User:Serendipodous/indigo/page 20

Canes Venatici

Ptolemy recorded them as uncontellated.

Canes Venatici: the hunting dogs, created by Johannes Hevalius in 1687.

Asterion, meaning "little star" ; the other, which contains the two brightest stars, is Chara, as Dear to the heart of her master.

Hunayn ibn Ishaq kolloboros= club, became kullab, the hooked staff.

Gerard of Cremona read kullab as kilab, dogs.

mag 4.2 Chara is only visible to the naked eye under darksky conditions.

Boötes hath unleash'd his fiery hounds.

Owen Meredith's Clytemnestra.

Hevalius

Johannes hevalius- actual name somewhat fluid (Jan hevelcke)

Like a surprisingly large number of astronomers, came from brewing.

gdansk 1611, born kingdom of poland. Eventually became mayor.

father of lunar topography (galileo)

system too cumbersome, replaced by riccioli. Galileo used maria first

today examples include the lunar alps.

Final Fantasy IV?

maker of lame constellations, including Scutum and lynx.

four years studying the moon, discovered libration

"eyes of a lynx"- so good he claimed he didn't need a telescope to map the stars. And he didn't.

Elizabeth hevalius- first in a long line of woman assistant astronomers

Madame Koopman Hevelius was "the first woman astronomer of which we have a picture showing her observing the heavens."

Chara

Beta CVn is considered to be slightly metal-poor,[8] which means it has a somewhat lower portion of elements heavier than helium when compared to the Sun. In terms of mass, age and evolutionary status, however, this star is very similar to the Sun.[20] As a result, it has been called a solar analog. It is about 3% more massive than the Sun,[6] with a radius 12% larger than the Sun's and 15% greater luminosity.

In 2006, astronomer Margaret Turnbull labeled Beta CVn as the top stellar system candidate to search for extraterrestrial life forms.[23] Because of its solar-type properties, astrobiologists have listed it among the most astrobiologically interesting stars within 10 parsecs of the Sun.[20] However, as of 2009, this star is not known to host planets.

Adriaan Van Maanan

about 68% of the Sun's mass but only 1% of its radius.

born Sneek, Netherlands, 1884, died California 1946, still doing astronomy admin after heart attack

J Kapteyn- Mount wilson

Of the 30 stars known when he died of 15th magnitude (10,000 to 1) known in 1946, VM found half

One he caught in 1917 is called Van Maanen's star

VM believed galaxies were visibly rotating- this became a point in the Great Debate, but it turned out to be instrument error

van Maanen published a parallax estimate of 0.246″, giving it an absolute magnitude of +14.8. This made it the faintest F-type star known at that time.[17] In 1923, Dutch-American astronomer Willem Luyten published a study of stars with large proper motions in which he identified what he called "van Maanen's star" as one of only three known white dwarfs, a term he coined in 1922.

The outer atmosphere has a temperature of approximately 6,110 K,[8] which is relatively cool for a white dwarf. As all white dwarfs steadily radiate away their heat over time, this temperature can be used to estimate its age, thought to be around 3 billion years.

projenitor 2.5 sm 900 my

evidence for material in its atmosphere means it must be replenished, probably by a ring of debris

gliese 508

double or triple?

553421

Y dwarfs are the coolest class of brown dwarfs known (Cushing et al. 2011; Kirkpatrick et al. 2012), with estimated effective temperatures (Teff) below 500 K

H2, He, H2S, CH4, H2O, and NH3 in the gas phase, and salt (KCl), sulfide (MnS, Na2S, and ZnS), and possible water ice condensates in the solid phase, which gravitationally settle within the atmosphere to form clouds

As a brown dwarf cools and passes through the MLTY sequence, various solid phase or liquid phase condensate clouds form until the atmosphere is eventually composed of layers upon layers of clouds, similar to the conditions seen in Jupiter

Interpretations of this variability range from simple holes in the clouds to variations in the thickness of uniform cloud decks. More recently, the potential for so-called “hot spots” or temperature variations giving rise to these variations has also been suggested

Krueger

Nepotism works

61 Cygni

is our nearest stellar neighbour in the northern hemisphere.

Milky way star, only naked eye on moonless nights

Bessel

Apprentice in business

cutting edge heliometer, best until the advent of cameras

1804 Olbers, Bremen 1799

eighth grade dropout- learn from books.

Halley's comet, calculation orbit

apprenticed to Olbers

mathematical prodigy

twice built telescope, catalogued his own errors

seven times higher salary, king of prussia, new observatory konigsberg

piazzi's flying star

After 25 years of attempts, thanks to state of the art measuring equipment, he measured 61 cygni's parallax in 1838

Present in the sky for most of the year, near many other stars to serve as a backdrop.

Gliese 1286

It's proxima

2mass...0427

T-dwarf, magenta colour, shows spectra for methane

Luytens star

500 thousand stars

Holberg

Sirius scintillates red at the horizon

Celestial manefestation of the goddess isis

Stars of Osiris (orion's belt) rise before Sirius

Osiris and Isis were returning from the Duat after several months

Khnum, lord of the Aswan cataract, would open his cave, sending the nile's flood downstream

Sothic cycle completed every 1461 years when the heliacal rising occured on 1 Thoth

Isis reassembled Osiris, gave birth to Horus, who married hathor. Hathor is often depicted with Sirius between her horns

Norman Lockyer observed that temples to Isis, aligned wiht sirius, were built on earlier misaligned foundations, to correct for precession.

Depending on location, topography and the precessional cycle, the heliacal rising of Sirius tends to occur in mid july

six degrees above the horizon (thickest atmosphere), sun 5 degrees below.

4th century astrologer Hephestion of Thebes: Sirius white, the flood would be high; if sirius was red, war.

