Waves in Saturn’s rings give precise measurement of planet’s rotation rate

Saturn from the Cassini orbiter [image credit: NASA]

This has been a tricky problem for years as explained below, and now appears to have been resolved. But whether that’s the end of the story remains to be seen.

Saturn’s distinctive rings were observed in unprecedented detail by NASA’s Cassini spacecraft, and scientists have now used those observations to probe the interior of the giant planet and obtain the first precise determination of its rotation rate, reports Phys.org.

The length of a day on Saturn, according to their calculations, is 10 hours 33 minutes and 38 seconds.

Does it snow on Mars?

Clouds on Mars [image credit: NASA]

H/T Discover Magazine

This wasn’t the first question that came to mind when I photographed these clouds, says Tom Yulsman @ ImaGeo.

But the beautiful phenomenon I witnessed eventually led me to it.
– – –
Mars is certainly cold. With temperatures that can plunge to more than negative 100 degrees Celsius, it’s bloody frigid!

But as cold as it might get, does it snow on Mars?

New Horizons opts for primary flyby path around Ultima Thule

The orbit of 2014 MU69 with the path of New Horizons [credit: NASA@Wikipedia]

“Ultima Thule” (2014 MU69) means “beyond the borders of the known world.” It takes nearly 300 years to orbit the Sun. Scientists ‘have no idea what to expect’.

After several weeks of sensitive searches for rings, small moons and other potential hazards around 2014 MU69, a Kuiper belt object nicknamed Ultima Thule, the dozen-member New Horizons hazard watch team gave the ‘all clear’ for the spacecraft to remain on a path that takes it about 2,200 miles (3,500 km) from Ultima Thule, instead of a hazard-avoiding detour that would have pushed it three times farther out, reports Sci-News.

“New Horizons is now targeted for the optimal flyby, over three times closer than we flew to Pluto. Ultima, here we come,” said New Horizons principal investigator Dr. Alan Stern, a researcher at Southwest Research Institute.

New Horizons will make its historic close approach to Ultima Thule at 12:33 a.m. EST on January 1, 2019.

See a passing comet this Sunday

Comet 46P/Wirtanen [image credit: NASA]

The comet can be found near the Pleiades star cluster, conditions permitting.

On Sunday, Dec. 16, the comet known as 46P/Wirtanen will make one of the 10 closest comet flybys of Earth in 70 years, and you may even be able to see it without a telescope, says Phys.org.

Although the approach will be a distant 7.1 million miles (11.4 million kilometers, or 30 lunar distances) from Earth, it’s still a fairly rare opportunity.

“This will be the closest comet Wirtanen has come to Earth for centuries and the closest it will come to Earth for centuries,” said Paul Chodas, manager of the Center for Near-Earth Object Studies at NASA’s Jet Propulsion Laboratory in Pasadena, California.

Hyperactive Comet Approaches Earth

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It has been billed as The Comet of The Year.

Spaceweather.com

Nov. 26, 2018: Small but hyperactive Comet 46P/Wirtanen is approaching Earth and could soon become visible to the naked eye. On Dec. 16th, the kilometer-wide ball of dirty ice will be less than 11.5 million km away–making it one of the 10 closest-approaching comets of the Space Age. It already looks magnificent through amateur telescopes. On Nov. 26th, Gerald Rhemann took this picture using a 12-inch reflector in Farm Tivoli, Namibia:

“The comet is currently gliding through the southern constellation Fornax,” says Rhemann. “If you look carefully at the image, you can see galaxy NGC 922 near the comet’s head, and another galaxy ESO 479-2 on the left.”

