Posts Tagged ‘planetary’

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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Credit: earth.com


Greetings Earthlings, or should we say ‘habitable-zone-dwelling asteroid dodgers’? We even have the right amount of atmosphere — not too little (like Mars) or too much (like Venus), and the essential oxygen.
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Pure chance is the reason that Planet Earth has stayed habitable for billions of years.

A new study has found that it’s nothing more than good luck that has kept our world full of life, reports I-news.

Scientists at the University of Southampton have carried out a mass simulation of climate evolution of 100,000 randomly generated planets.

Each planet was simulated 100 times with random climate-altering events occurring each time in order to see if habitable life could be sustained for three billion years like on Earth.

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Model dinosaur


The lead author of the study puts the blame on “the largest cataclysmic impacts and massive volcanism, perhaps sometimes working in concert.” The study says: ‘The correlations and similar cycles in marine and non-marine extinction episodes suggest a common cause’. Note: this is a follow-up to a 2015 study with the same lead author, also featured at the Talkshop.
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Mass extinctions of land-dwelling animals—including amphibians, reptiles, mammals, and birds—follow a cycle of about 27 million years, coinciding with previously reported mass extinctions of ocean life, according to a new analysis published in the journal Historical Biology.

The study also finds that these mass extinctions align with major asteroid impacts and devastating volcanic outpourings of lava called flood-basalt eruptions—providing potential causes for why the extinctions occurred, reports Phys.org.

“It seems that large-body impacts and the pulses of internal Earth activity that create flood-basalt volcanism may be marching to the same 27-million-year drumbeat as the extinctions, perhaps paced by our orbit in the Galaxy,” said Michael Rampino, a professor in New York University’s Department of Biology and the study’s lead author.

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Another round of the enduring hexagon mystery.
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With its dazzling system of icy rings, Saturn has been a subject of fascination since ancient times, says Phys.org.

Even now the sixth planet from the sun holds many mysteries, partly because its distance away makes direct observation difficult and partly because this gas giant (which is multiple times the size of our planet) has a composition and atmosphere, mostly hydrogen and helium, so unlike that of Earth.

Learning more about it could yield some insights into the creation of the solar system itself.

One of Saturn’s mysteries involves the massive storm in the shape of a hexagon at its north pole.

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Cyclones in Jupiter’s atmosphere [image credit: NASA]


At the south pole of Jupiter lurks a striking sight—even for a gas giant planet covered in colorful bands that sports a red spot larger than the Earth, says Phys.org.

Down near the south pole of the planet, mostly hidden from the prying eyes of humans, is a collection of swirling storms arranged in an unusually geometric pattern.

Since they were first spotted by NASA’s Juno space probe in 2019, the storms have presented something of a mystery to scientists.

The storms are analogous to hurricanes on Earth. However, on our planet, hurricanes do not gather themselves at the poles and twirl around each other in the shape of a pentagon or hexagon, as do Jupiter’s curious storms.

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Credit: NASA [click on image to enlarge]


The effects of relative proximity between these large moons seem to have been underrated. Not forgetting that Jupiter does have a big effect on Io, the closest Galilean moon to it.
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Jupiter’s “ocean world” moons may have strong gravitational effects on each other, raising big tides in each others’ subsurface seas, a new study suggests [Space.com reporting].

Surprisingly, these moon-moon tidal forces might generate more heat in the satellites’ oceans than the gravitational tugs of giant Jupiter, study team members found.

“That’s kind of interesting, because Jupiter is the biggest mass in that system, so its tidal forces are much bigger than one moon on another,” lead author Hamish Hay, who performed the work while at the University of Arizona’s Lunar and Planetary Laboratory, said in a statement.

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Venus


The presence of sulphur in the atmosphere hinted at this.
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A new study identified 37 recently active volcanic structures on Venus, reports Phys.org.

The study provides some of the best evidence yet that Venus is still a geologically active planet.

A research paper on the work, which was conducted by researchers at the University of Maryland and the Institute of Geophysics at ETH Zurich, Switzerland, was published in the journal Nature Geoscience on July 20, 2020.

“This is the first time we are able to point to specific structures and say ‘Look, this is not an ancient volcano but one that is active today, dormant perhaps, but not dead,'” said Laurent Montési, a professor of geology at UMD and co-author of the research paper. “This study significantly changes the view of Venus from a mostly inactive planet to one whose interior is still churning and can feed many active volcanoes.”

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Researchers now want to ‘understand both the processes that excite the waves and the processes that act to damp the waves.’
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A ringing bell vibrates simultaneously at a low-pitched fundamental tone and at many higher-pitched overtones, producing a pleasant musical sound, says Phys.org.

A recent study, just published in the Journal of the Atmospheric Sciences by scientists at Kyoto University and the University of Hawaii at Mānoa, shows that the Earth’s entire atmosphere vibrates in an analogous manner, in a striking confirmation of theories developed by physicists over the last two centuries.

