https://www.livescience.com/space/cosmology/scientists-discover-secret-symmetries-that-...

"Earth probably shouldn't exist.

"That's because the orbits of the inner solar system planets — Mercury, Venus, Earth and Mars — are chaotic, and models have suggested that these inner planets should have crashed into each other by now. And yet, that hasn't happened.

"New research published May 3 in the journal Physical Review X(opens in new tab) may finally explain why.

"Through a deep plunge into the models for planetary motion, the researchers discovered that the motions of the inner planets are constrained by certain parameters that act as a tether that inhibits the system's chaos. Besides providing a mathematical explanation for the apparent harmony in our solar system, the new study's insights may help scientists understand the trajectories of exoplanets surrounding other stars.

"Planets constantly exert a mutual gravitational pull on each other – and these little tugs constantly make minor adjustments to the planets' orbits. The outer planets, which are much larger, are more resistant to little tugs and so maintain comparatively stable orbits.

"The problem of inner planet trajectories, however, is still too complicated to solve exactly. In the late 19th century, mathematician Henri Poincaré proved that it is mathematically impossible to solve the equations governing the motion for three or more interacting objects, often known as the "three body problem." As a result, uncertainties in the details of the planets' starting positions and velocities balloon over time. In other words: It is possible to take two scenarios in which the distances between Mercury, Venus, Mars and Earth differ by the slightest amount, and in one the planets smash into each other and in another they veer apart.

***

"Delving through the math, Laskar and his colleagues then identified for the first time "symmetries" or "conserved quantities" in the gravitational interactions that create a "practical barrier in the chaotic wandering of the planets," Laskar said.

"These emergent quantities remain nearly constant and inhibit certain chaotic motions, but don't prevent them altogether, much like the raised lip of a dinner plate will inhibit food falling off the plate but not prevent it completely. We can thank these quantities for our solar system's apparent stability.

'Renu Malhotra(opens in new tab), Professor of Planetary Sciences at the University of Arizona who was not involved in the study, highlighted how subtle the mechanisms identified in the study are. Malhotra told Live Science that it is interesting that "our solar system's planetary orbits exhibit exceptionally weak chaos."

"In other work, Laskar and colleagues are searching for clues as to whether the number of planets in the solar system ever differed from what we currently see. For all the stability evident today, whether that has always been the case over the billions of years before life evolved remains an open question."

Comment: we still are a priveleged planet protected by a tiny bit of chaos in our neighboring planets motions. Earth needs this stability. God, as designer, provided it. Why some chaos? If God did it, it was required.

https://www.nature.com/articles/d41586-021-00456-7?utm_source=Nature+Briefing&utm_c...

"The presence of Planet Nine was proposed1 in 2016, when astronomers Mike Brown and Konstantin Batygin at the California Institute of Technology in Pasadena observed that the orbits of six trans-Neptunian objects (TNOs) — part of the Kuiper belt, a collection of small bodies orbiting the Sun beyond Neptune — seemed to be clustered together.

***

"To investigate whether the objects were truly clustered, Napier’s team built a computer model simulating ten billion evenly distributed ETNOs in the outer Solar System, and then calculated the chances that observing a small sample of these would produce results matching existing observations. The team concluded that there is no reason to think that ETNOs are not uniformly distributed, and that it’s possible that observed objects only seem to be clustered because of selection bias. “That doesn’t mean that Planet Nine isn’t there, but it’s not necessary to explain the data,” says Napier. “You could fit this data with clustered ETNOs as well — but if you hear hoofbeats, you should think horses, not zebras.”

"Brown, however, disagrees. “I plotted all their data on top of our old paper, and you just simply look at it, and it’s very clustered,” he says. “There’s actually strong evidence for Planet Nine in their data.” He points out that the paper does not include the six TNOs that he and Batygin used in their original research. He also argues that the researchers are “mixing dirt in with their ice cream”, because their analysis considers objects whose orbits might be affected by their proximity to Neptune.

***

"Lawler says new surveys of the outer Solar System are needed to look for any other evidence of clustering. One of the best chances will come from the Vera C. Rubin Observatory in Chile, which will begin a ten-year survey of the sky in 2022.

“'They’re going to detect thousands more Kuiper belt objects,” says Lawler. “I think we’ve really done all that we can with the data we currently have.”

"Even if it turns out Planet Nine isn’t there, Lawler says, it has sparked a lot of useful interest in the outer Solar System from astronomers. “The theory of Planet Nine has been fantastic for the study of the Kuiper belt,” she says."

