Archive for the ‘solar system dynamics’ Category

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Extreme geomagnetic storms are now thought to occur about once every 45 years, or every four solar cycles, on average.

Spaceweather.com

April 30, 2021: Imagine living in Florida. You’ll never see the Northern Lights … right? Actually, the odds may be better than you think. A new historical study just published in the Journal of Space Climate and Space Weather shows that great aurora storms occur every 40 to 60 years.

“They’re happening more often than we thought,” says Delores Knipp of the University of Colorado, the paper’s lead author. “Surveying the past 500 years, we found many extreme storms producing auroras in places like Florida, Cuba and Samoa.”

This kind of historical research is not easy. Hundreds of years ago, most people had never even heard of the aurora borealis. When the lights appeared, they were described as “fog,” “vapors”, “spirits”–almost anything other than “auroras.” Making a timeline 500 years long requires digging through unconventional records such as personal diaries, ship’s logs, local weather reports–often in languages that are foreign to…

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Talkshop readers will remember that as well as his work on modelling solar activity, Rick Salvador also built a planetary model to predict variation in Earth’s Length of Day (LOD). The model uses 13 frequencies derives from planetary and lunar motion to replicate changes in Earth’s spin rate.

Rick has retired from modelling now, so this is the final update on the model’s performance. The IERS LOD database was changed in early 2020, so the model performance update ends there. Over the last 4 years, Rick found that to keep it on track, he needed to add a -0.0006 second correction in June each year. The necessity for this is as yet unexplained and comments on possible reasons are encouraged.

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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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Some carbonaceous chondrites from earlier finds [image credit: NASA]


This rare type of meteorite (less than 5% of all known falls) was also collected by the Japanese Hayabusa space probe from an asteroid in 2010, but these UK samples arrived free of charge. The linked report includes an interview with the ‘wobbly legs’ researcher who collected it.
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Several rocky fragments have been recovered from the fireball that lit up the sky above southern England just over a week ago, reports BBC News.

They came down in the Winchcombe area of Gloucestershire.

A householder first alerted experts after noticing a pile of charred stone on his driveway. Other members of the public have since come forward with their own finds.

It’s 30 years since meteorite material was last retrieved in the UK.

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A New Form of Space Weather: Earth Wind

Posted: February 12, 2021 by oldbrew in moon, solar system dynamics, wind

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A water creation surprise here.

Spaceweather.com

Feb. 12, 2021: The sun is windy. Every day, 24/7, a breeze of electrified gas blows away from the sun faster than a million mph. Solar wind sparks beautiful auroras around the poles of Earth, sculpts the tails of comets, and scours the surface of the Moon.

Would you believe, Earth is windy, too? Our own planet produces a breeze of electrified gas. It’s like the solar wind, only different, and it may have important implications for space weather on the Moon.

“Earth wind” comes from the axes of our planet. Every day, 24/7, fountains of gas shoot into space from the poles. The leakage is tiny compared to Earth’s total atmosphere, but it is enough to fill the magnetosphere with a riot of rapidly blowing charged particles. Ingredients include ionized hydrogen, helium, oxygen and nitrogen.

Once a month, the Moon gets hit by a blast of Earth wind. It…

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Ned Nikolov, Ph.D. Has written to me with news of the presentations he made at this years AMS meeting. It’s vital we get people to understand the implications of the discoveries he and Karl Zeller have made. With our western governments jumping aboard the ‘Green New Deal’ and ‘NetZero’ bandwagons, we will need to work hard to rise awareness of viable alternative hypotheses for ‘climate change’ and ‘global warming’ which better explain the phenomena we can measure around us. Ned and Karl’s work should be given proper attention, because it strives for universality and general application of physics solar system wide, rather then treating Earth as a ‘special case’.

Two studies presented at the American Meteorological Society’s 34th Conference on Climate Variability and Change in January 2021 employed a novel approach to identify the forcing of Earth’s climate at various time scales. The new method, never attempted in climate science before, relies on the fundamental premise that the laws of nature are invariant across spacetime.

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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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Sunspots


In a recent post we looked at the average daily sunspot numbers, finding that far from the claimed decades-long decline of solar strength, averages were high from 1933-2008 followed by a sharp decline in the recently-ended solar cycle 24.

This time the focus moves to another metric from the same source, Wikipedia’s List of solar cycles.

