC is an optical and infrared instrument that is part of the Ralph instrument – the main imaging device of the probe.

Global mosaic of Pluto, based on images obtained by the LORRI and MVIC instruments onboard New Horizons. Credits: NASA/JHUAPL/SwRI/LPI

The Principal Investigator (PI) for the LORRI instrument is Andy Cheng, and it is operated from Johns Hopkins University Applied Physics Laboratory (JHUAPL) in Laurel, Maryland. Alan Stern is the PI for the MVIC and Ralph instruments, which are operated from the Southwest Research Institute (SwRI) in San Antonio, Texas. And as you can plainly see, the maps are quite detailed and eye-popping!

Dr. Stern, who is also the PI of the New Horizons mission, commented on the release of the maps in a recent NASA press statement. As he stated, they are just the latest example of what the New Horizons mission accomplished during its historic mission:

“The complexity of the Pluto system — from its geology to its satellite system to its atmosphere— has been beyond our wildest imagination. Everywhere we turn are new mysteries. These new maps from the landmark exploration of Pluto by NASA’s New Horizons mission in 2015 will help unravel these mysteries and are for everyone to enjoy.”

Global mosaic of Charon, based on images obtained by the LORRI and MVIC instruments onboard New Horizons. Credits: NASA/JHUAPL/SwRI/LPI

And these were not the only treats to come from the New Horizons team in recent days. In addition, the mission scientists used actual New Horizons data and digital elevation models to create flyover movies that show what it would be like to pass over Pluto and Charon. These videos offer a new perspective on the system and showcase the many unusual features that were discovered on both bodies.

The video of the Pluto flyover (shown above) begins over the highlands that are located to the southwest of Sputnik Planitia – the nitrogen ice basin that measures some 1,050 by 800 km (650 by 500 mi) in size. These plains constitute the western lobe of the feature known as Tombaugh Regio, the heart-shaped region that is named after the man who discovered Pluto in 1930 – Clyde Tombaugh.

The flyover also passes by cratered terrain of Cthulhu Macula before moving north past the highlands of Voyager Terra. It then turns south towards the pitted region known as Pioneer Terra before concluding over Tartarus Dorsa, a mountainous region that also contains bowl-shaped ice and snow features called penitentes (which are found on Earth and are formed by erosion).



The flyover video of Charon begins over the hemisphere that the New Horizons mission saw during its closest approach to the moon. The view then descends over Serenity Chasma, the wide and deep canyon that is named after the ship from the sci-fi series Firefly. This feature is part of the vast equatorial belt of chasms on Charon, which is one of the longest in the Solar System – 1,800 km (1,100 mi) long 7.5 km (4.5 mi) deep.

The view then moves north, passing over the Dorothy Gale crater and the dark polar region known as Mordor Macula (appropriately named after the domain of the Dark Lord Sauron in The Lord of the Rings). The video then turn south to fly over the northern terrain known as Oz Terra before finishing over the equatorial plans of Vulcan Planum and the mountain of Clarke Montes.

These videos were color-enhanced in order to bring out the surface details, and the topographic relief was exaggerated by a factor or two to three to emphasize the topography of Pluto and its largest moon. Digital mapping and rendering of these videos was performed by Paul Schenk and John Blackwell of the Lunar and Planetary Institute (LPI) in Houston.



It may be many years before another mission is able to travel to the Trans-Neptunian region and Kuiper Belt. As a result, the maps and videos and images that were taken by the New Horizons mission may the last glimpse some us get of the Pluto system. Luckily, the New Horizons mission has provided scientists and the general public with enough information to keep them busy and fascinated for years!

Further Reading: NASA

The post Hey Map Collectors, Here’s a New Map of Pluto! appeared first on Universe Today.

Long After Humanity is Gone and the Sun Dies, the Water Bears Will be There

Long After Humanity is Gone and the Sun Dies, the Water Bears Will be There:

Like all living creatures, stars have a natural lifespan. After going through their main sequence phase, they eventually exhaust their nuclear fuel and begin the slow process towards death. In our Sun’s case, this will consist of it growing in size and entering the Red Giant phase of its evolution. When that happens, roughly 5.4 billion years from now, the Sun will encompass the orbit’s of Mercury, Venus, and maybe even Earth.

