четверг, 16 августа 2018 г.

2018-2022 expected to be abnormally hot years

This summer’s world-wide heatwave makes 2018 a particularly hot year. As will be the next few years, according to a study led by Florian Sévellec, a CNRS researcher at the Laboratory for Ocean Physics and Remote Sensing (LOPS) (CNRS/IFREMER/IRD/University of Brest) and at the University of Southampton, and published in Nature Communications. Using a new method, the study shows that at the global level, 2018-2022 may be an even hotter period than expected based on current global warming.











2018-2022 expected to be abnormally hot years
Illustration depicting the strong likelihood of abnormally hot temperatures for the period of 2018-2022,
based on the PROCAST interannual climate prediction system (PRObailistic ForeCAST)
[Credit: © François Lamidon]

Warming caused by greenhouse gas emissions is not linear: it appears to have lapsed in the early 21st century, a phenomenon known as a global warming hiatus. A new method for predicting mean temperatures, however, suggests that the next few years will likely be hotter than expected.


The system, developed by researchers at CNRS, the University of Southampton and the Royal Netherlands Meteorological Institute, does not use traditional simulation techniques. Instead, it applies a statistical method to search 20th and 21st century climate simulations made using several reference models to find ‘analogues’ of current climate conditions and deduce future possibilities. The precision and reliability of this probabilistic system proved to be at least equivalent to current methods, particularly for the purpose of simulating the global warming hiatus of the beginning of this century.


The new method predicts that mean air temperature may be abnormally high in 2018-2022 – higher than figures inferred from anthropogenic global warming alone. In particular, this is due to a low probability of intense cold events. The phenomenon is even more salient with respect to sea surface temperatures, due to a high probability of heat events, which, in the presence of certain conditions, can cause an increase in tropical storm activity.


Once the algorithm is ‘learned’ (a process which takes a few minutes), predictions are obtained in a few hundredths of a second on a laptop. In comparison, supercomputers require a week using traditional simulation methods.


For the moment, the method only yields an overall average, but scientists now would like to adapt it to make regional predictions and, in addition to temperatures, estimate precipitation and drought trends.


Source: CNRS [August 14, 2018]



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Study of material surrounding distant stars shows Earth’s ingredients ‘pretty...

The Earth’s building blocks seem to be built from ‘pretty normal’ ingredients, according to researchers working with the world’s most powerful telescopes. Scientists have measured the compositions of 18 different planetary systems from up to 456 light years away and compared them to ours, and found that many elements are present in similar proportions to those found on Earth.











Study of material surrounding distant stars shows Earth's ingredients 'pretty normal'
Artists impression of white dwarf star (on right) showing dust disc,
 and surrounding planetary bodies [Credit: NASA]

This is amongst the largest examinations to measure the general composition of materials in other planetary systems, and begins to allow scientists to draw more general conclusions on how they are forged, and what this might mean for finding Earth-like bodies elsewhere.


“Most of the building blocks we have looked at in other planetary systems have a composition broadly similar to that of the Earth”, said researcher Dr Siyi Xu of the Gemini Observatory in Hawaii, who was presenting the work at the Goldschmidt conference in Boston.


The first planets orbiting other stars were only found in 1992 (this was orbiting a pulsar), since then scientists have been trying to understand whether some of these stars and planets are similar to our own solar system.


“It is difficult to examine these remote bodies directly. Because of the huge distances involved, their nearby star tends to drown out any electromagnetic signal, such as light or radio waves” said Siyi Xu. “So we needed to look at other methods”.


Because of this, the team decided to look at how the planetary building blocks affect signals from white dwarf stars. These are stars which have burnt off most of their hydrogen and helium, and shrunk to be very small and dense – it is anticipated that our Sun will become a white dwarf in around 5 billion years.


Dr Xu continued, “White dwarfs’ atmospheres are composed of either hydrogen or helium, which give out a pretty clear and clean spectroscopic signal. However, as the star cools, it begins to pull in material from the planets, asteroids, comets and so on which had been orbiting it, with some forming a dust disk, a little like the rings of Saturn. As this material approaches the star, it changes how we see the star. This change is measurable because it influences the star’s spectroscopic signal, and allows us to identify the type and even the quantity of material surrounding the white dwarf. These measurements can be extremely sensitive, allowing bodies as small as an asteroid to be detected”.


