4335 - MARS - was there water there?

 

-    4335  -  MARS  -  was there water there?  Evidence of ancient lake sediments at the base of Mars' Jezero crater offer new hope for finding traces of life in samples collected by NASA's Perseverance rover.  What about Venus? Did it have oceans?

--------------------------  4335  -  MARS  -  was there water there?

-

-    “Perseverance rover” found evidence of ancient lake sediments at the base of Mars' Jezero Crater offering new hope for finding traces of life in samples collected.

-

-   Perseverance touched down on Feb. 18, 2021 inside the Red Planet's 28-mile-wide Jezero Crater, which is believed to have once hosted a large lake and river delta. The rover has been scouring the crater in search of signs of past life and collecting and caching dozens of samples along the way for a possible future return to Earth.

-

-   Using the rover's “Radar Imager for Mars' Subsurface Experiment”  instrument, researchers from the University of California, Los Angeles and the University of Oslo revealed new clues about how sediment layers formed over time on the crater floor.

-

-    As Perseverance travels across the surface of Mars, the RIMFAX instrument sends radar waves downward at 4-inch (10-centimeter) intervals and measures pulses reflected from depths of about 65.6 feet (20 meters) below the surface to create a subsurface profile of the crater floor.

-

-   The RIMFAX data showed evidence of sediment deposited by water that once filled the crater. It's possible that microbial life could have lived in the crater at this time and, if such life existed on Mars, sediment samples from this area would contain signs of their remains.

-

-    Two distinct periods of deposition occurred, creating layers of sediments on the crater floor that appear regular and horizontal, much like strata layers seen on Earth. Fluctuations in the lake's water levels caused some of the sediment deposits to form an enormous delta, which Perseverance traversed between May and December 2022.

-

-    The radar measurements also show an uneven crater floor below the delta, which is likely due to erosion before sediments were first deposited. After, as the lake dried up over time, the sediment layers in the crater were eroded, forming the geologic features visible on the Martian surface today.

-

-    The changes preserved in the rock record are driven by large-scale changes in the Martian environment.

-

-    Looking at the next p;anet in the other direction we hope to learn why Venus died.   Venus is only slightly smaller than the Earth.  But for this planet's heat has betrayed it. The planet is now wrapped in suffocating layers of a poisonous atmosphere made of carbon dioxide and sulfuric acid.

-

-   The pressures on the surface reach almost 100 times the air pressure at Earth’s sea level. The average temperatures are over 700 degrees Fahrenheit, more than hot enough to melt lead, while the deepest valleys see records of over 900 degrees.

-

-   Like Mars, we suspect that Venus also once hosted a thinner, balmier atmosphere and a surface replete with liquid water oceans. The reasoning here is a little more tenuous than for Mars.  The thinking is that both Venus and Earth formed in a roughly similar fashion, in roughly the same orbits with roughly the same material. Thus we should have been born with roughly the same amount of water.

-

-    Like Earth, most of that water would have been chemically bound up in rock, buried deep in the mantle. But some of it may have leeched to the surface or been delivered by hosts of water-rich comets shortly after formation, building up a supply on the surface, once again stabilized by a thick atmosphere.

-

-   What doomed Venus was not any fault of its own, but our own treacherous Sun. As stars age they gradually brighten. Day by day it’s imperceptible, but over the course of millions of years it completely changes the character of a star. Billions of years ago our Sun’s habitable zone was shifted inwards compared to where it rests now, but with increased brightness comes increased heat, and  that habitable zone steadily creeps outwards over time.

-

-   Did Venus ever host life?   Temperatures on the surface make exploration nearly impossible. But it’s likely that it had water and a rich atmosphere, the basic ingredients were there. But if life did gain a foothold it did not last long. As our Sun aged, Venus got warmer and warmer. On a warmer planet, more water exists as vapor in the atmosphere than as liquid on the surface.

-

-   Venus reached a tipping point. With too much water vapor, the atmosphere of Venus became too good at trapping the heat radiating from the surface. That radiation could not penetrate the haze and make into space, but instead was ensnared within the atmosphere itself, heating it up.

-

-    Venus entered a feedback loop, dumping more heat into the atmosphere, which boiled the oceans into more vapor, which increased the temperatures, and so on. First the shallow lakes and streams were gone, then came the deeper oceans, until every scrap of water was blowing in the winds of the atmosphere.

