Posts Tagged ‘planetary’

Mars from NASA’s Hubble Space Telescope


The hunt is now on for the offending ‘missing ingredient’: “Carbon dioxide is a strong greenhouse gas, so it really was the leading candidate to explain the drying out of Mars,” said Kite, an expert on the climates of other worlds. “But these results suggest it’s not so simple.” The article calls this ‘unusual’, but is what it considers usual really so?
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Mars once ran red with rivers, says Phys.org.

The telltale tracks of past rivers, streams and lakes are visible today all over the planet.

But about three billion years ago, they all dried up—and no one knows why.

“People have put forward different ideas, but we’re not sure what caused the climate to change so dramatically,” said University of Chicago geophysical scientist Edwin Kite. “We’d really like to understand, especially because it’s the only planet we definitely know changed from habitable to uninhabitable.”

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A reconstruction of the Anglian ice sheet in Precambrian North London (credit: BBC / The Natural History Museum, London)


They claim this solves the so-called 100,000 year problem described by Wikipedia:
‘The 100,000-year-problem refers to the lack of an obvious explanation for the periodicity of ice ages at roughly 100,000 years for the past million years, but not before, when the dominant periodicity corresponded to 41,000 years. The unexplained transition between the two periodicity regimes is known as the Mid-Pleistocene Transition, dated to some 800,000 years ago.’ [41,000 years being the approximate obliquity cycle period]

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In a new study published today in the journal Science, the team from Cardiff University has been able to pinpoint exactly how the tilting and wobbling of the Earth as it orbits around the Sun has influenced the melting of ice sheets in the Northern Hemisphere over the past 2 million years or so.

Scientists have long been aware that the waxing and waning of massive Northern Hemisphere ice sheets results from changes in the geometry of Earth’s orbit around the Sun, says Phys.org.

There are two aspects of the Earth’s geometry that can influence the melting of ice sheets: obliquity and precession.

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Neptune


Planetary temperature conundrums are not confined to Earth. Nobody foresaw the observed changes that occurred on Neptune between 2018 and 2020.
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An international team of astronomers have used ground-based telescopes, including the European Southern Observatory’s Very Large Telescope (ESO’s VLT), to track Neptune’s atmospheric temperatures over a 17-year period, Phys.org.

They found a surprising drop in Neptune’s global temperatures followed by a dramatic warming at its south pole.

“This change was unexpected,” says Michael Roman, a postdoctoral research associate at the University of Leicester, UK, and lead author of the study published today in The Planetary Science Journal. “Since we have been observing Neptune during its early southern summer, we expected temperatures to be slowly growing warmer, not colder.”

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Mercury


Something similar was also detected on Mars a few years ago. One researcher commented: “The sudden intensification of a ring current causes the main phase of a magnetic storm.” Coronal mass ejections from the sun were identified as a cause.
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An international team of scientists has proved that Mercury, our solar system’s smallest planet, has geomagnetic storms similar to those on Earth, says Science Daily.

Their finding, a first, answers the question of whether other planets, including those outside our solar system, can have geomagnetic storms regardless of the size of their magnetosphere or whether they have an Earth-like ionosphere.

The research by scientists in the United States, Canada and China includes work by Hui Zhang, a space physics professor at the University of Alaska Fairbanks Geophysical Institute.

Their finding, a first, answers the question of whether other planets, including those outside our solar system, can have geomagnetic storms regardless of the size of their magnetosphere or whether they have an Earth-like ionosphere.

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Credit: NASA


Compensating for the lost time may prove challenging for scientists, says Astronomy magazine. Turning the internet clock back one second implies a repeat of a computer-generated timestamp for example, which might confuse some vital systems not designed to handle that.
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Ever feel like there’s just not enough time in the day? Turns out, you might be onto something.

Earth is rotating faster than it has in the last half-century, resulting in our days being ever-so-slightly shorter than we’re used to.

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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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Caption: This data visualization shows the ICON spacecraft in orbit around Earth. The green arrows show the strong, high-altitude winds—known as atmospheric tides—detected by ICON’s MIGHTI wind imager. These winds are not uniform and can be altered by changes in the lower-altitude atmosphere. This, in turn, changes the particle motion high in the ionosphere. Changes in plasma at 370 miles above Earth’s surface was also detected by ICON as shown in red. Magnetic field lines are shown in magenta and turn yellow as measurements of winds detected by MIGHTI (green arrows) influence the direction of plasma (red arrows). Credit: NASA’s Scientific Visualization Studio/William T. Bridgman
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One researcher said: “We found half of what causes the ionosphere to behave as it does right there in the data”. The hunt is on for the other half. Link includes animations.
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What happens on Earth doesn’t stay on Earth, says Phys.org.

Using observations from NASA’s ICON mission, scientists presented the first direct measurements of Earth’s long-theorized dynamo on the edge of space: a wind-driven electrical generator that spans the globe 60-plus miles above our heads.

The dynamo churns in the ionosphere, the electrically charged boundary between Earth and space.

It’s powered by tidal winds in the upper atmosphere that are faster than most hurricanes and rise from the lower atmosphere, creating an electrical environment that can affect satellites and technology on Earth.

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Observing a recurring feature of the Earth’s ring current system.

Spaceweather.com

Nov. 22, 2021: The biggest geomagnetic storm in years erupted this month when a Cannibal CME slammed into Earth’s magnetic field. Auroras spread as far south as California and New Mexico. Upon closer inspection, however, not all of those lights were auroras. Some were “SARs.”

