Tuesday, January 28, 2014

Dry Desert and Clear Skies

Norte Chico, Chile (January 8, 2006)

We live at the bottom of a turbulent ocean, an ocean of air that we call atmosphere. It is a thin layer, if we look at it from space: an almost impalpable skin. Still, for all creatures living at the bottom of this sea, it is a nurturing elixir, our sustenance, the source of life. For us astronomers, however, is more like a scourge!

Let me qualify. It is not that we astronomers don't like to breathe, that's not the issue. The problem is that this turbulent ocean is, well, turbulent. It is like looking up from the bottom of a swimming pool: you can still see the lifeguard looking down from the side of the pool, but she is all blurred. You would never tell that she has that concerned face as she is trying to figure out what the hell are you doing at the bottom, until she jumps in and pulls you out and your pool card is revoked. Crap! It is the same with the atmosphere, it blurs and distorts the light coming from the stars, making our billion-dollar telescopes worthless (well, almost). And that's not even all of it: even in crystal-clear days the sky is not really transparent: the pesky molecules that makes up our air are very selective about the color of the light they allow to pass through. In the visible range, the one the human eye can see, it is not so bad. But go slightly redder or slightly bluer (we have nice CCD detectors for that) and the atmosphere becomes increasingly opaque. The main culprits for this are some notorious molecules we all know about: water vapor, ozone and CO2. These molecules are particularly nasty in the infrared and microwave range: this is not surprising since they are powerful greenhouse gasses. They let Sun's radiation in, but don't allow the thermal infrared radiation from the ground to escape back to space. The heat is trapped and the poor planet overheats. If you are a climatologist, you should be concerned about CO2, which of these three molecules is the one we are artificially messing up to level not seen in millions of years. If you are an astronomers, however, your enemy is water. If you want to see the infrared stars you need to find the place with the least amount of water vapors on top of your head. Hence astronomers quest for dry high mountain deserts.

This is what northern Chile offers to astronomers. A dry highland desert with little or no precipitations, and a very dry air that is as transparent as it gets without leaving the atmosphere altogether and launch your telescope to space. The Las Campanas observatory is at the edge of the largest of the Chilean dry highlands: the Atacama desert. You can see the views in the photos of this post: rocks, sands and a sturdy fauna and flora perfectly adapted to an environment where it may not rain for years: an astronomer's dream, and a beautiful muse for a photographer looking for unadulterated landscapes of the nude Earth.

Norte Chico, Chile (January 8, 2006)


Saturday, January 25, 2014

Old Stars Never Die, They Slowly Fade Away

Las Campanas Observatory, Chile (January 9, 2006)

Like old soldiers in the WWII army ballad, most stars never die, they slowly fade away.

The fate of stars is assigned at birth. A few stars are born very massive, and they live a fast and furious life, burning bright like candles lit on both ends. After just a few million years, they run out of nuclear fuel and collapse under their own weight. This collapse rebounds in a final stupendous explosion, so bright that can be seen across the Universe. These are the events that we call supernovae. Massive stars are however very rare, and most stars are instead born with a low mass, like the Sun or even lighter. These stars burn quietly for a very long time, many billions of years, ending their life in a much less dramatic way. When they feel that the end is night, they become giants: swollen balloons of warm gas, deep red jewels in the night sky. They pulsate, like a tired throbbing heart, one single beat per year. They also smoke: a sooty fog blown out by a slow inexorable wind. A smog so thick that ends up engulfing the star and its planets in a dark cocoon, hiding them from sight. That's when these old stars disappear, fading away from the visible universe behind their curtain of death. Even for stars, however, nothing is forever. The veil finally dissipates, revealing the hot cinder remnant of the star, surrounded by a glowing nebula like a butterfly emerged from it cocoon. We call these fleeting beauties planetary nebulae.

