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Uranus and Neptune have amazing atmospheres, just like Jupiter and Saturn. The Hubble telescope is used periodically to monitor the condition of these atmospheres and to help uncover their secrets.

Voyager 2 is the only human probe to have reached Uranus and Neptune, providing close-up images of these ice giants as well as their moons and rings. The late André Brahic, one of the discoverers of the rings of Neptune had also fallen under the spell of Triton, the satellite of Neptune with cryovolcanism.

On this occasion, in August 1989, Voyager 2 had revealed the existence of the Great Dark Spot (GDS) on Neptune, in its southern hemisphere, apparently similar to the Great Red Spot of Jupiter, that is, an anticyclonic storm. It is, however, much more unstable. While this phenomenon existed at least since the XIX the century on Jupiter, the GDS eventually dissipate or become invisible in 1994, the Hubble telescope that had detected its first light only in recent years. A new dark Great Spot has appeared in the northern hemisphere later, but to disappear from the gaze of telescopes a few years later, there too.
Astronomers continue to study the meteorology of Neptune, as well as that of Uranus, from the ground and, of course, again with Hubble. It is the only one with the necessary sensitivity to detect major storms in the band color blue in the visible and showed the existence of a Great Dark Spot on Neptune's northern hemisphere at the end of the year 2018. Although qu'éloignée the Sun and therefore less supplied power than the atmosphere of Earth, the Neptune is surprisingly turbulent and active. It is now estimated that a large dark spot would appear on average every six years but would only last about two years.

The Nasa has just made public the images of the latest observations of the activity of Neptune, as well as that of Uranus with the Hubble telescope. They take place in a long-term program of monitoring these planets to uncover their secrets just as it is necessary to monitor, with satellites, the state of the Earth's atmosphere in the long term to understand it and predict its evolution. The data collected for the giants are archived as part of the Outer Planet Atmospheres Legacy ( OPAL ).

Neptune and Uranus, laboratories to understand planetary atmospheres

In the photo below (right-hand thumbnail) showing the last appearance of a large dark spot, a procession of white, shiny clouds of methane crystals is again visible. They are thought to be formed by currents of hydrogen and helium (also containing this gas ) which are diverted to higher altitudes, in much the same way as on Earth, when a similar atmospheric current meets an isolated mountain. Steam then condenses as the pressure changes, gaining altitude and spreading cloud cover around the top of the mountain.

Like the one on Jupiter, the formation of Neptune's stain remains elusive, and many mysteries remain about it. Hubble, however, has shown that an increase in the formation of methane ice clouds in 2016 preceded the appearance of a new Dark Great Spot. This suggests that this giant anticyclonic storm is beginning to form deep within the atmospheric layer surrounding the vast mantle of ice, itself encircling the rock core of Neptune - which is not a gas giant like Jupiter and Saturn but well a giant ice cream - before going back to the surface.

As for Uranus, is observed a kind of large bright white cap, matching thunderclouds, centered on its north pole and occupying a significant portion of its hemisphere (see photograph Hubble above). It is thought that this amazing structure is related to the fact that the axis of rotation of the ice giant is particularly inclined to the perpendicular of the plane of its orbit to the point of being almost parallel. Thus, Uranus alternately presents to the Sun its north pole, then its south pole during each orbit which lasts 84 years. This surprising inclination is due to giant collisions between Uranus and celestial bodies in its past.

However, this particular configuration must be the source of seasonal phenomena that are just as much. We are currently in the midst of the summer season of Uranus and its polar cloud cap is growing. Here too, what happens in the atmosphere of Uranus remains, despite everything, a subject of interrogation.

In both cases, these planets allow us to explore our atmospheric models under different conditions and therefore, to reproduce the equivalent of experiments in physics where we can control the parameters governing them. This should allow to better understand our planet but also the exoplanets outside the Solar System.

WHAT YOU MUST REMEMBER

• Mankind has been trying to better understand Uranus and Neptune since their discovery about two centuries ago.
• However, their real faces are revealed only on the occasion of the mission Voyager 2 which has, in particular, shown that Neptune had a Great Dark Task similar to the Great Red Task of Jupiter.
• The Hubble telescope has been used for decades now to regularly monitor the atmospheres of Neptune and Uranus to unlock the secrets.