Rhemann says that the comet’s emerald green atmosphere is 50 arcminutes wide. In other words–almost twice as wide as a full Moon. Its apparent diameter could double in the weeks ahead as the comet comes even closer. Because Wirtanen’s brightness is spread…

View original post 168 more words

Meet Antipholus and Antipholus, a very odd Kuiper Belt couple

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More twins than couple, as this 2008 blog post explains. It takes them 25-30 years to orbit each other and 290 years for the binary system to orbit the Sun.

astroengine.com

2001 QW322 is a highly split Kuiper Belt pair, orbiting eachother at a distance of 125,000 km

The Kuiper Belt is an eerie, mysterious and cold region of the Solar System. In it, there are billions of small pieces of rocks with lots of fancy names. As a general designation, all objects in the Kuiper belt are called “Kuiper-belt objects” (KBO’s for short). As the Kuiper belt is located in a region just beyond Neptune, they may also be known as trans-Neptunian objects (TNO’s). Inside the Kuiper belt, we have Pluto-like objects known as “Plutoids”, classical KBO’s called “Cubewanos” (the largest being the recently discovered Makemake) and a whole host of other objects such as icy objects soon to become the next generation of periodic comets.

We are only scraping the surface, finding only a small portion of KBOs. We know of a thousand, but astronomers believe there may…

View original post 542 more words

Dust storms on Titan spotted for the first time

Saharan dust storm [image credit: BBC]

The researchers report that ‘Titan displays particularly energetic meteorology at equinox in equatorial regions’. Associated strong winds ‘are expected to occur in downbursts during rare equinoctial methane storms—consistent with the timing of the observed brightenings’. On Earth, auroral activity is strongest at the equinoxes, so solar wind strength could be a factor in both phenomena.

Data from NASA’s Cassini spacecraft has revealed what appear to be giant dust storms in equatorial regions of Saturn’s moon Titan, reports Phys.org.

The discovery, described in a paper published on Sept. 24 in Nature Geoscience, makes Titan the third Solar System body, in addition to Earth and Mars, where dust storms have been observed.

Scientists find evidence for early planetary shake-up

NASA mission to Jupiter’s
trojan asteroids

Could evidence from a specific binary asteroid pair upset existing planetary theories? ‘The Jupiter trojans, commonly called Trojan asteroids or just Trojans, are a large group of asteroids that share the planet Jupiter’s orbit around the Sun.’ – Wikipedia. There are over a million of these, inhabiting two oval-shaped zones based around what are known as the Lagrangian points L4 and L5 of Jupiter’s orbit (see animation below).

Scientists at Southwest Research Institute (SwRI) studied an unusual pair of asteroids and discovered that their existence points to an early planetary shake-up in our solar system.

These bodies, called Patroclus and Menoetius [see flyby 6 in the graphic], are targets of NASA’s upcoming Lucy mission to the Trojan asteroids. They are around 70 miles wide and orbit around each other as they collectively circle the Sun.

Stealing from the Solar System: the effects of a stellar fly-by

The highly tilted orbit of Eris compared to the orbits of Ceres (light blue), Jupiter (maroon), Saturn (orange, Uranus (green), Neptune (blue), Pluto (olive, and MakeMake (red) [image credit: Fandom]

Could a ‘rogue’ star passing nearby have disturbed outer parts of the early solar system? Beyond Neptune things become somewhat different.

The outer reaches of our solar system harbor a number of mysterious features. Astrobites reports on whether a single stellar fly-by could help explain them all.

A star is born from the gravitational collapse of a cloud of gas and dust. Yet not all of the material ends up in the star, and instead forms a flat protoplanetary disk that surrounds the new star. Over time, the materials in this disk coalesce to form planets, moons, asteroids, and most other objects you might expect to find near a typical star.

Since protoplanetary disks are flat, the expectation is that all of the planets and objects orbiting a star that formed out of a protoplanetary disk should orbit on a single plane. So when we find stars with planets that orbit at multiple different inclinations, this raises questions.

Why Phi? – a long-term Jupiter-Saturn-Uranus model

Here we find a match between the orbit numbers of Jupiter, Saturn and Uranus and see what that might tell us about certain patterns in the solar system.