The team took measurements using spectrographs on the Keck telescope in Hawaii, the world’s largest optical and infrared telescope, and on the Hubble Space Telescope.


Siyi Xu continued, “In this study, we have focused on the sample of white dwarfs with dust disks. We have been able to measure calcium, magnesium, and silicon content in most of these stars, and a few more elements in some stars. We may also have found water in one of the systems, but we have not yet quantified it: it’s likely that there will be a lot of water in some of these worlds. For example, we’ve previously identified one star system, 170 light years away in the constellation Boötes, which was rich in carbon, nitrogen and water, giving a composition similar to that of Halley’s Comet. In general though, their composition looks very similar to bulk Earth.


This would mean that the chemical elements, the building blocks of earth are common in other planetary systems. From what we can see, in terms of the presence and proportion of these elements, we’re normal, pretty normal. And that means that we can probably expect to find Earth-like planets elsewhere in our Galaxy”.


Dr Xu continued “This work is still on-going and the recent data release from the Gaia satellite, which so far has characterized 1.7 billion stars, has revolutionized the field. This means we will understand the white dwarfs a lot better. We hope to determine the chemical compositions of extrasolar planetary material to a much higher precision”


Professor Sara Seager, Professor of Planetary Science at Massachusetts Institute of Technology, is also the deputy science director of the recently-launched TESS (Transiting Exoplanet Survey Satellite) mission, which will search for exoplanets. She said:


“It’s astonishing to me that the best way to study exoplanet interiors is by planets ripped apart and absorbed by their white dwarf host star. It is great to see progress in this research area and to have solid evidence that planets with Earth-like compositions are common–fueling our confidence that an Earth-like planet around a very nearby normal star is out there waiting to be found”.


Source: Goldschmidt Conference [August 15, 2018]




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Iron and titanium in the atmosphere of an exoplanet

Exoplanets, planets in other solar systems, can orbit very close to their host star. When, in addition to this, the host star is much hotter than our Sun, then the exoplanet becomes as hot as a star. The hottest “ultra-hot” planet was discovered last year by American astronomers. Today, an international team, led by researchers from the University of Geneva (UNIGE), who joined forces with theoreticians from the University of Bern (UNIBE), Switzerland, discovered the presence of iron and titanium vapours in the atmosphere of this planet. The detection of these heavy metals was made possible by the surface temperature of this planet, which reaches more than 4000 degrees. This discovery is published in the journal Nature.











Iron and titanium in the atmosphere of an exoplanet
Artist’s view of a sunset over KELT-9b. The nearby warm blue star covers 35° in the planet’s sky,
about 70 times the apparent size of the sun in the Earth’s sky. Under this scorching sun, the planet’s
atmosphere is warm enough to shine in reddish-orange tones and vaporize heavy metals
such as iron and titanium [Credit: Denis Bajram]

KELT-9 is a star located 650 light years from Earth in the constellation Cygnus (the Swan). With a temperature of over 10,000 degrees, it is almost twice as hot as the Sun. This star is orbited by a giant gas planet, KELT-9b, which is 30 times closer than the Earth’s distance from the Sun. Because of this proximity, the planet circles its star in 36 hours and is heated to a temperature of over 4,000 degrees. It’s not as hot as the Sun, but hotter than many stars. At present, we do not yet know what an atmosphere looks like and how it can evolve under such conditions.
That is why NCCR PlanetS researchers affiliated with the University of Bern recently performed a theoretical study on the atmosphere of the planet KELT-9b. “The results of these simulations show that most of the molecules found there should be in atomic form, because the bonds that hold them together are broken by collisions between particles that occur at these extremely high temperatures”, explains Kevin Heng, professor at the UNIBE. This is a direct consequence of the extreme temperature. Their study also predicts that it should be possible to observe gaseous atomic iron, in the planet’s atmosphere using current telescopes.