However, even before this happens, astronomers theorize that the Sun will dramatically heat up, which will render Earth uninhabitable to most species. But according to a new study by a team of researchers from Oxford and the University of Harvard, the species known as tardigrades (aka. the “water bear”) will likely survive even after humanity and all other species have perished.

This study, which was recently published in the journal Scientific Reports under the title “The Resilience of Life to Astrophysical Events“, was conducted by Dr. David Sloan, Dr. Rafael Alves Batista – from the Department of Astrophysics at Oxford University – and Dr. Abraham Loeb of the Harvard-Smithsonian Center for Astrophysics (CfA). As they indicate, previous studies into the effect Solar evolution will have on life have been rather lopsided.

Artist’s impression of the Earth scorched by our Sun as it enters its Red Giant Branch phase. Credit: Wikimedia Commons/Fsgregs

Essentially, much attention has been dedicated to whether or not humanity will survive our Sun leaving its main sequence phase. Comparatively, very little research has been conducted on whether or not life itself (and which lifeforms) will be able to survive this change. As such, they considered the most statistically-likely events that would be capable of completely sterilizing an Earth-like planet, and sought to determine what lifeforms could endure them.

As Dr. Loeb told Universe Today via email, their team wanted to consider if there was an extinction-level event that could eliminate all life on Earth (not just humans):

“We wanted to find out how long life may survive on a planet once formed. Most previous studies focused on the survival of humans which are very sensitive to changes in the atmosphere or climate of the Earth and can be eliminated by the impact of an asteroid (nuclear winter) or bad politics.”

What they found was that the species Milnesium tardigradum would survive all potential astrophysical catastrophes. What’s more, they estimated that these creatures will be around for another 10 billion years at least – far longer than what is anticipated for the human race! As Loeb indicates, this was not an outcome that they were expecting.

“To our surprise, tardigrades are likely to survive all astrophysical catastrophes,” he said. “Most likely, the DNA of tardigrades is able to repair itself quickly due to damage encountered by the environment. The process is not fully understood, and there is a group at Harvard University who studies the SNA of tardigrades with the hope of understanding it better.”

Scanning Electron Microscope (SEM) image of Milnesium tardigradum in active state. Credit: Schokraie E/Warnken U/Hotz-Wagenblatt A/Grohme MA/Hengherr S, et al.

To be fair, it has been known for some time that Tardigrades are the most resilient life form on Earth. Not only can they survive for up to 30 years without food or water (half their natural lifespan), they can also survive temperatures of up to 150 °C (302 °F) and as low as -200 °C (-328 °F). They have also shown themselves to be capable of enduring extremes in pressure, ranging from the 6000 atmospheres to the vacuum of open space.

Under these conditions, the research team concluded that they are likely to survive the Sun becoming a red giant and irradiating Earth, and will likely be alive even after the Sun has winked out of existence.  On top of that, tardigrades can even be brought back to life, under the right circumstances. Much like all life on Earth, tradigrades need water to survive, even though they can survive in a dry state for extended periods of time – up to ten years, in fact.

But even after being deprived of water to the point of death, scientists have found that these organisms can be reanimated once water is reintroduced. This was demonstrated in 2007 when a batch of tardigrades was dehydrated before being launched to Low Earth Orbit (LEO). After being exposed to the hard vacuum of space and UV radiation for 10 days, they were returned to Earth and rehydrated – at which point, the majority were revived and able to produce viable embryos.

The team also concluded that other cataclysmic events – such as an asteroid strike, exploding stars (i.e. a supernovae) or gamma ray bursts – pose no existential threat to tardigrades. As Loeb explained:

“We have found that asteroid impacts are capable of boiling off all the oceans on Earth, but only if the asteroid is more massive than 10¹⁸ kg [10,000 trillion metric tons]. Such events are extremely rare and will not happen before the Sun will die; the probability of them happening earlier is less than one part in a million.”