Comment: Debates like this advance our general knowledge. More research is awaited.

https://www.sciencemag.org/news/2021/02/claim-giant-planet-nine-solar-systems-edge-take...

"For planetary scientists, it was the boldest claim in a generation: an unseen extra planet, as much as 10 times the mass of Earth, lurking on the Solar System’s frontier, beyond Neptune. But the claim looks increasingly shaky, after a team of astronomers reported last week that the orbits of a handful of distant lumps of rock are not bunched together by the gravity of “Planet Nine,” as its proponents believe, but only seem clustered because that’s where telescopes happened to be looking.

"Planet Nine supporters aren’t backing down yet but one skeptic not involved with the new work says she is “very happy” to see it. The study has carried out “a more uniform analysis” than done previously of the far-off rocky bodies known as known as Trans-Neptunian Objects (TNOs), says astronomer Samantha Lawler of the University of Regina, who has tried and failed to simulate the clustered orbits in computer models with an extra planet.

***

"Napier says the team took account of when and where the telescopes pointed, and how sensitive they were to faint objects. With that data, the team calculated a “selection function” that varies across the sky. And sure enough, the extreme TNOs found by all three surveys were in or near areas where selection function was highest, the team reported on 11 February in a paper posted to the arXiv and accepted by Planetary Science Journal. As a result, Napier says, the team could not reject the null hypothesis that the extreme TNOs are uniformly distributed around the Solar System, which would rob Planet Nine of its foundational evidence. The clustering “is a consequence of where we look and when we look,” he says. “There’s no need for another model to fit the data.”

"Batygin doesn’t accept that conclusion. He points out that the DES survey looked largely in the area of the sky where the TNO cluster he and Brown identified resides and found more extreme TNOs. So ruling out clustering is “not logical,” he says. “The more relevant question to ask is: can their analysis distinguish between a clustered and uniform distribution, and the answer appears to be ‘no',” he says.

"Napier acknowledges that trying to draw conclusions from a sample of 14 TNOs is tricky. “There’s only so much statistical power you can draw with so few objects,” he says. The matter is unlikely to be settled, he adds, until the Vera Rubin Observatory—a powerful new survey telescope being built in Chile—starts observing in 2023. Its survey will have well defined selection biases and is likely to detect hundreds of new extreme TNOs. That, says Napier, “will be like Christmas morning.'”

Comment: Science marches forward with new telescopes and new discoveries. P lanet nine is still a maybe.

https://mail.yahoo.com/d/folders/1/messages/ADaw2p8HPAMoXqLyhQZsiE95GEs

"Existing hypotheses claim a mysterious ninth planet is hiding past Neptune, in the outskirts of our solar system. However, new research from astronomers at the University of Pennsylvania challenges any clustering trans-Neptunian rocks. Their data supporting this comes from the Dark Energy Survey, carried out at a Chilean observatory.

"’'We would not have formulated the Planet Nine idea if our data was the only data that existed,’ said (Pedro) Bernardinelli to New Scientist. The scientist's previous 2020 study, also using data from the Dark Energy Survey, found 316 trans-Neptunian objects, including 139 minor planets in the space past Neptune. The researcher's works ultimately seems to show that the faraway region is inhabited by numerous small objects which are uniformly distributed rather than grouped.'"

Comment: this is how science works. New data, changed result.

https://phys.org/news/2019-02-planet.html

"The papers offer new details about the suspected nature and location of the planet, which has been the subject of an intense international search ever since Batygin and Brown's 2016 announcement.

***

"The Planet Nine hypothesis is founded on evidence suggesting that the clustering of objects in the Kuiper Belt, a field of icy bodies that lies beyond Neptune, is influenced by the gravitational tugs of an unseen planet. It has been an open question as to whether that clustering is indeed occurring, or whether it is an artifact resulting from bias in how and where Kuiper Belt objects are observed.

"To assess whether observational bias is behind the apparent clustering, Brown and Batygin developed a method to quantify the amount of bias in each individual observation, then calculated the probability that the clustering is spurious. That probability, they found, is around one in 500.

"'Though this analysis does not say anything directly about whether Planet Nine is there, it does indicate that the hypothesis rests upon a solid foundation," says Brown, the Richard and Barbara Rosenberg Professor of Planetary Astronomy.

"The second paper is titled "The Planet Nine Hypothesis," and is an invited review that will be published in the next issue of Physics Reports. The paper provides thousands of new computer models of the dynamical evolution of the distant solar system and offers updated insight into the nature of Planet Nine, including an estimate that it is smaller and closer to the sun than previously suspected. Based on the new models, Batygin and Brown—together with Fred Adams and Juliette Becker (BS '14) of the University of Michigan—concluded that Planet Nine has a mass of about five times that of the earth and has an orbital semimajor axis in the neighborhood of 400 astronomical units (AU), making it smaller and closer to the sun than previously suspected—and potentially brighter. Each astronomical unit is equivalent to the distance between the center of Earth and the center of the sun, or about 149.6 million kilometers.

