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Showing posts with label Space & Astrophysics. Show all posts
Showing posts with label Space & Astrophysics. Show all posts

Thursday, 23 January 2020

ESA launches the first prototype oxygen extraction plant from the lunar regolith

📷 | ESA

NASA's Artemis mission will mark the return of humans to the moon since the last Apollo mission in 1972. But bringing astronauts to lunar soil is not the ultimate goal of space agencies. Some plans aim to install real permanent lunar bases in order to carry out scientific experiments and test different engineering techniques. One of the essential resources to manage to maintain these inhabited bases is oxygen. Even if the Moon does not have an atmosphere, the regolith that lines its surface contains a lot of oxygen. And to test the technique of extracting oxygen from the regolith, ESA will host the first large-scale prototype factory using this process.

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Last year, researchers published an article on how to extract oxygen from a lunar dust simulator (regolith); now the first prototype oxygen plant will attempt this extraction on a larger scale. If it works, the technology could provide humans with important resources that will aid future lunar missions, and perhaps even allow long-term bases and colonies on the Moon.



“ Having our own facility allows us to focus on producing oxygen, measuring it with a mass spectrometer when it is extracted from the regolith simulator. Being able to acquire oxygen from the resources found on the Moon would obviously be extremely useful for future lunar colonists, both for breathing and for the local production of rocket fuel "explains the chemist Beth Lomax of the University of Glasgow , in Scotland.

Oxygen is the main resource necessary for the establishment of permanent manned lunar bases. Geochemists have developed a way to extract the oxygen contained in the regolith. Credits: ESA

Extract the oxygen from the regolith by electrolysis into molten salt

The installation, located at the European Space Research and Technology Center of the European Space Agency in the Netherlands, will use the technique developed by Lomax and his colleagues. Geochemists know, on the basis of samples of the lunar regolith, that oxygen is really very abundant in this material. Between 40 and 45% of the regolith by weight is oxygen.

Using an exact copy of the lunar regolith made on Earth, called a simulator of the lunar regolith, attempts have been made in the past to figure out how to extract oxygen, with poor results - too complicated, too weak, or destructive of the regolith. The Lomax team has remedied this by using a technique called “molten salt electrolysis”.

The electrolysis in molten salt of the regolith extracts oxygen while producing usable metal residues. Credits: Lomax et al., Planetary and Space Science, 2019

First, the regolith is placed in a mesh basket. Calcium chloride - the electrolyte - is added and the mixture is heated to about 950 degrees Celsius, a temperature that does not melt the material. Then an electric current is applied. This extracts oxygen and migrates the salt to an anode, where it can be easily removed. This technique extracts up to 96% of the oxygen from the regolith; as a bonus, the remaining material from this process is a mixture of metal alloys.

Use materials left over from electrolysis

" This is another useful avenue of research, to see what are the most useful alloys that could be produced from these, and for what type of applications could they be used." Could they be 3D printed directly, for example, or would they require refinement? The precise combination of metals will depend on where, on the Moon, the regolith is mined - there would be significant regional differences, "said Alexandre Meurisse of the European Space Agency.



The current configuration of the system is based on commercial deoxidation plants, where oxygen is only a useless by-product which is discharged. However, as the facility evolves, a means of storing oxygen will be included. The end goal, of course, is to develop a system that could work on the Moon, using a real lunar regolith, not a simulator.


Bibliography:

ESA opens oxygen plant – making air out of moondust

17/01/2020

http://www.esa.int/Enabling_Support/Space_Engineering_Technology/ESA_opens_oxygen_plant_making_air_out_of_moondust


Friday, 6 December 2019

Microgravity Brings New Hope For the Cancer Patients



Practical medical examinations of astronauts in recent years have revealed that space travel involves a number of health risks: osteoporosis, reduced lung volume, loss of muscle density, exposure to radiation, and so on. However, conversely, space can also bring unexpected therapeutic solutions. This is what biologists have discovered by observing that, immersed in microgravity, the cancer cells are unable to recognize and assemble, and eventually become neutralized.

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Since 2014, Joshua Choi, a biomedical engineering researcher at the University of Technology Sydney, has been studying the effects of microgravity on the physiology and cells of the human body. Early next year, he and his research team will visit the ISS to test a new method of treating cancer based on microgravity.

According to Chou, his research was inspired by a conversation he had with the late Stephen Hawking. During the conversation, Hawking noticed that nothing in the Universe defies gravity. Later, when a friend of Cabbage was diagnosed with cancer, he remembered what Hawking said and began to wonder, " What would happen to cancer cells if we removed them from gravity? ".


Cancer cells accustomed to evolve in a classical gravitational environment

In simple terms, cancer is a disease in which cells begin to divide uncontrollably and spread to certain parts of the body. Cancer cells do this by coming together to form a solid tumor in the body, which then develops until cells invade healthy tissues - such as the heart, lungs, brain, liver, pancreas, etc.

The process by which cancer develops and spreads would seem to indicate that there is a way in which cells are able to detect and gravitate together to form a tumor. However, researchers in biomedicine know that mechanical forces are the only way for cancer cells to detect each other, and that these forces have evolved to operate in a gravitational environment.

Immerse cancer cells in microgravity to block their evolution

This prompted Chou to think of ways in which the absence of gravity could prevent cancer cells from dividing and spreading. He and his team have tested the effects of microgravity on cancer cells in their laboratory. To do this, one of his students created a device that essentially consists of a container the size of a tissue box with a small centrifuge inside.

The researchers used a rotating arm centrifuge to recreate microgravity conditions. Credits: Sascha Kopp et al.

The cells of different cancers are contained in a series of tubes inside the centrifuge, which then rotates them until they experience the sensation of microgravity. As Chou said, the results have been rather encouraging. " Our work has shown that, in a microgravity environment, 80 to 90% of the cells of the four types of cancer tested - ovary, breast, nose and lung - were deactivated and then killed ."

a) Under the effect of microgravity, thyroid cancer cells are forced to rearrange their cytoskeleton. b) Culture of cancer cells under normal conditions; the cancerous tissue formed is dense. c) Cultivation of cancer cells in microgravity; the cancerous tissue formed is loose, porous and weakly bound. Credits: Sascha Kopp et al.

When subjected to microgravity conditions, the cancer cells were unable to detect themselves and therefore had a hard time getting together.

