Archive for the ‘Gravity’ Category

Credit: reference.com

Plate tectonics has always been good for a science controversy or two. This one throws some solar-planetary spice into the mix, putting a focus on the Earth-Moon barycentre.
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A study led by geophysicist Anne M. Hofmeister in Arts & Sciences at Washington University in St. Louis proposes that imbalanced forces and torques in the Earth-moon-sun system drive circulation of the whole mantle, says Phys.org.

The new analysis provides an alternative to the hypothesis that the movement of tectonic plates is related to convection currents in the Earth’s mantle.

Convection involves buoyant rise of heated fluids, which Hofmeister and her colleagues argue does not apply to solid rocks.

They argue that force, not heat, moves large objects.

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Escaping a planet’s gravity is supposed to be difficult, but some Martian dust does just that.

Spaceweather.com

July 6, 2021: Dust storms on Mars are bigger than we thought; they even spill into space. According to a recent paper in JGR Planets, Mars appears to be leaking dust, filling a huge volume of the inner solar system with gritty debris. You can see it with your naked eye. The bright triangle in this image from the Haleakalā Observatory in Hawaii is marsdust:

“A friend described it as blazing,” says Rob Ratkowski, who took the picture on Feb. 10th. “It was bright and very obvious.”

It’s called Zodiacal Light, and astronomers have long wondered what causes it. The usually faint triangle is sunlight scattered by dust in the plane of our solar system. The dust, it turns out, comes from Mars.

NASA’s Juno spacecraft flew through the dust cloud en route to Jupiter between 2011 and 2016. Dust grains smashed into Juno at about 10,000 mph…

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Einstein’s Eclipse

Posted: March 23, 2021 by oldbrew in Astrophysics, Gravity, solar system dynamics
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Some real science to remember.

Spaceweather.com

March 22, 2021: On May 29, 1919, the Moon slid in front of the sun and forever altered our understanding of spacetime. It’s known as “Einstein’s Eclipse.” Using his newly-developed theory of relativity, the young German physicist predicted that the sun’s gravity should bend starlight–an effect which could only be seen during a total eclipse. More than 100 years later, Petr Horálek (ESO Photo Ambassador) and Miloslav Druckmüller (Brno University of Technology) have just released a stunning restoration of the photo that proved Einstein right:

The original picture was taken in May 1919 by astronomers Andrew Crommelin and Charles Rundle Davidson, who traveled from the Greenwich Observatory in London to the path of totality in Sobral, Brazil. They were part of a global expedition organized by Sir Arthur Eddington, who wanted to test Einstein’s strange ideas. Glass photographic plates from the expedition were typical of early 20th century astrophotography, colorless…

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Clouds on Mars [image credit: NASA]


Regarding the Earth’s equivalent Chandler wobble, Wikipedia says: ‘Since the Chandler wobble should die down in a matter of decades or centuries, there must be influences that continually re-excite it.’ Presumably the same will apply to Mars, but as relevant observations are all fairly recent no conclusion can be reached at present.
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Spacecraft find that Mars oscillates 10 centimeters off its axis of rotation, says Eos.

In a first for a solar system body other than Earth, scientists have detected the Chandler wobble on Mars, a repeated movement of the poles on the surface of the planet away from its average axis of rotation.

The Chandler wobble arises when a rotating body isn’t a perfect sphere. This imbalance affects its spin.

The result is a wiggle resembling that of a swaying top as it loses speed, rather than the smooth spin of a perfectly balanced globe.

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Antarctica


If they were hoping to see a steady rate of change that matched carbon dioxide emission levels, they were disappointed. Natural variations inconveniently got in the way, two in particular: ‘When two extreme snowfall events in 2009 and 2011 dropped around 600 gigatons of snow and ice, the East Antarctic Ice Sheet thickened so much that it temporarily halted the entire continent’s ice losses, said Wang—a pattern that had previously escaped notice.’
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A new analysis of long-term satellite records shows the East Antarctic Ice Sheet is unexpectedly dependent on fluctuations in weather.

This study may improve models of how much sea levels will rise, says Eos News.