"'At five Earth masses, Planet Nine is likely to be very reminiscent of a typical extrasolar super-Earth," says Batygin, an assistant professor of planetary science and Van Nuys Page Scholar. Super-Earths are planets with a mass greater than Earth's, but substantially less than that of a gas giant. "It is the solar system's missing link of planet formation. Over the last decade, surveys of extrasolar planets have revealed that similar-sized planets are very common around other sun-like stars. Planet Nine is going to be the closest thing we will find to a window into the properties of a typical planet of our galaxy.'"

Comment: The saga goes on, with no solid answer so far.

***

"My favorite characteristic of the Planet Nine hypothesis is that it is observationally testable," Batygin says. "The prospect of one day seeing real images of Planet Nine is absolutely electrifying. Although finding Planet Nine astronomically is a great challenge, I'm very optimistic that we will image it within the next decade."

Comment:

https://www.sciencedaily.com/releases/2019/01/190121103346.htm

"The strange orbits of some objects in the farthest reaches of our solar system, hypothesised by some astronomers to be shaped by an unknown ninth planet, can instead be explained by the combined gravitational force of small objects orbiting the Sun beyond Neptune, say researchers.

"The alternative explanation to the so-called 'Planet Nine' hypothesis, put forward by researchers at the University of Cambridge and the American University of Beirut, proposes a disc made up of small icy bodies with a combined mass as much as ten times that of Earth. When combined with a simplified model of the solar system, the gravitational forces of the hypothesised disc can account for the unusual orbital architecture exhibited by some objects at the outer reaches of the solar system.

***

"'If you remove planet nine from the model and instead allow for lots of small objects scattered across a wide area, collective attractions between those objects could just as easily account for the eccentric orbits we see in some TNOs," said Sefilian, who is a Gates Cambridge Scholar and a member of Darwin College.

"Earlier attempts to estimate the total mass of objects beyond Neptune have only added up to around one-tenth the mass of Earth. However, in order for the TNOs to have the observed orbits and for there to be no Planet Nine, the model put forward by Sefilian and Touma requires the combined mass of the Kuiper Belt to be between a few to ten times the mass of Earth.

"'When observing other systems, we often study the disc surrounding the host star to infer the properties of any planets in orbit around it," said Sefilian. "The problem is when you're observing the disc from inside the system, it's almost impossible to see the whole thing at once. While we don't have direct observational evidence for the disc, neither do we have it for Planet Nine, which is why we're investigating other possibilities. Nevertheless, it is interesting to note that observations of Kuiper belt analogues around other stars, as well as planet formation models, reveal massive remnant populations of debris.

"'It's also possible that both things could be true -- there could be a massive disc and a ninth planet. With the discovery of each new TNO, we gather more evidence that might help explain their behaviour.'"

Comment: It is hard to prove a negative. Proof will require seeing Planet Nine

QUOTE: "The presumption back in 1995 was that astronomers would find many exoplanetary systems where the probability of advanced life possibly existing in that system would be greater than zero. More than twenty-three years later, with a database of 2,888 planetary systems and 3,877 planets, only one planetary system and only one planet possess the characteristics that the possible existence of advanced life needs. It requires little effort to discern the identity of that single planetary system and single planet."

DAVID: Our planet is special and so is our solar system. God at work.

dhw: I wonder why the authors specify “advanced life”. Do they expect to find primitive life? Even the simplest form of life is extremely complex. But I’m afraid it will make no difference to theists or atheists if life is or is not found. If it’s not found, atheists will say: “Lucky us.” Theists will say: “God at work.” If it’s found, atheists will say: “In the right conditions, life will arise spontaneously.” Theists will say: “God at work.” I’m not sure, though, how many theists will say: “God specially designed these primitive forms of life on Planet X because his sole purpose was to specially design H. sapiens on Planet Earth.”

The authors were describing the opinions of scientists many years ago. Hugh Ross, a theistic scientist, is simply expressing how unusual our Earth seems to be.

DAVID: Our planet is special and so is our solar system. God at work.