-

-    With its proximity to the ever-brightening Sun, the water vapor did not last long. Solar radiation pummeled it, disassociating its chemical bonds and sending the oxygen and hydrogen flying away beyond our solar system.

-

-   If Venus had plate tectonics like the Earth, then this is where that process came to end. With no water to act a lubricant, the great slow grinding of the plates seized up, locking the crust in place. This constant churning acts as a natural sink for carbon: the carbon dioxide binds to rocks which get pulled deep into the mantle, preventing too much carbon from building up in the atmosphere.

-

-    But without the cleansing effect of plate tectonics, carbon dioxide levels rose to dangerous heights, its own ability to absorb radiation from the surface choking off any remaining hope for rescuing the planet. Eventually the atmosphere would pile upon itself until it reached its present swollen size.

-

-    As our Sun aged, Venus strangled itself.   Venus is not alone in sharing that fate, for the Sun has not yet reached its final days. It continues to brighten, bringing more warmth to the solar system day by day, its habitable zone steadily inching outwards with every passing year.

-

-    At some point, approximately 500 million years from now, Venus will not be alone, The Earth’s oceans will boil, our continents will halt their ancient motion, and we will finally be twins with our sister: dead, lifeless, and strangling on our own bloated atmosphere.  This will definitely end our coffee club.

-

-

January 31, 2023         MARS  -  was there water there?          4335

------------------------------------------------------------------------------------------                                                                                                                       

--------  Comments appreciated and Pass it on to whomever is interested. ---

---   Some reviews are at:  --------------     http://jdetrick.blogspot.com ----- 

--  email feedback, corrections, request for copies or Index of all reviews

---  to:  ------    jamesdetrick@comcast.net  ------  “Jim Detrick”  -----------

--------------------- ---  Wednesday, January 31, 2024  ---------------------------------

 

 

 

 

 

           

 

 

4334 - ASTEROID - sample returned

 

-    4334  -  ASTEROID  -  sample returned?     NASA's OSIRIS REx asteroid sample the most expensive material on Earth?  The mission cost $1.16 billion for just under 9 ounces of asteroid dust. But it's hardly the most expensive material in science.

------------------------------------  Asteroid Bennu

-------------------------  4334  -   ASTEROID  -  sample returned

-

-   After a journey of seven years and nearly 4 billion miles, NASA's “OSIRIS-REx” spacecraft landed gently in the Utah desert on the morning of September 24, 2023, with a precious payload. The spacecraft brought back a sample from the asteroid Bennu.

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-   Roughly half a pound of material collected from the 85 million-ton asteroid  will help scientists learn about the formation of the solar system, including whether asteroids like Bennu include the chemical ingredients for life.

-

-    NASA's mission was budgeted at $800 million and will end up costing around $1.16 billion for just under 9 ounces of sample (255 g). But is this the most expensive material known? Not even close.

-

-    A handful of asteroid works out to $132 million per ounce, or $4.7 million per gram. That's about 70,000 times the price of gold, which has been in the range of $1,800 to $2,000 per ounce ($60 to $70 per gram).

-

-   The first extraterrestrial material returned to Earth came from the Apollo program. Between 1969 and 1972, six Apollo missions brought back 842 pounds  of lunar samples.

-

-   The total price tag for the Apollo program, adjusted for inflation, was $257 billion. These Moon rocks were a relative bargain at $19 million per ounce ($674 thousand per gram).

-

-    NASA is planning to bring samples back from Mars in the early 2030s to see if any contain traces of ancient life. The Mars Sample Return mission aims to return 30 sample tubes with a total weight of a pound (450 g). The Perseverance rover has already cached 10 of these samples.

-

-   However, costs have grown because the mission is complex, involving multiple robots and spacecraft. Bringing back the samples could run $11 billion, putting their cost at $690 million per ounce ($24 million per gram), five times the unit cost of the Bennu samples.

-

-   Some space rocks cost nothing. Almost 50 tons of free samples from the solar system rain down on the Earth every day. Most burn up in the atmosphere, but if they reach the ground they're called meteorites, and most of those come from asteroids.

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-    Most meteorites are stony, called chondrites, and they can be bought online for as little as $15 per ounce (50 cents per gram). Chondrites differ from normal rocks in containing round grains called chondrules that formed as molten droplets in space at the birth of the solar system 4.5 billion years ago.

-

-    Iron meteorites are distinguished by a dark crust, caused by melting of the surface as they come through the atmosphere, and an internal pattern of long metallic crystals.