As more coastal communities face the looming threat [Talkshop note: unsupported assertion] of rising sea levels, it’s more important than ever to accurately predict changes in one of the greatest potential sources of sea level rise—the melting of Antarctica’s massive ice sheet.

Recently, scientists analyzed nearly 2 decades’ worth of data from sensitive NASA satellites documenting mass changes in the Antarctic Ice Sheet.

They found the ice inventory ebbed and flowed across the continent in unexpectedly variable patterns.

Traditionally, some groups of Antarctic researchers have assumed the rate of change across the ice sheet is constant, but they drew their conclusions from data sets that spanned only a few years, said Lei Wang, a geodesist at The Ohio State University who will present this research at AGU’s virtual Fall Meeting 2020.

“These long data records give us the capability to characterize the ice sheet’s variation over a range of timescales,” rather than just modeling seasonal variations and short-term trends, Wang said.

Understanding Long-Term Trends

The Antarctic Ice Sheet, the largest mass of ice on Earth, is divided into two unequal portions, with the East Antarctic Ice Sheet covering about two thirds of the continent. The West Antarctic Ice Sheet, although smaller, has historically been more closely studied because it’s melting faster. (The East Antarctic Ice Sheet sits on bedrock above sea level, said Wang, so it is less susceptible to the effects of the warming ocean.) NASA estimates Antarctica has lost 149 billion metric tons of ice per year since 2002.

When so much ice is involved, projections of how sea levels will respond are uncertain—especially when trends already are so difficult to gauge.

Indeed, the field still argues about sea level changes in the past century, said Jim Davis, the study coauthor and a geodesist at the Lamont-Doherty Earth Observatory at Columbia University. “We’ve got to get to the point where we can talk about what’s happening this year in sea level change,” he said.

To do that, researchers need a more sophisticated model of how Antarctica’s shield of ice is evolving.

Full article here.


The plan is to use abandoned coal mining shafts globally as power storage plants, and/or drill their own shafts if necessary. Costs are estimated to be lower than other existing energy storage options (see report for details).
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Gravity has been the center of wonderment for physicists, mathematicians and thinkers of all kinds for centuries, says TechXplore.

In the early 1600s, astronomer Galileo dropped balls from the Tower of Pisa and declared that gravitational acceleration is the same for all objects.

Decades later, Isaac Newton expanded on those thoughts and devised his theory of gravity, that all particles attract all other particles with a force directly proportional to the square of the distance between their centers.

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Browsing twitter recently I ran across this short video of a solar flare shot a few days ago.

After asking for some clarification on frame rate I was really intrigued.

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How to Shape a Spiral Galaxy

Posted: December 10, 2019 by oldbrew in Astrophysics, Electro-magnetism, Gravity, research

Spiral galaxy NGC 5457 aka the Pinwheel Galaxy [image credit: European Space Agency & NASA]


No mention of electricity here, although it’s required to create the magnetism: ‘The magnetic behavior of a material depends on its structure, particularly its electron configuration’ – Wikipedia. We’re told these electromagnetic forces stretch for 24,000 light years in one galaxy, but understanding them is still in its infancy.

New observations from SOFIA are shedding light on how spiral-shaped galaxies, like our own Milky Way, get their iconic shape, says NASA.

Our Milky Way galaxy has an elegant spiral shape with long arms filled with stars, but exactly how it took this form has long puzzled scientists. New observations of another galaxy are shedding light on how spiral-shaped galaxies like our own get their iconic shape.

Magnetic fields play a strong role in shaping these galaxies, according to research from the Stratospheric Observatory for Infrared Astronomy, or SOFIA.

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View from the Moon [credit: NASA]


Moons don’t generally ‘shrink’, so what’s going on here? The abstract of the research paper speaks of compressional stresses, but the only potential source of compression would seem to be the Earth. It’s known that ‘the crust on the far side is a lot thicker than it is on the near side’, as discussed here.

The moon is still tectonically active, like Earth, generating moonquakes as our planet creates earthquakes, a new study based on Apollo mission data found.