In brief: Hubble pays tribute to Neptune

By Jean-Baptiste Feldmann published on 15/07/2011

Neptune was discovered ... a year ago! At least in Neptunian time. The eighth planet of the Solar System has indeed completed its first complete orbit since its discovery in the 19 century. An anniversary that the Hubble Space Telescope had to celebrate.

On September 23, 1846, the German astronomer Johann Gottfried Galle found  Neptune in his telescope according to the calculations of position made by the French Urban Le Verrier. For the first time, a planet was discovered through mathematics.

Since 2006 and the decision of the International Astronomical Union to exclude Pluto from the solar system planets club, Neptune is the planet furthest away from the Sun. Orbiting about thirty astronomical units (which makes it invisible to the naked eye from the Earth with a magnitude of 8), Neptune puts 164.79 years to perform a complete revolution, the time that has elapsed since his discovery. In August 1989, the planet received a visit from the Voyager 2 spacecraft, which discovered 5 new satellites (13 of which are known today, the most famous of which is Triton ) and confirmed the presence of Trojan's rings and asteroids.

To celebrate Neptune's first complete orbit since its discovery, the Hubble telescope used its wide-field camera and photographed the different faces of the rotating planet on June 25 and 26. The thick atmosphere of Neptune (mainly consisting of hydrogen and helium) is the seat of tremendous storms where winds can reach 2,000 kilometers per hour.

Methods of laser coloring of metals accessible to both artists and mass production: this is what Russian researchers are proposing today. A new means of expression that is efficient and accurate, without chemicals that are potentially toxic.

Images of color labeled laser on metals, it is not new. But researchers from the ITMO University (Russia) today explain how, thanks to a single laser emitting nanosecond pulses, they have been able to implement three different colorization techniques.

"After the laser treatment, various micro and nanostructures are formed. This creates optical effects that change the color of the treated surface, " says Nadezhda Shchedrina. A technique that can be implemented in a limited time, to create both small and large images.

A laser and three techniques for a color palette

The color of the metal can first be modified by oxidation. The laser produces a thin film of oxide on the metal surface. When light hits this film, a color appears due to interference. Another method is the formation of nanoparticles of sizes between 5 and 50 nanometers. In this case, it is the phenomenon of resonance of plasmon surface that gives rise to colors, depending on the size of the particles. Finally, the laser structuring technique consists in melting a part of the metal surface to create a periodic network of grooves or slots. The scattered light then produces colors that depend on the viewing angle.

These methods can find applications in the field of art, but also in that of mass production of jewelry, for example. They could also be used to create systems that help fight counterfeit.

Metals of all colors thanks to a femtoliter

By sculpting, literally, the surface of a metal using very short laser pulses, an American team claims to be able to give just about any color to any metal.

Article by Jean-Luc Goudet published on 05/02/2008

In 2006, Chunlei Guo and his team at the Institute of Optics at the University of Rochester, New York, had already exhibited an amazing black metal. It was not a particular alloy, but any metal made almost completely black, that is, capable of absorbing light in all wavelengths of the visible. The same team has perfected the principle and is able to change the color of metal to give it any shade.

How do they do? The laboratory of Chunlei Guo is specialized in the use of fem to lasers, emitting a pulse of extremely short duration, of the order of several femtoseconds (1 femtosecond is worth 10 -15 seconds). We can thus arrive at powers of the order of a hundred terawatts. In their laboratory, Chunlei Guo's team manages to concentrate this photonic flood on a very small surface.

How to cut cauliflowers

The energy is such that the metal is deformed. The secret of these scientists is to have managed to control these deformations to carve reliefs at the nanometer scale and the micrometer. In 2006, the metal thus obtained had a much larger surface, because of this roughness which formed furrows, crests and various forms, cauliflower for some. This surface increase made the method an interesting way to manufacture catalysts, for example for fuel cells, which act by adsorption, that is to say by temporarily fixing the active ingredients on their surface.

