Thursday, December 29, 2016

Peking University

Peking University, Beijing, China (May 25, 2016)

Peking University is the top higher learning institution in mainland China. It is also the first modern national university established in the country, founded in 1898 replacing the old imperial academy.

KIAA at Peking University
As I mentioned before, the purpose of my trip to China was to participate to a scientific meeting. The meeting was not in the University, but was organized by the Kavli Institute for Astronomy and Astrophysics (KIAA), which is located in the campus of Peking University. The institute occupies a modern building made in a traditional style (photo on the left), situated next to the pond in the photo above. The University campus is on the former site of the Qing Dynasty imperial gardens, and is an attraction in itself with the numerous traditional style buildings, pagodas and manicured gardens. The central Weiming lake is very beautiful, and is surrounded by many walking paths, smaller gardens and ponds, and there are several museums that are worth the visit. The campus is very popular, and there is a permanent line of tourists at its main gate during the security check before entering the grounds . If you want to visit the gardens in your next visit to Beijing it is well worth it, but remember to bring along your documents to gain access (that is true for all touristic attractions, including the Forbidden City and the National Museum). 

Peking University
I actually managed to avoid the line at the entrance since I was accompanied by a colleague of mine that works at KIAA, one of the organizers of the conference. He is from the Netherlands and a few years back found a new scientific home in the institute. He was not the only person I visited on campus: the fellow with me in the photo on the right was one of my office-mates when I was in graduate school in Trieste (Italy). After graduating he worked for a while in Sweden (his interest are theoretical calculations about black hole mergers) and then returned to China where he is now chair of the department. I was very happy to meet him after so many years. He was a very gracious host and walked me around the campus, showing me the architecture and the landscaping, and telling me about the history of the university. We also had some time to talk about his experience of getting back to China after having lived and worked for a long time in Europe. The government is investing a lot in science, and his department is expanding significantly, with new hiring and the development of state-of-the art astronomical facilities. This is something I gathered also from other sources, and that is true in other fields of physics (e.g. particle physics), where both the quantity and quality of Chinese scientific production has greatly improved in recent years (I see that also in my own department faculty and graduate students coming from China).

I sometime get asked why somebody would want to move from a more free country (e.g. the Netherlands) to a place with a less democratic form of government. I am in no position to judge: people make their own choice based on their own circumstances, priorities, family constraints. We don't chose the place where we go to live and work in abstract terms: there are many factors that influence our decisions. Both my friends are happy to live in Beijing and work in the university: the place definitely shows the kind of dynamism that physics and space science had in the US in the 50s, at the heigh of time when the american government believed and strongly supported science. In other fields it may be different. I heard from some sources that humanities are suffering under a more strict ideological control that is being exerted by the current leadership, in a change with respect to the more laissez-fare attitude of the previous government. Science however appears to still have little central oversight, and a lot of support and funding in today's China.

Weiming Lake and the Boya Pagoda, Peking University, Beijing, China (May 25, 2016)

Friday, December 16, 2016

The National Museum of China

National Museum of China, Tiananmen Square, Beijing, China (May 22, 2016)

With over 2,2 million square feet of display space, the National Museum of China is one of the largest in the world, and it is visited by 7.5 million visitors every year. The museum is on the east side of Tiananmen Square. Still tired after the long walk the day before, we decided to make it our destination, after strolling for some time under the Tiananmen Square relentless sun.

Terracotta Army
The museum is in fact two different museums combined. One part is dedicated to the history of China through the ages, literally, the first artifact being the 1.7 million years old Yanmu Man (元謀人). The other side is instead dedicated to a somewhat hagiographic portrait of the legacy of the Chinese Revolution. I don't need to tell you which side we visited... It was actually worth it. The collection of ancient artifacts, revealing how China had a very refined culture at time when our progenitors were still living in caves, is impressive. The bronze artifacts, in particular, are stunning: some of them are incredibly massive (there is a rectangular vessel weighting more than 800 kg), but at the same time have most delicate ornaments and inscriptions. Whoever made them really knew their craft. The museum has sections covering each and every dynasty in the long history of China. Each with a different style, a different concept of art. One small display has a sample of the famous "terracotta army", with one horse and two soldiers. I was happy to see it there since the whole thing is far from Beijing, impossible for me to visit during this trip.