Light reveals the chemical components of the atmosphere


The UNIGE FOUR ACES team, which is also part of the NCCR PlanetS at the Department of Astronomy of the Faculty of Science of the UNIGE, had observed this planet precisely as it was moving in front of its host star (i.e. during a transit). During transit, a tiny fraction of the light from the star filters through the planet’s atmosphere and analysis of this filtered light can reveal the chemical composition of the atmosphere. This is achieved with a spectrograph, an instrument that spreads white light into its component colours, called a spectrum. If present among the components of the atmosphere, iron vapour would leave a well-recognisable fingerprint in the spectrum of the planet.


Using the HARPS-North spectrograph, built in Geneva and installed on the Telescopio Nazionale Galileo in La Palma, astronomers discovered a strong signal corresponding to iron vapour in the planet’s spectrum. “With the theoretical predictions in hand, it was like following a treasure map,” says Jens Hoeijmakers, a researcher at the Universities of Geneva and Bern and lead author of the study, “and when we dug deeper into the data, we found even more,” he adds with a smile. Indeed, the team also detected the signature of another metal in vapour form: titanium.


This discovery reveals the atmospheric properties of a new class of so-called “ultra-hot Jupiter”. However, scientists believe that many exoplanets have completely evaporated in environments similar to KELT-9b. Although this planet is probably massive enough to withstand total evaporation, this new study demonstrates the strong impact of stellar radiation on the composition of the atmosphere. Indeed, these observations confirm that the high temperatures reigning on this planet break apart most molecules, including those containing iron or titanium. In cooler giant exoplanets, these atomic species are thought to be hidden within gaseous oxides or in the form of dust particles, making them hard to detect. This is not the case on KELT-9b. “This planet is a unique laboratory to analyze how atmospheres can evolve under intense stellar radiation,” concludes David Ehrenreich, principal investigator with the UNIGE’s FOUR ACES team.


Source: Université de Genève [August 15, 2018]




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Old species learn new tricks…very slowly

A quick look at the fossil record shows that no species lasts forever. On average, most species exist for around a million years, although some species persist for much longer. A new study published in Scientific Reports from paleontologists at the Smithsonian Tropical Research Institute in Panama shows that young species can take advantage of new opportunities more easily than older species: a hint that perhaps older species are bound to an established way of life.











Old species learn new tricks...very slowly
Stiff setae extend away from the edge of cupuladriid bryozoan colonies, and work in synchrony to allow the colony
 to “walk” over the sea floor [Credit: Aaron O’Dean, Smithsonian Tropical Research Institute]

“We’re lucky to live and work in Panama where nature has set up its own evolutionary experiment,” said Aaron O’Dea, STRI paleontologist. “When the Caribbean Sea was isolated from the Pacific Ocean by the slow uplift of the Isthmus of Panama, nutrient levels fell and Caribbean coral reefs proliferated. We can use the excellent fossil record to observe how Caribbean life responded to this dramatic environmental and ecological transformation.”
The team’s best choice for tracking the change was a peculiar family of marine animals known as the cupuladriid bryozoans. These relatively small animals consist of unusual, free-living, disc-shaped colonies of individuals called zooids. “Colonies form through sexual reproduction or asexually by cloning, as bits of the colony break off and continue to grow,” said STRI post-doc and coauthor Blanca Figuerola. “They abound on the sea floor along the continental shelf across the tropics, filtering plankton from the water via a beautiful waving crown of tentacles. When colonies die, their hard skeletons remain, and are exceptionally abundant as fossils.”











Old species learn new tricks...very slowly
A free-living cupuladriid bryozoan colony filter feeding with its many crowns of tentacles
[Credit: Aaron O’Dea, Smithsonian Tropical Research Institute]

O’Dea’s group collected and identified more than 90,000 cupuladriid colonies from 200 fossil samples and 90 more recent samples collected by dredging the sea floor. The samples contained mud, sand, coral remains and other indicators of the kind of habitats where the bryozoans had lived. The team measured the abundances of the 10 most common species along gradients of these environmental and ecological indicators.
“We were intrigued to find that, even though all species could expand into the new Caribbean habitats created after final formation of the Isthmus, different species did so at different speeds,” said O’Dea. “The patterns were clear–old species that originated before 8 million years ago took 2 million years longer to expand into the new habitats than the younger species.”