Towards in situ confirmation of results ... And the development of new cancer therapies

The next step, which will take place early next year, will be for the team to send their experience in the ISS aboard a space module specifically designed for this purpose (SpaceX will provide launch services). Chou and his colleagues will spend the duration of the experiment (seven days) in the field, where they will follow the progress of the experiment and will perform live cell imaging via data sources.

Joshua Chou, holding the experimental prototype that will be sent to the ISS next year. Credits: Sissy Reyes

Once the experiment is over, the cells will be frozen for their return trip to Earth. Chou and his colleagues will then examine them to look for genetic modifications. If the results on board the ISS confirm what Chou and his team discovered in the laboratory, he hopes they will be able to develop new treatments that can have the same effect as microgravity and neutralize the ability of cancer cells to to detect oneself.

Ideally, these treatments would not be a cure but could complement existing cancer treatment regimens. Combined with drugs and chemotherapy, treatments derived from this research would effectively slow the spread of cancer in the human body, making conventional treatments more effective and short-lived (and less expensive as well).



Source

Wednesday, 4 December 2019

If they exist, cosmic strings would be much harder to detect than expected


Following the Big Bang, the Universe has undergone several phase transitions that have resulted in broken symmetry of the physical laws. According to some cosmological models, some of these breaks in symmetry would have resulted in the formation of particular cosmic structures at the meeting point of unstable regions of the Universe; these structures are called topological defects, and cosmic strings are one of them. Cosmologists initially thought that signatures of these linear energy structures could be detected in the cosmic microwave background. However, recently, physicists have shown that these signatures would be too weak for their detection to be possible.

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Cosmic strings are hard to imagine, according to Oscar Hernández, a physicist at McGill University in Montreal. " Have you ever walked on a frozen lake? Have you noticed any cracks in the ice? It's still pretty solid, but cracked, "he says. These cracks are formed by a phase transition process similar to that of cosmic strings.


Topological defects predicted by physics beyond the Standard Model

Imperfect meeting points on the surface of a frozen lake form long cracks. In the structure where space and time intersect, they form cosmic strings, if the underlying physics is correct.

Researchers believe that in space, some fields determine the behavior of forces and fundamental particles. The first transition phases of the Universe gave birth to these fields. Today, these points of intersection between fields would appear as infinitely thin lines of energy across space.

Several simulations have shown, if they exist well, the distribution of the cosmic strings during the evolution of the Universe. These topological defects are provided by many theoretical models. Credits: Nature

Most physicists think that the standard model is incomplete. " Many extensions of the standard model naturally lead to cosmic strings after inflation. So, what we have is an object that is predicted by many models. Therefore, if they do not exist, all these models are excluded.

Cosmic strings: they would be impossible to detect in the cosmic microwave background

Hernández and Razvan Ciuca of Marianopolis College in Westmount, Quebec, had previously argued that a convolutional neural network - a powerful type of pattern search software - would be the best tool for locating string evidence in the CMB.

Assuming a perfect and noise-free CMB card, they wrote in a separate article in 2017, a computer using this type of neural network should be able to find cosmic strings even if their energy level (or "voltage") is remarkably low.

But in this new article published on the arXiv server , they showed that in reality, it is almost impossible to provide enough CMB data for the neural network to detect these potential strings. Other brighter microwave sources obscure the CMB and are difficult to disentangle completely. Even the best microwave instruments are imperfect, with limited resolution and random fluctuations in the accuracy of recording from one pixel to another.

They found that all these factors, and more, added to a level of information loss that no current or planned CMB recording and analysis method could ever overcome. This method of chase cosmic strings is a dead end. This does not mean that everything is lost, however.


A new method for detecting cosmic strings

A new method based on measurements of the expansion of the universe in all directions, in old parts of the Universe, could work. This method - called 21-centimeter intensity mapping - does not rely on the study of individual galaxy motions or on accurate CMB images.

Instead, it is based on measurements of the rate at which hydrogen atoms move away from the Earth, on average, in all parts of deep space. This method should be able to provide sufficiently constrained data to restart the hunt for cosmic strings.


Bibliography:

Information Theoretic Bounds on Cosmic String Detection in CMB Maps with Noise
Razvan Ciuca1  Oscar F. Hern´andez1,2†

1Department of Physics, McGill University, 3600 rue University, Montr´eal, QC, H3A 2T8, Canada

2Marianopolis College, 4873 Westmount Ave.,Westmount, QC H3Y 1X9, Canada

Source

Monday, 2 December 2019

Unusual radio variations suggest the existence of a new type of binary star system


In current models, binary star systems generally describe couples involving giant stars with white dwarfs or stars like our Sun. In these systems, the smaller companion emits electromagnetic bursts under the gravitational effect of the giant star. Recently, astrophysicists have detected, in the Milky Way, a binary system involving a giant star and an undetermined companion, the couple not responding to the classical properties of such systems. Given the data collected so far, it could be a whole new class of binary system.

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After observing part of the southern hemisphere sky near the constellation Altar for about two months using MeerKAT, a radio telescope based in the Karoo Desert in South Africa, astrophysicists have noticed something strange. The radio emission of an object illuminated by a factor of three, about three weeks of observation. Intrigued, they continued to look at the object and followed the observations of other telescopes. They discovered that the unusual object came from a system of binary stars in the Milky Way.



The results of the study were published in the journal MNRAS. This is the first time that MeerKAT has discovered a "transient source" - an unstable object that is undergoing a significant change in brightness. In view of his name, MKT J170456.2-482100, he was found in the first observed field with the telescope, which means that it is likely to be the tip of an iceberg of transient sources waiting to discovery.

Luminosity variations detected thanks to the collaboration of several telescopes

The researchers began by matching the source to the position of a star, called TYC 8332-2529-1, about 1800 light-years from Earth. Because this star is brilliant, they had predicted that a number of different optical telescopes, detecting visible light rather than radio waves, would have already observed it in the past. And fortunately, this turned out to be the case, allowing them to use these data to learn more about this giant star (2.5 solar masses).

Graphic and images showing radio emission variations observed by astrophysicists. Credits: LN Driessen et al. 2019

Some of the optical telescopes, including ASAS, KELT and ASAS-SN, have provided more than 18 years of star observations. These revealed that the brightness of the star changed over a period of 21 days. Astrophysicists used the SALT telescope to obtain the optical spectra of the star. This can be used to determine the chemical elements present in the star, as well as the presence of a magnetic field.