If the metal turned black, it was because these multiple forms, with various dimensions but of the order of the wavelengths of the visible light, absorbed them all. Since 2006, the team has made progress and can now obtain patterns of different sizes. Chunlei Guo and his assistant Anatoliy Vorobyev are now able to choose the color of metal. An apple - green steel, lemon - yellow aluminum or purple gold should be achievable ... The authors believe that the process could become industrialize, to tint objects without painting.
It will still solve some problems, such as reducing the cost of fem to lasers and, for the process itself, reduce the processing time, currently about thirty seconds for a surface of a few square centimeters. A little long to color a car ... Moreover, the team does not say how these delicate nanometric or micrometric structures resist wearing.

Paleoanthropologists seek to better understand Neanderthals. And specify their diet is one of the ways they use for this purpose. A fine study of the isotopes of collagen residues in Neanderthal fossils confirms the suspicions issued for some time. The Neanderthals ate most of the meat of the large mammals they lived next to.

The disappearance of Neanderthals remains an enigma that always leaves one puzzled. While not only could he hybridize with modern man, he was capable of behaviors as sophisticated as those believed to be unique to Homo sapiens.  And since he does not seem to have had a net evolutionary disadvantage, how can he explain that he has lost the race of survival and evolution, and all the more so since there is no trace of extermination of Neanderthals organized by sapiens?

There are certainly some fundamental differences to explain what happened but we are still looking for them. This is why paleoanthropologists are looking for any additional information. However, recently, several troubling indications have led them to reconsider the diet generally attributed to Neanderthals. There were already some tracks with these remains found in the caves and tools used as well as, of course, fossils of animals testifying to a fauna that was contemporary to them. These elements were all good reasons to think that they should at least feed on mammoth meat and reindeer.

However, at the beginning of XXI, the century science helps in learning more today than it did not allow the prehistorians it a century ago; their vision of the Neanderthals was rudimentary and false on many points. DNA amplification techniques have established that sapiens and Neanderthals have mixed with remains of genetic material found in the found bones of Neanderthals; in the same way, it is possible to use certain isotope measurement techniques to make these fossilized remains talk about Neanderthals' diet.

Previous studies have focused on the composition of collagen, a common protein in animals, in Neanderthal bones. They had come to the conclusion that their diet was mainly meaty but with a small vegetarian component, which was not unlike, of course, that of Homo sapiens. But recently, studies of nitrogen isotopes have caused trouble.

No fish in the Neanderthals diet

The researchers had measured particularly high levels of a certain isotope, leaving room for several interpretations; in particular, Neanderthals ate fish, putrid meat, or even weaned late compared to modern humans. In fact, intersected with other indications, one could even involve cannibalism.

But today, an international team of researchers - of which Jean-Jacques Hublin, professor and director of the Max Planck Institute of Evolutionary Anthropology - is a member, publishes an article in  PNAS  and revisits this debate by using the isotopic data of collagen nitrogen in a new way.

The collagen samples come from the bones of two Neanderthal subjects found in France, respectively in the cave of the Reindeer, in Arcy-sur-Cure and that of the Cottés. Behind this new method used, the idea is based on the fact that we can differentiate diets at the level of differences in nitrogen isotope for the different amino acids forming the protein that is collagen.

The researchers showed that, in both cases, there was actually a trace of a diet with fish, in accordance also with the fact that no trace of fish remains fresh water is found in these two caves. Therefore, the Neanderthal mother of the infant, whose bones were in the cave of the Reindeer (to be precise, the collagen came from a tooth), had a meaty diet and deprived of fish. This is interesting information because, on the contrary, fish was part of the Homo sapiens diet.

Finally, the researchers concluded that Neanderthals massively consumed fresh meat from large mammals, in this case, mammoths, mainly reindeer and horses. This diet, which could contain plants, was even very stable over time, even after the arrival of modern humans in Europe.

WHAT YOU MUST REMEMBER

• Recent analyses of N isotopes in collagen found in Neanderthal remains suggest that they can feed on large quantities of fish or rotting meat.
• New and finer analyzes confirm that the Neanderthal diet was predominantly composed of fresh meat from large mammals such as mammoths or reindeer. The fish should not be on the menu but the plants were not excluded.