These moonquakes likely happen because the moon is quivering as it shrinks, researchers added.

On Earth, tectonic activity, such as earthquakes and volcanism, results from shuffling of the crust’s tectonic plates driven by the churning of the planet’s molten interior, says Charles Quoi at Space.com.

However, the moon is much smaller than Earth and therefore largely cooled off long ago, so one might not expect much, if any, tectonic activity.

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Willis Eschenbach recently complained that I banned him from the talkshop. He makes this complaint, on average, annually. Usually in a comment attacking Dr Ned Nikolov and Dr Karl Zeller.

On the occasions I’ve bothered to respond, I’ve pointed out to Willis that in fact he banned himself from the talkshop, something he maintains is a lie. Below the break is the screenshot of his parting comment, made on the talkshop in mid-January 2012.

Every interaction I’ve had with Willis since has reminded me how fortunate we were that he decided to deprive us of his brilliance.

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Last Wednesday I attended the talk by Professor Valentina Zharkova hosted by the GWPF in London. She delivered a superb lecture including news of new work improving her model by including quadrupole magnetic parameters. In the Q & A session that followed, I got the opportunity to point up the connection between her model output and Rick Salvadors.

zharkova salvador models

I got a very positive response, including an invitation to collaborate on further work. We discussed this further over dinner, when I gave her a printed copy of Rick’s 2013 PRP paper.

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energy-budget-fixed

Question: If I had a container, full with air, and I suddenly decreased the volume of the container, forcing the air into a smaller volume, will it be considered as compression, will it result in an increase in temperature, and why?

Answer on Stack Exchange by Luboš Motl: Yes, it is compression and yes, it will heat up the gas.

If there’s no heat exchange between the gas and the container (or the environment), we call it an adiabatic process. For an adiabatic process involving an ideal gas (which is a very good approximation for most common gases), pVγ is constant where γ is an exponent such as 5/3. Because the temperature is equal to T=pV/nR and pV/pVγ=V1−γ is a decreasing function of V, the temperature will increase when the volume decreases.

Macroscopically, the heating is inevitable because one needs to perform work p|dV| to do the compression, the energy has to be preserved, and the only place where it can go is the interior of the gas given by a formula similar to (3/2)nRT.

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Of course this may sound ‘far out’, but let’s have a look at the short video from VoA News anyway.

In today’s energy-hungry world, scientists are constantly revisiting every renewable resource looking for ways to increase efficiency.

One researcher in the Netherlands believes even gravity can be harnessed to produce free electricity on a scale sufficient to power small appliances.

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salvador-projection

I was trained as an engineer and then did a degree in the History and philosophy of science.

I know how to calculate forces, I understand thermodynamics and radiative theory and I don’t ignore data inimical to any hypothesis.

After thirty years of monitoring and appraising the data, the global warming hypothesis and working out what really causes climatic change I’ve concluded that it ain’t CO2. The real causes of climatic change at the planetary scale are the enormous forces transferring energy between solar system bodies.

Jupiter and Saturn between them hold over 85% of the angular momentum of the system. Venus has, within an order of magnitude, the same gravitational force on the Earth-Moon system as Jupiter. The two of them have shaped the orbit of our Moon, whose tidal forces have a profound effect on the overturning circulation of Earth’s oceans, which contain 1000 times more heat than the atmosphere of which CO2 comprises 0.04%.

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As the Talkshop reaches the milestone of 5 million visits, do we hear echoes of Scotty of Star Trek fame: ‘Ye cannae change the laws of physics’? Does fundamental mean universal – or could some ‘laws’ depend on where you look in the universe? Meanwhile Tallbloke is boldly going…somewhere… 😎

A study that will ‘test our understanding of how the Universe works, particularly outside the relatively narrow confines of our planet’ is being undertaken by an international team of researchers led by the University of Leicester, reports Phys.org.

The research probes whether the fundamental laws of physics are the same everywhere in the universe.

In their new study, the Leicester-led team assesses whether these laws are the same within the hot, dense conditions in the atmosphere of a dying white dwarf star as here on Earth.