-

-     They cost $50 per ounce ($1.77 per gram) or even higher. Pallasites are stony-iron meteorites laced with the mineral olivine. When cut and polished, they have a translucent yellow-green color and can cost over $1,000 per ounce ($35 per gram).

-

-    More than a few meteorites have reached us from the Moon and Mars. Close to 600 have been recognized as coming from the Moon, and the largest, weighing 4 pounds (1.8 kg), sold for a price that works out to be about $4,700 per ounce ($166 per gram).

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-     About 175 meteorites are identified as having come from Mars. Buying one would cost about $11,000 per ounce ($388 per gram).

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-    Researchers can figure out where meteorites come from by using their landing trajectories to project their paths back to the asteroid belt or comparing their composition with different classes of asteroids. Experts can tell where Moon and Mars rocks come from by their geology and mineralogy.

-

-   The limitation of these "free" samples is that there is no way to know where on the Moon or Mars they came from, which limits their scientific usefulness. Also, they start to get contaminated as soon as they land on Earth, so it's hard to tell if any microbes within them are extraterrestrial.

-

-    Some elements and minerals are expensive because they’re scarce. Simple elements in the periodic table have low prices. Per ounce, carbon costs one-third of a cent, iron costs 1 cent, aluminum costs 56 cents, and even mercury is less than a dollar (per 100 grams, carbon costs $2.40, iron costs less than a cent and aluminum costs 19 cents). Silver is $14 per ounce (50 cents per gram), and gold, $1,900 per ounce ($67 per gram).

-

-   Seven radioactive elements are extremely rare in nature and so difficult to create in the lab that they eclipse the price of NASA's Mars Sample Return. Polonium-209, the most expensive of these, costs $1.4 trillion per ounce ($49 billion per gram).

-

-    Gemstones can be expensive, too. High-quality emeralds are 10 times the price of gold, and white diamonds are 100 times the price of gold.  High-quality white diamonds can cost millions of dollars.

-

-    Some diamonds have a boron impurity that gives them a vivid blue hue. They're found in only a handful of mines worldwide, and at $550 million per ounce ($19 million per gram) they rival the cost of the upcoming Mars samples, an ounce is 142 carats, but very few gems are that large.

-

-   The most expensive synthetic material is a tiny spherical "cage" of carbon with a nitrogen atom trapped inside. The atom inside the cage is extremely stable, so can be used for timekeeping. “Endohedral fullerenes” are made of carbon material that may be used to create extremely accurate atomic clocks. They can cost $4 billion per ounce ($141 million per gram).

-

-     Antimatter occurs in nature, but it's exceptionally rare because any time an antiparticle is created it quickly annihilates with a particle and produces radiation.

-

-   The particle accelerator at CERN can produces 10 million antiprotons per minute. That sounds like a lot, but at that rate it would take billions of years and cost a billion billion (10^18) dollars to generate an ounce (3.5 x 10^16 dollars per gram)

-

- Last year Earth had more than 100 close encounters with large asteroids. What are the odds of a direct hit in the near future?

-

-    Asteroids are chunks of rock left over from the formation of our Solar System. Approximately half a billion asteroids with sizes greater than four metres in diameter orbit the Sun, traveling through our Solar System at speeds up to about 30 kilometers per second, about the same speed as Earth.

-

-  The threats asteroids pose are real. Famously, about 65 million years ago, life on Earth was brought to its knees by what was likely the impact of a big asteroid, killing off most dinosaurs. Even a four-meter object traveling at a relative speed of up to 60 kilometers per second is going to pack a punch.

-

-    How many asteroids hit Earth and how many can we expect to zip past us?

Asteroid statistics and the threats posed by asteroids of different sizes. NEOs are “near-Earth objects”, any small body in the Solar System whose orbit brings it close to our planet. From left to right the size of asteroid increased from 4 meters up to 10,000 meters, as does the frequency.

-

-     Asteroid statistics and the threats posed by asteroids of different sizes. NEOs are near-Earth objects, any small body in the Solar System whose orbit brings it close to our planet. (Image credit: NASA)

-

-     Earth experiences frequent but low-impact collisions with small asteroids, and rare but high-impact collisions with big asteroids. In most cases, the smallest asteroids largely break up when they hit Earth’s atmosphere, and don’t even make it down to the surface.

-

-   When a small asteroid (or meteoroid, an object smaller than an asteroid) hits Earth’s atmosphere, it produces a spectacular “fireball”, a very long-lasting and bright version of a shooting star, or meteor. If any surviving bits of the object hit the ground, they are called “meteorites”. Most of the object burns up in the atmosphere.