Magellan telescope
I am telling you this story because the primary scientific reason for my 2002 trip to Chile was to spy on these cocoons where old stars hide in their final moments. For this project we used the newly built Magellan telescope (photo on the left), equipped with a new camera we shipped all the way from Arizona: an infrared camera, because with light of this invisible color we can lift the veil surrounding these stars, revealing their secrets. There are many reasons why we want to understand the how and why these stars end their like in such a mysterious way. For starters, the Sun is one of them, although it will take several more billion years before all this will happen. The more pressing reason, however, rests in the nature of the holy smoke that these old stars spew around in their final disappearing act. Talking about smoke was not a poetic license on my part, but rather a quite literal description. For many of these stars the composition of these cocoons is rich in carbon and many complex organic molecules: the building blocks of life. Studying the death of these stars will lead to understand how life arose in the Universe. We literally are stardust, and these stars are the fairies that seeds an otherwise sterile Galaxy with the ingredients of life.

Las Campanas Observatory, Chile (January 8, 2006)

Wednesday, January 22, 2014

Looking for Exomoons and Diapers along the Panamericana

Along the Panamericana, Chile (May 4, 2002)
My first trip to Chile happened in 2002, and I was scheduled to use the newly built Magellan "Baade" 6.5 meters aperture telescope. Getting time on large telescopes is hard, so the usual observing runs at facilities like the twin Magellan telescopes don't last more than a few nights. If you get good weather you return home with a treasure trove of data which will feed your research for months. If the gods of rain are instead against you... well you have gone all the way to the end of the world, and back, for nothing. My 2002 trip to Chile was however different. I went there to help testing a camera never before used on that telescope, so we had plenty of engineering time to debug our instrument. Lots of time: a 20 nights run. Spending such a long period at the telescope is cool, until of course you realize that for that same long time you are stuck on top of a mountain, in some deserted isolated place.

OGLE Telescope Dome
Salvation in this 2002 run came in the form of a friend of mine, Grzegorz, an astronomer from Poland working for the Optical Gravitational Lensing Experiment (OGLE). This project uses the small telescope shown in the photo on the left. OGLE is a very cool program, scanning the sky in the search of a rare phenomenon in which a star acts as a lens for a background object. The physics of the phenomenon is related to Einstein's General Relativity: massive objects deflects light due to their gravitational field. Even the Sun does it: if you could see the stars during daytime you would notice that the ones near the Sun would appear in a slightly different place than where they are supposed to be. This is an experiment that you cannot normally do, because during daytime there is no way to see the stars. Except of course when there is an eclipse, in which case the glare of the Sun is blocked by the Moon and you can see the sky behind as if it was night time. This measurement was in fact first accomplished in 1919, and was the first test to demonstrate the validity of Einstein's theory of gravity. OGLE tries to do the same but using other stars rather than the Sun, when they randomly align with stars farther away. This is an extremely rare event, because it requires an almost perfect alignment, but if you look continuously at a large number of stars, sooner or later you are bound to get lucky. For this reason OGLE looks at the two Magellanic Clouds (dwarf galaxies close to the Milky Way) and at the bulge of our own Galaxy, where millions of stars can be surveyed without having to cover an impossibly large area. When one of this millions of stars flickers because of this gravitational lensing effect, one can derive the properties of the lensing object from the characteristics of the flickering. With this techniques we can see very faint stars that we would not be able to detect directly, and count them, which is important to have a reliable census of the kind of stars that populate our Galaxy. Sometimes we even get some surprise: in some rare cases these flickering events may be followed by a secondary, fainter flicker, due to a planet orbiting the star that caused the primary lensing event. One month ago the OGLE people got an even bigger surprise: a peculiar lensing event that could have been caused by a "free floating" giant planet with an Earth-size exo-moon, roaming the Galaxy alone after having been ejected from their native planetary system. This could be the very first detection of a moon in another solar system.

Given the nature of the OGLE survey, Grzegorz is often stuck at Las Campanas Observatory for months on end. When that happens he bring to the observatory his whole family, which in 2002 meant his wife and a very young child. It also means that he has a car, which is a necessity if you need to be able to get away from the self-contained, but very utilitarian, environment of the observatory. Which brings us to the second part of the title of this story. At some point during their stay, Grzegorz run out of diapers for the kid, and decided to drive down the mountain in a quest for diapers in the villages around the observatory. I went along with him.