TJJ See- tacitus- phoenix returns after 1461 years, sothic cycle

coins dating to the end of the sothic cycle have phoenixes on them

phoenix greek name for Bennu

Sirius may be ancient indo european, from sanskrit Tishtrya

Homer compares Sirius to bright bronze armor

Association with flames

het of summer, atmospheric distortion, caused scintillation, made sirius turbulent and unsettled.

The island of ceos, heliacal rising, check for epidemics

Noah Brosch

Bright stars are considered too mundane

heliacal rising, summer solstice, flooding of the nile

flammarion, warning dog

sothis= brilliant

sirius red in antiquity

mummification drying was set at 70 days, even though it would have taken less time- 70 days was the time Sirius was behind the Sun

Teh jewel on the brow of ra, carried before him on his solar boat

Locky6er fund that seven egyptian temples were oriented so that the light of Sirius would fal o9n their altars

Babylon, "sirrush" (no relation( a dragon with lion and eagle legs that filled a dog like role to Marduk

Sumerians, Babylonians and Persians called Sirius the arrow, fired from Orion's bow (or aimed at Orion that makes more sense)

Phoenicians called it the barker, and other semitic cultures, such as the Akkadians, and chaldeans, and even babylonians, appeared to have referred to Sirius as the dog star in some form

teh Sirius mystery

temple based his account on writings by 19th century anthropologists

to polo littlet seed star in orbit around sirius very dense so dens that all erthly beings together cannot lift it

saturn hand rings, Jupiter had four moons

A century later, other antrhopologists found no evidence of such knowledge among the dogon

accoounts by aquainteneces of gruikle's swingle Dogon informnant said he necver spoke of sirius as a double star system

mithraism depicted sirius as as bloodthirsty dog

One zoroastrian myth made sirius responsible, at the direction of Ormazed of course, for the Great Flood

the star that come forth at harvest time and plain seen his rays shin forth amid the host sf stars in the darkness of the night, the star whose name men call orions dog- iliad

Eratosthenes said that stars wre called seirios for the brightness of their light

Aratus, phenomena, summer was caused by the combined heat of sirius nd the sun

but when the artichoke flowers, and the chriping grasshopper sits in the tree and pours down his shrill song continually from under his wings in the season of wearisome heat, then goats are plumpest and wine sweetest, women are most wanton but men the feeblest, because sirius parches head and kneees and the skin is dry through heat- hesiod

Poliny- honey is derived from air, and when mervury, venus or jupiter rise with Sirius, then honey is sweeter

Sirius was tied to heat and disease, if sirius was hazy, disease, if sirius was bright, health

scandinavian mythology the dog of sigurd, the deerslayer,

the zulu beluieved that once sirius rose red, then it was time to go to bed

Under aldebaran, the date shines# under betelgeuse it darkens under sirius it is ripe

beduin

China described as a wolf, hunted by an archer with a bow and arrow

tien lang, celestial jackal (wolf?)

bow pointing at sirius

the inuit knew sirius as the moon dog, the Pawnee as the wolf star,

pawnee believed it guided souls along the Milky Way

Cherokee believe it is a wolf star that guards the milky way alongside antares

For teh Maori, of coure, sirius represented winter

Ptolemy's star catalogue

the brilliant on the mouth called the dog and reddish

kirros, the adjective was used to describe shades of wine,and was equivalent to rose

but in his other star catalogue, the tetrabiblios, despite naming many stars as red, such as aldabaran, betelgeuse and arcturus, does not call Sirius red

Seneca described the stars of Canicula shine red, which apparently meant just Sirius, not Canis minor

egyptians depicted sirius as a red triangle

several greek and roman sources describe sirius as red

chinese sources of the period call sirius a white star, or that it appeared to change colour

sirius appearing red for the smae reason the sun does?

observed at heliacal rising subrise, mist over alexandria coastal

Sirius

sirius;s proper motion means it was 70 degrees frm its current positin, and muchy fainter, 5 millionj years ago

edmond halley 1717 37 arcmin

1834 bessel wiggly motion w procyon invisible companions

macromegas

clark Sirius b 31 Jan 1862

Bessel 1834

I adhere to the coniction that procyon and Sirius are geuine binary systems, each consisting of a visible and an invisible star. we hae no reason to suppose that liminosity is a necessary property of cosmic bodies. The visibility of countless stars is no argment against the invisibility of others

50 year period

Alvan george Bassett |Clark, lenscrafters testing a new lens on Sirius, "Father! Sirius has a companion!" flammarion

the pup

Otto struve, half the mass of A bu8t 19 th times dimmer. "the two bodies are of very different constitution".

10 arcseconds distance

nickel 500 m 10 th bright

Measuremetns since the disovery have placed a value for the combined system of 3 solar masses, with a and b splitting 2 to 1.

Hussey suggested it may b a giant planet shining by refelcted light

50k yfn sirius 2.39 pc from earth, arginally br9ighter 150k yfn Vega brightest star f0r 250ky

A 12 17kK, B 10kK

cno of pre d B? sirius metal poor?

Levitics 17:7 se'irim, not adoration of devils, but Sirius?

1982: cno abundance -c n+ -o possibly due to absorbing cno from B progenitor?