In addition, they allow scientists to know if a star is moving, because the movement causes the shift of spectral lines (Doppler shift). Spectra revealed that the star had a magnetic field and gravitated around a companion star every 21 days.

A stellar companion of unknown nature

However, only a very weak signature of the companion star is visible. This suggests that the companion must be of less mass than the giant star, with however 1.5 solar masses. So, what could this companion be? A white dwarf may seem likely, as they are often part of binary star systems like this one. However, most have a lower mass than the companion observed.

The radio emission itself could be caused by the magnetic activity of the giant star, similar to a solar flare but much brighter and more energetic. However, these eruptions are usually observed on dwarf stars rather than on giant stars.

Many binary systems involve a giant star and a white dwarf, so the electromagnetic bursts result from the accretion of matter of the second by the first. But the different data collected show that this is not the case of the newly discovered system. Credits: Pearson Ed

Known star systems associating a giant star and a star similar to the Sun could explain the results obtained, the magnetic activity of the giant star giving rise to light flares. However, that does not suit, because nothing indicates in the spectrum that the binary companion is actually a star similar to that of the Sun.


A new class of binary system?

Ben Stappers, the principal investigator of MeerTRAP, one of the teams working on the project, explains that since the properties of the system do not fit easily with our current knowledge about binary stars, it could represent a source class entirely news. It could be a kind of exotic system never seen before and involving a giant star emitting radiation in orbit around a neutron star.



MeerKAT will continue to observe this source every week for the next four years as the ASAS-SN optical telescope continues to observe the giant star. This will inform the dynamics of this system, how the bursts occur, and ultimately help to understand how it was formed.


Bibliography:

MKT J170456.2–482100: the first transient discovered by MeerKAT

L N Driessen, I McDonald, D A H Buckley, M Caleb, E J Kotze, S B Potter, K M Rajwade, A Rowlinson, B W Stappers, E Tremou ...

Monthly Notices of the Royal Astronomical Society,
Volume 491, Issue 1, January 2020, Pages 560–575,
https://doi.org/10.1093/mnras/stz3027
Published: 30 October 2019

Tuesday, 26 November 2019

First direct observation of the transfer of energy between the surface and the crown of the Sun


Although it has been studied for decades, the Sun still has some mysteries. This is particularly the case of the temperature difference observed between the crown and the solar surface, the first being much hotter than the second. Several theoretical models have been proposed to explain this phenomenon, in particular the model of plasma spicules. And for the first time, astrophysicists were able to directly observe this process.

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Astrophysicists have already suggested that solar plasma jets called spicules, from within, were responsible for the warming effect, and for the first time, they were able to directly observe this process. New observations show that when the magnetic fields on the Sun's surface reverse and realign, spicules are formed. The study was published in the journal Science.

Direct and detailed observation of solar spicules

The energy of the magnetic field is converted into kinetic and thermal energy, which is then transferred to the spicules pushing through the chromosphere to the outermost layer of the Sun's atmosphere, the corona.

The idea of ​​the spicules responsible for the magnetic tension of the Sun has already been evoked using detailed computer simulations. Now, using high resolution images of Big Bear Solar Observatory (BBSO) telescopes, astronomers have seen this in situ .

" The unprecedented high-resolution observations of BBSO's Goode solar telescope clearly show that when magnetic fields of opposite polarities reconnect in the lower atmosphere of the Sun, these plasma jets are powerfully ejected, " explains solar physicist Wenda Cao, from New Jersey Institute of Technology.

BBSO telescopes allowed astrophysicists to obtain detailed images of the formation and evolution of solar spicules. Credits: Tanmoy Samanta et al. 2019

These jets are 200 to 500 kilometers wide and reach thousands of kilometers before dissipating. They also move about 100 km / s. The researchers also used images captured by NASA's Solar Dynamics Observatory satellite in the Extreme Ultraviolet Spectrum (EUV) to measure energy transfer in the upper layers of the Sun's atmosphere.

Better understand the dynamics of spicules and their role in the enigma of the temperature of the solar corona

These images confirmed that spicules could reach temperatures of about 1 million degrees Celsius. This high energy explosion may well be enough to heat the crown at the high temperatures recorded by the instruments. High resolution images with BBSO are essential for data collection. They offer unprecedented levels of detail.

Multilayer view of solar spicules: (left to right) NASA Solar Dynamics observatory crown observations, followed by images of NJIT's Big Bear Solar Observatory on the chromosphere, photosphere, and magnetic fields associates. Credits: NJIT

This is the first time we have seen direct evidence of how spicules are generated. We followed these dynamic characteristics of the H-alpha spectral line, measured magnetic fields at their starting point, captured the migration of emerging magnetic elements, and verified their interaction with existing magnetic fields of opposite polarity, "says Cao.

Although the new study is not enough to prove exhaustively that spicules heat the crown, the dynamics of spicules are much better understood now. " Our observations on spike formation, subsequent warming, and return fluxes reveal a complete mass cycle process between the chromosphere and the crown, " the researchers conclude.

In this video, NASA explores the solar structure and its different components using different instruments:



Bibliography:

 Generation of solar spicules and subsequent atmospheric heating

Tanmoy Samanta1, Hui Tian1,*, Vasyl Yurchyshyn2, Hardi Peter3, Wenda Cao2, Alphonse Sterling4, Robertus Erdélyi5,6, Kwangsu Ahn2, Song Feng7, Dominik Utz8, Dipankar Banerjee9, Yajie Chen1

Science  15 Nov 2019:
Vol. 366, Issue 6467, pp. 890-894
DOI: 10.1126/science.aaw2796

Thursday, 21 November 2019

First detection of sugars necessary for life found in meteorites



The origin of life on Earth is an open question and represents a field of active research. Although prebiotic models of the appearance of life have been proposed, the process of appearance of building blocks of life (amino acids, nucleic acids, sugars, etc.) is still very little constrained. One of the hypotheses currently proposed proposes an extraterrestrial origin of these components within the framework of a model called panspermia. In this model, the constituents of life would have been brought to the primitive Earth through the incessant bombardment of comets and meteorites. And recently, researchers have for the first time discovered ribose and other sugars necessary for life in two meteorites, thus reinforcing this hypothesis.

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An international team of researchers has found sugar molecules essential for life in meteorites. This new discovery adds to the growing list of biologically important compounds found in meteorites, furthering the hypothesis that chemical reactions in asteroids - the parent bodies of many meteorites - can make certain life ingredients. If this is correct, the bombardment of meteorites on the primitive Earth may have helped the appearance of life by providing the basic elements.