-

-   How many asteroids fly right past Earth?   Once per year, on average, a four-meter asteroid will intersect the surface of Earth.   If you doubled that surface area, you’d get two per year. Earth’s radius is 6,400km. A sphere with twice the surface area has a radius of 9,000km. So, approximately once per year, a four-meter asteroid will come within 2,600 km of the surface of Earth – the difference between 9,000 km and 6,400 km.

-

-   Double the surface area again and you could expect two per year within 6,400 km of Earth’s surface, and so on. This tallies pretty well with recent records of close approaches.

-

-    Astronomers consider anything passing closer than the Moon – approximately 300,000 km – to be a “close approach”.   In 2022 there were 126 close approaches, and in 2023 we’ve had 50 so far.

-

-     Now, consider really big asteroids, bigger than one kilometer in diameter. The same highly simplified logic as above can be applied. For every such impact that could threaten civilization, occurring once every half a million years or so, we could expect thousands of near misses (closer than the Moon) in the same period of time.

-

-    Such an event will occur in 2029, when asteroid 153814 (2001 WN5) will pass 248,700km from Earth.  Approximately 95% of asteroids of size greater than one kilometer are estimated to have already been discovered, and the skies are constantly being searched for the remaining 5%.

-

-     When a new one is found, astronomers take extensive observations to assess any threat to Earth.  The Torino Scale categorises predicted threats up to 100 years into the future, the scale being from 0 (no hazard) to 10 (certain collision with big object).

-

-   Currently, all known objects have a rating of zero. No known object to date has had a rating above 4 (a close encounter, meriting attention by astronomers).

-

-Technology has advanced to the point we have a chance to do something if we ever do face a big number on the Torino Scale. Recently, the DART mission collided a spacecraft into an asteroid, changing its trajectory. In the future, it is plausible that such an action, with enough lead time, could help to protect Earth from collision.

-

-

January 31, 2024           ASTEROID  -  sample returned?               4312

------------------------------------------------------------------------------------------                                                                                                                        

--------  Comments appreciated and Pass it on to whomever is interested. ---

---   Some reviews are at:  --------------     http://jdetrick.blogspot.com ----- 

--  email feedback, corrections, request for copies or Index of all reviews

---  to:  ------    jamesdetrick@comcast.net  ------  “Jim Detrick”  -----------

--------------------- ---  Wednesday, January 31, 2024  ---------------------------------

 

 

 

 

 

           

 

 

-- 4333 - The BIGGEST STARS - and planets?

 

-    4333  -  The BIGGEST  STARS -  and planets?    The biggest star in the universe, that we know of,  makes our sun look tiny speck.   The biggest star, UY Scuti , is a variable hypergiant with a radius around 1,700 times larger than the radius of the sun.

-------------------------  4333  -  The BIGGEST  STARS -  and planets?

-

-    --------------------------------------   Galaxies of stars

 To put Scuti's size in perspective, the volume of almost 5 billion suns could fit inside a sphere the size of UY Scuti. 

-

-    Our sun is enormous, more than a million Earths could fit inside of it. But on a stellar scale, it could be swallowed up by about half of all stars observed so far.

-

-    In 1860, German astronomers at the Bonn Observatory first cataloged UY Scuti, at the time naming it “BD -12 5055”. During a second observation, astronomers realized it grows brighter and dimmer over a 740-day period, leading to its classification as a “variable star.”

-

-   The star lies near the center of the Milky Way, roughly 9,500 light-years away from Earth. Located within the constellation Scutum, UY Scuti is a hypergiant star.   “Hypergiants”, larger than supergiants and giants, are rare stars that shine very brightly. They lose much of their mass through fast-moving stellar winds.

-

-   All stellar sizes are estimates.  The complication with stars is that they have diffuse edges.   Most stars don't have a rigid surface where the gas ends and vacuum begins, which would have served as a harsh dividing line and easy marker of the end of the star.

-

-    Instead, astronomers rely on a star's photosphere to determine its size. The photosphere is where the star becomes transparent to light and the particles of light, or photons, can escape the star.

-

-    If UY Scuti replaced the sun in the center of the solar system, its photosphere would extend just beyond the orbit of Jupiter. The nebula of gas ejected from the star extends far beyond the orbit of Pluto, to 400 times the distance between the Earth and the sun.