1989 cr v sr y zr overabndant, (Am) others solar abundances

210 km/s for B 170km/s for A 30 km/s for F

Sirius's rotation is slower thn expected

Westgate 1933 rv 0, pole on

trandfer of mass from B to A- intrinsically slow rotation, stats demand

Sirius's magnetic field is weak,to nonexsistent

Vega iras noexcess sirius

Kervella

The age of the Sirius system has been poorly debated in the literature. Based on Wood’s (1995) sequences of cooling age of WD (carbon-oxygen model with thick H layer), Sirius B is found to be a young WD of about 160 (Holberg et al. 1998) to 210 ± 20 Myr (Holberg, private communication). The revisited mass of Sirius B (1.034 M�) corresponds to a progenitor mass of ≈7 M�, i.e. the approximate mass of a B5 main sequence star, from the empirical initial to final mass relation of Weidemann (2002). Such a massive star evolves to a WD in 40 ± 5 Myr. Consequently, assuming a simultaneous origin of both A & B components, the Sirius system is expected to be between 200 and 250 Myr old

sirius

y ∼1.5–1.6 au in the progenitor binary. This is smaller than the radius attained in the AGB phase of a ∼5.0–5.6 M star, and thus the two must almost certainly have interacted in the past. H

great filter

Anders Sandberg: alone in the universe means we must protect ourselves from existential risk

We still have no idea how likely abiogenesis is.

Karl Schroeder, scifi writer: "any sufficiently advanced technology is indistinguishable from nature."

Novels, plays, callled the Great Filter

Robin Hanson

Evidence and theory seems to suggest there are few to no filters. One must be wrong

Life will colonise. Only a few individuals are required to enter a new ecological niche

New niches will open with advancing technology

Some of our descendants will colonise planets, stars and galaxies

In a universe without FTL, it is unlikely cultures will remain homogenous. Therefore it is impossible to assume the motives of all of them

Even a deadly probe-dropping culture would still likley colonise, since it provides resources for more deadly probes and bars systems from competitors

Only a small amount of radioactive waste can change a star's spectrum. Converting an asteroid belt into solar collectors would alter a star's spectrum

No civilization in the past universe has reached the explosive point

We have managed to explain our planet, star system, galaxy and other galaxies entirely through the invokation of natural processes.

The Great Filter implies that one of the steps toward galactic colonisation is improbable.

Even if we as a society choose the "stable" path, someone in the next million years should choose the explosive path

For example, if our prospects are likely bleak we should search out and take especially seriously any plausible scenarios, such as nuclear war or ecological collapse, which might lead to our future inability to explode across the universe.

With such a warning in hand, we might, for example, take extra care to protect our ecosystems, perhaps even at substantial expense to our economic growth rate. We might be even especially cautious regarding the possibility of world-destroying physics experiments. And we might place a much higher priority on projects like Biosphere 2, which may allow some part of humanity to survive a great disaster.

advanced tool use has only evolved once, in us

First, large-scale engineering such as orbiting solar collectors made from asteroids, Dyson spheres, and stellar disassembling might be effectively impossible, explaining why nearby stars look so natural. Second, structures that best use such resources might happen to almost always preserve natural spectra and other appearances.

I personally think that most of the Great Filter is most likely to be explained by the steps I think we understand the least about: the steps in the biological evolution of life and intelligence.

Hanson dismissed social scientific explanations, such as Sagan arguing that we must transition from material growth to non-material goals, as wishful thinking when applied to all species.

Examination of why societies like Easter Island collapse

Nick Bostrom

"Dead rocks and lifeless sands would lift my spirit"

Eukaryotic, multicellularity, sexual reproduction are all possible filters

Any existential threat we can conceive of, such as global warming, environmental devastation, or nuclear war, would only delay the explosion by a few thousand years

If the great filter is before us, then we can expect to go extinct, and "must relinquish all hope of colonising the galaxy".

"the worst news ever printed in a newspaper" "Nothing in the above reasoning precludes the Great Filter from being located both behind us and ahead of us. It might both be extremely improbable that intelligent life should arise on any given planet, and very improbable that intelligent life, once evolved, should succeed in becoming advanced enough to colonize space."

Caitlin Grace

If the „simulation argument‟ is true, humanity may be living in a simulation, in which case there is an extinction risk from those who simulate our world losing interest in running it (Bostrom 2003a).

Another indirect risk resulting from ecological damage is the temptation to interfere on a larger scale to fix the problems, such as through geoengineering, which may lead to other existential risks (Cirkovic & Cathcart 2004).

Given how enormous the filter is, for indifference to colonization to be a large filter step, it would need to be an inevitable outcome of virtually all advanced civilizations, not just a plausible story about one. There would need to be a ubiquitous mechanism leading civilizations to change their values as well as a strong tendency for them to have effective global enforcement of this preference.

One view is that on awakening (before learning the number of your room) you have learned nothing, since everyone would awaken in your situation under either hypothesis. Since the coin was fair, you should still be fifty percent sure that it fell heads. If that is so, upon learning you are in one of the first ten rooms you must update to be 99 percent sure the coin fell heads, since being among the first ten rooms was certain if the coin landed heads and had a one percent chance if the coin landed tails. Another view is that on waking you should be 99 percent sure that the coin landed tails, since you had a much higher likelihood of being created if many people were created. After learning you are in one of the first ten rooms you should then be fifty percent confident of heads. The correct answer is disputed. The two opinions above coincide with the answers given by the two main reasoning principles advanced to deal with indexical information. The first answer agrees with the Self Sampling Assumption (SSA) formulated by Nick Bostrom and used implicitly by others (Bostrom 2002a; Leslie 1992; Franceschi 2004; Leslie 1993; Lewis 2001), and the second with the Self Indication Assumption (SIA) which has been formulated, or used implicitly in some form, by several authors (Kopf et al. 1994; Dieks 1992; Olum 2002; Dieks 2007; Monton 2003; Hanson 1998a; Elga 2000).