Blue and white porcelain vase
A large section of the museum is dedicated to the ceramic wares. This is an art that China has been developing for tens of thousand of years, with the first pottery produced in neolithic times, almost 20,000 years ago. The blue and white porcelains (青花, literally "blue flowers") are the ones that I found more appealing, like the vase in the small photo on the right. This is a style that dates back from the 9th to the 14th century, when the blue pigment based on cobalt minerals were first imported from Persia. It is interesting how the technique, after being perfected by Chinese artists, found its way back to the middle east, inspiring a renaissance of ceramic production with islamic themes. The world is after all is small, and goes in circles... Other interesting sections of the museum were the one dedicated to the development of Chinese writing, and the innumerable artifacts with astronomical significance, like the many maps of the sky, with the stars grouped in the strangely familiar yet alien patters of the Chinese constellations. We spent the whole afternoon in the museum, until one by one our legs and backs started to give way to age (well, at least in my case), and we finally made our way back to the train station under Tiananmen Square, and to the hotel for dinner and the final rest before the first day of our conference meeting.

Floral Exposition in front of the National Museum of China, Tiananmen Square, Beijing, China (May 22, 2016)

Sunday, November 20, 2016

The Front Gate in Tiananmen Square

Zhengyangmen, Tiananmen Square, Beijing, China (May 22, 2016)

With one more day before the conference was scheduled to start, we went back to Tiananmen Square, this time taking the subway to the right stop. The square is indeed very large, and surrounded by a number of monumental building. To the north there is the main gate to the Forbidden City (see panorama below), the entrance we used the day before to visit the Palace Museum.

Mausoleum of Mao Zedong
On the opposite site there is the imposing Zhengyangmen (正陽門), or "the gate of the zenith sun". The gate once guarded the south entrance to the inner city, as part of Beijing historic city walls. The walls are now gone, but the gate is still an important geographic marker along the north-south axis of the city. First built in 1419 during the Ming dynasty, the gate guarded the entrance to the imperial city. In 1900 the gate was destroyed during the Boxer rebellion, when a Chinese militia rebelled against foreign imperialism and Christian missionaries. The rebellion was crushed during the battle of Beijing, when an Eight-Nation Alliance invaded the city: the tower played a prominent role during the fighting. Zhengyangmen was later reconstructed by the Qing dynasty, in direct violation of the Boxer protocol (one of the "Unequal Treaties" imposed to China by the invading powers). The tower of course is not the only prominent building in the square. The equally imposing Chairman Mao Memorial Hall (毛主席紀念堂) stands at the center of the Square, with the crystal coffin where the embalmed body of the "Great Helmsman" is visited by the millions (kind of ironic given that Mao himself wished to be buried). A very controversial historical figure abroad, Mao Zedong is still very popular in China.

Since it was built, the centrality of Tiananmen Square made it the stage of several important protests that happened on the site, the last of which the "June Forth Incident" (六四事件). These are the 1989 student's revolt that in the West are known as the Tiananmen Square protests, forcibly repressed by the government when it declared martial law. Access to the square is now heavily controlled, with fences and security gates along its entire perimeter, and plenty of security cameras (zoom-in at the lamp post in the photo on the left), in part because of the terrorist attack that killed 5 people in 2013.

Tiananmen Square, Beijing, China (May 22, 2016)

Sunday, October 16, 2016

Ancient Script

The Forbidden City, Beijing, China (May 21, 2016)

China is old. You won't realize it based on the modern buildings in the post-Olympics busy Beijing, but just enter in on one of the many pavilions inside the Palace Museum and you will breathe the air of history. The Forbidden City is actually one of the largest museum of the world, with 980 surviving buildings and 8707 rooms covering a total 720,000 square meters.