-

-    NASA's Hubble Space Telescope reveals the supercluster Westerlund 1, home of one of the largest known stars. “Westerlund 1-26”, a red supergiant, has a radius more than 1,500 times that of the sun.

-

-    UY Scuti's large radius does not make it the most massive, or heaviest, star. That honor goes to “R136a1”, which weighs in at about 300 times the mass of the sun but only about 30 solar radii. UY Scuti, in comparison, is only about 30 times the mass of the sun, but far greater in volume.

-

-   Size comparisons are still more complicated because UY Scuti doesn't remain stagnant. The star varies in brightness as it varies in radius. And the measurement we have now has a margin of error of about 192 solar radii. The variation or margin of error each could allow other stars to beat out UY Scuti in the race for size. In fact, there are as many as 30 stars whose radii approach or surpass UY Scuti's smallest estimated size, so the behemoth shouldn't sit too securely on its throne.

-

-   Which star would take UY Scuti's place if its size were reevaluated? Here are a few that could take the crown from the giant currently measured at 1,700 times the width of the sun:

-

-   “WOH G64” was once thought to measure a whopping 3,000 times the width of the sun. Newer measurements put it at around 1,504 suns wide. It is a red hypergiant star in the Large Magellanic Cloud, which is a satellite galaxy of the Milky Way. Like UY Scuti, WOH G64 varies in brightness.

- 

-    “Westerlund 1-26”, measures more than 1,500 times the width of the sun.

-

-    “NML Cygni” is measured at 1,639 times the width of the sun.

-

-    “KY Cygni” measures close to 1,033 times the width of the sun.

-

-      “VY Canis Majoris” has been most recently measured to be about 1,420 times the width of the sun. This red hypergiant star was once estimated to be 1,800 to 2,200 times the width of the sun, but new measurements have brought it down to size.

-

-      What is the biggest planet ever found?  The universe is vast and in the scheme of things, our planet is tiny. Even in our own solar system, Earth is dwarfed by gas giants like Jupiter. But are there bigger planets out there? How much bigger? What is the biggest planet we know of?

-

-   The answer depends on several factors, including how you define a planet. Even so, there are a few candidates for the largest known planet. One of the largest is “ROXs 42Bb”, a gas giant orbiting a star about 460 light-years from Earth. It is about nine times the mass of Jupiter and has a radius of about 2.5 that of Jupiter.

-

-    There are a couple of planets that are actually protoplanets, so they're still being assembled.    These two protoplanets both orbit the star “PDS 70” about 370 light-years from Earth and have a radius between two and four times that of Jupiter. Another candidate for the largest planet, “HAT-P-67 b”, had a radius larger than two times that of Jupiter, which is similar to ROXs 42Bb.

-

-    Why the uncertainty? One reason has to do with the different ways scientists measure the size of exoplanets. ROXs 42Bb, for instance, was directly imaged, "seen" as an independent object using the Keck Telescope.

-

-    The protoplanets orbiting PDS 70 were also directly imaged. Scientists don't have any way to directly measure the size of these planets, so they have to infer their size based on other factors like their brightness and patterns in the wavelengths of light they give off. Scientists use models to determine these things, and these models are not always 100% correct.

-

-    Other objects are detected using the “transit method”, which is when an object appears to cross in front of its host star during its orbit and temporarily dims the star. Exoplanets detected in this way, like “HAT-P-67 b”, can be directly measured.   This planet has over twice the radius of Jupiter.

-

-    The other uncertainty comes from the issue of how to define a planet. Though most people know that stars are very large and planets are much smaller, there's a middle ground, an object called a “brown dwarf,” which is too small to be a star but is larger than a planet.

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-     Though the core of a brown dwarf is not hot enough to fuse regular hydrogen like a star would, it can fuse deuterium, a special form of hydrogen that contains a neutron.   Scientists agree that brown dwarfs are not planets. What's less clear is how to distinguish between the two.

-

-    Some people identify a strict cut off in mass.  Anything above 13 Jupiter masses is a brown dwarf and anything below is a planet."

-

-    But more recent observations have revealed that the universe doesn't necessarily "agree" with this rule.   The turnover between planet and brown dwarf can happen at a much higher mass, maybe 25 times the mass of Jupiter or even more massive.

-

-   Although we would call ROXs 42Bb a planet (or a "planetary-mass companion") they suspect its formation was more similar to how stars form. Typically, planets like Jupiter form a rocky core, which attracts a disk of dust and gas that gradually becomes a globular planet. ROXs 42Bb may have formed in a different way, where parts of the dust and gas disk were so massive and heavy that they collapsed in on themselves.