In the case of the atmosphere, the “music” comes not as a sound we could hear, but in the form of large-scale waves of atmospheric pressure spanning the globe and traveling around the equator, some moving east-to-west and others west-to-east.

Each of these waves is a resonant vibration of the global atmosphere, analogous to one of the resonant pitches of a bell.

The basic understanding of these atmospheric resonances began with seminal insights at the beginning of the 19th century by one of history’s greatest scientists, the French physicist and mathematician Pierre-Simon Laplace.

Research by physicists over the subsequent two centuries refined the theory and led to detailed predictions of the wave frequencies that should be present in the atmosphere. However, the actual detection of such waves in the real world has lagged behind the theory.

Now in a new study by Takatoshi Sakazaki, an assistant professor at the Kyoto University Graduate School of Science, and Kevin Hamilton, an Emeritus Professor in the Department of Atmospheric Sciences and the International Pacific Research Center at the University of Hawaii at Mānoa, the authors present a detailed analysis of observed atmospheric pressure over the globe every hour for 38 years.

The results clearly revealed the presence of dozens of the predicted wave modes.

Full article here.


This is easily shown from the 74 Jupiter-Saturn conjunctions in the period:
1 J-S = 19.865036 sidereal years = 19.865036*365.25636 days = 7255.8307
(7255.8307*74) / 365.259636 (anomalistic year) = 1469.99945 (1470)

So Earth reaches its perihelion with the Sun exactly 1470 times per 74 J-S.

Both numbers are even, so why is the Dansgaard-Oeschger event not at half the period?
The short answer is: Neptune.

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It now seems all planetary bodies can have magnetospheres, whether or not they have a significant magnetic field. This would also help to explain why Venus, with hardly any ‘protective’ magnetic field, has a much thicker atmosphere than Earth. Wikipedia might need an update.
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Five years after NASA’s MAVEN spacecraft entered into orbit around Mars, data from the mission has led to the creation of a map of electric current systems in the Martian atmosphere, reports Phys.org.

“These currents play a fundamental role in the atmospheric loss that transformed Mars from a world that could have supported life into an inhospitable desert,” said experimental physicist Robin Ramstad of the University of Colorado, Boulder.

“We are now currently working on using the currents to determine the precise amount of energy that is drawn from the solar wind and powers atmospheric escape.” Ramstad is lead author of a paper on this research published May 25 in Nature Astronomy.

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Credit: NASA


This BBC link includes a video which shows the weakening of the magnetic field over the last 400 years (under ‘Magnetic flip’ sub-heading).
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In an area stretching from Africa to South America, Earth’s magnetic field is gradually weakening, says Phys.org.

This strange behaviour has geophysicists puzzled and is causing technical disturbances in satellites orbiting Earth.

Scientists are using data from ESA’s Swarm constellation to improve our understanding of this area known as the ‘South Atlantic Anomaly.’

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Saturn’s hexagon


The ever-mysterious hexagon goes under the microscope, or telescope at least.

A rich variety of meteorological phenomena takes place in the extensive hydrogen atmosphere of Saturn, a world about 10 times the size of the Earth.

They help us to better understand similar features in the Earth’s atmosphere, says Phys.org.

Among Saturn’s atmospheric phenomena is the well-known “hexagon,” an amazing wave structure that surrounds the planet’s polar region.

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Image credit: NASA-ISS


Dust storms are common in the region, and sometimes bear resemblance to weather events on Mars, according to NASA.
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A surging dust storm and trailing dust cloud captured an astronaut’s attention as the International Space Station (ISS) was passing over South America, says NASA’s Earth Observatory.

Dust storms are common in Patagonia and familiar for people in Comodoro Rivadavia, a coastal city in southern Argentina.

The primary source of dust is Lago Colhué Huapí, a shallow lake adjacent to the much deeper Lago Musters.

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Magnetic North on the move [credit: ESA]


They have a go at doing so, anyway. To make it more complicated, the South Magnetic Pole is also moving, but at a much lesser rate.

European scientists think they can now describe with confidence what’s driving the drift of the North Magnetic Pole, says BBC News.

It’s shifted in recent years away from Canada towards Siberia.

And this rapid movement has required more frequent updates to navigation systems, including those that operate the mapping functions in smartphones.

A team, led from Leeds University, says the behaviour is explained by the competition of two magnetic “blobs” on the edge of the Earth’s outer core.

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Image credit: naturalnavigator.com


We’re told: ‘They refer to what they’ve found as ANTS, for Active Nearside Tectonic System’, which is ‘a mysterious system of tectonic features (ridges and faults) on the lunar nearside, unrelated to both lava-filled basins and other young faults that crisscross the highlands.’ Tectonic activity on one side only sounds a bit unlikely somehow, but what about tidal disturbance from Earth? We know it works the other way round: the Moon causes tides on Earth. Of course the Moon is tidally locked to Earth, hence the term ‘nearside’.
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Researchers have discovered a system of ridges spread across the nearside of the Moon topped with freshly exposed boulders, reports Phys.org.