First direct evidence of the existence of extraterrestrial ribose

The team discovered ribose and other bio-essential sugars, including arabinose and xylose, in two carbon-rich meteorites, NWA 801 (CR2 type) and Murchison (CM2 type).

Ribose is a crucial component of RNA (ribonucleic acid). RNA serves as a messenger molecule, copying the genetic instructions of the DNA molecule (deoxyribonucleic acid) and transmitting them to molecular factories within the cell, called ribosomes, which read RNA to construct specific proteins.

Structures of sugars (pentoses) discovered in the two meteorites. Credits: Yoshihiro Furukawa et al. 2019

" Other important elements in life have already been discovered in meteorites, including amino acids (protein components) and nucleic bases (components of DNA and RNA), but sugars have been an element missing among the main building blocks of life, "said Yoshihiro Furukawa of Tohoku University, Japan. " The research provides the first direct evidence of ribose in space and the contribution of sugar to Earth. The extraterrestrial sugar could have contributed to the formation of RNA on the prebiotic Earth, which probably led to the origin of life .

" It's remarkable that a molecule as fragile as ribose can be detected in such an old material, " says Jason Dworkin, an astrobiologist at NASA's Goddard Center. " These results will help guide our sample analyzes of the original Ryugu and Bennu asteroids, which will be returned by Hayabusa 2 of the Japan Aerospace Exploration Agency and NASA's OSIRIS-REx space probe ."


Ribose: a sugar used in the composition of RNA

A persistent mystery about the origin of life is how biology could have come from non-biological chemical processes. DNA contains the genetic instructions necessary for the functioning of a living organism. However, RNA also contains information and many researchers believe that it evolved first and was later replaced by DNA. This is because RNA molecules have abilities that are lacking in DNA.

Structure of the RNA. RNA uses ribose as sugar, unlike DNA that uses deoxyribose. Credits: BioC

RNA can reproduce without the need for other molecules, and it can also initiate or accelerate chemical reactions as a catalyst. These results support the possibility that RNA has coordinated the mechanism of life before DNA.

" The sugar contained in DNA (2-deoxyribose) was not detected in any of the meteorites analyzed in this study. This is important because there may be a lack of extraterrestrial ribose delivery to the early Earth, which is consistent with the hypothesis that RNA evolved first, "explains Danny Glavin.

Sugars brought by meteorites from space

The team discovered sugars by analyzing powdered meteorite samples using gas chromatography mass spectrometry, which sorts and identifies molecules based on their mass and electrical charge. They found that the abundances of ribose and other sugars ranged from 2.3 to 11 parts per billion in NWA 801, and from 6.7 to 180 parts per billion in the Murchison meteorite.

With the Earth now full of life, the team had to take into account the possibility that meteorite sugars could have simply come from a terrestrial contamination. Several sources of data indicate that contamination is unlikely, including isotopic analysis. Isotopes are versions of a different mass element because of the number of neutrons in the nucleus of the atom.

The isotopic analysis of the sugars found in the meteorites confirmed that they came from space, not from the Earth. Credits: Yoshihiro Furukawa et al. 2019

Carbon chemistry on Earth uses carbon 12 compared to the heavier version (carbon 13). However, the carbon contained in meteorite sugars was significantly enriched in carbon 13, beyond the amount observed in terrestrial biology, which corroborates the conclusion that it comes from space.

Towards a better understanding of the emergence of life on Earth

The team plans to analyze more meteorites to get a better idea of ​​the abundance of extraterrestrial sugars. They also plan to determine whether extraterrestrial sugar molecules have a preferred left or right orientation. Some molecules come in two varieties that are inverted images of each other. On Earth, life uses left amino acids and straight sugars.

Since it is possible that the opposite works perfectly - right amino acids and left sugars - scientists want to know where this preference comes from. If some processes in asteroids favor the production of one variety over another, then perhaps the influx from space via meteorite impacts has made this variety more abundant on the ancient Earth.

Bibliography:

 Extraterrestrial ribose and other sugars in primitive meteorites

 Yoshihiro Furukawa, Yoshito Chikaraishi, Naohiko Ohkouchi,  View ORCID ProfileNanako O. Ogawa, Daniel P. Glavin,  View ORCID ProfileJason P. Dworkin, Chiaki Abe, and Tomoki Nakamur

PNAS first published November 18, 2019

https://doi.org/10.1073/pnas.1907169116


Wednesday, 20 November 2019

Unique glow never seen before discovered, thanks to the MeerKAT radio telescope


There is talk of a "unique and never seen before glow" in the press release published on the University of Manchester website which presents the discovery made by a group of scientists who used the MeerKAT radio telescope in South Africa to discover a source of radio emissions that it quickly lit up to a level out of the ordinary for a period of three weeks.

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This is a "transient" astronomical event, events in which the emitting source appears and then disappears or becomes brighter and then weaker again in periods of time that can be calculated in seconds, days or even years.


In this case the researchers found that the source comes from a binary system of two objects that orbit each other every 22 days. What are the components of this binary system is still uncertain as is the cause of the anomalous glow they have identified.

What is known is that the source is located near a K type subgiant star, with a mass twice that of the Sun, previously identified in the constellation of the Altar.

"Once we discovered that the glow of the radio source coincided with a star, we discovered that the star emits through almost the entire electromagnetic spectrum from X-rays to the wavelengths of UV and radio rays," explains Laura Driessen, researcher of the University of Manchester who led the team that made the discovery and then published their work in Monthly Monthly of the Royal Astronomical Society .

According to Ben Stappers, a researcher from the same university that participated in the study, we may be faced with a new class of radio wave emitter objects that is completely new as its properties do not coincide with those of the models we are currently aware of.




Bibliography:

MKT J170456.2−482100: the first transient discovered by MeerKAT


L N Driessen, I McDonald, D A H Buckley, M Caleb, E J Kotze, S B Potter, K M Rajwade, A Rowlinson, B W Stappers, E Tremou, P A Woudt, R P Fender, R Armstrong, P Groot, I Heywood, A Horesh, A J van der Horst, E Koerding, V A McBride, J C A Miller-Jones, K P Mooley, R A M J Wijers

Monthly Notices of the Royal Astronomical Society, stz3027,

https://doi.org/10.1093/mnras/stz3027



Tuesday, 19 November 2019

NASA confirms the presence of water vapor on the surface of Europa


The fourth largest natural satellite of Jupiter and sixth largest in the Solar System, Europa has been of interest to planetologists for many years. About forty years ago, the Voyager program provided the first detailed picture of the veined surface of the icy moon. In the last decades, the data collected on Europa has made it a priority target for space agencies in the search for life. And recently, planetologists have confirmed the presence of water vapor in Europe.