Old species learn new tricks...very slowly
Aaron O’Dea, paleontologist at the Smithsonian Tropical Research Institute, examines marine fossils
 in the Dominican Republic [Credit: Sean Mattson, STRI]

“Perhaps younger species, which have smaller populations, are less tied to their history,” said former STRI post-doc and University of Saskatchewan researcher Santosh Jagadeeshan, another co-author. “Old species, with large, settled populations may be less able to escape from established roles and defined environmental tolerances because they mate with each other creating a high gene flow that makes it hard for genes for new traits to become established. It seems you can’t teach an old dog new tricks in evolution, either.”


Source: Smithsonian Tropical Research Institute [August 15, 2018]



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Britain’s dry summer reveals ancient sites

Previously hidden archaeological sites have emerged in fields across Britain after the hot, dry summer exposed new cropmarks, the Historic England agency said on Wednesday. Aerial photographs have exposed patterns which reveal the sites of prehistoric settlements, burial mounds and Iron Age, Bronze Age and Roman farms.











Britain’s dry summer reveals ancient sites
Prehistoric ceremonial landscape near Eynsham, Oxfordshire. The cropmarks reveal buried remains of later Prehistoric
(circa 4000BC-700BC) funary monuments, together with settlement. This site was known about and is protected
as a scheduled monument, but there are features, such as a circle of pits that have not been visible for years
[Credit: © Historic England]

Among the new discoveries are two Neolithic monuments near Milton Keynes in central England. These are rectangular-shaped constructions believed to have been enclosed paths or processional ways, usually dating from between 3,600 and 3,000BC.


One monument was recently mapped, but until this year another one next to it was hidden beneath a bank of earth that is being gradually ploughed away. Several of the finds are in the south-west region of Cornwall, including an Iron Age round — a settlement surrounded by a circular ditch — in St Ives.











Britain’s dry summer reveals ancient sites
Two Neolithic cursus monuments near Clifton Reynes, Milton Keynes. They are one of the oldest monument types in
the country, usually dating from between 3600 and 3000BC. Until this year, the enclosure on the right has lain
hidden beneath a medieval bank known as a headland that is being ploughed away. They are generally thought
 to be enclosed paths or processional ways, while they may also have served to demarcate or even act
as a barrier between different landscape zones [Credit: © Historic England]










Britain’s dry summer reveals ancient sites
Iron Age Round, St Ive, Cornwall. The circular feature visible in the centre of this photograph is probably a Round.
Rounds were widespread in Cornwall in the Iron Age [Credit: © Historic England]











Britain’s dry summer reveals ancient sites
Prehistoric Settlement, Lansallos, Cornwall 
[Credit: © Historic England]










Britain’s dry summer reveals ancient sites
Iron Age square barrows, Pocklington, Yorkshire 
[Credit: © Historic England]










Britain’s dry summer reveals ancient sites
Prehistoric settlement or cemetery, Stoke by Clare, Suffolk 
[Credit: © Historic England]











Britain’s dry summer reveals ancient sites
Roman Farm, Bicton, Devon [Credit: © Historic England]










Britain’s dry summer reveals ancient sites
Prehistoric farms, Stogumber, Somerset 
[Credit: © Historic England]










Britain’s dry summer reveals ancient sites
Prehistoric Enclosure, Churchstanton, Somerset 
[Credit: © Historic England]

Crops planted above ancient ditches or other earthworks often flourish because the disturbed ground retains more moisture than undisturbed soil. As a result, in drought conditions, they stay green longer. In contrast, crops planted above the remnants of ancient stone walls grow less well, and after a dry spell are often more bleached in colour.


When viewed from above, both can give a clear outline of what lies beneath. “This spell of very hot weather has provided the perfect conditions for our aerial archaeologists to ’see beneath the soil’ as cropmarks are much better defined,” said Duncan Wilson, chief executive of Historic England.


“The discovery of ancient farms, settlements and Neolithic cursus monuments is exciting. “The exceptional weather has opened up whole areas at once rather than just one or two fields and it has been fascinating to see so many traces of our past graphically revealed.”