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This guest post from Stephen Wilde offers a descriptive theoretical and qualitative perspective on the ‘gravito-thermal’ theory. It covers the vertical profile of the atmosphere as well as the surface temperature comprehensively quantified by Nikolov and Zeller’s latest paper.

How conduction and convection cause a greenhouse effect arising from atmospheric mass.
Stephen Wilde

Introduction

The current scientific consensus is that Earth’s so called ‘greenhouse effect’ is caused by the presence of radiating gases in the atmosphere but many years ago, I learned what  I then understood to be the consensus view that it is actually a result of atmospheric mass such that the radiative characteristics of the atmosphere are either wholly or largely irrelevant.

The ‘greenhouse effect’ is an apt description for the mass based phenomenon because warming, descending air (which is occurring over half the planet at any given moment) will inhibit convection in the same way as does a greenhouse roof and by dissipating clouds it increases incoming sunlight through that barrier to convection just like the transparency of a greenhouse roof.

If the greenhouse effect is attributable to atmospheric mass rather than radiative characteristics then the fact that the vast bulk of Earth’s atmosphere is comprised of mass that is non-radiative is likely to mean that human emissions of radiative gases are not important as a regulator of surface temperature.

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As long time regulars at the Talkshop know, our ongoing research into the links between planetary motion and solar variation has occasionally borne fruit in unexpected ways. The ‘shorthand’ for the sum of all planetary vectors is the Sun’s motion with respect to the barycentre of the solar system. This is the path the Sun is forced to follow by the ongoing evolution of the motion of all the planets. We have found various tantalising near-correlations between aspects of this motion and solar activity levels suggestive of some kind of mechanistic linkage.

We have been ridiculed for years by the WUWT wankers among others for working on this theory. Various other solar researchers have attempted ‘disproofs’ of a planetary effect on solar activity too. They all tell us the planets are “too small and too far away to affect the Sun”.

Last year, we featured a post concerning the work of Shepherd, Zharkov and Zharkova, who have been coming at the solar variation problem from another angle. They resolved the solar-hemispheric components of the solar polar fields into two separate curves, representing shallow and deep solar ‘dynamos’.

ApJ501502_aptepseps.dvi

Combining the curves together produces a good representation of changing solar activity levels. Their prediction is, like ours from our planetary model, for a big solar slowdown extending through the middle decades of this century. The mainstream climate scientists tried to get the press release revoked…

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Atacama Large Millimeter/submillimeter Array (ALMA) in Chile, the largest astronomical project in the world –
Magellanic Clouds near top of image [credit: NASA / Ames]


It’s unimaginably vast: astronomers say ‘this structure is a 75,000 light-year long filament of gas and dust’. Trying to separate out the effects of gravity and magnetism here should be an interesting challenge.

A magnetic field appears to span the space between the Large and Small Magellanic Clouds, the two dwarf galaxies being consumed by our Milky Way Galaxy, reports Sky & Telescope via Sott.net.

For stargazers in the Northern Hemisphere, it’s easy to forget that the Milky Way is actively consuming two dwarf galaxies. Those in the Southern Hemisphere have a front row seat to watch our galaxy wreak havoc on the Large and Small Magellanic Clouds (LMC and SMC).

But there’s more to the story — the dwarfs are not only gravitationally interacting with the Milky Way but with each other as well.

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venus_atm
A wave from pole to pole in the cloud tops that doesn’t move – but then disappears? Another Venus conundrum emerges.

A massive, un-moving structure has been discovered in the upper atmosphere of Venus, reports the IB Times.

Scientists detected the feature with the Jaxa’s Akatsuki spacecraft and they believe it is some sort of gravity wave – although they do not understand how it ended up at the altitude of cloud tops.

The bow-shaped structure was first spotted in December 2015 and a team led by scientists from Rikkyo University in Japan were able to observe it over several days.

It measured 10,000km in length and was brighter and hotter than the surrounding atmosphere. When scientists attempted to observe it again a month later, it had disappeared. The team published their findings in the journal Nature Geoscience.
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