You can imagine how the search went. As described very well by Kelly Clancy in this essay, the area around Las Campanas is a dry highland desert. The only inhabited centers that you will encounter along the Panamericana highway that is crossing the region are tiny villages with tin-roof houses. They are mostly living off subsistence agriculture adapted to the very arid climate of the area. The large photo on top and the panoramic at the bottom show the typical landscape: naked mountains crossed by dirt roads, and in the fall season rows of aji peppers left to dry under the Sun. The villages have only small stores where you can find basic needs products. While that apparently includes lots of Nestle canned food, the inventory doesn't really include single use diapers: these are luxury items that make very little sense when you can rather use a washable cloth, reusable as many times as you want. It didn't take long to realize that the people we asked for the diapers were quite baffled by our inquiries. Diapers (or the lack thereof) are a #FirstWorldProblem.

In the end we did find some temporary solution to Grzegorz's problem, and drove back to the observatory, but not before stopping on a side road where we saw the petroglyphs in the small photo on the right. As it happens, the Panamericana highway retraces the the same route of an ancient Inca trail, a road that for a thousand years has enabled the commerce between the center of the Inca civilization in Cuzco, and these villages at the periphery of the empire. These same villages are still there, and they will still fight the parched highland desert well after we will have abandoned our telescopes and returned to our ivory towers.

Sideroad off the Panamericana Highway, Chile (April 30, 2002)

Saturday, January 18, 2014

Mountains and Telescopes in the Chilean Andes

Las Campanas, Chile (January 6, 2006)

The north of Chile is the astronomer's paradise, and hosts many of the largest aperture telescopes looking at the southern skies (the northern sky is best seen from Hawaii or the US southwest). There are two main reasons for this: dry high mountains and political stability. The high plateau in northern Chile are shielded by the Andes from the easterly moist winds: raising above the inversion layer in the atmosphere, the Andes stops the Clouds on their east side, leaving deserts to the west and forests (the Amazon) and grasslands (the pampa) to the east. Lacks of clouds means transparent nights and a sky with little turbulence, in turn guaranteeing excellent observing conditions for most of the year. Political stability means the possibility of building long-term expensive projects, and the creation of the necessary infrastructures. The dirty secret of astronomy is that Chile was chosen not because it was the best absolute place in the Andes, but because Pinochet's dictatorship was guaranteeing long-term commitment in exchange for investor countries to overlook the human right violations in the country. In the end, modern democratic Chile got a good deal out of the observatories (Chile is now the world's country with more guaranteed telescope time in the world, and an astronomer's mecca), but at the time I suspect there was a lot of looking the other way from the community.

Las Campanas, Chile
I have been in Chile several times, visiting the Las Campanas Observatory (LCO). LCO is in the "Norte Chico", which is a region one hour (by small plane) north of Santiago, but not as north to be on the border with Peru (the "Norte Grande"). The closest city is La Serena, a nice town on the coast, renowned vacation place thanks to its long sandy beaches. Two other observatories are in the area: the observatory of Cerro Tololo (managed by the NOAO, the organization providing open access time to US-based astronomers) and the La Silla Observatory (managed by ESO, the European Southern Observatory). LCO is instead a partnership of the Carnegie Observatories with the Smithsonian Astrophysical Observatory (SAO): my ticket to the telescope was through SAO, where I had been employed for many years. I will post photos of the LCO telescopes at some other time, but you can see the telescope domes of La Silla in the panoramic below: can you find the white dots on the crest of the mountain on the left? The photo was taken from the minibus driving me from La Serena to Las Campanas. The large photo above and the small one on the left show the sunset from the LCO terrace, shot the first night I arrived at the site. As you can see the area is very isolated, with just a few little villages in the valleys below, guaranteeing no light pollution that would blind the delicate astronomical instruments. This is actually a serious issue for modern astronomy: the main sites in Arizona, for example, are in a constant struggle to keep down light pollution from the Tucson metropolitan area, which are bright enough to seriously degrade the site. To prevent this issue, the Chilean government has recently established a vast protected area around the observatory sites in the Atacama desert (this is in the Norte Grande), to favor the construction of the new 30 meters telescope (the European Extremely Large Telescope, or E-ELT) that Europe is building there.