Ancient Script
This is much more than can be seen in just a brief afternoon visit, so we cherry-picked a few collections to visit, and that was still mind-blowing. I am not known to be a meticulous tourists, of the very organized sort that reads tons of guides and one month in advance of the trip knows the exact itinerary to maximize a visit. I do buy a guide or two, but then wait to the last minute before actually opening them, so that by the time of the tour I only have a sketchy idea of what I can see. Not the most efficient way, but on the other hand it leaves one's mind open to the surprise of discovery. This visit was no exception. It was also a hot day, and we had already walked a lot just to get to to the Forbidden City entrance, so it didn't take very long until we found ourselves looking for a cool place to rest. This is how we found a pavilion with the holy combination of shade, air conditioning, and an impressive collection of fine bronze utensils, musical instruments and weapons, some of them 5,000 years old.

Ancient Script
Several of the items were actually inscribed, with ancient characters that were at the same time familiar and novel. One example is in the photo above, that shows an example of such writing (on the left) with the corresponding modern characters. The resemblance is there, but the older version is more closely representing an actual drawing of the subject it portraits, while the modern equivalent is more stylized. The legendary origin of the Chinese characters refers to the mythical Cangjie (倉頡), the four-eyed historian of the equally mythical Yellow Emperor, the founder of Chinese civilization and the ancestor of all Chinese people. Legend has that Cangjie used his four pupils to see things that nobody else could see, including ghosts and deities, and was very observant. Tasked by his emperor to devise a method to record informations for posterity, he was inspired by the footprint of a pixiu (a winged lion), and created a large number of symbols to represent all things: the ancient Chinese script. Another version of the legend postulates that Cangjie was instead inspired by the veins in the shell of turtles: particularly interesting postulation, given that archeologists have unearthed fragments of turtle shells with actual writing on them. Whatever the inspiration, the legend of Cangjie would place the invention of Chinese writing around 2700-2600 BC, when the Yellow emperor reigned.

The earliest record of actual writing (apart from individual isolated signs inscribes on bones), however, go about as back as the Shang dynasty (about 1200 BC). One example is the inscription in the ox scapula shown in the small photo above (left), which I photographed the following day at the National Museum of China. That is where we will go in the next post.

The Forbidden City, Beijing, China (May 21, 2016)

Saturday, October 8, 2016

Forbidden City

The Forbidden City, Beijing, China (May 21, 2016)

The Forbidden City is BIG. After walking around its whole length along its perimeter wall and moat, we finally reached Tiananmen Square: there is where the South entrance to the Forbidden City is located, under a gigantic portrait of Chairman Mao, Mona Lina smiling at the long line of tourists clearing the security check leading to the red plastered walls of the monumental Gate of the Heavenly Peace.

The Inner Golden River
The Forbidden City had been the seat of Chinese imperial power for almost 500 years, until the 1912 abdication of Puyi, the last emperor of China. For the following twelve years the last emperor was confined in the Inner Court of the sprawling complex, while the Outer Court was, for the first time in history, opened to the public. This arrangement ended in 1924, when a coup ended once and for all the Qing dynasty and the imperial rule in China. The Japanese invasion, and then the Chinese Civil War caused many of the treasures in the Forbidden City to be evacuated. Much was returned at the end of War War II, but a small but highly valuable part of the collection is still missing, kept in the National Palace Museum in Taipei. In the years following the establishment of the People's Republic of China the palace was left in disrepair, and sometimes directly threatened of destruction, as during the Cultural revolution when in the eyes of the revolutionary zeal it became a symbol of the overthrown oppressive imperial power. It was only saved when the premier Zhou Enlai sent an army battalion to defend the city. In 1987 the Forbidden City was declared a World Heritage site and the Chinese government has finally recognized its cultural (and economic, given its value as a touristic attraction) importance. Now administered by the Palace Museum, it is undergoing a massive restoration project aimed to bring back the splendor of its buildings in their pre-1912 state (much has been already done, but we could see areas still fenced off as the works continue).

Even though only part of the complex is open to the public, the sheer size of the structure is too much to be visited in a single day. One walks from courtyard to courtyard, passing under one gate after the other in what is the largest collection of preserved ancient wood structures in the world. The courtyard opening on the Meridian Gate is so expansive that a wide canal flows through it, crossed by 5 marble bridges (the Inner Golden River, small photo on the left). With 14.6 million annual visitors (for what I could see, a large fraction of them are Chinese nationals, or come from nearby asian countries) it is the most visited museum in the world.