715 U = 60072.044 years
2040 S = 60072.895 years
5064 J = 60072.282 years
Data source: Nasa/JPL – Planets and Pluto: Physical Characteristics

The Jupiter-Saturn part of the chart derives directly from this earlier Talkshop post:
Why Phi? – Jupiter, Saturn and the de Vries cycle

Proof of ‘Planet Nine’ may be sewn into medieval tapestries

Room for one more? [image credit: NASA]

There’s a suspicion of confirmation bias, or seeing what you wanted to see, in stories like this. But we’ll look for any merits in the ideas anyway. Claims that Planet 9 can’t hide much longer haven’t proved correct so far.

Observations made a thousand years ago could help modern scientists find the theoretical “Planet Nine” in the outer reaches of the solar system, says Live Science.

The far reaches of the outer solar system may be home to an icy giant — a hypothetical planet scientists have dubbed “Planet Nine.”

Meanwhile, archives back on Earth are home to dozens of medieval records documenting the passage of comets through the heavens. Now, two researchers from Queen’s University Belfast in Northern Ireland are hoping to use these old scrolls and tapestries to solve the modern astronomical mystery of Planet Nine.

Geometric clusters of cyclones churn over Jupiter’s poles

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

Octagon and pentagon (8:5) shapes at the poles, with groups of cyclones in a 9:6 (= 3:2) polar ratio. Fascinating.

Jupiter’s poles are blanketed by geometric clusters of cyclones and its atmosphere is deeper than scientists suspected, says Phys.org.

These are just some of the discoveries reported by four international research teams Wednesday, based on observations by NASA’s Juno spacecraft circling Jupiter.

One group uncovered a constellation of nine cyclones over Jupiter’s north pole and six over the south pole. The wind speeds exceed Category 5 hurricane strength in places, reaching 220 mph (350 kph).

The massive storms haven’t changed position much—or merged—since observations began.

Why Phi? – Jupiter, Saturn and the ice giants

Giant planets of the solar system [image credit: universetoday.com]

This post on the ice giants Uranus and Neptune follows on from this one:
Why Phi? – Jupiter, Saturn and the inner solar system

The main focus will be on Uranus. A planetary conjunction of three bodies (e.g. two planets and the Sun, in line) is also known as a syzygy.

Here’s the notation for the table shown below:
J-S = Jupiter-Saturn conjunctions
S-U = Saturn-Uranus conjunctions
U-N = Uranus-Neptune conjunctions

Each of the columns: U, S-U, J-S shows a Fibonacci progression.

Accuracy of best match is between 99.965% and 99.991%.

Quoting Wikipedia: ‘The mathematics of the golden ratio and of the Fibonacci sequence are intimately interconnected.’
The Greek letter φ (phi) represents the golden ratio.

Planets around other stars are like peas in a pod

Jupiter-sized exoplanet [Wikipedia]

It seems the planetary structure of our solar system is an oddity compared to most of the exoplanetary systems so far discovered. On the other hand it’s easier to find planets close to their stars than those a long way away, so what is known so far might not be giving us the whole picture.

An international research team led by Université de Montréal astrophysicist Lauren Weiss has discovered that exoplanets orbiting the same star tend to have similar sizes and a regular orbital spacing, says Phys.org.

This pattern, revealed by new W. M. Keck Observatory observations of planetary systems discovered by the Kepler Telescope, could suggest that most planetary systems have a different formation history than the solar system.

Thanks in large part to the NASA Kepler Telescope, launched in 2009, many thousands of exoplanets are now known. This large sample allows researchers to not only study individual systems, but also to draw conclusions on planetary systems in general.

Sidorenkov and Wilson: new solar retrograde motion paper

Sun at solar system barycentre 1990 [via Arnholm’s solar simulator]

H/T Michele Casati

INFLUENCE OF SOLAR RETROGRADE MOTION ON TERRESTRIAL PROCESSES
N.S.Sidorenkov, Ian Wilson

ABSTRACT. The influence of solar retrograde motion on secular minima of solar activity, volcanic eruptions, climate changes, and other terrestrial processes is investigated. Most collected data suggest that secular minima of solar activity, powerful volcanic eruptions, significant climate changes, and catastrophic earthquakes occur around events of solar retrograde motion.