SARs are pure red arcs of light that ripple across the sky during strong geomagnetic storms. Here’s an example from Finland in 2018:

“The SAR was visible to the naked eye for nearly 30 minutes and, after fading a bit, remained visible to my camera for another hour and a half,” recalls photographer Matti Helin.

On Nov 4, 2021, Earth experienced a veritable SAR storm. “We photographed SARs as far south as the McDonald Observatory in Texas,” reports Jeff Baumgardner of Boston University’s Center for Space Physics. “The bands of light swept over our cameras near Boston, then headed south. We knew something special was…

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Diagram showing solid-body rotation of the Earth with respect to a stationary spin axis due to true polar wander. [Credit: Wikipedia]

The researchers say their finding ‘challenges the notion that the spin axis has been largely stable over the past 100 million years.’
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We know that true polar wander (TPW) can occasionally tilt whole planets and moons relative to their axes, but it’s not entirely clear just how often this has happened to Earth, says ScienceAlert.

Now a new study presents evidence of one such tilting event that occurred around 84 million years ago – when dinosaurs still walked the Earth.

Researchers analyzed limestone samples from Italy, dating back to the Late Cretaceous period (100.5 to 65.5 million years ago), looking for evidence of shifts in the magnetic record that would point towards an occurrence of TPW.

Bacteria fossils trapped in the rock, forming chains of the mineral magnetite, offer some of the most convincing evidence yet of true polar wander in the Late Cretaceous – and it may help settle a scientific debate that’s been going on for decades.

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Mars [image credit: ESA]


Wikipedia says: ‘Within the Solar System there are five candidates for Schumann resonance detection besides the Earth: Venus, Mars, Jupiter, Saturn, and Saturn’s biggest moon Titan.’ The frequencies reported from Mars in 2009 are also found on Earth.
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The interaction of dust particles in Martian dust storms may cause electric fields that are powerful enough to have charges that induce standing electromagnetic waves known as Sсhumann resonances, reports Phys.org.

This is the conclusion drawn by physicists from HSE University, the Space Research Institute, and MIPT. The paper was published in the journal Icarus.

Mars has been a focus of active study over the last decade, with researchers looking at possible space missions to the planet. Knowledge about the Martian atmosphere increases the chances that such missions will be successful.

In particular, the behavior of dust particles and the plasma-dust system on the surface of Mars should be taken into account in planning space trips.

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Mars_NASA

Mars [image credit: NASA]

Researchers say this could open the door to prediction of dust storms, which can seriously affect the solar panels of devices sent to investigate distant bodies like Mars. They also suggest such patterns may be common to all planetary atmospheres.
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Annular modes explain much of the internal variability of Earth’s atmosphere but have never been identified as influential on other planets, says Sci-News.

On Earth, the regularity of storm systems in the middle latitudes is associated with what is called an annular mode — a variability in atmospheric flow that is unrelated to the cycle of seasons.

Annular modes affect the jet stream, precipitation, and cloud formations across the planet.

They explain up to one-third of the variability in wind-driven ‘eddies,’ including blizzards in New England and severe storm outbreaks in the Midwest.

In a new study, Yale University researchers Juan Lora and J. Michael Battalio found that annular modes on Titan and Mars are even more influential than they are on Earth.

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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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EarthspaceScientists previously proposed 26 million year cycles of mass extinctions, but this appears to correct the period. They suggest ‘cycles of activity in the Earth’s interior’ could be behind their new period, but then say: ‘However, similar cycles in the Earth’s orbit in space might also be pacing these events.’ Their study also says ‘a strong secondary signal occurs at a period 8.9 Myr’.
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Geologic activity on Earth appears to follow a 27.5-million-year cycle, giving the planet a ‘pulse,’ according to a new study published in the journal Geoscience Frontiers. Phys.org reporting.

“Many geologists believe that geological events are random over time. But our study provides statistical evidence for a common cycle, suggesting that these geologic events are correlated and not random,” said Michael Rampino, a geologist and professor in New York University’s Department of Biology, as well as the study’s lead author.

Over the past five decades, researchers have proposed cycles of major geological events—including volcanic activity and mass extinctions on land and sea—ranging from roughly 26 to 36 million years.

But early work on these correlations in the geological record was hampered by limitations in the age-dating of geologic events, which prevented scientists from conducting quantitative investigations.

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Image credit: livescience.com

The problem is, the ‘wrong’ side is warmer than the other one. Enter Rodinia.
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We’ve known for a long time that Earth’s fiery interior is destined to burn out in the distant future, although new research indicates that this process may be occurring faster on one side of the planet than the other, says IFL Science..

By analyzing the movement of continents and oceanic plates over the past 400 million years, researchers have determined that parts of the planet have remained more insulated than others, leading to an asymmetrical pattern of heat loss.

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Lagrange points in the Sun–Earth system (not to scale). A small object at L4 or L5 will hold its relative position [Credit: Xander89 @ Wikipedia]


More about Lagrange points here.
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A recently discovered asteroid appears to be an Earth Trojan, orbiting a gravitationally stable area with only one other known occupant, says Sky & Telescope.

Trojans are asteroids gravitationally locked to stable Lagrange points either 60° ahead (L4) or behind (L5) the planets in their orbits around the Sun. 2020 XL5 was found around the L4 point.

Massive Jupiter has more than 9,000 Trojans.

In theory, Trojan orbits would be stable around every planet except Saturn, where Jupiter’s gravity pulls them away.

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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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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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