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What makes this moon so attractive is the possibility that it has all the ingredients necessary for life. Planetologists have evidence that one of these ingredients, liquid water, is present under the icy surface and can sometimes burst into space in the form of gigantic geysers. But so far no one has been able to confirm the presence of water in these plumes by directly detecting the water molecule.

Europa: water vapor and a potential ocean of liquid water

Now, an international research team led by NASA's Goddard Space Flight Center has directly detected water vapor for the first time over the surface of Europa. The team did this detection by surveying Europa through one of the largest telescopes in the world in Hawaii.

By confirming the presence of water vapor over Europa, planetologists can better understand the inner workings of the moon. For example, it helps to support the idea that there is an ocean of liquid water, perhaps twice as large as the Earth's, beneath the thick ice shell of that moon. Some astrophysicists suspect that another source of water for the plumes could be shallow reservoirs of melted water ice.

Although planetologists have still not surveyed the interior of Europe, the predominant hypothesis suggests the existence of an ocean of liquid water beneath its frozen surface. Credits: NASA

" The essential chemical elements (carbon, hydrogen, oxygen, nitrogen, phosphorus and sulfur) and energy sources, two of the three requirements of life, are present throughout the Solar System. But the third - liquid water - is a little hard to find beyond the Earth, "said Lucas Paganini, NASA's planetologist. " Although the scientists have not yet detected the liquid water directly, we have found the second best thing: water in the form of steam ."

First direct detection of water molecules over Europa

In Nature Astronomy , Paganini and his team said they detected enough water ejected from Europa (at a rate of 2360 kilograms per second) to fill an Olympic pool in minutes. However, the authors also discovered that water appears too rarely, at least in sufficient quantity, to be detected from Earth.

" For me, the interest of this work is not only the first direct detection of water over Europa, but also its absence within the limits of our detection method, " says Paganini.

Indeed, Paganini's team detected the weak but distinct signal of water vapor during 17 nights of observation between 2016 and 2017. Looking at the moon from WM Keck observatory at the top of Mauna Kea volcano in Hawaii, researchers have seen water molecules on the main hemisphere of Europa. (Europa, like the Earth's moon, is gravitationally locked on its host planet, so the main hemisphere is always oriented in the direction of the orbit, while the secondary hemisphere is always in the opposite direction).

Differentiate terrestrial water vapor from that of Europa: models in reinforcement

For this, the researchers used a Keck observatory spectrometer, which measures the chemical composition of planetary atmospheres by means of the infrared light they emit or absorb. Molecules such as water emit specific frequencies of infrared light when they interact with solar radiation.

When interacting with solar radiation, water molecules emit specific infrared frequencies. Credits: Michael Lentz / NASA Goddard

Detecting water vapor on other worlds is a challenge. Existing spacecraft have limited capabilities to detect it, and scientists using ground-based telescopes must take into account the distortion effects of the Earth's atmosphere.

To minimize this effect, Paganini's team used complex mathematical and computer modeling to simulate the conditions of the Earth's atmosphere, in order to differentiate between atmospheric water from Earth and Europa from the atmosphere. data returned by the Keck spectrograph.

We conducted rigorous safety checks to eliminate potential contaminants in ground observations, " said Avi Mandell, a planetologist on the Paganini team. " But in the end, we will have to get closer to Europa to see what is really happening ."

Structure of Europa: study it in detail thanks to the Europa Clipper mission

Scientists will soon be able to get close enough to Europa to resolve their outstanding questions about the internal and external functioning of this possibly habitable world. The next mission, Europa Clipper, which is scheduled for launch in the mid-2020s, will complete half a century of scientific discoveries that began with a modest photo.

When it arrives in Europa, the Clipper orbiter will carry out a detailed study of the surface, the deep interior, the weak atmosphere, the submarine ocean and possibly even smaller active vents. Clipper will try to take images of all the plumes and sample the molecules he will find in the atmosphere to study with his mass spectrometers. He will also look for a site from which a future lander could collect a sample.

In this video, NASA returns in detail on the detection of water vapor in Europa:



Bibliography:

Article: A measurement of water vapour amid a largely quiescent environment on Europa

authors: L. Paganini, G. L. Villanueva, L. Roth, A. M. Mandell, T. A. Hurford, K. D. Retherford & M. J. Mumma

Nature Astronomy

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Sunday, 17 November 2019

Another mystery on Mars: Oxygen appears and disappears without explanation



With the mystery of Mars methane still unresolved , the space robot Curiosity brought scientists a new puzzle: Martian oxygen.

The information came by measuring the seasonal levels of all gases in the atmosphere directly above the surface of the Gale Crater, where Curiosity is located. The result is disconcerting.

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On Mars, oxygen, the gas most creatures on Earth use to breathe, behaves in a way that scientists have so far failed to explain through any known chemical process.

Over the course of three Martian years (nearly six years of Earth), a Curiosity instrument called SAM ( Sample Analysis at Mars ) inhaled the air of the Gale Crater and analyzed its composition.

The results confirmed the composition of the Martian surface atmosphere: 95% by volume of carbon dioxide (CO2), 2.6% of molecular nitrogen (N2), 1.9% of argon (Ar), 0.16% of molecular oxygen. (O 2), and 0.06% carbon monoxide (CO).

Measurements also revealed how molecules in Martian air blend and circulate with changes in air pressure throughout the year. These changes are induced when CO2 gas freezes at the poles in winter, lowering air pressure across the planet after air redistribution to maintain pressure balance. When CO2 evaporates in spring and summer and mixes on Mars, the air pressure increases.

The oxygen mystery of Mars

In this environment, data show that nitrogen and argon follow a predictable seasonal pattern, with their concentration increasing and decreasing over the year relative to the amount of CO2 in the air.

Scientists expected oxygen to keep pace, but that is not the case. Instead, the amount of oxygen in the air rises throughout spring and summer by up to 30 percent, and then returns to the levels predicted by known autumn chemistry. This pattern repeats each spring, although the amount of oxygen added to the atmosphere varies, implying that something is producing oxygen and then taking it away.