The ridges could be evidence of active lunar tectonic processes, the researchers say, possibly the echo of a long-ago impact that nearly tore the Moon apart.

“There’s this assumption that the Moon is long dead, but we keep finding that that’s not the case,” said Peter Schultz, a professor in Brown University’s Department of Earth, Environmental and Planetary Sciences and co-author of the research, which is published in the journal Geology.

“From this paper it appears that the Moon may still be creaking and cracking—potentially in the present day—and we can see the evidence on these ridges.”

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Credit: infobarrel.com


Super-rotation of its thick atmosphere, that is. The researchers believe their findings could also be a model for tidally-locked exoplanets with atmospheres.

An international research team led by Takeshi Horinouchi of Hokkaido University has revealed that this ‘super-rotation’ is maintained near the equator by atmospheric tidal waves formed from solar heating on the planet’s dayside and cooling on its nightside.

Closer to the poles, however, atmospheric turbulence and other kinds of waves have a more pronounced effect. The study was published online in Science on April 23.

Venus rotates very slowly, taking 243 Earth days to rotate once around its axis. Despite this very slow rotation, Venus’ atmosphere rotates westward 60 times faster than its planetary rotation.

This super-rotation increases with altitude, taking only four Earth days to circulate around the entire planet towards the top of the cloud cover. The fast-moving atmosphere transports heat from the planet’s dayside to nightside, reducing the temperature differences between the two hemispheres.

“Since the super-rotation was discovered in the 1960s, however, the mechanism behind its forming and maintenance has been a long-standing mystery,” says Horinouchi.

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The atmosphere of Venus has surprised and puzzled scientists before.

Philosopher Nicholas Rescher once wrote, “Scientific discoveries are often made not on the basis of some well-contrived plan of investigation, but through some stroke of sheer luck,” quotes Phys.org.

For a team of researchers at the Johns Hopkins Applied Physics Laboratory (APL) in Laurel, Maryland, that statement couldn’t be more true.

What started as a dry run to ensure instruments on NASA’s Mercury Surface, Space Environment, Geochemistry and Ranging (MESSENGER) spacecraft worked properly later turned into a 10-year saga that resulted in a chance discovery unrelated to the mission’s target planet, Mercury. It’s about Venus and its atmosphere.

The team reports April 20 in Nature Astronomy that data fortuitously collected by MESSENGER reveals a sudden rise in nitrogen concentrations at about 30 miles above Venus’ surface, demonstrating the planet’s atmosphere isn’t uniformly mixed, as expected. That finding upends an understanding about Venus’ atmosphere that has prevailed for decades.

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As the video reminds us: Earth’s atmosphere is mostly (78%) nitrogen. Plus about 21% oxygen at sea level, and a few minor trace gases – one or two of which some people like to fixate on.

Researchers have used a new geochemical tool to shed light on the origin of nitrogen and other volatile elements on Earth, which may also prove useful as a way to monitor the activity of volcanoes, says ScienceDaily.

Their findings were published April 16, 2020, in the journal Nature.

Nitrogen is the most abundant gas in the atmosphere, and is the primary component of the air we breathe. Nitrogen is also found in rocks, including those tucked deep within the planet’s interior.

Until now, it was difficult to distinguish between nitrogen sources coming from air and those coming from inside the Earth’s mantle when measuring gases from volcanoes.

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Saturn’s aurora


The report says: ‘Density decreases with altitude, and the rate of decrease depends on temperature.’ Or is it the other way round, i.e. density influences temperature?

The upper layers in the atmospheres of gas giants—Saturn, Jupiter, Uranus and Neptune—are hot, just like Earth’s, says Phys.org.

But unlike Earth, the Sun is too far from these outer planets to account for the high temperatures. Their heat source has been one of the great mysteries of planetary science.

New analysis of data from NASA’s Cassini spacecraft finds a viable explanation for what’s keeping the upper layers of Saturn, and possibly the other gas giants, so hot: auroras at the planet’s north and south poles.

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Greenland ice sheet (east coast) [image credit: Hannes Grobe @ Wikipedia]


Of course the other question about the start of an ice age still remains.

New University of Melbourne research has revealed that ice ages over the last million years ended when the tilt angle of the Earth’s axis was approaching higher values, reports Phys.org.

During these times, longer and stronger summers melted the large Northern Hemisphere ice sheets, propelling the Earth’s climate into a warm ‘interglacial’ state, like the one we’ve experienced over the last 11,000 years.

The study by Ph.D. candidate, Petra Bajo, and colleagues also showed that summer energy levels at the time these ‘ice-age terminations’ were triggered controlled how long it took for the ice sheets to collapse, with higher energy levels producing fast collapse.

Researchers are still trying to understand how often these periods happen and how soon we can expect another one.

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