Historic England also discovered an Iron Age burial site in Yorkshire, northern England, with cropmarks representing square ditches surrounding a burial mound. Further details have also emerged of existing sites, including lost Elizabethan buildings and gardens associated with Tixall Hall in Staffordshire.


Source: AFP [August 15, 2018]



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Excavations of the University of Cyprus at the citadel of ancient Paphos (Kouklia)

The Department of Antiquities of Cyprus (Ministry of Transport, Communications and Works) announced the completion of the University of Cyprus’ 13th field project at Palaipaphos, under the direction of Professor Maria Iacovou (Department of History and Archaeology, Archaeological Research Unit). The 2018 excavations took place between May and July and concentrated on the plateau (citadel) of Hadjiabdoulla, one kilometer east of the sanctuary of Aphrodite.











Excavations of the University of Cyprus at the citadel of ancient Paphos (Kouklia)
Wall excavated on the northern side of the plateau [Credit: Department of Antiquities of Cyprus]

According to the results of the Ancient Paphos landscape analysis project, which has been running since 2006, the Hadjiabdoulla plateau was the administrative-economic centre (i.e. the acropolis) of Ancient Paphos during the Cypro-Classical period.











Excavations of the University of Cyprus at the citadel of ancient Paphos (Kouklia)
The Kouklia-Palaipaphos site [Credit: Department of Antiquities of Cyprus]

Along the Northern side of the plateau, the archaeological mission of the University of Cyprus has identified and is investigating a complex architectural unit, which was constructed at the beginning of the 5th century BC by the Paphos royal dynasty, within the context of its economic administration. The unit’s production and storage facilities are located in corridors that develop outside the acropolis walls. Up to now, 65 metres of the fortification wall have been revealed, as well as 6 different units and communication corridors.











Excavations of the University of Cyprus at the citadel of ancient Paphos (Kouklia)
Plan of the excavations [Credit: Department of Antiquities of Cyprus]

The masonry survives at 2 metres in height, while the fill has helped preserve the workshop installations, where various moveable finds have been excavated, such as mill stones, basins, olive presses, weights and water pipes. A variety of palaeo-environment remains have survived (such as, animal bones, seeds, olive pips, charcoal and slag), which are being collected and analysed following state-of-the-art methods, so as to be able to reconstruct the economic model of the ancient city.











The eastern corridor [Credit: Department
of Antiquities of Cyprus]

In Units 3 and 4 investigations have confirmed the production of olive oil. Unit 1 mainly served as a storage area, since large quantities of local and imported amphorae (mainly wine amphorae) were found in this area, reflecting the extent of the trade networks maintained by ancient Paphos in the Cypro-Classical period (end of the 6th century BC) with Carthage, Egypt, the coast of modern-day Lebanon, Syria, the Aegean (Thasos, Kos, Mende, Rhodes and Chios) and the coast of Asia Minor (Ephesus, Samos, Miletus), especially from the 4th to the 2nd century BC.











Excavations of the University of Cyprus at the citadel of ancient Paphos (Kouklia)
Unit 2 and the eastern corridor [Credit: Department of Antiquities of Cyprus]

The aim of the 2018 excavations was to complete investigations in Units 2, 5 and 6, as well as of the corridor in the east, which communicates with these.











Excavations of the University of Cyprus at the citadel of ancient Paphos (Kouklia)
Murex shells collected from Unit 2 [Credit: Department of Antiquities of Cyprus]

Large quantities of murex shells were collected from the entire surface area of Unit 2. Following analysis of the shells by specialist Dr Demetra Mylona, it was confirmed that, the extraction of the purple dye from the shells was conducted in nearby areas, which have not yet been identified. The shells were then concentrated in Unit 2 for secondary processing and use (e.g. for making hydraulic mortar).











Excavations of the University of Cyprus at the citadel of ancient Paphos (Kouklia)
Drainage pipes in Unit 5 [Credit: Department of Antiquities of Cyprus]

Units 5 and 6 to the North, are part of an industrial installation, which is situated between two parallel retaining walls, under which stone pipes have been excavated, which lead to a stone bathtub in Unit 6. Due to the lack of macroscopic data from the pipes and the bathtub, it is not yet certain what these monumental installations were producing. As a result of funding from the A.G. Leventis Foundation for the 2017-2018 investigations, sampling was taken for microscopic analysis of starch and phytoliths. The analysis will be conducted at the Wiener Laboratory of the American School of Classical Studies in Athens.