"The first time we saw this, we were racking our brains," said Sushil Atreya, professor of climate and space science at the University of Michigan.

The team set out to look for possible explanations, first considering the possibility that CO2 or water (H2O) molecules could release oxygen when they separate into the atmosphere, leading to a brief rise in oxygen. But that would consume five times more water than there is in the atmosphere of Mars, and CO2 decomposes too slowly to generate it in such a short time. What about decreasing oxygen? Couldn't solar radiation break oxygen molecules into two atoms, which would then leak into space? No, the scientists concluded, as it would take at least 10 years for oxygen to disappear through this process.

"We are struggling to explain this," said Melissa Trainer, planetary scientist at NASA's Goddard Space Flight Center. "The fact that oxygen behavior doesn't repeat perfectly every season makes us think it's not a problem that has to do with atmospheric dynamics. It has to be a chemical source and a sinkhole that we can't yet explain."

The amount of oxygen in the air increases throughout spring and summer by up to 30 percent, and then returns to the levels predicted by known autumn chemistry

Methane and oxygen, biological and abiotic

The history of oxygen is curiously similar to the methane mystery of Mars. Methane is constantly in the air inside the Gale Crater in such small quantities (0.00000004% on average) that it almost goes unnoticed by the most sensitive instruments ever sent to Mars. Although methane increases and decreases seasonally, it increases abundantly by about 60% in the summer months for unexplained reasons - in fact, methane also fires randomly and dramatically, but no one has yet any idea why.

With the new oxygen discoveries at hand, the NASA team wonders if a chemistry similar to the one that is generating the natural seasonal variations of methane can also explain the variations in oxygen - the two gases even float together, but only occasionally.

"We are beginning to see this tantalizing correlation between methane and oxygen for much of the year on Mars," said Atreya. "I think there's something there. I don't have the answers yet. No one has."

Oxygen and methane can be produced biologically (from microbes, for example) and abiotically (from water and rock-related chemicals). Scientists are considering all options, although we have no convincing evidence of biological activity on Mars.

The Curiosity robot has no instruments that can definitely tell whether the source of methane or oxygen on Mars is biological or geological. With current data, nonbiological explanations are more likely.

Bibliography:

Article: Seasonal variations in atmospheric composition as measured in Gale Crater, Mars

Authors: Melissa G. Trainer, Michael H. Wong, Timothy H. McConnochie, Heather B. Franz, Sushil K. Atreya, Pamela G. Conrad, Franck Lefèvre , Paul R. Mahaffy, Charles A. Malespin, Heidi LK Manning, Javier Martín-Torres, Germán M. Martínez, Christopher P. McKay, Rafael Navarro-González, Alvaro Vicente-Retortillo, Christopher R. Webster, Maria-Paz Zorzano

Magazine : Journal of Geophysical Research: Planets

DOI: 10.1029 / 2019JE006175  

Thursday, 14 November 2019

The Japanese space probe Hayabusa-2 returns to Earth with samples of an asteroid


Yesterday, the Japanese space probe Hayabusa-2 left its orbit around a distant asteroid and is now heading for the Earth after an exemplary mission. The latter will yield important samples, which could help scientists solve some of the mysteries about the origins of the Solar System.

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For the spacecraft, the long return journey began Wednesday, Nov. 13, 2019, and is expected to reach Earth "by the end of 2020," said Japan Aerospace Exploration Agency (JAXA).

"  We hope that Hayabusa-2 will provide us with new scientific knowledge, " said project director Yuichi Tsuda. The probe will bring back to Earth "carbon and organic matter", which will provide data on "how matter is dispersed in the solar system, why it exists on the asteroid and how it is related to the Earth", Tsuda added.

Below: The images taken by the Hayabusa-2 probe as it leaves the orbit of the asteroid are also displayed in the control room. This is a camera that continues to take scientifically valid photographs, but this time, the pictures were taken for the pleasure of all.



The mission of the Japanese space probe (the size of a large fridge) took her to some 300 million kilometers from the Earth, where she was able to analyze and explore the asteroid Ryugu, whose name means "Palace of Dragon "in Japanese. A name referring to a castle at the bottom of the ocean, in an ancient fable.

In April 2019, the Hayabusa-2 space probe launched an "impactor" on the asteroid in order to "stir" materials that had never been exposed to the atmosphere. The probe was then able to collect dust samples from the surface of the asteroid and never exposed to space vacuum so far. A first !

Scientists hope this will provide clues to the nature of the Solar System at birth, about 4.6 billion years ago. " I feel half-sad and half-determined, so we can do our best to bring the probe home. Ryugu has been at the heart of our daily lives for a year and a half ...  "said Tsuda.

The surface of the asteroid Ryugu, photographed in detail by the Hayabusa-2 probe at 64 and 67 meters altitude. Credits: JAXA

Now, the Hayabusa-2 space probe has begun its return to planet Earth. It will be released permanently from the gravity of the asteroid on November 18, and can start at full speed its main engines at the beginning of December.

Tsuda said the six-year mission, whose total cost is around 30 billion yen (about $ 278 million), had exceeded expectations at the scientific level, but he also admitted that his team had to deal with many technical problems. It took three and a half years for the probe to get to the asteroid, but the return trip should be much shorter because now the Earth and the Ryugu asteroid are much closer (because of their respective current positions).

The Hayabusa-2 probe is expected to deposit the collected samples in the southern Australian desert, but "JAXA is negotiating the details of this part of the mission with the Australian government," Tsuda said.

Note that this probe succeeds the first JAXA asteroid explorer, Hayabusa (which means "hawk" in Japanese). The first probe was sent back to Earth with dust samples of a small asteroid in 2010, despite several setbacks during its epic seven-year odyssey, and was hailed as a scientific triumph.

According to the current plan, Hayabusa-2 will continue its journey into space after depositing its capsule containing the samples on Earth, and could even " perform a new exploration of asteroid, " said spokesman JAXA Keiichi Murakami. "  The team has just started to study what could be done (after the probe has deposited the capsule), but there are no concrete plans for a new destination,  " Tsuda said.