Artist’s concept of a collision between proto-Earth and Theia, believed to happened 4.5 billion years ago. Credit: NASA

In fact, the last time an object large enough to boil the oceans (2 x 10¹⁸ kg) collided with Earth occurred roughly 4.51 billion years ago. On this occasion, Earth was struck by a Mars-sized object named Theia, which is believed to be what caused the formation of the Moon. Today, there are only a dozen known asteroids or dwarf planets in the Solar System that have this kind of mass, and none of them will intersect the Earth’s orbit in the future.

As for supernova, they indicated that an exploding star would need to be 0.14 light-years from Earth in order for it to boil the oceans from its surface. Since the closest star to our Sun (Proxima Centauri) is 4.25  light years away, this scenario is not a foreseeable risk. As for gamma-ray bursts, which are even rarer than supernova, the team determined that they too are too far away from Earth to pose a threat.

The implications of this study are quite fascinating. For one, it reminds us just how fragile human life is compared to basic, microscopic life forms. It also demonstrates that similarly hardy organisms could exist in a variety of locations that we may have once considered too hostile for life. As Dr Rafael Alves Batista, one of the co-authors on the study, said in a University of Oxford press release:

“Without our technology protecting us, humans are a very sensitive species. Subtle changes in our environment impact us dramatically. There are many more resilient species’ on earth. Life on this planet can continue long after humans are gone. Tardigrades are as close to indestructible as it gets on Earth, but it is possible that there are other resilient species examples elsewhere in the Universe. In this context there is a real case for looking for life on Mars and in other areas of the Solar System in general. If Tardigrades are earth’s most resilient species, who knows what else is out there?’”

The tiny Tardigrade: Nature’s toughest creature? Credit: Katexic Publications, unaltered, CC2.0)

And as Dr. Loeb explained, studies like this have potential benefits that go far beyond assessing our own survivability. Not only do they help us understand life’s ability to endure catastrophic events – which is essential to understanding how and where life could emerge in the Universe – but they also offer possibilities on how we might better our own chances of survival.

“We get a better understanding of the conditions under which life will persist,” he said. “In about a billion years, when the Sun will heat up life will cease, but until then it will continue in some form. Understanding the self-repair mechanism of the DNA on tardigrades could potentially help in combating disease for humans as well.”

And all his time, we thought cockroaches were the toughest critters on the planet, what with their ability to withstand a nuclear holocaust. But these eight-legged creatures, which are arguably cuter than cockroaches too, clearly have the market on toughness cornered. We’re just lucky they only get up to 0.5 mm (0.02 in) in size, otherwise we might have something to worry about!

Further Reading: University of Oxford, Scientific Reports

The post Long After Humanity is Gone and the Sun Dies, the Water Bears Will be There appeared first on Universe Today.

This is the One of the Largest Structures We Know of in the Universe

This is the One of the Largest Structures We Know of in the Universe:

The Milky Way Galaxy, which measures 100,000 to 180,000 light years (31 – 55 kiloparsecs) in diameter and contains 100 to 400 billion stars, is so immense that it boggles the mind. And yet, when it comes to the large-scale structure of the Universe, our galaxy is merely a drop in the bucket. Looking farther, astronomers have noted that galaxies form clusters, which in turn form superclusters – the largest known structures in the Universe.

The supercluster in which our galaxy resides is known as the Laniakea Supercluster, which spans 500 million light-years. But thanks to a new study by a team of Indian astronomers, a new supercluster has just been identified that puts all previously known ones to shame. Known as Saraswati, this supercluster is over 650 million light years (200 megaparsecs) in diameter, making it one the largest large-scale structures in the known Universe.

The study, which recently appeared in The Astrophysical Journal under the title “Saraswati: An Extremely Massive ~ 200 Megaparsec Scale Supercluster“, was conducted by astronomers from the Inter University Center for Astronomy & Astrophysics (IUCAA) and the Indian Institute of Science Education and Research (IISER), with assistance provided by a number of Indian universities.

The distribution of galaxies, from Sloan Digital Sky Survey (SDSS), in Saraswati supercluster. Credit: IUCAA

For the sake of their study, the team relied on data obtained by the Sloan Digital Sky Survey (SDSS) to examine the large-scale structure of the Universe. In the past, astronomers have found that the cosmos is hierarchically assembled, with galaxies being arranged in clusters, superclusters, sheets, walls and filaments. These are separated by immense cosmic voids, which together create the vast “Cosmic Web” structure of the Universe.