-

-    The way an object forms is not currently a part of the formal definition of a planet. Some scientists refer to planetary-mass companions that formed like this as "sub-brown dwarfs.  What to call “ROXs 42Bb”  because of its high mass ratio (its mass compared to the mass of its star) and how far away from that star, over five times the distance between our sun and Neptune.

-

-    Though the debate over what "counts" as a planet may seem arbitrary, it highlights big questions about what different planetary systems might look like, particularly those vastly different from ours.

-

-

January 31, 2024               The BIGGEST  STARS -  and planets?     4333  

---------------------------------------------------------------------------------------                                                                                                                       

--------  Comments appreciated and Pass it on to whomever is interested. ---

---   Some reviews are at:  --------------     http://jdetrick.blogspot.com ----- 

--  email feedback, corrections, request for copies or Index of all reviews

---  to:  ------    jamesdetrick@comcast.net  ------  “Jim Detrick”  -----------

--------------------- ---  Wednesday, January 31, 2024  ---------------------------------

 

 

 

 

 

           

 

 

4330 - MAGNETIC STARS?

 

-    4330  -   MAGNETIC  STARS?  -    Why do Earth's magnetic poles flip?   Every so often, Earth's magnetic poles completely flip. What causes this to happen? And how do these reversals affect life on Earth?

--------------------  4330  -     MAGNETIC  STARS?

-    Earth, our rocky, watery oasis in the cosmos is the ideal place for life to flourish for a number of reasons.   We sit at just the right distance from our home star for liquid water to exist on the planet's surface.

-

-    The gravitational pull of other large planets helps protect us from collisions with wandering meteorites. And the planet's magnetic field encircles Earth with a protective barrier that shields us from charged particles hurtling through space.

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-   Earth's magnetic field is generated by the complex flow of molten metallic material in the outer core of the planet. The flow of this material is affected both by the rotation of Earth and the presence of a solid iron core, which results in a dipolar magnetic field where the axis roughly aligns with the rotational axis of the planet.

-

-    Hidden in the chemical composition of ancient rocks are clues that Earth's magnetic field is a dynamic, shifting phenomena. Cooling magma rich in iron minerals is pulled into alignment with Earth's magnetic field, similar to how a needle is pulled to point towards north on a compass. The study of ancient geomagnetic fields recorded in rocks is the subject of a discipline known as "paleomagnetism."

-

-   “Paleomagnetic” research has provided scientists with the knowledge that Earth's magnetic field has shifted and even reversed in polarity many times in the geological past. But why?   What causes the magnetic poles to flip?

-

-    Earth's magnetic field varies at very short timescales and extremely long ones, ranging from milliseconds to millions of years. The interaction of the magnetic field with charged particles in space can alter it at short timescales, while perturbations in the magnetic field at longer timescales are caused by internal processes unfolding in the outer liquid core of the Earth.

-

-    Fluctuations in the magnetic field caused by the movement of metallic material in the outer core have brought about full reversals of the magnetic field's polarity in Earth's past.

-

-    Paleomagnetic studies which have studied previous states of the magnetic field have shown there are two possible states of polarity, the current 'normal' state, where the lines of force of the field enter towards the center of the Earth in the northern hemisphere and exit towards the outside of the Earth in the southern hemisphere. The inverse, or 'reverse' polarity is also equally as probable and stable.

-

-    Paleomagnetic studies have shown that polarity reversals of Earth's magnetic field are not periodic and cannot be predicted. This is largely because of the behavior of the mechanisms that are responsible for it.

-

-    The flow of the metallic fluid, mostly molten iron, in the outer core of the Earth is chaotic and turbulent. Polarity reversals occur during periods of low geomagnetic field intensity, during which the intensity of the dipolar component drastically decreases, and the structure of the field is unstable. 

-

-    The transitory period of polarity reversal appears as a geologically instantaneous, with a duration spanning up to a few thousand years.

-

-    When the magnetic field is prone to flipping, it is in a state of reduced intensity, resulting in a greater exposure of Earth's atmosphere to solar wind and cosmic rays in the form of charged particles.

-

-    A recent study showed that during the “Laschamps excursion”, a recent period of low magnetic field intensity which occurred only 41,000 years ago, the global cosmic ray flux reaching the Earth's atmosphere was up to three times higher than today's value.