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We finally know more about what would have preceded the Big Bang


In the framework of the "pre-Big Bang" model, implying that the Big Bang is preceded by a first inflation, scientists theorize that the universe was formed in two stages. It would first spread rapidly from a dense mass of matter, then entered a phase of expansion more progressive but very energetic, commonly called "Big Bang". However, the way in which these two stages are related has long been misunderstood by researchers. As part of a new study of this period of the Universe and involving this initial theory, physicists finally think they have solved this mystery remained unanswered for decades, and suggest a way to explain the connection between these two eras primitive.

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During the first primitive period, the Universe would have gone from a small dense mass of matter to nearly a half-million times (x 10 48 ) its size in less than a trillionth of a second (10 -12 s) . In the context of the pre-Big Bang model, this period of rapid inflation was followed by a more gradual but violent expansion phase, the Big Bang.

During the Big Bang, a "ball" of extremely hot matter composed of fundamental particles (protons, neutrons and electrons ) then developed and cooled to form the first atoms, stars and galaxies .

The standard Big Bang theory , which also describes cosmic inflation, remains the most widely supported explanation for the beginnings of our universe. However, scientists are still puzzled as to how these completely different expansion periods are nested.

To solve this mystery, a team of researchers from Kenyon College, the Massachusetts Institute of Technology (MIT) and the University of Leiden in the Netherlands, simulated the critical transition between cosmic inflation and the Big Bang as part of a pre-Big Bang model; a period called "reheat".

" The post-inflation warm-up period defines the conditions of the Big Bang and, in a sense, places the 'Bang' in the Big Bang,  " David Kaiser, a professor of physics at MIT , said in a statement . " It's a time of transfer, when hell is unleashed and the matter behaves in a complex way  ."

The history of the universe (standard model of the Big Bang). Above, inflation, which generates two types of waves: gravitational waves and density waves. Below, the radius of the visible Universe, from the Big Bang (t0), then the inflation (white / yellow), the formation of the protons, the beginning of the nuclear fusion, the end of the nuclear fusion (3 minutes), up to the 13.8 billion years that the Universe has today. Credits: DrBogdan / Yinweichen / Wikimedia

When the Universe developed into a "fraction of a second" during cosmic inflation, all existing matter spread out in all directions, leaving in space an empty, cold place, devoid of "soup." primordial "(dense and hot cluster of particles) necessary to start the Big Bang. During the warm-up period, it is thought that the energy that propelled inflation broke down into particles, said Rachel Nguyen, PhD student in physics at the University of Illinois and lead author of the study.

Once these particles are produced, they bounce off and bump into each other, transferring inertia and energy,  " Nguyen said. " And this is what thermises and warms the universe to define the initial conditions of the Big Bang  ".

In their model, Nguyen and his colleagues simulated the behavior of an exotic form of matter called inflaton. Scientists believe that the scalar field of this material, which is similar in nature to that of the Higgs boson, is responsible for creating the energy field that has led to cosmic inflation.

Their model showed that, under proper conditions, the hypothetical scalar field energy could be efficiently redistributed to create the diversity of particles needed to warm the primitive Universe. The results of the study are available in Physical Review Letters.

Gravity: it would react differently to very high energies

" When we study the primitive universe, we perform an experiment with particles at very high temperatures,  " said Tom Giblin, an associate professor of physics at Kenyon College in Ohio and co-author of the study. " The transition from the cold inflationary period to the warm period should contain essential evidence about the particles that actually exist at these extremely high energies."

A fundamental question that still afflicts physicists is how gravity behaves to the extreme energies present during inflation. Albert Einstein's theory of general relativity defines that all matter is affected by gravity in the same way, where the force of gravity is constant, regardless of the energy of the particle. However, because of the strange properties of quantum mechanics, scientists now think that at very high energies matter reacts differently to gravity.

The team incorporated this hypothesis into their model by modifying the interaction force of particles with gravity. They then discovered that the more they increased the force of gravity, the more the inflaton effectively transferred energy to produce the Hot Bang's field of hot material particles.

Additional clues needed to support the model

" The universe contains so many secrets, encoded in a very complex way  ," said Giblin. " It's our job to study the nature of reality by offering a 'decoding device' - a way to extract information from the universe. For this, we use simulations to predict what the universe should look like, so that we can actually begin to decode it. This warm-up period should have left an imprint somewhere. We just have to find it  . "

But identifying this footprint could prove to be a very complex task. Our first glimpse of the Universe is a "bubble of radiation" left a few hundred thousand years after the Big Bang: the cosmic microwave background (CMB). However, the CMB only evokes the state of the universe during the first critical seconds of its birth. Physicists hope that future observations of gravitational waves will provide the additional clues needed to support their model.


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Thursday, 7 November 2019

A new study suggests that the Universe is actually spherical and closed (not flat)


The study of the curvature of the Universe is an active field of research in cosmology. In recent years, the many data collected by observation missions such as WMAP and Planck have shown a locally null curvature of the Universe, indicating that the latter is certainly flat. The data match so well with each other that the model of the flat Universe is today integrated into the standard cosmological model. However, an anomaly derived from data collected by the Planck Space Observatory in 2018, concerning the cosmic microwave background, could be interpreted as a sign of a closed spherical universe.

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On the basis of data collected last year by the Planck satellite of the European Space Agency, cosmologists have argued that the Universe is actually curved and closed, like an expanding sphere. This means that a beam of photons drawn in a straight line would eventually return to its starting point, crossing other beams in its path; whereas these beams would remain parallel in the scenario of the flat Universe.

According to an international team of astronomers led by Eleonora Di Valentino of the University of Manchester in the United Kingdom, their findings present a "cosmological crisis" that calls for "radical rethinking of the current model of cosmological concordance". The key in determining the curvature of the Universe lies in the way gravity curves the path of light, an effect predicted by Einstein and called the gravitational lens .

Unlike a flat Universe (zero curvature) where light beams would continue indefinitely their stroke in a straight line, in a closed Universe (positive curvature), they would eventually return to their starting point. Credits: Lucy Reading-Ikkanda

Anomaly A lens : it could be explained by a closed sphere Universe

It is not about any light but the cosmic microwave background (CMB), that is to say the electromagnetic radiation bathing the Universe, whose first emission dates back to 380,000 years after the Big Bang during a phase called Recombination (capture of electrons by atomic nuclei).

The Planck satellite data, particularly from 2018, show that CMB has a more pronounced gravitational lens effect than expected. The Planck Collaboration has called this anomaly A lens , and this has not yet been resolved, but the team believes that an explanation could be the curvature of the Universe. The study was published in the journal Nature Astronomy.