Keywords: barycentric motion of the sun; secular minima of solar activity, volcanic eruptions, climate changes; the historical process of humankind.

Considering the sun in climate change

Credit: BBC

The fact is we live in a *solar* system. As the author concludes: ‘It is time … to focus on understanding the sun-climate connection. We need to see the sun in climate change.’

There is a lot of debate about the sun’s role in global warming and climate change says David Wojick, Ph.D.. Some scientists argue that the sun plays the dominant role, making human activity insignificant.

Much of this argument is based on statistical analysis of very long proxy records. One can see a very good example of this thinking, as well as the debate surrounding it, in a recent article on Judith Curry’s Outstanding “Climate, Etc.” science blog.

The article is titled “Nature Unbound VI Centennial to millennial solar cycles.”

NASA fixes Voyager 1 deep space probe by firing thrusters not used in 37 years

Getting any response from 13 billion miles away is quite a feat.
But what will the aliens make of Chuck Berry?

Engineers experience “joy and incredulity” as a successful test extends the life of the farthest human-made object from Earth, reports Sky News.

NASA has been able to extend the life of one of its space probes travelling 13 billion miles from Earth by firing up dormant thrusters not used for 37 years.

Voyager 1 was launched in September 1977 and is the only human-made object in interstellar space – the environment between the stars.

But after four decades of exploration which have taken in fly-bys of Jupiter and Saturn, engineers found that the primary thrusters which orient the space probe had severely degraded.

So, in an attempt to keep Voyager 1 operable, NASA tested four thrusters on the back side of the spacecraft which have not been used 1980.

Why Phi? – Jupiter, Saturn and the inner solar system

From left, Mercury, Venus, Earth and Mars. [Credit: Lunar and Planetary Institute]

The planetary theory aspect appears a bit later, but first a brief review of some relevant details.

In this Talkshop post: Why Phi? – a triple conjunction comparison we said:
(1) What is the period of a Jupiter(J)-Saturn(S)-Earth(E) (JSE) triple conjunction?
JSE = 21 J-S or 382 J-E or 403 S-E conjunctions (21+382 = 403) in 417.166 years (as an average or mean value).

(2) What is the period of a Jupiter(J)-Saturn(S)-Venus(V) (JSV) triple conjunction?
JSV = 13 J-S or 398 J-V or 411 S-V conjunctions (13+398 = 411) in 258.245 years (as an average or mean value).

Since JSV = 13 J-S and JSE = 21 J-S, the ratio of JSV:JSE is 13:21 exactly (in theory).

As these are consecutive Fibonacci numbers, the ratio is almost 1:Phi or the golden ratio.

Haze keeps Pluto cool by kicking heat out to space, say scientists

Pluto probe

Uncertainty abounds here. Scientists expected –173° Celsius but ‘the probe found temperatures closer to –203° — with no obvious explanation.’ Perhaps there is a place where enlightenment could be found, if they cared to look.

Meanwhile the ‘gas only’ theory is under pressure [sic] again, as Pluto’s atmosphere apparently defies expectations.

Pluto may be the only place in the solar system whose atmosphere is kept cool by solid hazes, not warmed by gas, says Science News.

Blame Pluto’s haze for the dwarf planet’s unexpected chilliness. Clusters of hydrocarbons in the atmosphere radiate heat back into space, keeping the dwarf planet cool, a new study suggests.

Why Phi? – solar and lunar rotation

This started as a search for a period when the Sun and the Moon would both complete a whole number of rotations.
The result was:
Solar: 25.38 days * 197 = 4999.860 d
Lunar: 27.321662 * 183 = 4999.864 d
(data sources: see reference notes at end)

Taking these as equivalent, we have 197-183 = 14 ‘beats’.
197 = 14*14, +1
183 = 13*14, +1
4999.864 / 14 = 357.13314 days
357.13314 days * 45/44 = 365.2498 days
45 * 14 (630) beats = 44 * 14 (616) calendar years, difference = 0.022 day