The Self Sampling Assumption (SSA) developed by Bostrom (2002a) solves the above problem (Bostrom 2002c). Intuitively, what matters in science is the assumption that whatever you observe is much more likely to be a common observation than an uncommon one. So instead of taking P(E|H) to be the probability that E is observed at least once by someone given H, when we do science we understand it as something like the expected proportion of people who observe E under hypothesis H. SSA formalizes that idea. Under SSA, P(E|H) is replaced by the proportion of your reference class who receive evidence E if hypothesis H is true. Your reference class is a set of people or creatures similar to you, which will be discussed further shortly. We will call the set of people you could possibly be, given your information, your information set. For instance in God‟s Coin Toss above, if your reference class were „people in the experiment‟, under either hypothesis one hundred percent of them have your experience of waking up (and so are in your information set), so your posterior is the same as your prior: fifty percent to heads for a fair coin. When you learn that your number is between one and ten, under a heads hypothesis one hundred percent of your reference class shares your observations, while under tails only one percent do, so Bayes‟ theorem can be used to update strongly in favour of heads.

For instance in God‟s coin toss, initially the tails world contains one hundred times as many observers in your information set as the heads world does, and both worlds are equally likely based on other information. This means SIA says the tails hypothesis is one hundred times more likely. After learning your number is between one and ten, the number of people in your situation is equal under each hypothesis, so both hypotheses are equally likely.

Damascus

we may try to escape this fate, but we can’t learn what the event was (at least until we carry out extensive space exploration, which will likely be possible only after the most vulnerable period for human civilization is already past

“Consequently, ceteris paribus, the more likely that an existential risk strategy has been unsuccessfully tried in the past by another civilization, the less likely it will work for us. The strategies with the lowest cost, fewest negative side effects, and highest chance of success are the ones most likely to have been tried.

Peacock

If there is a Great Filter, then the most natural account of it is that it is nothing more than Lotka’s Law or some similar power law that drastically limits the number of species that survive a long succession of survival challenges. What matters the most to survival in the long run is not the type of survival challenge, but the number of them. The number of species that can be expected to survive n survival trials will go roughly as an inverse power of n. This implies that the Filter is something that is neither strictly before us nor strictly after us, but rather a factor which operates all the time.

The problem with the von Neumann probe hypothesis is that the spread of the probes could well be subject to the same Lotkan limitations as the long-term survival of ordinary biological organisms. Although this requires more study, it is probably safe to say (at least to a coarse approximation) that in biology, unfettered proliferation and radiation are exponential, while long-term survival is described by power laws.

Terrestrial and tectonic risks could include massive volcanism, Gaian bottlenecks, or other sorts of natural climate change perhaps due to lethal nonlinearities in oceanicatmospheric or ecosystem dynamics. It is worth noting that most of the major and medium-sized mass extinction events throughout Earth’s history have been climatological, often (though not always) trigged by greenhouse emissions due to massive volcanism. (A major impact played a role in the terminal Cretaceous extinction 66 mya). Biological risks could include epidemic disease due to emergent pathogens, hostile actions by a technologically superior extraterrestrial species (highly unlikely, one hopes, but not inconceivable), or (again) some factor of which we presently have no knowledge.

Possibilities

March

Astronomers from Japan, Taiwan and Princeton University have discovered 83 quasars powered by supermassive black holes in the distant universe, from a time when the universe was less than 10 percent of its present age. 83 previously unknown very distant quasars. Together with 17 quasars already known in the survey region, the researchers found that there is roughly one supermassive black hole per cubic giga-light-year "It is remarkable that such massive dense objects were able to form so soon after the Big Bang," said Michael Strauss, a professor of astrophysical sciences at Princeton University who is one of the co-authors of the study. "Understanding how black holes can form in the early universe, and just how common they are, is a challenge for our cosmological models." This is a milestone of cosmic history, but astronomers still don't know what provided the incredible amount of energy required to cause the reionization. A compelling hypothesis suggests that there were many more quasars in the early universe than detected previously, and it is their integrated radiation that reionized the universe. "The number of quasars seen is significantly less than needed to explain the reionization

By using the new technology, the researchers determined how much of the dust came from regular stars churning away, and how much came from supernovas (less than 1 percent). The percentage that originated from supernovas was higher than expected—this suggests that more of the star dust that makes it to Earth has a supernova origin. And that suggests that more of the star dust in space originated in supernovae than has been thought. The dust studied by the researchers was obtained from chondrite samples found in Northwest Africa.

June

A distant galaxy more massive than our Milky Way—with more than a trillion stars—has revealed that the 'cores' of massive galaxies in the Universe had formed already 1.5 billion years after the Big Bang, about 1 billion years earlier than previous measurements revealed. Researchers published their analysis on November 6, 2019 in The Astrophysical Journal Letters, a journal of the American Astronomical Society. "If we point a telescope to the sky and take a deep image, we can see so many galaxies out there," said Masayuki Tanaka, paper author and associate professor of astronomical science in the Graduate University for Advanced Studies and the National Astronomical Observatory of Japan. "But our understanding of how these galaxies form and grow is still quite limited—especially when it comes to massive galaxies." Galaxies are broadly categorized as dead or alive: dead galaxies are no longer forming stars, while living galaxies are still bright with star formation activity. A 'quenching' galaxy is a galaxy in the process of dying—meaning its star formation is significantly suppressed. Quenching galaxies are not as bright as fully alive galaxies, but they're not as dark as dead galaxies. Researchers use this spectrum of brightness as the first line of identification when observing the Universe. The researchers used the telescopes at the W.M. Keck Observatory in Hawaii to observe a quenching galaxy in what is called the Subaru/XMM-Newton Deep Field. This region of the sky has been closely observed by several telescopes, producing a wealth of data for scientists to study. Tanaka and his team used an instrument called MOSFIRE on the Keck I telescope to obtain measurements of the galaxy. They obtained a two-micron measurement in the near-infrared spectrum, which the human eye cannot see, but it confirmed that the light from the galaxy was emitted just 1.5 billion years after the Big Bang. The team also confirmed that the galaxy's star formation was suppressed.