I wonder why the authors specify “advanced life”. Do they expect to find primitive life? Even the simplest form of life is extremely complex. But I’m afraid it will make no difference to theists or atheists if life is or is not found. If it’s not found, atheists will say: “Lucky us.” Theists will say: “God at work.” If it’s found, atheists will say: “In the right conditions, life will arise spontaneously.” Theists will say: “God at work.” I’m not sure, though, how many theists will say: “God specially designed these primitive forms of life on Planet X because his sole purpose was to specially design H. sapiens on Planet Earth.”

https://www.reasons.org/explore/blogs/todays-new-reason-to-believe/read/todays-new-reas...

"Astronomers have detected and measured the mass and/or orbital features of 3,869 planets in 2,887 planetary systems beyond the solar system.1 This ranks as a staggering rate of discovery, given that the first confirmed detection of a planet orbiting another hydrogen-fusion-burning star was as recent as 1995.2 What do the characteristics of these systems reveal about potential habitability for advanced life?

***

"The Italian team reported on the frequency of inner low-mass planets in the presence of outer gas giant planets.3 The Chinese astronomers, Wei Zhu and Yanqin Wu, reported on relationships they discovered between super-Earth planets and cold gas giant planets.

"The three most common exoplanets discovered to date are super-Earths, hot Jupiters, and cold Jupiters. Super-Earth planets are those with masses and radii greater than Earth’s but less than Neptune’s. Hot Jupiters are planets more massive than Saturn that orbit their host stars closer than Earth orbits the Sun. Cold Jupiters are planets more massive than Saturn that are more distant from their host stars than Earth is from the Sun.

"Of the 3,869 confirmed exoplanets, astronomers possess both a measured value of the mass and a measured value of the orbital radius for 1,553 planets. Of these 1,553 exoplanets, 20.5 percent are super-Earths, 33.0 percent are cold Jupiters, and 37.7 percent are hot Jupiters.

***

"For more than a decade, astronomers have recognized that the solar system is highly unusual. It possesses cold Jupiters closer to the Sun than 14 times Earth’s distance from the Sun but lacks one or more super-Earth planets, hot Jupiters, or cold Jupiter planets with orbital eccentricities greater than 0.09. Each one of these four features, if present in a planetary system, rules out the possibility of any kind of advanced life existing in the system.

"How many of the known multiple-planet systems exhibit these life-essential features? The answer for the 638 known multi-planet exoplanetary systems is zero.13 How about the known exoplanetary systems where only one planet has been discovered? Of these 2,249 systems, they either lack a cold Jupiter closer than 14 times Earth’s distance from the Sun or the planet they contain possesses characteristics that would rule out the possible existence of another planet in the system capable of sustaining advanced life.

"The presumption back in 1995 was that astronomers would find many exoplanetary systems where the probability of advanced life possibly existing in that system would be greater than zero. More than twenty-three years later, with a database of 2,888 planetary systems and 3,877 planets, only one planetary system and only one planet possess the characteristics that the possible existence of advanced life needs. It requires little effort to discern the identity of that single planetary system and single planet."

Comment: Our planet is special and so is our solar system. God at work

https://blogs.scientificamerican.com/observations/our-solar-system-is-even-stranger-tha...

"In addition to our solar system, we now know of over 400 multi-planet systems, thanks largely to the Kepler Mission. Kepler is a NASA spacecraft (named after the 17th century German astronomer) that was launched in 2009 for the sole purpose of discovering exoplanets—worlds orbiting other stars. It finds those exoplanets by continuously measuring the brightnesses of about 100,000 stars and waiting for the starlight from any of them dim ever so slightly due to the shadow of a planet in transit. The transit of each planet is unique, allowing the discovery of multiple planets orbiting the same star.

***

"The pattern I found on that sunny afternoon: planets in the same system tend to be the same size. For example, if one planet is 1.5 times the radius of Earth, the other planets in the system are very likely to be 1.5 times the radius of Earth, plus or minus a little bit.

"This is not at all what my colleagues and I expected. In our solar system, planets range from the size of Mercury (less than half the radius of Earth) to Jupiter (more than ten times the radius of Earth). The whole population of exoplanets discovered by Kepler ranges from one quarter the size of Earth to about twenty times the size of Earth. Yet, despite this wide range of possible sizes, planets tend to be about the same sizes as their neighbors.

***

"A widely accepted (but unconfirmed) theory about planet formation involves the rise of so-called “oligarchs,” young precursors of planets that each influence a swath of fixed width within the disk around the star. (Pluto is no longer considered a planet because Pluto was never big enough to be an oligarch.)

"Oligarchic theory predicts roughly equal-mass oligarchs spaced at regular intervals, with the size of the oligarch dependent on the width of its influence. However, because our solar system is not a system of equal-mass planets at regular spacing, the rise of oligarchs is considered a mere chapter in our solar system’s history, an early pattern that was later overwritten by violent impacts that formed our very dissimilar terrestrial planets."