The Forbidden City, Beijing, China (May 21, 2016)

Saturday, October 1, 2016

Just Two Subway Stops to the Forbidden City

The Moat and Wall of the Forbidden City, Beijing, China (May 21, 2016)

China is 13 hours ahead of the time zone where I live, which is as bad as it gets since it completely invert the sleep/awake cycle. Being able to function after such a time slip requires some adjustment, so I planned to arrive in Beijing two days before the start of my meeting. Adjusting to a new time zone however works only if you resist hitting the bed during the day, and stuck to the sleep schedule of the new location. That means keeping busy while the internal clock gets in sync with the sun.

Forbidden City Moat
I decided to spend the first adjustment day visiting the Forbidden City, just a short subway ride from my hotel. It is in fact quite easy to move around in Beijing. The city has 18 lines, 334 stations and 554 km (344 miles) of tracks making the Beijing subway the second largest system in the world (after Shanghai). All this is quite recent, since only two lines where in operation before 2002, with the largest expansion was completed for the summer Olympics games hosted in 2008. Since I read about how imposing was the wall and moat surrounding the Forbidden City, I convinced my graduate student that went along for the trip that we should get off the train before the main entrance, and walk a little along the wall. According to my map that meant walking for just a couple of stops, strolling through a modern boulevard leading straight to the back side of the Forbidden City, and then walking along the moat to the main entrance facing Tiananmen square on the opposite side. The weather was pleasantly warm and sunny, and the air exceptionally clear, without the dense cap of smog that the city is notorious for. What could go wrong?

Well, what went wrong is that I apparently don't know how to properly read distances on a map. The distance between the two stops turned out to be over 3 miles, and took a couple of hours to navigate in the heavy traffic of the big city, to then arrive at the entrance of the Forbidden City, which is something that in itself takes at least a full day to visit. My graduate student was not amused, and she is still reminding me of this episode every time she want to point out how my judgment may not be up to the task when we explore new directions in our daily research work. From that point onward she got in charge of navigating our excursions on the city's transport system. The trick for a successful career in academia is finding students that are smarter than you...

The Moat and Wall of the Forbidden City, Beijing, China (May 21, 2016)

Saturday, September 24, 2016

Flying to the Far East

Somewhere over Iowa (May 19, 2016)

When I was a student in Pisa, I spent countless hours watching the world pass by, from the window of the intercity train that would ferry me back and forth between the city where I was studying, and the one where my family lived in the North of Italy. It seemed a very long trip at the time (about 200 miles that the train would cover in 4 hours), even though in my current midwestern frame of reference it is but around the corner. I relished watching the life of strangers pass-by from the second class window, like an unscripted movie pasted together by a director not quite awake from a surrealist dream. A way to suspend one's own thoughts by borrowing fleeting moments of other people's life.

Des Moines Airport
Since I came to the US, trains ceased to be my main method of transportation. The distances here are much larger than in Europe, and the trains themselves are just a shadow of their past glory, when they opened the Frontier to civilization (our particular variant of it) and genocide (of the people that had already civilized these wanted lands). In the US you either move by car, (the mechanical overlords that control America's suburbia commuters' life) or you fly. I started to fly a lot. To the observatories on top of remote desert mountains where I would use giant pieces of glass to pierce the sky (or, most often than not, the hated clouds) in invisible light. To far away cities where I would meet like-minded astro-obsessed individual, where we would discuss in conference the mysteries found in these observations. Even though the pace of my travel has decreased since moving to a University (teaching commitments) and since I started to use space telescopes (you don't really have to travel to space to use them), I still fly a lot. In about a decade I clicked over three quarters of a million miles, on just one of the many airlines that had been ferrying me around. This is more than 4 times the distance from the Earth to the Moon.

The next few posts will be about one of such trips. Mid-May this summer, as soon as the classes ended and the students were given to know their fate after the final exam, I packed my carry-on luggage and drove to the Des Moines airport, ready to fly to Beijing via Chicago. This was my first time in China, a country I had been always curious about, but never visited before. As I was traveling light, I made the objectionable choice of leaving my DSLR camera home. All the photos you will see in this series, including the ones in this post, were therefore shot as JPEG with an iPhone 6, and subsequently processed with Lightroom on my computer. In the next posts I will talk about the conference, and the places and people I visited in the trip. I hope you will enjoy coming along!