No matter how elegant your theory is, experimental data will have the last word. Observations of the retrograde motion of the planets were fundamental to the Copernican revolution, in which the sun replaced Earth at the centre of the solar system. And the unusual orbit of Mercury provided a spectacular confirmation of the theory of general relativity. In fact, our entire understanding of the universe is built on observed, unexpected anomalies. Now our new paper, published in Nature Astronomy, has come to a conclusion that may unleash a crisis in cosmology—if confirmed. We show that the shape of the universe may actually be curved rather than flat, as previously thought—with a probability larger than 99%. In a curved universe, no matter which direction you travel in, you will end up at the starting point—just like on a sphere. Though the universe has four dimensions, including time. The result was based on recent measurements of the Cosmic Microwave Background, the light left over from the Big Bang, collected by the Planck Satellite. According to Albert Einstein's theory of general relativity, mass warps space and time around it. As a result, light rays take an apparent turn around a massive object rather than travelling in a straight line—an effect known as gravitational lensing. There is much more such lensing in the Planck data than there should be, which means the universe could contain more dark matter—an invisible and unknown substance—than we think. In our study, we showed that a closed universe can provide a physical explanation to this effect, because it is able to host a lot more dark matter than a flat universe. Such a universe is perfectly compatible with general relativity.Not all cosmologists are convinced by a closed universe though—previous studies have suggested the cosmos is indeed flat. And if a spherical universe is a solution to the lensing anomaly, then we have to deal with several significant consequences. First of all, we have to revise a fundamental cornerstone of cosmology—the theory of cosmological inflation. Inflation describes the first instants after the Big Bang, predicting a period of exponential expansion for the primordial universe.The theory was developed over the past 40 years to explain why distant parts of the universe look the same and have the same temperature, when they are too far apart to ever have been in contact. Inflation solves the problem because it means that far-flung regions of the universe would once have been connected. But the period of rapid expansion that hurled these regions apart is also thought to have also brought the universe to flatness with exquisite precision. Once we assume that the universe is curved, the Planck data is essentially in disagreement with all other datasets. This all boils down to a real crisis for cosmology, as we say in our paper. For these reasons, cosmologists are cautious—and many of them prefer to attribute the results to a statistical fluke that will resolve when new data from future experiments are available. It is certainly possible that we turn out to be wrong. But there is one main reason, in our opinion, why this anomaly should not be merely discarded. In particle physics, a discovery should reach an accuracy of at least five "sigmas" to be accepted by the community. Here we are slightly above three sigmas, so we are clearly below this acceptance level. But while the standard model of particle physics is based on known and proven physics, the standard cosmological model is based on unknown physics. At the moment, the physical evidence for the three pillars of cosmology—dark matter, dark energy (which causes the universe to expand at an accelerated rate) and inflation—comes solely from cosmology. Their existence can explain many astrophysical observations. But they are not expected either in the standard model of particle physics that governs the universe on the smallest scales or in the theory of general relativity that operates on the large scales. Instead, these substances belong to the area of unknown physics. Nobody has ever seen either dark matter, dark energy or inflation—in the laboratory or elsewhere. So while an anomaly in particle physics can be regarded as a hint that we may need to invent completely new physics, an anomaly in cosmology should be regarded as the only way we have to shed light on completely unknown physics. Therefore, the most interesting result of our paper is not that the universe appears to be curved rather than flat, but the fact that it may force us to rearrange the pieces of the cosmic puzzle in a completely different way. Conventional theory, which backs inflation theory, suggests that after the Big Bang, the universe expanded in a way that was flat—two lights shone in parallel would travel forever in parallel. But now, after studying data sent back to Earth from the Planck space observatory (which mapped cosmic microwave background radiation over the years 2009 to 2013) Di Valentino, Melchiorri and Silk have come to disagree with conventional thinking. They claim that there is evidence that the universe is closed—that it is shaped like a sphere. If you shine two lights into the dark of space, they suggest, at some point, the light would come back around to you from behind The researchers came to this conclusion after looking at data from the Planck space observatory that showed a discrepancy between the concentration of dark matter and dark energy and outward expansion; there was more gravitational lensing than theory has predicted. Such an imbalance, they claim, would have the universe collapsing in on itself, resulting in a sphere shape. Others who have looked at the same data prior to this new effort have called the data from the observatory a statistical fluke. The research trio note that there are other problems with the flat theory as well, such as scientists' inability to accurately measure the Hubble constant; each team that tries finds a different answer. There have also been problems with reconciling surveys of dark energy with a flat model. They conclude by acknowledging that with current technology there is no way to settle the debate—new devices will need to be invented that will be able to measure microwave background radiation in ways not subject to debate. Astronomers led by Eduardo Bañados of the Max Planck Institute for Astronomy have discovered a gas cloud that contains information about an early phase of galaxy and star formation, merely 850 million years after the Big Bang. The cloud was found serendipitously during observations of a distant quasar, and it has the properties that astronomers expect from the precursors of modern-day dwarf galaxies. When it comes to relative abundances, the cloud's chemistry is surprisingly modern, showing that the first stars in the universe must have formed very quickly after the Big Bang. The results have been published in the Astrophysical Journal. But when Bañados analyzed a more detailed spectrum, obtained with the Magellan Telescopes at Las Campanas Observatory in Chile, he recognized that there was something else going on: The weird spectral features were the traces of a gas cloud that was very close to the distant quasar—one of the most distant gas clouds astronomers have yet been able to identify. From the spectrum of the gas cloud, the researchers could immediately tell the distance of the cloud, and that they were looking back into the first billion years of cosmic history. They also found traces of several chemical elements including carbon, oxygen, iron, and magnesium. However, the amount of these elements was tiny, about 1/800 times the abundance in the atmosphere of our sun. Astronomers summarily call all elements heavier than helium "metals;" this measurement makes the gas cloud one of the most metal-poor (and distant) systems known in the universe. Michael Rauch from the Carnegie Institution of Science, who is co-author of the new study, says: "After we were convinced that were were looking at such pristine gas only 850 million years after the Big Bang we started wondering whether this system could still retain chemical signatures produced by the very first generation of stars." Finding these first generation, so-called "population III" stars is one of the most important goals in reconstructing the history of the universe. In the later universe, chemical elements heavier than hydrogen play an important role in letting gas clouds collapse to form stars. But those chemical elements, notably carbon, are themselves produced in stars, and flung into space in supernova explosions. For the first stars, those chemical facilitators would simply not have been there, since directly after the Big Bang phase, there were only hydrogen and helium atoms. That is what makes the first stars fundamentally different from all later star The analysis showed that the cloud's chemical make-up was not chemically primitive, but instead the relative abundances were surprisingly similar to the chemical abundances observed in today's intergalactic gas clouds. The ratios of the abundances of heavier elements were very close to the ratios in the modern universe. The fact that this gas cloud in the very early universe already contains metals with modern relative chemical abundances poses key challenges for the formation of the first generation of stars. This study implies that the formation of the first stars in this system must have begun much earlier: the chemical yields expected from the first stars had already been erased by the explosions of at least one more generation of stars. A particular time constraint comes from supernovae of type Ia, cosmic explosions that would be required to produce metals with the observed relative abundances. Such supernovae typically need about 1 billion years to happen, which puts a serious constraint on any scenarios of how the first stars formed.