Comment: Another article which shows we live in a very special and unusual solar system. We can add this to the fine tuning theories.

https://www.newscientist.com/article/2181371-distant-dwarf-planet-called-the-goblin-cou...

"Our solar system just got a little spookier. A new dwarf planet called The Goblin has been discovered orbiting the sun in the hinterland beyond Pluto, and its elongated path hints that the long-sought Planet X may be travelling through the outer reaches of the solar system as well.

"This new dwarf planet, officially called 2015 TG387, is likely a ball of ice and is about 300 kilometres in diameter. It was first spotted by a team of astronomers using the Subaru telescope in Hawaii in October 2015, hence its Halloween-themed name. The International Astronomical Union’s Minor Planet Center announced the discovery on 1 October 2018.

"Its extremely elongated orbit means that at times it is 2300 times as far from the sun as Earth is, and it never gets closer to the sun than about twice as far out as Pluto. The dwarf planet moves so slowly that it took years to confirm its orbit with multiple observations.

“'Currently we would only detect 2015 TG387 when it is near its closest approach to the sun. For some 99 per cent of its 40,000-year orbit, it would be too faint to see,” said David Tholen at the University of Hawaii in a statement.

"He and his colleagues found The Goblin during their hunt for the hypothetical Planet X, a large planet believed to be lurking at the edge of the solar system that may account for disturbances in the orbits of smaller objects like The Goblin. The gravity of such a large planet would tug on smaller objects as they pass by, potentially herding them into a cluster of objects orbiting together – like the one The Goblin is part of.

"The most distant objects in our solar system tend to have similar elongated orbits. The team ran simulations that included a Super-Earth-like planet in the distant solar system, and found that such a planet would stabilise The Goblin’s orbit.

"'These simulations do not prove that there’s another massive planet in our solar system, but they are further evidence that something big could be out there,” said Chad Trujillo at North Arizona University in a statement."

Comment: The search goes on as more evidence is found. It will be fun naming it if confirmed.

https://www.sciencedaily.com/releases/2018/06/180604131719.htm

"Bumper car-like interactions at the edges of our solar system -- and not a mysterious ninth planet -- may explain the dynamics of strange bodies called "detached objects," according to a new study.

***

"One theory for its unusual dynamics is that an as-of-yet-unseen ninth planet beyond Neptune may have disturbed the orbits of Sedna and other detached objects. But Madigan and her colleagues calculated that the orbits of Sedna and its ilk may result from these bodies jostling against each other and space debris in the outer solar system.

"'There are so many of these bodies out there. What does their collective gravity do?" said Madigan of the Department of Astrophysical and Planetary Sciences (APS) and JILA. "We can solve a lot of these problems by just taking into account that question."

***

"Detached objects like Sedna get their name because they complete humongous, circular orbits that bring them nowhere close to big planets like Jupiter or Neptune. How they got to the outer solar system on their own is an ongoing mystery.

"Using computer simulations, Madigan's team came up with one possible answer. Jacob Fleisig, an undergraduate studying astrophysics at CU Boulder, calculated that these icy objects orbit the sun like the hands of a clock. The orbits of smaller objects, such as asteroids, however, move faster than the larger ones, such as Sedna.

"'You see a pileup of the orbits of smaller objects to one side of the sun," said Fleisig, who is the lead author of the new research. "These orbits crash into the bigger body, and what happens is those interactions will change its orbit from an oval shape to a more circular shape."

"In other words, Sedna's orbit goes from normal to detached entirely because of those small-scale interactions. The team's observations also fall in line with research from 2012, which observed that the bigger a detached object gets, the farther away its orbit becomes from the sun.

***

"The findings may also provide clues around another phenomenon: the extinction of the dinosaurs. As space debris interacts in the outer solar system, the orbits of these objects tighten and widen in a repeating cycle. This cycle could wind up shooting comets toward the inner solar system -- including in the direction of Earth -- on a predictable timescale."

Comment: Either planet 9 will be seen or this alternative theory will be accepted. Just takes time and observations. We need to learn about solar debris, so we don't end up like he dinos.

https://www.quantamagazine.org/a-new-worlds-extraordinary-orbit-points-to-planet-nine-2...

"Now, astronomers are reporting that they have spotted another distant world — perhaps as large as a dwarf planet — whose orbit is so odd that it is likely to have been shepherded by Planet Nine. The object confirms a specific prediction made by Konstantin Batygin and Michael Brown, the astronomers at the California Institute of Technology who first argued for Planet Nine’s existence. “It’s not proof that Planet Nine exists,” said David Gerdes, an astronomer at the University of Michigan and a co-author on the new paper. “But I would say the presence of an object like this in our solar system bolsters the case for Planet Nine.”