Chicago O'Hare Airport (May 19, 2016)

Saturday, September 10, 2016

Grand Marais at Night

Grand Marais, MN (Aug 19, 2016)

Grand Marais is a small center on the shores of Lake Superior, on the Minnesota side. Until the 1920s it could only be reached via boat through the lake. That made the town an important port in the area, thanks to the double bays that offered shelter from the severe storms that hits the area in winter.

Walking at sunset
The original name of the place, the Ojibwe Gichi-Biitoobiig, meant "double water", in reference to these two coves separated by a thin promontory protruding into the lake. A long walkway connects the two harbors, sneaking on the red rock all the way to the lighthouse at the end of the west side cove. A second lighthouse protects the cove from the opposite side. The promontory is now reinforced with a concrete drywall, to protect the fishing port that you can see in the panorama below. A placid mirror of still water bathed in the pink hues of the sunset. The walkway is traced right on top of the seawall, and in some points is just a foot wide. That was not enough for Kero, with his ingrained dislike of water. He panicked and stopped midway, refusing to set one paw more in what he considered a watery trap for his samoyeds instinct. I cannot fault him for that: in the natural environment of samoyeds (Siberian tundra), falling from the ice into liquid water would be a death sentence... So we had to turn back, but not before taking a couple of shots of other tourists walking on the ruby red rocks, or of the lighthouses in the fast approaching darkness.

Grand Marais is not isolated anymore and is now easily reachable driving along the scenic route 61, an hour past the Split Rock Lighthouse. It is a small and livable town, with many excellent restaurants and pubs. We had dinner  at the Harbor House Grille, with Kero that was allowed to stay with us on the nice patio. We got a local fresh fish, that turned out to be just perfect. Well worth the visit.

Grand Marais, MN (Aug 19, 2016)

Wednesday, September 7, 2016

The Split Rock Lighthouse State Park

Split Rock Lighthouse, MN (Aug 19, 2016)

On November 27, 1905, a storm system moved through the Great basin, bringing fresh easterly winds to the Great Lake region. By early morning the next day the winds had reached 68 miles per hour in the harbor of Duluth, Minnesota, on the shores of Lake Superior. It became known as the Mataafa storm, after one of the 29 ships that sank that day. During the storm the water of the lake on the North Shore were raised by almost three feet above normal, and heavy ice and snow covered the region. The temperature were so low that one of the body of the unfortunate sailors from the Maatafa wreck had to be chopped out of solid ice from the bay to be given a proper burial.

Split Rock Lighthouse Park
The portion of the Lake Superior shore where the wrecks occurred was named as the most dangerous coast of the whole Great Lakes region. To prevent a similar tragedy to repeat in future storms, the Pittsburg Shipping Company, owner of many of the lost vessels, lobbied the government to provide some protection in the form of a lighthouse. The Split Rock Lighthouse was built, on a 140-feet rock cliff overlooking Beaver Bay, not far from the site of another shipwrec from that fatal storm, that of the Madeira shooner-barge. With its octagonal shape, steel-frames brick building, it is the most picturesque lighthouse on the Great Lakes. When it was built there were no roads along the North Shore of Lake Superior, and all construction materials had to be supplied by water, and lifted on the cliffs with a crane. Its dramatic location made it a popular touristic attraction for sailors and excursion boats, and in 1924 a road was built from Duluth to allow land access. This was the beginning of Route 61 now connecting all the previously isolated towns on the North Shore, all the way to Grand Marais. Now retired, the lighthouse was added to the National Register of Historic Places in 1969, and designated as National Historic Landmark in 2011.