Paleolithic Neanderthal diet: mammoth with vegetables

Article by Laurent Sacco published on 2016-03-17

Why did the Neanderthal Man disappear? Should we look for the reason in his diet? Still, it would be necessary to know precisely. Thanks to isotopic chemistry we now know more about the Paleolithic Neanderthals. On the menu: 80% mammoth meat and rhinoceros, plus 20% plants.

The "Paleolithic Diet" is very fashionable but what is the reality? What did humans eat tens of thousands of years ago? The dentition of prehistoric men and the remains of meals give us an idea today but it remains vague, lacking a machine to go back in time. There are still one of this kind discovered in the early XX the century: the isotopic chemistry. This technique provides amazing information.

There are several isotopes of elements such as carbon, nitrogen, sulfur, and oxygen. Depending on the physiology of the animals and their diets, their bones and collagen contain particular proportions of these isotopes or others. Oxygen isotopes, for example, have been involved in the debate over the warmth or poïkilothermal character of the dinosaurs and certain marine reptiles that were their contemporaries. These same isotopes also made it possible to determine the way of life of the famous dinosaurs: it was semi-aquatic.

More recently, isotope chemistry has been used to know the diet of British King Richard III. This year, members of the Center for Research on Human Evolution and Paleoenvironment in Tübingen applied it to the study of the diet of the Neanderthals, this cousin of Homo sapiens with whom, the fact is now proven, there were hybridizations.

Neanderthal, a big eater of mammoth meat and rhinoceros

More generally, the researchers looked at collagen found in bones from two sites in Belgium that belonged to Neanderthals and mammoths, bison, bears and cave lions but also to horses and woolly rhinos. All this small world lived from 45,000 to 40,000 years ago. Collagen is an abundant protein in animals, where it is present in cartilage, tendons, skin, and bones.

It was found that the predators of the day mainly fed on prey smaller than them and occupying specific ecological niches But it was not the same for the Neanderthals. Their Paleolithic diet consisted of about 80% mammoth meat and woolly rhinoceros. During the Pleistocene, these animals inhabited mainly the cold steppes that covered much of Eurasia, from central Spain and southern England to Mongolia and southern Siberia.

In addition, about 20% of the Neanderthal diet consisted of plants. These conclusions are little different from those of studies of the diet of modern men. Since Neanderthal ate the same thing, it seems that his disappearance 30,000 years ago is not attributable to his diet.

From the data collected by the Soho mission, a Franco-Russian team calculated that the atmosphere extended up to 630,000 kilometers beyond the Earth! It would, therefore, encompass the Moon. Jean-Loup Bertaux, director of research emeritus at the CNRS and former head of the photometer who acquired the data in question, explains this rather surprising discovery.

While the space boundary was arbitrarily set at 80 and 100 kilometers above sea level, an international team including two CNRS researchers has just discovered that our atmosphere extends up to 630,000 kilometers, almost twice as much. far than the Moon, six times farther than the limit so far supposed! The data recorded by the Swan photometer on board the space-based observatory Soho of Sun, almost twenty years ago (between 1996 and 1998) allowed the French-Russian team led by Jean-Loup Bertaux, research director emeritus at the CNRS, to calculate that the geocorona extended up to twice the distance Earth-Moon. The study has just been published in the journal  Journal of Geophysical Research.

Did you know?

Set at 100 kilometers above sea level, the Kármán line is recognized by the International Aeronautical Federation (FAI). The second arbitrary boundary is located 20 kilometers lower (80 km altitude). She is recognized by NASA and the US Air Force.

A rather surprising discovery that also means that the atmosphere of "  the Earth is much wider than the thin blue ring that surrounds our planet seen from space  ", says Jean-Loup Bertaux, former head of the Swan photometer. Beyond that circle, she "  continues to be" melt "into space, is ending in a vast cloud of atoms of hydrogen which is called geocorona  " explains the scientist also a senior researcher of the Atmosphere Laboratory, media, space observations (Latmos).
That said, at this distance, the atmosphere has nothing to do with the one that allows us to live on Earth. In reality, the Earth's atmosphere quickly becomes extremely tenuous: "  At  60,000km, it is already composed of only 70 atoms per cubic centimeter ... and halfway, at the Moon, only 0, 2 atoms per cubic centimeter. To say the void ... or almost. Do not imagine being able to breathe air on the surface of the Moon!