Excavations of the University of Cyprus at the citadel of ancient Paphos (Kouklia)
Unit 6 [Credit: Department of Antiquities of Cyprus]

More information on the 2006 to 2018 missions, as well as frequent updates onPULP (The Palaepaphos Urban Landscape Project)(including the team members, special scientists, lectures delivered both in Cyprus and abroad, as well as publications) can be found on the Project’s website https://ucy.ac.cy/pulp/


Source: Department of Antiquities of Cyprus [August 16, 2018]



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Hendrefor Burial Chambers, nr. Pentraeth, Anglesey, North Wales,…








Hendrefor Burial Chambers, nr. Pentraeth, Anglesey, North Wales, 14.8.18.


This is the second time I have visited this site and the first time I’ve been up close to it. The remains of two potential passage graves that have collapsed, it becomes apparent that at least one of these must have been huge. The orthostats are tall and the obvious capstone is sizeable. The other remains of the second chamber make it harder to imagine a clear structure. Whilst the site may be ruined, it still gives some impression of a prehistoric complex that must have been impressive. 


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Solar System 10 Things: Spitzer Space Telescope


Our Spitzer Space Telescope is celebrating 15 years since its launch on August 25, 2003. This remarkable spacecraft has made discoveries its designers never even imagined, including some of the seven Earth-size planets of TRAPPIST-1. Here are some key facts about Spitzer:


1. Spitzer is one of our Great Observatories.



Our Great Observatory Program aimed to explore the universe with four large space telescopes, each specialized in viewing the universe in different wavelengths of light. The other Great Observatories are our Hubble Space Telescope, Chandra X-Ray Observatory, and Compton Gamma-Ray Observatory. By combining data from different kinds of telescopes, scientists can paint a fuller picture of our universe.


2. Spitzer operates in infrared light.



Infrared wavelengths of light, which primarily come from heat radiation, are too long to be seen with human eyes, but are important for exploring space — especially when it comes to getting information about something extremely far away. From turbulent clouds where stars are born to small asteroids close to Earth’s orbit, a wide range of phenomena can be studied in infrared light. Objects too faint or distant for optical telescopes to detect, hidden by dense clouds of space dust, can often be seen with Spitzer. In this way, Spitzer acts as an extension of human vision to explore the universe, near and far.


What’s more, Spitzer doesn’t have to contend with Earth’s atmosphere, daily temperature variations or day-night cycles, unlike ground-based telescopes. With a mirror less than 1 meter in diameter, Spitzer in space is more sensitive than even a 10-meter-diameter telescope on Earth.


3. Spitzer was the first spacecraft to fly in an Earth-trailing orbit.



Rather than circling Earth, as Hubble does, Spitzer orbits the Sun on almost the same path as Earth. But Spitzer moves slower than Earth, so the spacecraft drifts farther away from our planet each year.


This “Earth-trailing orbit” has many advantages. Being farther from Earth than a satellite, it receives less heat from our planet and enjoys a naturally cooler environment. Spitzer also benefits from a wider view of the sky by orbiting the Sun. While its field of view changes throughout the year, at any given time it can see about one-third of the sky. Our Kepler space telescope, famous for finding thousands of exoplanets – planets outside our solar system – also settled in an Earth-trailing orbit six years after Spitzer.


4. Spitzer began in a “cold mission.”



Spitzer has far outlived its initial requirement of 2.5 years. The Spitzer team calls the first 5.5 years “the cold mission” because the spacecraft’s instruments were deliberately cooled down during that time. Liquid helium coolant kept Spitzer’s instruments just a few degrees above absolute zero (which is minus 459 degrees Fahrenheit, or minus 273 degrees Celsius) in this first part of the mission.


5. The “warm mission” was still pretty cold.



Spitzer entered what was called the “warm mission” when the 360 liters of liquid helium coolant that was chilling its instruments ran out in May 2009.