***

"The Dark Energy Survey first detected evidence for the new object in late 2014. Gerdes and his colleagues have spent the years since then tracking its orbit and trying to understand its origins. In the new paper, they describe how they ran many simulations of the object within the known solar system, letting the clock run forward and backward 4.5 billion years at a time. Nothing could explain how the object landed in such a tilted orbit. It wasn’t until they added in a ninth planet — a planet with characteristics that perfectly match Batygin and Brown’s predictions — that the wacky orbit finally made sense. “The second you put Planet Nine in the simulations, not only can you form objects like this object, but you absolutely do,” said Juliette Becker, a graduate student at Michigan and the lead author on the new paper. A strong and sustained interaction with Planet Nine appears to be the only way to pump up the object’s inclination, pushing it away from the plane of the solar system. “There is no other reasonable way to populate the Kuiper belt with such highly inclined bodies,” Batygin said. “I think the case for the existence of Planet Nine is now genuinely excellent.”

"Other astronomers aren’t so certain — in part because the early solar system remains a mystery. Scientists suspect that the sun was born within a cluster of stars, meaning that the early planets might have had many close encounters with other stars that sent them on paths that seem impossible today. And even once the stars dispersed, the early solar system likely contained tens of thousands of dwarf planets that could have provided the gravitational nudges needed to push 2015 BP519, as the new object is called, into such an odd orbit. “To me, Planet Nine is one of a number of ways that the solar system could have unfolded,” said Michele Bannister, an astronomer at Queen’s University Belfast who was not involved in the study. “It’s a potential idea.” But at the moment it is just that — an idea.

"Yet when astronomers examine the larger universe, the idea doesn’t seem all that surprising. Planets between two and 10 times the mass of Earth are incredibly common throughout the galaxy, which makes it odd that our solar system doesn’t harbor one. “If it wasn’t in our own solar system — if the stakes weren’t so high — I think that the hypothesis would almost certainly be correct,” Laughlin said. “It’s only the fact that it’s so amazing that tends to give me pause.'”

Comment: This increases the possibility for planet nine. Good theories are predictive of confirmatory results.

https://www.space.com/39390-alien-planets-reveal-our-strange-solar-system.html

"Our solar system may be an oddball in the universe. A new study using data from NASA's Kepler Space Telescope shows that in most cases, exoplanets orbiting the same star have similar sizes and regular spacing between their orbits.

"By contrast, our own solar system has a range of planetary sizes and distances between neighbors. The smallest planet, Mercury, is about one-third the size of Earth — and the biggest planet, Jupiter, is roughly 11 times the diameter of Earth. There also are very different spacings between individual planets, particularly the inner planets.

"This means our solar system may have formed differently than other solar systems did, the research team suggested, although more observations are needed to learn what the different mechanisms were.

"The planets in a system tend to be the same size and regularly spaced, like peas in a pod. These patterns would not occur if the planet sizes or spacings were drawn at random," Lauren Weiss, the study's lead author.

***

"After running a statistical analysis, the team found that a system with a small planet would tend to have other small planets nearby — and vice-versa, with big planets tending to have big neighbors. These extrasolar systems also had regular orbital spacing between the planets.

"'The similar sizes and orbital spacing of planets have implications for how most planetary systems form," researchers said in the statement. "In classic planet-formation theory, planets form in the protoplanetary disk that surrounds a newly formed star. The planets might form in compact configurations with similar sizes and a regular orbital spacing, in a manner similar to the newly observed pattern in exoplanetary systems."

"In our own solar system, however, the story is very different. The four terrestrial planets (Mercury, Venus, Earth and Mars) are very widely spaced apart. The team pointed to evidence from other research that Jupiter and Saturn may have disrupted the structure of the young solar system. While the statement did not specify how, several other research studies have examined the movements of these giant planets and their potential impact on the solar system.

***

"'Regardless of their outer populations, the similarity of planets in the inner regions of extrasolar systems requires an explanation," researchers said in the statement. "If the deciding factor for planet sizes can be identified, it might help determine which stars are likely to have terrestrial planets that are suitable for life.'"

Comment: More evidence that our solar system is very special. It is obvious that it is specially made to provide for an Earth that can easily produce and maintain life.

https://www.sciencedaily.com/releases/2018/01/180109141918.htm

"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. 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.