After the main table of data they introduce another one, stating:
The following table is instead divided into (unofficial) cycles starting and ending with a maximum, to give a better feel for the number of spotless days associated with each minimum.

For this short exercise the ‘Spotless days’ column of data will be split into two groups of six, comparing the overall average of each from the list.

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What if … A Perfect CME Hit Earth?

Posted: January 22, 2021 by oldbrew in solar system dynamics
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Are you sitting comfortably? Well, you might not be after reading this…

Spaceweather.com

Jan. 21, 2021: You’ve heard of a “perfect storm.” But what about a perfect solar storm? A new study just published in the research journal Space Weather considers what might happen if a worst-case coronal mass ejection (CME) hit Earth. Spoiler alert: You might need a backup generator.

For years, researchers have been wondering, what’s the worst the sun could do? In 2014, Bruce Tsurutani (JPL) and Gurbax Lakhina (Indian Institute of Geomagnetism) introduced the “Perfect CME.” It would be fast, leaving the sun around 3,000 km/s, and aimed directly at Earth. Moreover, it would follow another CME, which would clear the path in front of it, allowing the storm cloud to hit Earth with maximum force.

None of this is fantasy. The Solar and Heliospheric Observatory (SOHO) has observed CMEs leaving the sun at speeds up to 3,000 km/s. And there are many documented cases of…

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Data courtesy of Solen.info

Back in November it looked like solar cycle 25 was finally getting underway, with daily sunspot numbers peaking up to 80, and the 30 day Wolf number climbing over 30 in early December. Since then though, the Sun has relapsed into a low activity state.

This won’t come as any surprise to Talkshop followers, we’ve been saying that cycle 25 would be very low for most of the last decade. Our group research culminated in late 2013 with publication of Rick Salvador’s orbital resonance model in the journal ‘Pattern Recognition in Physics’. We provided an update on the validation of the model a while back, showing it has remained on track since publication.

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The NLCs are playing a game of hide-and-seek this season, bemusing regular observers.

Spaceweather.com

Jan. 8, 2021:

They’re back. Noctilucent clouds (NLCs), recently missing, are once again circling the South Pole. And, in an unexpected twist, they’ve just appeared over Argentina as well.

“This is a very rare event,” reports Gerd Baumgarten of Germany’s Leibniz-Institute of Atmospheric Physics, whose automated cameras caught the meteoritic clouds rippling over Rio Grande, Argentina (53.8S) on Jan. 3rd:

A second camera recorded the clouds at even higher latitude: Rio Gallegos (51.6S). At this time of year, noctilucent clouds are supposed to be confined to the Antarctic–not Argentina. In the whole history of atmospheric research, NLCs have been sighted at mid-southern latitudes only a handful of times.

“Personally, I am thrilled to see NLCs in Argentina, as I had not expected them to occur so far north,” says Natalie Kaifler of the German Aerospace Center (DLR), who operates a lidar (laser radar) alongside one of Baumgarten’s…

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In fact it’s unprecedented, in recent history at least. But 2021 is predicted to be even shorter.
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Scientists around the world have noted that the Earth has been spinning on its axis faster lately—the fastest ever recorded, says Phys.org.

Several scientists have spoken to the press about the unusual phenomenon, with some pointing out that this past year saw some of the shortest days ever recorded.

For most of the history of mankind, time has been marked by the 24-hour day/night cycle (with some alterations made for convenience as the seasons change). The cycle is governed by the speed at which the planet spins on its axis.

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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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Is it a coincidence that we’re just past the end of the lowest sunspot cycle for over a century?

Spaceweather.com

Dec. 28, 2020: Something strange is happening 50 miles above Antarctica. Or rather, not happening. Noctilucent clouds (NLCs), which normally blanket the frozen continent in December, are almost completely missing. These images from NASA’s AIM spacecraft compare Christmas Eve 2019 with Christmas Eve 2020:

“The comparison really is astounding,” says Cora Randall of the University of Colorado’s Laboratory for Atmospheric and Space Physics. “Noctilucent cloud frequencies are close to zero this year.”

NLCs are Earth’s highest clouds. They form when summertime wisps of water vapor rise up from the poles to the edge of space. Water crystallizing around specks of meteor dust 83 km (~50 miles) above Earth’s surface creates beautiful electric-blue structures, typically visible from November to February in the south, and May to August in the north.