CNRS, the Paris Observatory—PSL and the University of Franche-Comté have now shown that Mimas may have moved closer to Saturn in the recent past, making the moon a kind of remote snowplough that widened the initial gap, giving it the 4500 km width it has today. If on the other hand the orbit of Mimas moved outwards, the particles would return to their original position, rather as if a snowplough were to reverse and stop pushing the snow, letting it spread out again. Using numerical simulations, the researchers calculated that Mimas must have migrated inwards by 9000 km over a few million years in order to open up the 4500 km gap that currently makes up the Cassini Division. A natural satellite, such as the Moon, normally tends to move away from its planet rather than closer to it. In order to migrate inwards, a moon has to be able to lose energy, particularly by heating up, which would cause its internal ice to melt and weaken its outer crust. However, the state of Mimas' surface, which still bears the scars of relatively ancient meteorite impacts, does not tally with such a scenario. The researchers' second hypothesis, which remains to be confirmed, is that the loss of heat was shared out between Mimas and Enceladus, another of Saturn's moons, through orbital resonance. This would have caused the creation of the internal oceans that the Cassini spacecraft detected below the surface of both these bodies. Today, Mimas has begun to migrate outwards again. According to the researchers' calculations, the Cassini Division is likely to take around 40 million years to close up again.

December

The Parker Solar Probe's first measurements show that variations in the wind's speed and in the magnetic field are much greater than observed near Earth. For example, the magnetic-field sensors detected large flips in the direction of the magnetic field. We have no idea what these "switchbacks" really are. But the measurements show that they coincide with increases in the speed of the solar wind flowing away from the sun. This happens through short and strong "jets"—increases in the flow speed of the solar wind with a duration of just a few minutes. The exact nature of the magnetic switchbacks and jets are certainly a puzzle that we must resolve in the future. They are so intensive that they may actually be a major factor for driving the acceleration of the solar wind. The instruments on the probe also detected many smaller fluctuations in the electromagnetic fields. Like the switchbacks, we have known about their existence from previous measurements, but their intensity near the sun is really surprising. This suggests they may actually have an important role in the heating of the solar corona as well as accelerating the solar wind.

Proxima b

November

Astrophysicists at the Georgia Institute of Technology modeled a theoretical twin of Earth into other star systems called binary systems because they have two stars. They concluded that 87% of exo-Earths one might find in binary systems should have axis tilts similarly steady to Earth's, an important ingredient for climate stability that favors the evolution of complex life. "Multiple-star systems are common, and about 50% of stars have binary companion stars. So, this study can be applied to a large number of solar systems," said Gongjie Li, the study's co-investigator an assistant professor at Georgia Tech's School of Physics.Single-star solar systems like our own with multiple planets appear to be rarer. In Alpha Centauri AB, star B, about the size of our sun, and the larger star, A, orbit one another at about the distance between Uranus and our sun, which is a very close for two stars in a binary system. The study modeled variations of an exo-Earth orbiting either star but concentrated on a modeled Earth orbit in the habitable zone centered around B, with A being the orbiting star. A's orbit is very elliptical, passing close by and then moving very far away from B and slinging powerful gravity, which, in the model, overpowered exo-Earth's own dynamics. Its tilt and orbit varied widely; adding our moon to the model didn't help. "Around Alpha Centauri B, if you don't have a moon, you have a more stable axis than if you do have a moon. If you have a moon, it's pretty much bad news," Quarles said. Even without a moon and with mild axis variability, complex, Earthlike evolution would seem to have a hard time on the modeled exo-Earth around B. "The biggest effect you would see is differences in the climate cycles related to how elongated the orbit is. Instead of having ice ages every 100,000 years like on Earth, they may come every 1 million years, be worse, and last much longer," Quarles said. But a sliver of hope for Earthlike conditions turned up in the model: "Planetary orbit and spin need to precess just right relative to the binary orbit. There is this tiny sweet spot," Quarles said.

August

McGill Physics student Evelyn Macdonald and her supervisor Prof. Nicolas Cowan used over a decade of observations of Earth's atmosphere taken by the SCISAT satellite to construct a transit spectrum of Earth, a sort of fingerprint for Earth's atmosphere in infrared light, which shows the presence of key molecules in the search for habitable worlds. This includes the simultaneous presence of ozone and methane, which scientists expect to see only when there is an organic source of these compounds on the planet. Such a detection is called a "biosignature".