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-   Currently, there is no significant evidence of a correlation between mass extinctions of life on Earth and geomagnetic polarity reversals. However, linking rates of species extinction and with periods of low magnetic field intensity is hindered by uncertainties in the known timescale of these magnetic 'flips'.

-

-   Additionally, magnetic reversals happen frequently on geological timescales (several hundred times in the past 160 million years), while recorded mass extinction events occur every hundred million years or so much less frequently.

-

-    In terms of human civilization, it is not the shifting of the magnetic poles that is directly concerning, but the resulting period of reduced geomagnetic field intensity. Society is growing increasingly reliant on technology, and the effects of a reduced magnetic field intensity should be seriously considered by international organizations.

-

-     The risks to which our planet and civilization is exposed could have significant impacts on civil society, how we do commerce, security, communications, power infrastructure, satellites and the lives of people in low Earth orbit. Unfortunately, the sporadic nature of magnetic variations and reversals means we cannot predict when exactly this will happen, all we know is that it will happen.

-

-  A new cosmic object has been found that is the most magnetic star in the universe.  The record-breaking find of a star 43,000 times more magnetic than the sun could help unravel the mystery of how magnetars form.

-

-   The star, known as “HD 45166”, has a unique, helium-rich spectral signature that hints at an unusual origin.   In addition to setting records, it might represent the first stage in the lifecycle of a magnetar, a strange type of neutron star.

-

-    Neutron stars are the densest known celestial objects in the universe, packing a sun's worth of mass into a ball no wider than a city. Their highly magnetic versions magnetars have some of the strongest known magnetic fields in the universe. Neutron stars and magnetars form in the wake of massive supernova explosions, when the leftover material from a dead star condenses back into an extremely dense, hot object.

-

-   Astronomers are still trying to understand what conditions produce magnetars versus regular neutron stars.   Located 3,000 light-years from Earth in the constellation Monoceros (the Unicorn), “HD 45166” has puzzled scientists for more than a century. The star behaves similarly to a type of extremely bright stellar object known as a Wolf-Rayet star, except that it is smaller, dimmer and has an abnormally high concentration of helium.

-

-    Using data from several ground observatories, astronomers discovered that HD 45166 is extremely magnetic, a record-smashing 43,000 times more magnetic than the sun. The researchers suspect that, unlike most massive helium stars, which evolve from red supergiants, HD 45166 formed during a merger between two smaller stars. They also believe that in several million years, it will explode into a modest supernova and re-form as a magnetar.

-

-    This proto-magnetar represents a new type of stellar object never seen before,  a massive magnetic helium star.

-

-

January 10, 2023                 MAGNETIC  STARS?                            4312

------------------------------------------------------------------------------------------                                                                                                                       

--------  Comments appreciated and Pass it on to whomever is interested. ---

---   Some reviews are at:  --------------     http://jdetrick.blogspot.com ----- 

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---  to:  ------    jamesdetrick@comcast.net  ------  “Jim Detrick”  -----------

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4332 - PLANETS - that may support life?

 

-    4332  -  PLANETS  -   that may support life?    James Webb Space Telescope recently found traces of methane and carbon dioxide in the atmosphere of exoplanet “K2-18-b”, an exoplanet 8.6 times as massive as Earth about 120 light-years from us. The signature may be a sign of a water ocean.

-------------------------  4332  -  PLANETS  -   that may support life?

-    Searching for liquid water on exoplanets is the key to finding life among the stars.  Researchers have hypothesized that if the atmosphere of an exoplanet has less CO2 than its neighbors, there may be vast quantities of water on its surface, or even life.

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-    Finding liquid water on planets outside the solar system is a major challenge. Of the 5,000 or so exoplanets we've discovered, liquid water hasn't  been confirmed on any. The best scientists can do is detect traces of water in exoplanet atmospheres and determine whether planets could theoretically support water in the liquid state.

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-    We know that initially, the Earth's atmosphere used to be mostly CO2, but then the carbon dissolved into the ocean and made the planet able to support life for the last four billion years.

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-    Once carbon is dissolved in the oceans, tectonic activity then locks it away in Earth's crust, creating an effective carbon sink. This is partly why our planet has significantly lower CO2 levels compared with our neighbors.  Earth's atmosphere is around 0.04% CO2, whereas the atmospheres on Venus and Mars are both over 95% CO2.