A crucial point: Noctilucent clouds form during summer. And that’s the problem. Although summer officially started in Antarctica one week…

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Credit: wcia.com


How to see it, plus videos – here.
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Jupiter and Saturn will merge in the night sky Monday, appearing closer to one another than they have since Galileo’s time in the 17th century, says Phys.org.

Astronomers say so-called conjunctions between the two largest planets in our solar system aren’t particularly rare.

Jupiter passes its neighbor Saturn in their respective laps around the sun every 20 years.

But the one coming up is especially close: Jupiter and Saturn will be just one-tenth of a degree apart from our perspective or about one-fifth the width of a full moon.

They should be easily visible around the world a little after sunset, weather permitting.

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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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Credit: cherishthescientist.net

‘Scientists use an extended, 22-year solar cycle to make the forecast’ is the sub-heading to the article. In other words the Hale cycle. At the end of last year The Talkshop detailed Plenty of predictions from a wide range of research groups, including our own, made in 2013. A possible (?) early indicator is that the ‘smoothed minimum’ of sunspots at the start of solar cycle 25 is given by Wikipedia as 1.8, the lowest recorded since cycle 7 (0.2) in 1823.
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In direct contradiction to the official forecast, a team of scientists led by the National Center for Atmospheric Research (NCAR) is predicting that the Sunspot Cycle that started this fall could be one of the strongest since record-keeping began, says NCAR News.

In a new article published in Solar Physics, the research team predicts that Sunspot Cycle 25 will peak with a maximum sunspot number somewhere between approximately 210 and 260, which would put the new cycle in the company of the top few ever observed.

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Sunspots [image credit: NASA]


Wikipedia’s Solar activity and climate web page says:
Solar activity has been on a declining trend since the 1960s, as indicated by solar cycles 19-24, in which the maximum number of sunspots were 201, 111, 165, 159, 121 and 82, respectively.

We’re probably not surprised that they prefer a metric which appears to support their often-expressed view in various climate-related pages that modern global warming can’t be natural.

But is the sunspot maximum the most relevant metric to judge the level of solar activity by? Another Wikipedia page is its List of Solar Cycles.

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Quote: ‘STEVE is a recently identified atmospheric phenomenon caused by supersonic plasma jets flowing at altitudes >100 km.’ Scientists continue to wrestle with its electromagnetic mysteries.

Spaceweather.com

Nov. 22, 2020: Just when you thought STEVE couldn’t get any weirder. A new paper published in the journal AGU Advances reveals that the luminous purple ribbon we call “STEVE” is often accompanied by green cannonballs of light that streak through the atmosphere at 1000 mph.

“Citizen scientists have been photographing these green streaks for years,” says Joshua Semeter of Boston University, lead author of the study. “Now we’re beginning to understand what they are.”

STEVE is a recent discovery. It looks like an aurora, but it is not. The purple glow is caused by hot (3000 °C) rivers of gas flowing through Earth’s magnetosphere faster than 13,000 mph. This distinguishes it from auroras, which are ignited by energetic particles raining down from space. Canadian aurora watchers first called attention to the phenomenon about 10 years ago, whimsically naming it STEVE; researchers have been studying it ever since.

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Bright Comet Erasmus

Posted: November 22, 2020 by oldbrew in Astronomy, News, solar system dynamics

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Short video here.

Spaceweather.com

Nov. 21, 2020: Every 2000 years, Comet Erasmus (C/2020 S3) visits the inner Solar System. News Flash: It’s back. Discovered on Sept. 17, 2020, by South African astronomer Nicolas Erasmus, the dirty snowball is plunging toward the sun for a close encounter inside the orbit of Mercury on Dec. 12th. This is what it looks like:

Gerald Rhemann took the picture Friday morning, Nov. 20th, using a 12-inch telescope in Farm Tivoli, Namibia. “The tail is magnificent,” he says. “In fact, I couldn’t fit it in a single field of view. This two-panel composite shows the first 3 degrees–and it keeps going well past the edge of the photo.”

Comet Erasmus is brightening as it approaches the sun. Right now it is 7th magnitude–an easy target for backyard telescopes. Forecasters believe it will more than triple in brightness to 5th magnitude by the time it dips inside the orbit of Mercury…

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