The researchers showed that the anomaly in the spectrum of the cosmic microwave background could be interpreted as the sign of a closed universe (blue). Credits: Eleonora Di Valentino et al. 2019

"A closed universe can provide a physical explanation for this, with the Planck CMB spectrum now pointing to a positive curvature of greater than 99% confidence. Here we study further evidence of a closed universe collected by Planck, showing that positive curvature naturally explains the abnormal amplitude of the lens effect, "the researchers write.

An interpretation incompatible with all current data

A curved universe may explain this anomaly, but there are several important issues, including the fact that all other analyzes of Planck datasets, including the same data from 2018, concluded that the standard cosmological model is correct, including concerning a flat universe.

There are also other problems, and the team took care to note them in its article. One is Hubble's constant, which gives the rate of expansion of the Universe; it is a real problem in cosmology today. The different measures of this constant give different values, and to consider a curved universe makes this measurement even more complex.

The interpretation of the authors of the article (red and blue) is incompatible with the current data from different missions of cosmological observation (gray). Credits: Eleonora Di Valentino et al. 2019


Data from baryonic acoustic oscillation studies on dark energy are also inconsistent with the Closed Universe model, as are data on gravitational distortion obtained from observations of weak gravitational lenses . One other article also suggests that the anomaly A lens is simply a statistical bias in the data collected.

Future studies are needed to clarify the nature of the anomaly

Astrophysicists George Efstathiou and Steven Gratton of the University of Cambridge also analyzed Planck's 2018 data and found signs of curvature. But when compared to other Planck data sets and baryonic acoustic oscillations data, they found "solid evidence to support a spatially flat universe".

Much of the data seems to be in favor of a flat universe rather than a closed universe, except for the anomaly A lens . " Future steps will be needed to clarify whether the observed discrepancies are due to undetected systematics, new physics, or simply statistical fluctuation, " the researchers conclude.

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Wednesday, 6 November 2019

Mercury Transit: A rare astronomical event to observe on November 11, 2019


The year 2019 has been rich in observable astronomical phenomena, and it will end on November 11 with a relatively infrequent event: the transit of Mercury. The first planet in the Solar System will travel on a path through the solar disk. The event will be visible from most of the Earth's surface, with the appropriate equipment.

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Such a sight is relatively rare seen from Earth. From our point of view, only the transits of Mercury and Venus are visible. This event will be the fourth of the 14 Mercury transits that will take place in the 21st century. In contrast, Venus transits occur in pairs, with each pair spaced more than a century apart.

Mercury will take about 5.5 hours to travel in front of the Sun. Transit will be widely visible from most of the Earth, including from the Americas, the Atlantic and Pacific Oceans, New Zealand, Europe, Africa and West Asia. However, it will not be visible in Central and East Asia, Japan, Indonesia and Australia.

On May 9, 2016, Mercury made a spectacular transit, many astronomers having observed its passage in front of the Sun. The transit of 11 November should be identical. Credits: NASA's Goddard Space Flight Center / SDO / Genna Duberstein

A transit in several stages visible from the Earth

Transit begins before sunrise for observers in western North America. The transit ends after sunset for Europe, Africa, West Asia and the Middle East. The entire transit will be visible from end to end over eastern North America, Central and South America, southern Greenland and a small part of West Africa.

In France , it will be possible to observe the beginning of the passage and the maximum (minimum distance between the center of Mercury and the center of the Sun). However, the rest of the passage, and its end, will not be observable because the Sun will be lying down.

Times of observation of the transit of Mercury according to the different time zones. In Paris (UTC + 1), the hours of passage are those you see under UTC, adding 1h (for example 14h35 for Contact 1). Credits: Space.com

The first contact takes place when the disk of Mercury touches for the first time the eastern edge of the Sun. It takes about two minutes for the Mercury disk to move completely to the Sun's disk (second touch). The most important transit occurs when Mercury appears closest to the center of the Sun. The third contact is when the leading edge of Mercury reaches the western edge of the Sun. Two minutes later, Mercury completely leaves the solar disk (fourth touch).

Observation of the transit of Mercury: precautions are necessary

Mercury will appear as a black dot, representing only about 0.5% of the Sun's diameter. It will take a magnifying telescope at least 50 times to see it.

Special precautions should be taken when viewing the solar disk. Be careful never to look directly at the sun with a telescope. The visual requirements are the same as those for observing sunspots and partial solar eclipses - you need to use special sunscreens to protect your eyes.

It is much safer to project the image of the Sun using a telescope on a white card or a screen. If you use a telescope with a large aperture, for example 20 centimeters or more, place a circular mask in front of the lens or mirror to fix the image, reducing the amount of light and heat striking the lens or mirror.

A different transit depending on the time of the year

Since the orbit of Mercury is inclined 7 degrees from the plane of Earth's orbit, most of the time, when Mercury arrives at a lower conjunction (when it is between the Earth and the Sun), it moves above or below the Sun and does not pass through the solar disk from our terrestrial point of view. But in two points of the orbit of Mercury, it crosses the orbital plane of the Earth (called "node").

Astronomical characteristics of the transit of Mercury of November 11, 2019. Credits: F. Espenak

The Earth crosses the knot line every year on May 8th or 9th, then six months later, on November 10th and 11th. Transit may occur when a lower conjunction of Mercury occurs several days after these dates. When a transit occurs in May, Mercury is near the point of aphelion in its orbit - the furthest point from the Sun and closest to the Earth. If Mercury passes in the center of the Sun in May, the transit time can last nearly 8 hours.

When a transit takes place in November, as it will be this month, Mercury is near the point of perihelion of its orbit - the closest point to the Sun and farthest from the Earth, and where its apparent velocity is faster. As such, a central transit in November lasts only 5.5 hours, which is about what we will see on November 11th. And the number of transits in November is twice as large as the number of transits in May.

Predictability of mercurial transits

Mercury transits do not happen at random. At intervals of 13 and 33 years, Mercury and the Earth return almost simultaneously to the same points in their respective orbits, often resulting in repeated transit after this time interval. So, in connection with the coming transit of November 11, we can go back and find transits that happened 13 years ago, November 8, 2006, and 33 years ago, November 13, 1986.

Interestingly, the transits of May 9, 1970 and November 10, 1973, both fell on a Saturday, while the transits of May 9, 2016 and November 11, 2019 are both on a Monday. The next transit of Mercury will not take place before November 13, 2032.

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