Norte Chico, Chile (January 6, 2006)

Wednesday, January 15, 2014

Piopiotahi and the Mountains of Fiordland

Milford Sound, New Zealand (June 3, 2008)


Maui was the first mortal man. He wasn't born so... in fact he almost wasn't born at all. He was the last son of Taranga, who rejected him as an infant and threw him into the sea. Rangi, the god of the sky, took pity of him: so it happened that Maui was raised by Rangi as one of his children. Years later Maui went to look for his mother and siblings. He found them in her home, and confronted his mother. She at first denied his claims, but finally relented and accepted him as is last son, the one that she had in her old age, which she abandoned at sea in her girdle. So Maui become known as Maui-the-girdle-of-Taranga and was accepted in her home.

A fall in Milford Sound
His brothers were jealous, but were eventually won over by his indefatigable personality. A Maori Hercules, he enlisted his brothers in a series of superhuman enterprises, among which snaring the Sun, stealing the fire from the gods and raising land from the ocean. When he was bored he transformed his brother-in-law into a dog and stole his grandmother jawbone. He was restless, always in search of a new challenge.

And the ultimate challenge he found, when he decided that he would seek and defeat Hine-nui-te-po, the first woman and the goddess of the underworld. Rangi warned him that he would perish in the attempt, but he decided to try anyway. He gathered the company of the birds of the forest, and set out to the west, where the sky meet the Earth and the Sun sets. There he found Hine, asleep and revealing the entrance to the underworld. Set in-between her tights, it was a dark cave encrusted with sharp flints and gemstones, ready to crush anybody daring to venture inside. His companions the birds again warned him that he would die if he tried to enter the cave, and that they would laugh at him for his recklessness. But he didn't want to hear any of it, and prepared to go inside, his mighty war club tightly tied to his arm. Just as he was at the entrance of the cave, however, the piopio bird burst into a laugh. The old lady suddenly awoke, shut close her legs and cut Maui in two.

This was the end of Maui, who became the first men to die, after which all humans are bound to death. The piopio was overwhelmed with sorrow, and flew to the deserted lands to the south, where the sea enters the mountains in deep cold fiords. There he was found many years laters by Maori explorers, the piopiotahi, the lone fantail bird still in mourning for having caused the mortality of humankind. That's the name the Maori gave to the fiord that we call Milford Sound. [You can read more about the myths and legends of New Zealand at the Te Ara encyclopedia]

We visited Milford Sound in our 2008 trip to New Zealand. To access the fiord one has to drive to a scenic mountain road that passes through the mountains in the panorama below. The fiord itself is very spectacular, with high peaks (like Mitre Peak, the triangular pyramid on the left in the photo above) raising straight from its deep dark waters. The waters are dark because the high rainfall in the area (feeding the numerous waterfalls like the one on the left) wash in the fiord the tannin-rich vegetation growing on their steep slopes. That makes Milford Sound waters very opaque, and give rise to a unique ecosystem in which fish and coral species that in other areas of the world only live at great depth, are here accessible just a few meters from the surface.

With this story, is time to leave the island of Middle Earth and cross the Pacific due East, where the mighty mountain chain of the Andes, with their telescopes scrutinizing the southern sky, are waiting.

Along the road to Milford Sound, New Zealand (June 3, 2008)

Friday, January 10, 2014

Of Wandering Islands and Sleeping Giants

Lake Wanaka, New Zealand (June 2, 2008)

The New Zealand's south island is not just an interrupted chain of mountains. There are valleys, of course, which were created by the glaciers when Earth was an all-white ice-age snowball. Once the glaciers retired, the scarred valleys were filled with water, which formed lakes. Not just some lakes, 3,820 of them, if you count just the ones with a surface area larger than 1 hectare.