At the “warm” temperature of minus 405 Fahrenheit, two of Spitzer’s instruments – the Infrared Spectrograph (IRS) and Multiband Imaging Photometer (MIPS) – stopped working. But two of the four detector arrays in the Infrared Array Camera (IRAC) persisted. These “channels” of the camera have driven Spitzer’s explorations since then.


6. Spitzer wasn’t designed to study exoplanets, but made huge strides in this area.



Exoplanet science was in its infancy in 2003 when Spitzer launched, so the mission’s first scientists and engineers had no idea it could observe planets beyond our solar system. But the telescope’s accurate star-targeting system and the ability to control unwanted changes in temperature have made it a useful tool for studying exoplanets. During the Spitzer mission, engineers have learned how to control the spacecraft’s pointing more precisely to find and characterize exoplanets, too.


Using what’s called the “transit method,” Spitzer can stare at a star and detect periodic dips in brightness that happen when a planet crosses a star’s face. In one of its most remarkable achievements, Spitzer discovered three of the TRAPPIST-1 planets and confirmed that the system has seven Earth-sized planets orbiting an ultra-cool dwarf star. Spitzer data also helped scientists determine that all seven planets are rocky, and made these the best-understood exoplanets to date.


Spitzer can also use a technique called microlensing to find planets closer to the center of our galaxy. When a star passes in front of another star, the gravity of the first star can act as a lens, making the light from the more distant star appear brighter. Scientists are using microlensing to look for a blip in that brightening, which could mean that the foreground star has a planet orbiting it. Microlensing could not have been done early in the mission when Spitzer was closer to Earth, but now that the spacecraft is farther away, it has a better chance of measuring these events.


7. Spitzer is a window into the distant past.



The spacecraft has observed and helped discover some of the most distant objects in the universe, helping scientists understand where we came from. Originally, Spitzer’s camera designers had hoped the spacecraft would detect galaxies about 12 billion light-years away. In fact, Spitzer has surpassed that, and can see even farther back in time – almost to the beginning of the universe. In collaboration with Hubble, Spitzer helped characterize the galaxy GN-z11 about 13.4 billion light-years away, whose light has been traveling since 400 million years after the big bang. It is the farthest galaxy known.


8. Spitzer discovered Saturn’s largest ring.



Everyone knows Saturn has distinctive rings, but did you know its largest ring was only discovered in 2009, thanks to Spitzer? Because this outer ring doesn’t reflect much visible light, Earth-based telescopes would have a hard time seeing it. But Spitzer saw the infrared glow from the cool dust in the ring. It begins 3.7 million miles (6 million kilometers) from Saturn and extends about 7.4 million miles (12 million kilometers) beyond that.


9. The “Beyond Phase” pushes Spitzer to new limits.



In 2016, Spitzer entered its “Beyond phase,” with a name reflecting how the spacecraft operates beyond its original scope.


As Spitzer floats away from Earth, its increasing distance presents communication challenges. Engineers must point Spitzer’s antenna at higher angles toward the Sun in order to talk to our planet, which exposes the spacecraft to more heat. At the same time, the spacecraft’s solar panels receive less sunlight because they point away from the Sun, putting more stress on the battery.



The team decided to override some autonomous safety systems so Spitzer could continue to operate in this riskier mode. But so far, the Beyond phase is going smoothly.


10. Spitzer paves the way for future infrared telescopes.



Spitzer has identified areas of further study for our upcoming James Webb Space Telescope, planned to launch in 2021. Webb will also explore the universe in infrared light, picking up where Spitzer eventually will leave off. With its enhanced ability to probe planetary atmospheres, Webb may reveal striking new details about exoplanets that Spitzer found. Distant galaxies unveiled by Spitzer together with other telescopes will also be observed in further detail by Webb. The space telescope we are planning after that, WFIRST, will also investigate long-standing mysteries by looking at infrared light. Scientists planning studies with future infrared telescopes will naturally build upon the pioneering legacy of Spitzer.


Read the web version of this week’s “Solar System: 10 Things to Know” article HERE


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Mantle xenon has a story to tell http://www.geologypage.com/2018/08/mantle-xenon-has-a-story-to-tell.html


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