***

"In this new analysis led by Weiss and published in The Astronomical Journal, the team focused on 909 planets belonging to 355 multi-planet systems. These planets are mostly located between 1,000 and 4,000 light-years away from Earth. Using a statistical analysis, the team found two surprising patterns. They found that exoplanets tend to be the same sizes as their neighbors. If one planet is small, the next planet around that same star is very likely to be small as well, and if one planet is big, the next is likely to be big. They also found that planets orbiting the same star tend to have a regular orbital spacing.

"'The planets in a system tend to be the same size and regularly spaced, like peas in a pod. These patterns would not occur if the planet sizes or spacings were drawn at random." explains Weiss.

"The similar sizes and orbital spacing of planets have implications for how most planetary systems form. In classic planet formation theory, planets form in the protoplanetary disk that surrounds a newly formed star. The planets might form in compact configurations with similar sizes and a regular orbital spacing, in a manner similar to the newly observed pattern in exoplanetary systems. However, in our solar system, the inner planets have surprisingly large spacing and diverse sizes. Abundant evidence in the solar system suggests that Jupiter and Saturn disrupted our system's early structure, resulting in the four widely-spaced terrestrial planets we have today. That planets in most systems are still similarly sized and regularly spaced suggests that perhaps they have been mostly undisturbed since their formation.

"To test that hypothesis, Weiss is conducting a new study at the Keck Observatory to search for Jupiter analogs around Kepler's multi-planet systems. The planetary systems studied by Weiss and her team have multiple planets quite close to their star. Because of the limited duration of the Kepler Mission, little is known about what kind of planets, if any, exist at larger orbital distances around these systems. They hope to test how the presence or absence of Jupiter-like planets at large orbital distances relate to patterns in the inner planetary systems.

"Regardless of their outer populations, the similarity of planets in the inner regions of extrasolar systems requires an explanation. If the deciding factor for planet sizes can be identified, it might help determine which stars are likely to have terrestrial planets that are suitable for life."

Comment: My explanation of our different solar system is it was purposely designed for life, just as the universe is designed to allow life.

https://cosmosmagazine.com/space/new-evidence-for-the-mysterious-planet-nine

"The existence of this planet, colloquially known as Planet Nine, has been suspected for several years due to the tilted orbits of these objects, which suggests that they have gravitationally interacted with a planet the size of Neptune several hundred times further out from the Sun than the Earth.

"The bodies in these tilted orbits are a population of large Trans-Neptunian Objects (TNOs), which lie on extremely elliptical orbits out beyond Neptune and Pluto. One of the best known is Sedna, a 1000-kilometre world discovered in 2003.

"But the new work suggests that Planet Nine may also exert a stabilising influence on these bodies, keeping them from being ejected from the solar system by interactions with Neptune, whose orbit they sometimes approach.

"Sedna itself is in a stable orbit, says Juliette Becker, a doctoral student at the University of Michigan, Ann Arbor, but others are on orbits so easily affected by Neptune that they should have been knocked out of orbit (and potentially been thrown into the Sun, collided with another planet, or been kicked entirely out of the Solar System) in as little as 10 million years. And yet, 4.5 billion years after the birth of the Solar System, they are still here for us to see.

"It’s a mystery, she says, until you add Planet Nine into the equation. Then, interactions with Planet Nine dampen the effect of Neptune’s occasional gravitational kicks. “Instead of getting kicked out of the Solar System it hops to a new orbit,” she said at a meeting of the American Astronomical Society’s Division for Planetary Sciences in Provo, Utah, on 7 October. “Planet Nine enhances the dynamic stability of these objects.”

"Furthermore, she says, not all orbits for Planet Nine will have this stabilising effect.
And since it is also known that Planet Nine must be in an orbit that tilts these same TNO orbits, the two effects – tilting orbits and stabilising them – can be used to further narrow the parts of the sky astronomers need to search for the elusive planet.

"Further assisting the quest, Becker announced that astronomers reviewing images from a sky-watch known as the Dark Energy Survey have found a ninth TNO similar to the eight others. Nicknamed Caju (the Portuguese word for “cashew”) it lies in a highly eccentric orbit that averages about 450 times farther out than the Earth. Based on its brightness, it is probably on the order of 480 kilometres across, Becker added – though she noted that this is just an estimate.

"The new finds are exciting because they will help astronomers find Planet Nine, if indeed it exists, adds Mike Brown, a planetary scientist from California Institute of Technology in Pasadena, California, who was not part of the study team."