Lake Hawea
Being New Zealand, these lakes have a lot of legends about them. One refers to the lake pictured above, and goes like this. There was once a man that lived in Wanaka. He had a fishing station at the lake with the same name. One day he was fishing on the shores of the lake when the finger of land where he was standing, with a loud noise like, broke off and floated away like a water-bird. What happened is that under the grass where he was standing there was a tipua, which was something like a water spirit. Maybe it was a kappa, like they have in Japan? Maybe, but in any case the poor fishermen was so scared that he forgot to jump on the shore before it was too late, and was transported to the newly created floating island, Taki-karara, which is still wandering around the lake with its unlucky occupant.

Another Maori legend has a more happy ending, but concerns a place that is not pictured in this blog. It is about lake Wakatipu, an S-shaped water body near Queenstown. The tale is told by Amanda in her "A Dangerous Business" blog. It is a forbidden-love story. Her name was Manata, and she was the daughter of an important chief. His name was Matakauri, and he was a dashing poor commoner. They were in love, and wanted to marry. Not so fast, said Manata's father, as poor Matakauri was not what he had in mind for his daughter. Well, things never go according to plans, not even if you are a big chief: before he could find an appropriate groom for Manata, she was kidnapped by Matau, a giant monster living in the mountains. Manata's father declared that whoever would succeed in freeing his daughter, he will have her as bride. Clearly a perfect opportunity for Matakauri, who entered the lair of the monster while he was sleeping at night, found Manata and brought her to safety without waking the sleeping giant. He clearly did a much better job than a certain hobbit that could not even steal a gem without waking a dragon. This was not the end of the story, though, because Matau was kind of pissed and wanting revenge. So Matakauri had to go back and hunt the monster, before the wretched creature could lay waste of Manata, her father and the whole village. Ever the sleepy head, Matau was caught again in morpheus hands, curled in between the snowy mountains. An easy prey for Matakauri, that set him on fire. The fire burned intensely for many days, until it melted all the snow of the mountains. The water rushed to occupy the space created by the charred monster, and formed lake Wakatipu, which in Maori means "The Hollow of the Giant".

Lake Wanaka, New Zealand (June 2, 2008)


Friday, January 3, 2014

Aoraki and Rarakiroa

Mt. Cook (Aoraki) and Mt. Tasman (Rarakiroa), New Zealand (June 1, 2008)

In the creation myth of the Ngai Tahu people, at the beginning the gods were living in the ocean of nothingness. At that time Raki (the Sky) was married with Pokoharua-te-po, and they had several children, the eldest of which was Aoraki (the Clouds in the Sky). One day Raki left Pokoharua-te-po, to join Papatuanuku (the Earth): from their union the world was born.

The mists of lake Matheson
Aoraki and his brothers, curious to visit their new stepmother, decided to descend from the heaven to visit Papatuanuku. They took the great canoe from the sky (Te Waka o Aoraki) and descended on the oceans of Earth. Once they saw Papatuanaki with their father, however, they realized that Raki would never return to the heavens, and felt sorry for their abandoned mother. They set to return to Pokoharua-te-po, once more raising to the heavens with their waka. Unfortunately things didn't go according to the plan. Their canoe failed to raise and was overwhelmed by the growing winds and swelling tides, and got overturned by the waves. The brothers climbed back on the overturned canoe, waiting for rescue from the gods. Time passed, and nobody came. Their hair became white and they turned to stone. Their waka was transformed in the South Island of New Zealand, and the brothers in the Southern Alp peaks. Aoraki, the elder son of the god of the Sky, became the tallest peak of all, the one the Pakeha (the fair skinned ones) call Mount Cook. [adapted from the Ko Tane web site]

The area of Aoraki and Rarakiroa (Mount Tasman) are sacred to the Ngai Tau people. As part of the Waitangi Treaty settlement in 1998, the whole area was returned to the tribe, to be then donated back for the benefit of all the New Zealand people. It is now part of the Aoraki / Mount Cook National Park. The treaty also provided the restoration of all Maori geographical names, including the mountains, following their common english names. To underline the importance of Aoraki for the Ngai Tau culture, the Maori name of Mount Cook precedes its english name.

Fox Glacier in front of Mt. Tasman (June 1, 2008)

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