View from Corundum Point
Since 1945 the lighthouse is part of the Split Rock Lighthouse State park, managed by the Minnesota Department of Natural Resources. We visited the park on our free day during our summer trip to the North Shore. The park is beautifully maintained, with many trails on land, and even a kayak and canoe route along the lake shore. We spent the whole day walking around the park, with Kero leading the way from one pebbly beach to the next (see for example the panorama below). The park has several camping grounds easily accessible from the road; something to consider for the next time we will visit (assuming that Kero would be up for camping... we never tried staying overnight in a tent with him that and I am not sure he would be relaxed enough to actually let us sleep). Before turning back to the cabin we rented, we climbed up a trail leading to Corundum Point, a rocky outcrop raising from the lake with an excellent view on both sides of the shore (little photo above on the right). The point claims its name for the belief that the outcrop was rich of corundum mineral (Al2O3, the same gem as emerald). A crushing house was built high on the lake shore to process the mineral, that however turned out to just be a hard rock, and not the precious gem. One can still see the foundation of the mining buildings along the steep (and sometimes almost lost in the vegetation) trail.

After a quick lunch with some cheese I "smuggled" from Italy, we went back to the car, for a quick stop on the cabin we rented near Lutsen, before heading north to Grand Marais for dinner.

Split Rock Lighthouse Park, MN (Aug 19, 2016)

Saturday, August 27, 2016

The Belt of Venus in the Iron Range

Lutsen, Lake Superior, MN (Aug 18, 2016)

One week ago we drove up all the way to the Minnesota shore of Lake Superior, to spend a couple of days bracing for the beginning of the new semester. After loading Kero and a few supplies in the car we headed to Lutsen, where we found a last minute vacancy in a "Sea Villas" resort on the lake shore.

Belt of Venus
The cabins were very nice, and also quite dog friendly, meaning that Kero got to enjoy the view and had a chance of barking his head off to the waves, when we explored the rocky beach just in front of the porch. The view was indeed nice: all the photos in this post were taken from the grass in front of the porch, just as the sun was setting, and the moon rising on the placid waters of the lake. Do you see the banded sky in all the photos of this post? The blue, then pink, then sunset-colored sky? It is called "belt of Venus", and it is seen in clear skies opposite to the direction of the setting sun. The pink color is due to the light of the sunset scattered back by the fine dust particles high in the Earth's atmosphere. The dark blue zone that separates the pink from the horizon is instead the shadow of Earth projecting in the sky. The red rocks on the shore are not of that color because of the sunset: they are really that red, due to the high content of iron in the mineral in the area. After all, this is part of the Minnesota Iron Range.

You can see some of the cabins in the panorama below. We stayed there two nights, in between two days of driving (Lutsen is a 7.5 hours drive from Ames), with the middle day spent hiking along the lake shore, and having a nice dinner in Gran Marais (but this are stories for the next posts).

Lutsen, Lake Superior, MN (Aug 18, 2016)

Monday, August 15, 2016

Did We Found the Aliens?

Artistic impression of a swarm of comet-like fragments transiting in front of KIC 8462852. The debris tails left behind each fragment could be responsible for the observed dimming of the star (source: NASA/JPL-Caltech). The inset shows the image of the star as observed at infrared wavelength with NASA's Spitzer Space telescope (Marengo et al. 2015)

Well, most likely not. But before addressing the alien situation, let me first take a step back.

It all started with the Kepler SpaceTelescope, NASA’s facility tasked with finding worlds orbiting other stars. The spacecraft worked beautifully: since its 2009 launch it has already found 1041 extrasolar planets, with thousands more waiting for confirmation. Even after surviving a near-death experience due to the failure of its reaction wheels (the crucial devices that maintain its precise pointing), Kepler is still churning out top science, discovering new planets and characterizing their stars.

It is not one of the planets discovered by Kepler, however, that has astronomers around the world furiously scratching their head. It is a star, one of the 160,000 stars that Kepler monitored continuously for over 4 years during its main mission, that gave us the biggest surprise. It turns out that this star, with the uninspiring name KIC 8462852[1] has been undergoing a “dimming” behavior so unique to start a veritable firestorm of speculations among the scientific community, and the public as well.