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-   If scientists observe a similarly low-carbon atmosphere on an exoplanet, it could indicate the presence of vast oceans similar to our own.  Looking for CO2 is easier than finding liquid water. CO2 absorbs infrared radiation very well, meaning it produces a strong signal that scientists can detect.

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-   It's also possible to perform this technique with existing telescopes, such as the James Webb Space Telescope (JWST). Ground-based observations should also be possible because of the specific wavelength CO2 is measured at whereas Earth's atmosphere can torpedo experiments at other wavelengths by partially absorbing the signals.

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-       Another scenario could contribute to an atmosphere low in carbon: life itself. The main ways life on our planet captures carbon are through photosynthesis and making shells, and around 20% of all carbon capture on Earth is caused by biological processes.

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-    JWST found the unambiguous signature of water on exoplanet “WASP-96B”. A new technique may make it even easier for telescopes like JWST to find water.

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-    As researchers keep discovering more exoplanets, more atmospheres will also be spotted. And this technique could help figure out whether they could sustain life.

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-  Another scenario could contribute to an atmosphere low in carbon: life itself. The main ways life on our planet captures carbon are through photosynthesis and making shells, and around 20% of all carbon capture on Earth is caused by biological processes.

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-   Although the approach looks like it'll work in principle, there may still be hurdles, as it's not clear how many terrestrial exoplanets also have atmospheres. Finding the perfect system to test this on might turn out to be a little bit more challenging than we previously thought.

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January 28, 2023          PLANETS  -   that may support life?              4332

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--------  Comments appreciated and Pass it on to whomever is interested. ---

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4331 - SMALLEST BROWN DWARF STAR?

 

-    4331  -  SMALLEST  BROWN  DWARF  STAR?     James Webb telescope finds universe's smallest 'failed star' in cluster full of mystery molecules.   They have spotted what may be the smallest known brown dwarf, a "failed star" that's only three or four times larger than Jupiter.

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-----------------  4331  -  SMALLEST  BROWN  DWARF  STAR?

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-    Astronomers using the telescope (JWST) may have identified the smallest star in the known universe.  Or , at least, the smallest known object that began forming like a star, before fizzling out as a ”brown dwarf”.

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-    One basic question you'll find in every astronomy textbook is, what are the smallest stars?  Using the JWST, they spotted the tiny proto-star in a star cluster named “IC 348”, which is located 1,000 light-years from Earth. The object is likely to be a brown dwarf, a type of celestial object that blurs the line between planet and star.

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-    Brown dwarfs are not quite stars, but they come close. Essentially, they are stars that failed to ignite, earning them the unflattering nickname "failed stars." Brown dwarfs are not massive enough to sustain typical hydrogen fusion in their cores.

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-    However, they do have enough mass to emit light and heat from fusing a specialized type of hydrogen, called deuterium. Deuterium is a stable form of hydrogen with an added neutron, whereas normal hydrogen only has a proton in its nucleus.

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-    Most stars are incredibly dense compared to even the biggest planets; our own sun is about 1,000 times the mass of Jupiter, the largest planet in our solar system, but its diameter is only 10 times that of Jupiter.

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-    In comparison, a large brown dwarf could pack about 80 Jupiters inside. But this particular brown dwarf is only three or four times more massive than Jupiter .  Easily making it the smallest "star," or star-like object, ever discovered. It is also very young; the star cluster that it belongs to is just 5 million years old.

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-      NASA's Cassini probe detected the same molecular signature in the atmosphere of Saturn's moon Titan, but this is the first time it has been seen outside of the solar system.

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-    In addition to being minuscule, the brown dwarf and its neighbors appear to have an intriguing molecule floating around in their atmospheres. The researchers detected a spectral signature from an unidentified hydrocarbon, a molecule that contains some of the raw ingredients for life as we know it.

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-    Models for brown dwarf atmospheres don't predict its existence.  We're looking at objects with younger ages and lower masses than we ever have before, and we're seeing something new and unexpected.

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-   Taken together, these observations could help researchers paint a clearer picture of how stars form, and how they fail. The researchers hope that future work will reveal even smaller stellar objects, as well as any tiny true stars that may be hiding nearby.

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January 27, 2023       SMALLEST  BROWN  DWARF  STAR?           4331

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--------  Comments appreciated and Pass it on to whomever is interested. ---

---   Some reviews are at:  --------------     http://jdetrick.blogspot.com ----- 

--  email feedback, corrections, request for copies or Index of all reviews

---  to:  ------    jamesdetrick@comcast.net  ------  “Jim Detrick”  -----------

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