Superclusters, which are the largest coherent structures in the Cosmic Web, are basically chains of galaxies and galaxy clusters that can extend for hundreds of millions of light years and contain trillions of stars. In the end, the team found a supercluster located about 4 billion (1226 megaparsecs) light-years from Earth – in the constellation Pisces – that is 600 million light-years wide and may contain the mass equivalent of over 20 million billion suns.

They gave this supercluster the name “Saraswati”, the name of an ancient river that played an important role in the emergence of Indian civilization. Saraswait is also the name of a goddess that is worshipped in India today as the keeper of celestial rivers and the goddess of knowledge, music, art, wisdom and nature. This find was particularly surprising, seeing as how Saraswati was older than expected.

Essentially, the supercluster appeared in the SDSS data as it would have when the Universe was roughly 10 billion years old. So not only is Saraswati one of the largest superclusters discovered to date, but its existence raises some serious questions about our current cosmological models. Basically, the predominant model for cosmic evolution does not predict that such a superstructure could exist when the Universe was 10 billion years old.

Diagram of the Lambda-CDM model, which shows cosmic evolution from the Big Bang/Inflation Era and the subsequent expansion of the universe.  Credit: Alex Mittelmann.

Known as the “Cold Dark Matter” model, this theory predicts that small structures (i.e. galaxies) formed first in the Universe and then congregated into larger structures. While variations within this model exist, none predict that something as large as Saraswati could have existed 4 billion years ago. Because of this, the discovery may require astronomers to rethink their theories of how the Universe became what it is today.

To put it simply, the Saraswati supercluster formed at a time when Dark Energy began to dominate structure formation, replacing gravitation as the main force shaping cosmic evolution. As Joydeep Bagchi, a researcher from IUCAA and the lead author of the paper, and co-author Shishir Sankhyayan (of IISER) explained in a IUCAA press release:

‘’We were very surprised to spot this giant wall-like supercluster of galaxies… This supercluster is clearly embedded in a large network of cosmic filaments traced by clusters and large voids. Previously only a few comparatively large superclusters have been reported, for example the ‘Shapley Concentration’ or the ‘Sloan Great Wall’ in the nearby universe, while the ‘Saraswati’ supercluster is far more distant one. Our work will help to shed light on the perplexing question; how such extreme large scale, prominent matter-density enhancements had formed billions of years in the past when the mysterious Dark Energy had just started to dominate structure formation.’’

As such, the discovery of this most-massive of superclusters may shed light on how and when Dark Energy played an important role in supercluster formation. It also opens the door to other cosmological theories that are in competition with the CDM model, which may offer more consistent explanations as to why Saraswati could exist 10 billion years after the Big Bang.

One thing is clear thought: this discovery represents an exciting opportunity for new research into cosmic formation and evolution. And with the aid of new instruments and observational facilities, astronomers will be able to look at Saraswait and other superclusters more closely in the coming years and study just how they effect their cosmic environment.

Further Reading: IUCAA, The Astrophysical Journal

The post This is the One of the Largest Structures We Know of in the Universe appeared first on Universe Today.

Moon Shadow versus Sun Reflection

Moon Shadow versus Sun Reflection:

Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

2017 July 17



Moon Shadow versus Sun Reflection

Image Credit: Himawari-8, NASA's SVS (GSFC)


Explanation: What are those lights and shadows crossing the Earth? As the featured five-second time-lapse video progresses, a full day on planet Earth is depicted as seen from Japan's Himawari-8 satellite in geostationary orbit high above the Pacific Ocean. The Sun rises to the right and sets to the left, illuminating the half of Earth that is most directly below. A reflected image of the Sun -- a Sun glint -- is visible as a bright spot that moves from right to left. More unusual, though, is the dark spot that moves from the lower left to upper right That is the shadow of the Moon, and it can only appear when the Moon goes directly between the Earth and the Sun. Last year, on the day these images were taken, the most deeply shadowed region experienced a total eclipse of the Sun. Next month a similarly dark shadow will sweep right across the USA.

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