The reason why this otherwise ordinary star is so special is that KIC 8462852 during  some of its dimming episodes decreased its brightness by as much as 20%. This kind of behavior is normally associated to events where an opaque body (e.g. a planet) transits in front of its star, partially blocking its light. When that happens, however, the dimming is usually less than one percent, it repeats periodically, and has a very well defined ingress and egress profile. Whatever obscured the light from KIC 8462852, however, did it in a very disorderly fashion, managing to occult as much as 1/5 of the disk of the star. This is unprecedented, rising the intriguing possibility that the culprit could be some gigantic artificial structure being built around of the star with the purpose of intercepting its light and use it as the ultimate energy source. Such structures, known as “Dyson Spheres”, have been described as the next step of an alien civilization that, having outgrown its home planet, expands to occupy its entire planetary system. In this view the dimming episodes observed around KIC 8462852 would be caused by the elements of an incomplete Dyson sphere transiting in front of the star, as the structure is still being assembled.

But, is this what is really happening around KIC 8462852?

Spitzer Space telescope (artist's impression)
and our spectrum of KIC 8462852.
As advanced as an alien civilization could be, it must still satisfy the fundamental laws of physics. And among such laws, are the principles of thermodynamics: if a Dyson sphere is intercepting a large fraction of the light from the star it surrounds, it must be heated in the process, and it must dissipate vast amounts of residual heat in the form of thermal radiation. To test this hypothesis, and to search for natural explanations for the unusual behavior of KIC 8462852, together with my students I have analyzed archival data from another NASA facility, the Spitzer Space telescope, designed to observe the cosmos in infrared light. Spitzer happened to observe this star several months after the last dimming episode detected by Kepler, offering the perfect opportunity to check for evidences of waste thermal emission from any structure closely orbiting the star. As shown in the analysis we published in the November issue of The Astrophysical Journal Letters, we didn’t find any sign of infrared radiation in excess of the light from the star. Whatever caused the anomalous dimming of KIC 8462852 is not anymore orbiting the star up close, but must have receded to the frigid outskirts of the system, where any leakage radiation would be tuned to a wavelength much longer than the infrared radiation to which Spitzer is sensitive. This is hardly the behavior expected from a Dyson sphere closely encircling a star. Furthermore, an extensive search for extraterrestrial intelligence (SETI) transmission has so far failed to detect any signal coming from this system (the gamma-ray astronomy group in our department has also been involved in this search).

If not aliens, what is then happening on the doorstep of KIC 8462852? We still don’t know for sure. The leading hypothesis is that the dimming was caused by the fragments of some small planetary body (a large asteroid or a dwarf planet) that had the misfortune to break-up along a highly eccentric orbit circling the star (such breakup events are rare, but not unprecedented). As the fragments approached their orbit’s periastron the furious radiation from the star could have caused ablation and sublimation of volatile elements from the surface of the fragments, leading to the formation of enormous and opaque streams of left-behind debris, capable to partially obscure the star. This process is not different from the mechanism in which Solar System comets form their dusty tails as they sweep around the Sun; it is just on a vastly more massive scale. By the time Spitzer trained its optics toward KIC 8462852 the fragments and debris tails would have had enough time to travel along their orbit to the outskirt of the system, where not even the sensitive infrared detectors of Spitzer could have detected their residual heat.

We still don’t know if this hypothesis will hold true: more data is needed to confirm or rule out this scenario. For this reason, we have launched an international effort to monitor the star from space and from the ground, hoping to catch a future dimming episode and perhaps detect the elusive thermal radiation that must be associated with it. In the meantime, KIC 8462852 remains one of the most mysterious stars in our Galaxy, a puzzle that has stimulated the curiosity of scientist and public alike, and that we hope will soon reveal its wondrous secrets.

[1] KIC stands for “Kepler Input Catalog” and the index code, despite appearances, is not a telephone number, although it does answers a landline in Pleasantville, IA (don’t try this at home).
and that we hope will soon reveal its wondrous secrets.

This article was first published on the 2016 issue of "Quanta and Cosmos", the Alumni Newsletter of the Iowa State University Department of Physics and Astronomy.

This image is unrelated to the topic of the post but hey, this is my photoblog so I want to have a photo shot by me in it. Las Campanas Observatory, Chile. Note that KIC 8462852 is in the Kepler Field (in between the Cygnus and Lyra constellations), so it is not visible from the southern hemisphere.