A geocorona who will not prevent the good progress of human activities nearby and on the Moon

But it should be known that these particles, essentially hydrogen atoms, pose no threat to manned flights to the moon, or to astronauts aboard the lunar outpost that will be built close to the moon. Moon on the horizon 2025. As for those who will be active on the lunar soil, the risk is also marginal. They will especially have to worry about the Sun, the main source of radiation that could affect them.

On the other hand, this discovery is "   a step further towards a refinement of the measurements  " and could serve to "  correct the errors of observation of the sky in the ultraviolet  ". Indeed, the hydrogen atoms emit ultraviolet radiation that could parasitize future astronomical observations conducted in the geocorona. Whether on the Moon or in its vicinity, "  the telescopes space  studying the  chemical composition  of stars and galaxies should consider these interferences  ."

Finally, this discovery also has a playful side. In addition to knowing today that the Moon is moving in Geocouronne, it is amusing to think that the "Apollo astronauts on the surface of the Moon did not know that they were bathing in the atmosphere of the Earth! "

WHAT YOU MUST REMEMBER

• The atmosphere of the Earth extends far beyond what was thought.
• An international team has calculated that it extends up to 630,000 kilometers from the Earth, encompassing the Moon.
• Two French researchers participated in this study, including Jean-Loup Bertaux, former head of the instrument, to whom we owe the data that allowed this calculation.

The first private space mission to the Moon, carried by the Israeli SpaceIL, was successfully launched on 21 February 2019. The probe, called Bereshit, is expected to land in April on the visible side of the moon, making Israel the fourth country in history to achieve a moon landing.

The first Israeli probe to the Moon, and the first developed by a private organization, SpaceIL, began Thursday, February 21, 2019, its journey to the moon, where it must arrive in seven weeks to try to make Israel the fourth country to achieve a moon landing.

A Falcon 9 rocket from space company SpaceX flew safely from Cape Canaveral in Florida at around 20.45 (01.45 GMT Friday), a shot taken live from Israel in the middle of the night by many engineers and supporters of the mission, and by Prime Minister Benjamin Netanyahu, who waved Israeli flags from the control center of the Israeli Aerospace Industries (IAI) aerospace company  , partner of the project.

Then, half an hour later, more than 750 kilometers above Africa and at a speed of 35,000 km / h, the second stage of the rocket deployed the probe, called Bereshit (Genesis, in Hebrew). She will perform several orbits elliptical around the Earth, which will serve as an impetus, with the help of its engine to take in a second time the direction of the Moon, where the landing is scheduled on 11 April. The rocket also carried an Indonesian satellite and a US Air Force satellite.

Objective: to be the first private probe to alun

"It's a big step for Israel, and it's a big step for Israeli technology," Mr. Netanyahu enthused, turning away the famous words of Neil Armstrong, the first man on the moon. "The real fuel of this machine is the boldness and genius of Israel," he said, and despite the size of Israel,  "we are giants. "

The initiative is private, promoted since 2010 by SpaceIL, a non-profit organization. But the project is an object of national pride in Israel, where it is repeated that only three nations have so far succeeded in alienating: the United States, Russia and China (only Americans have walked on the moon).

Initially, the project was to respond to the Google Lunar XPrize contest, which wanted to reward $ 30 million for the first private aircraft to land before March 2018. No one had reached it in time, but the SpaceIL team continued the mission and bought a secondary seat in SpaceX's rocket.

Originally planned at $ 10 million, the mission eventually cost 100, but  "it is the least expensive gear to attempt such a mission, " insists the IAI group. It is notably the businessman and philanthropist Morris Kahn who financed the development of the robot.

The moon landing itself is the main mission, even if a scientific instrument is carried away to measure the lunar magnetic field. Bereshit is designed to last only a few days. A capsule in the robot contains digital discs with children's drawings, songs, and images of Israeli symbols, memories of a Holocaust survivor, and a Bible.