So the beat period of the two rotations is 44/45ths of a year, i.e. the difference in number of rotations is exactly 1 in that length of time.
630 beats = 616 years (630 – 616 = 14)
616/45 = 13.68888 calendar years = 4999.8663 days
184 lunar sidereal months (rotations) = 4999.864 days

Then something else popped up…

The Phi factor:
‘We recover a 22.14-year cycle of the solar dynamo.’ (2016 paper)
See: Why Phi? – modelling the solar cycle

Solar Hale cycle = ~22.14 years (est. mean)
13.68888 * Phi = 22.149~ years
22.14 / 13.68888 = 1.61737 (99.96% of Phi)
(55/34 = 1.617647)

From the same post:
Jupiter-Saturn axial period (J+S) is 8.456146 years.
That’s when the sum of J and S orbital movement in the conjunction period = 1
13.68888 / 8.456146 = 1.618808
Phi = 1.618034

Conclusion:
This cycle of solar and lunar sidereal rotation (SRC) sits at the mid-point of the Phi²:1 ratio between the J+S axial period and the mean solar Hale cycle, i.e. with a Phi ratio to one and inverse Phi to the other.
SRC = (J+S) * Phi
SRC = Hale / Phi
SRC = Hale – (J+S)
(Mean Hale value is assumed)

In a period of 616 years there are 45 SRC.
The period is 44 * 14 years = 45 SRC = 45 * 14 beats.
SRC * (45/44) = 14 years.

Cross-checks:
Carrington rotations per 616 y = 8249
8249 CR / 45 = 4999.865 days

Synodic months per 616 y = 7619
7619 SM / 45 = 4999.856 days
8249 – 7619 = 630 = 45 * 14

45*183 sidereal months = 8235
8235 – 7619 = 616
8249 CR – 8235 Sid.M = 14
Beat period of CR and Sid.M = 616/14 = 44 years = 45 * (13.6888 / 14)
Every 44 years there will be exactly one less lunar rotation (sidereal month) than the number of Carrington rotations.

8249 CR – 7619 synodic months = 630 = 45 * 14
630 – 616 = 14
– – –
The anomalistic year

The beat period of the tropical month and solar sidereal rotation * 45/44 = the anomalistic year.
(27.321582 * 25.38) / (27.321582 – 25.38) = 357.14265 days
45 * 357.14265 = 16071.419 days
44 * 365.259636 = 16071.423 days

The anomalistic year is the time taken for the Earth to complete one revolution with respect to its apsides. The orbit of the Earth is elliptical; the extreme points, called apsides, are the perihelion, where the Earth is closest to the Sun (January 3 in 2011), and the aphelion, where the Earth is farthest from the Sun (July 4 in 2011). The anomalistic year is usually defined as the time between perihelion passages. Its average duration is 365.259636 days (365 d 6 h 13 min 52.6 s) (at the epoch J2011.0).
http://en.wikipedia.org/wiki/Year#Sidereal.2C_tropical.2C_and_anomalistic_years
– – –
Data sources

— Carrington Solar Coordinates:
Richard C. Carrington determined the solar rotation rate by watching low-latitude sunspots in the 1850s. He defined a fixed solar coordinate system that rotates in a sidereal frame exactly once every 25.38 days (Carrington, Observations of the Spots on the Sun, 1863, p 221, 244). The synodic rotation rate varies a little during the year because of the eccentricity of the Earth’s orbit; the mean synodic value is about 27.2753 days.
http://wso.stanford.edu/words/Coordinates.html

— The standard meridian on the sun is defined to be the meridian that passed through the ascending node of the sun’s equator on 1 January 1854 at 1200 UTC and is calculated for the present day by assuming a uniform sidereal period of rotation of 25.38 days (synodic rotation period of 27.2753 days, Carrington rotation).
http://jgiesen.de/sunrot/index.html

The sidereal month is the time between maximum elevations of a fixed star as seen from the Moon. In 1994-1998, it was 27.321662 days.
http://scienceworld.wolfram.com/astronomy/SiderealMonth.html