"We have used an ocean circulation model to identify which planets will have the most efficient upwelling and thus offer particularly hospitable oceans. We found that higher atmospheric density, slower rotation rates, and the presence of continents all yield higher upwelling rates. A further implication is that Earth might not be optimally habitable—and life elsewhere may enjoy a planet that is even more hospitable than our own.

July

Planets become snowballs when their atmospheric carbon dioxide levels drop too low from a combination of rainfall and erosion. Water absorbs carbon dioxide and turns it into carbonic acid, which reacts with rocks on the ground during erosion. This interaction breaks carbonic acid down more. It binds with minerals, which are then carried to the oceans and eventually stored into the seafloor. 00000Scientists previously thought carbon dioxide removal from a planet's atmosphere stopped during snowball phases because all of its surface water was frozen. But surprisingly, the new study found some snowball planets continue to lose carbon dioxide even after they've frozen. This means the planets would have to have some non-frozen ground and occasional rainfall for water to continue to remove carbon dioxide from the atmosphere Some of the warmer snowball planets the study's authors simulated had land areas warm enough to hold liquid water and life even when their oceans were frozen to their equators. They found land areas in the center of the continents away from the frozen oceans could reach temperatures above 10 degrees Celsius (50 degrees Fahrenheit). This is much warmer than the lowest temperature at which life can reproduce, which scientists estimate to be minus 20 degrees Celsius (minus 4 degrees Fahrenheit).

June

a UC Riverside–led team discovered that a buildup of toxic gases in the atmospheres of most planets makes them unfit for complex life as we know it. "To sustain liquid water at the outer edge of the conventional habitable zone, a planet would need tens of thousands of times more carbon dioxide than Earth has today," said Edward Schwieterman, the study's lead author and a NASA Postdoctoral Program fellow working with Lyons. "That's far beyond the levels known to be toxic to human and animal life on Earth." The new study concludes that carbon dioxide toxicity alone restricts simple animal life to no more than half of the traditional habitable zone. For humans and other higher order animals, which are more sensitive, the safe zone shrinks to less than one third of that area. What is more, no safe zone at all exists for certain stars, including two of the sun's nearest neighbors, Proxima Centauri and TRAPPIST-1. The type and intensity of ultraviolet radiation that these cooler, dimmer stars emit can lead to high concentrations of carbon monoxide, another deadly gas. Carbon monoxide binds to hemoglobin in animal blood—the compound that transports oxygen through the body. Even small amounts of it can cause the death of body cells due to lack of oxygen. Carbon monoxide cannot accumulate on Earth because our hotter, brighter sun drives chemical reactions in the atmosphere that destroy it quickly.

May

A new study by researchers based at the University of Vienna and at the Space Research Institute of the ÖAW in Graz has shown that young stars can rapidly destroy the atmospheres of potentially-habitable Earth-like planets, which is a significant additional difficulty for the formation of life outside our solar system. When orbiting young stars with high activity levels, the thermospheres of planets are heated to much higher temperatures which, in extreme cases, can cause the gas to flow away from the planet. These results have significant implications for the early evolution of the Earth and for the possibility of Earth-like atmospheres forming around M-dwarfs. For the Earth, the most likely explanation for why the atmosphere was not lost is that the early atmosphere was dominated by carbon dioxide, which cools the upper atmosphere by emitting infrared radiation to space, thereby protecting it from the heating by the early Sun's high activity. The Earth's atmosphere could not have become nitrogen dominated, as it is today, until after several hundred million years when the Sun's activity decreased to much lower levels. More dramatically, the results of this study imply that for planets orbiting M-dwarf stars, they can only form Earth-like atmospheres and surfaces after the activity levels of the stars decrease, which can take up to several billion years. More likely is that many of the planets orbiting M-dwarf stars have very thin or possible no atmospheres. In both cases, life forming in such systems appears less likely than previously believed.

March

Edward W. Schwieterman, a NASA postdoctoral program fellow at the University of California, Riverside; the carbonate silicate cycle- the closer a planet is to the inner edge of the habitable zone, the less co2 is required for it. 1000 times as much co2

Jan

Harvard University, where postdoctoral researcher Manasvi Lingam and Professor Abraham Loeb Mdwarfs 400 to 750 nm Not habitable; unable to exceed the minimum UV flux that is required to ensure a biosphere similar to that of Earth.

Rocky planets orbiting red dwarf stars may be bone dry and lifeless.. a rapidly eroding dust-and-gas disk encircling the young, nearby red dwarf star AU Microscopii (AU Mic) by VLT. Fast-moving blobs of material appear to be ejecting particles from the AU Mic disk. If the disk continues to dissipate at this rapid pace, it will be gone in about 1.5 million years. In that short time, icy material from comets and asteroids could be cleared out of the disk. One theory is that powerful mass ejections from the turbulent star expelled them.

However, something important happens when planets decrease in size: As they warm, their atmospheres expand outward, becoming larger and larger relative to the size of the planet. These large atmospheres increase both the absorption and radiation of heat, allowing the planet to better maintain a stable temperature. The researchers found that atmospheric expansion prevents low-gravity planets from experiencing a runaway greenhouse effect, allowing them to maintain surface liquid water while orbiting in closer proximity to their stars. The researchers found that the critical size is about 2.7 percent the mass of Earth. If an object is smaller than 2.7 percent the mass of Earth, its atmosphere will escape before it ever has the chance to develop surface liquid water, similar to what happens to comets today. To put that into context, the moon is 1.2 percent of Earth mass and Mercury is 5.53 percent.