Non-Israeli partners participated. SpaceIL will communicate with the probe using antennas from the  Swedish Space Corporation. The Nasa has made available its  Deep Space Network to return to Earth data Bereshit. The US Space Agency has also installed a laser retro-reflector on the robot to test the laser's potential for space navigation.

The new race for the Moon

The renewed interest in the Moon sometimes called the "eighth continent" of the Earth, is global, the year 2019 being particularly busy. China, which had filed its robot "Jade Bunny" in 2013, sent in January on its hidden side its Chang'e-4, and it plans other missions. India hopes to become the fifth lunar country in the spring with its Chandrayaan-2 mission, which will include a moon and a mobile robot. Japan plans to send a small lunar lander, called SLIM, to study a volcanic area by 2020-2021.

As for Americans, the return to the moon is now the official policy of NASA, according to the guidelines of President Donald Trump in 2017. To achieve this, the US space agency changes model and no longer wants to design the missions itself. It has launched tenders for the private space sector, in full swing in the United States. She would like to send pennants at the end of the year, but more likely in 2020.

NASA has also launched the project of a lunar orbit station, supposed to be completed in 2026, to serve the return of astronauts on lunar soil in 2028. The return to the Moon is seen as the preparation for sending humans on Mars, in the next decade at the earliest.

WHAT YOU MUST REMEMBER

• With the launch of a spacecraft on February 21, 2019, for the Moon, SpaceIL is well on its way to becoming the first private company to achieve a moon landing.
• SpaceIL is about to become the first private company to land on the moon!
• Article by Rémy Decourt, published on 07/02/2019

SpaceIL is about to become the first private company to land on the moon!

Fifty years after the Apollo missions, SpaceIL, a small Israeli company, is about to open a new chapter of the space conquest with the launch of Beresheet (Genesis in Hebrew), a  lunar lander. This lander originally planned to compete in the Google Lunar X Prize, has seen its development continue despite the cancellation of this prize. It will land on the sea of Serenity from where it will realize measurements of the lunar magnetic field.

While ArianeGroup and ESA are considering a mission to the Moon, launched by Ariane 6 over the next few years, the SpaceX Falcon 9 is about to launch the SpaceIL Technology lunar lander. This lander will embark as an auxiliary passenger on a scheduled commercial flight on February 18th.

Baptized  Beresheet (Genesis in Hebrew), this lander was one of the competitors in the Google Lunar X Prize contest, whose goal was to see, for the first time, a private company land on the moon. In March 2018, it was canceled because none of the five teams still in the running had been able to land on the Moon before the date set (March 31, 2018). Despite the cancellation of this competition, some of the competitors had decided to continue the development of their project, including the Israeli team SpaceIL.

Built with Israel Aerospace Industries, Beresheet is a high module of 1.5 meters, two meters wide for a launch mass of 585 kg including 400 kg of propellant. It must land on the moon two to two and a half months after its launch. A length of the journey may seem long astonishment while the distance of the Moon to the Earth in a straight line, is only a few days. But, to limit the propulsion of propellant, the lender will use the force of gravity from the Earth to set off for the Moon. It will perform three orbits around the Earth. Two other orbits around the Moon will be needed to break the craft and allow it to land at the planned location.
If successful, it will be not only the first Israeli spacecraft to land on the moon but also the very first private lender to land there. The lender will have a very short lifespan, only a few days, until the batteries run out.

Near Luna 21 and Apollo 17

Beresheet will land in the Sea of Serenity in which Luna 21 (January 1973) and Apollo 17 (December 1972) landed. This site was obviously not chosen at random. He is known for his magnetic anomalies that the only instrument on board the lander will measure. The other highlight of the mission will be the attempt to take off very briefly from the lunar soil. Not to leave the Moon and return to Earth, but to make a displacement of several tens of meters, even a few hundred. A joke inherited from the Google Lunar X Prize which provided for several objectives awarded financially including that of moving a distance of several tens of meters.

Beresheet will also ship two DVRs and an Arch disk containing digital files. They will include the Declaration of Independence and the National Anthem of Israel, songs in Hebrew, the Old Testament and Jewish prayer for a safe journey known as "Wayfarer's Prayer", paintings by Israeli children, Israeli literature and the flag, among others.