Numerical models have shown that Proxima Centauri b probably lost a large amount of its water in its early life stages—an amount comparable to an ocean on Earth—but despite this, it is still possible that some liquid water remained in warmer regions of the planet, maybe in a tropical belt or at the hemisphere facing the central star in case of locked rotation. This makes other factors affecting habitability, such as the magnetic activity of the host star, particularly important, as activity-related phenomena (flares, coronal mass ejections, strong UV flux) can erode a planet's atmosphere, rendering it uninhabitable in the long term.

The strong flaring activity of Proxima Centauri has already been known to astronomers, and several superflares were observed previously. During such eruptions, extremely large amounts of energy are released that may reach 1033 ergs, or 10 times the Carrington event in 1859, the strongest flare ever seen on the sun—consider such a flare from a much smaller star. In 2016, during one these superflares, the brightness of Proxima Centauri increased by a factor of 70 compared to its quiescent state —it became the only cool red dwarf visible to the naked eye, albeit only for a few minutes. Researchers of the Konkoly Observatory of the MTA CSFK (Budapest, Hungary), led by Krisztián Vida, investigated Proxima Centauri using the newest data from the Transiting Exoplanet Survey Satellite (TESS) space telescope. The primary task of the TESS is to search for Earth-like exoplanets around nearby brighter stars. In its initial two-year mission, it will cover almost the entire sky, spending about a month at each region. TESS observed Proxima Centauri in two sectors between April and June this year. In the ~50 day-long time series, the researchers identified 72 flares: The star spent about 7 percent of its time flaring. The researchers found signs of oscillations in the light curves of the two largest flares with a time scale of a few hours. These may be due to oscillation of the radiating plasma, or due to periodic reconnections of the magnetic field. The estimated energy of the eruptions was between 1030 and 1032 ergs. These do not reach superflare level, but according to the distribution of the observed events, flares with an energy of 1033 ergs are expected to occur three times a year, while eruptions of one magnitude larger would happen every two years. Such frequent, high-energy eruptions almost certainly have a severe impact on the atmosphere of Proxima Centauri b: The atmosphere probably cannot relax to a steady state between eruptions, and is continuously altered. This scenario is similar to observations in the TRAPPIST-1 system, another cool red dwarf that hosts exoplanets.

Lead author and Rice graduate student Alison Farrish and her research adviser, solar physicist David Alexander, led their group's first study to characterize the "space weather" environment of stars other than our own to see how it would affect the magnetic activity around an exoplanet. It's the first step in a National Science Foundation-funded project to explore the magnetic fields around the planets themselves. In the study published in The Astrophysical Journal, the researchers expand a magnetic field model that combines what is known about solar magnetic flux transport—the movement of magnetic fields around, through and emanating from the surface of the sun—to a wide range of stars with different levels of magnetic activity. The model is then used to create a simulation of the interplanetary magnetic field surrounding these simulated stars. In this way they were able to hypothesize the potential environment experienced by such "popular" exoplanet systems as Ross 128, Proxima Centauri and TRAPPIST 1, all dwarf stars with known exoplanets. "Depending on where it is within the extended magnetic field of the star, it is estimated that some of these habitable zone exoplanets could lose their atmospheres in as little as 100 million years," Alexander said. "That is a really short time in astronomical terms. The planet may have the right temperature and pressure conditions for habitability, and some simple lifeforms might form, but that's as far as they're going to go. The atmosphere would be stripped and the radiation on the surface would be pretty intense.

August

GJ1061, which is the 20th-closest star system, approximately 17.5 light-years away. It is classified as a small, low-mass (M dwarf) star with low volatility, suggesting it might have habitable planets. The group reports that they found evidence of three planets and possibly a fourth circling GJ1061. All three of the planets were found to be slightly larger than Earth and all three orbit close to the star—each takes just days to make its way around. The researchers focused on one planet in particular, which they named planet d. They found it took only 13 days for it to make its way around its star. The researchers calculated that such a distance puts it in the Goldilocks zone. They also note that, unfortunately, M dwarf stars tend to have a volatile history. If planet d was blasted with radiation for millions of years, it is not likely suitable to harbor life now.

November

in collaboration with researchers at the University of Colorado Boulder, NASA's Virtual Planet Laboratory and the Massachusetts Institute of Technology, discovered that only planets orbiting active stars—those that emit a lot of ultraviolet (UV) radiation—lose significant water to vaporization. Planets around inactive, or quiet, stars are more likely to maintain life-sustaining liquid water. The researchers also found that planets with thin ozone layers, which have otherwise habitable surface temperatures, receive dangerous levels of UV dosages, making them hazardous for complex surface life. "For most of human history, the question of whether or not life exists elsewhere has belonged only within the philosophical realm," said Northwestern's Howard Chen, the study's first author. "It's only in recent years that we have had the modeling tools and observational technology to address this question." "Still, there are a lot of stars and planets out there, which means there are a lot of targets," added Daniel Horton, senior author of the study. "Our study can help limit the number of places we have to point our telescopes."

Spotlight

draughts with toth, birth of Osiris, Horus, Set, Isis and Nepthis

three seasons, flood season, sowing season, and harvest season

Egyptian calendars began on the autumn equinox, between flood and sowing

heliacal rising of Sirius marked the flooding of the Nile, leaving the calendar, too sacred to touch, to fall out of sync with the seasons, and corresponding festivals with them

Ptoelmy I decreed that 1 day should be added as the "Festival of the Good-Doing Gods" 283 BC

It failed.

In Babylon, intercalculary month were added randomly by royal decree

and then they discovered the metonic cycle

Originally, the greeks used a three months in eight years correction, but eventually switched to the Metonic cycle. Whether Meton borrowed the cycle from the babylonians or invented it independently is not known

In 46 BC, the Roman calendar was 117 days ahead of the season. with months added by decree, it fell into disrepair.