Comment: The evidence piles up.

https://www.sciencedaily.com/releases/2017/10/171004144511.htm

"'There are now five different lines of observational evidence pointing to the existence of Planet Nine," said Konstantin Batygin, a planetary astrophysicist at Caltech in Pasadena, California, whose team may be closing in. "If you were to remove this explanation and imagine Planet Nine does not exist, then you generate more problems than you solve. All of a sudden, you have five different puzzles, and you must come up with five different theories to explain them."

***

"Six known objects in the distant Kuiper Belt, a region of icy bodies stretching from Neptune outward toward interstellar space, all have elliptical orbits pointing in the same direction. That would be unlikely -- and suspicious -- enough. But these orbits also are tilted the same way, about 30 degrees "downward" compared to the pancake-like plane within which the planets orbit the sun.

"Breadcrumb number three: Computer simulations of the solar system with Planet Nine included show there should be more objects tilted with respect to the solar plane. In fact, the tilt would be on the order of 90 degrees, as if the plane of the solar system and these objects formed an "X" when viewed edge-on. Sure enough, Brown realized that five such objects already known to astronomers fill the bill.

"Two more clues emerged after the original paper. A second article from the team, this time led by Batygin's graduate student, Elizabeth Bailey, showed that Planet Nine could have tilted the planets of our solar system during the last 4.5 billion years. This could explain a longstanding mystery: Why is the plane in which the planets orbit tilted about 6 degrees compared to the sun's equator?

"'Over long periods of time, Planet Nine will make the entire solar-system plane precess or wobble, just like a top on a table," Batygin said.

"The last telltale sign of Planet Nine's presence involves the solar system's contrarians: objects from the Kuiper Belt that orbit in the opposite direction from everything else in the solar system. Planet Nine's orbital influence would explain why these bodies from the distant Kuiper Belt end up "polluting" the inner Kuiper Belt.

"'No other model can explain the weirdness of these high-inclination orbits," Batygin said. "It turns out that Planet Nine provides a natural avenue for their generation. These things have been twisted out of the solar system plane with help from Planet Nine and then scattered inward by Neptune."

***

"Other scientists offer a different possible explanation for the Planet Nine evidence cited by Batygin. A recent analysis based on a sky mapping project called the Outer Solar System Origins Survey, which discovered more than 800 new "trans-Neptunian objects," suggests that the evidence also could be consistent with a random distribution of such objects. Still, the analysis, from a team led by Cory Shankman of the University of Victoria, could not rule out Planet Nine."

Comment: Neptune was found by analyzing gravitational influences. This is the same method.

https://www.newscientist.com/article/mg23531324-100-planets-in-other-star-systems-fit-a...

"EXOPLANETARY systems are like peas in a pod, whatever type of star the planets orbit. This challenges our ideas about how such systems form.

"A team led by Lauren Weiss at the University of Montreal in Canada has looked at 909 planets discovered by the Kepler space telescope in 355 systems. All planets in a given system seem to be close in size and similarly spaced in their orbits when compared with planets in other systems. “We see this pattern happening again and again,” says Weiss – regardless of what kind of star these planets are orbiting.

"That’s not what we’d expect, given how we think star systems are born: that stars form from a cloud of gas and dust, pulling it into a thick disc as they rotate. Denser clusters of gas and dust within the disc condense into planets, suggesting there should be a link between planets and their star.

"The team thinks something other than stellar mass must influence how protoplanetary discs give rise to planets, such as the total mass of the disc, the solid mass within the disc or what happens to the disc after a planet’s initial formation.

“'There’s probably something related to the physics of the disc that the planets are forming in that is determining how big the planets grow and how far apart from each other they end up,” says Weiss. “But this idea has yet to be tested.”

"It’s also possible that these patterns are just a fluke created by our limited data. Kepler can only find planets with short orbital periods – those that crossed in front of their star during the four years of the spacecraft’s mission. That’s like only looking at Mercury, Venus, Earth and Mars in our own system.

"So can we really build theories on Kepler’s limited observations? “That’s the question that keeps me and many other people up at night!” says Weiss."

Comment: It is possible our system is unique in order to have life on Earth, but the thought that the Keppler system cannot see systems like ours must be considered.

https://cosmosmagazine.com/space/jupiter-is-the-most-ancient-planet-in-the-solar-system

"Jupiter is the oldest planet in the solar system, according to research published in the journal Proceedings of the National Academy of Sciences (PNAS).

"Scientists led by Thomas S. Kruijer of the University of Münster, in Germany, measured concentrations of molybdenum and tungsten isotopes derived from iron meteorites to model the age of the system’s largest planet.

"There are two distinct groups of iron meteorites, the researchers suggest, which arose separately within the nebula cloud from which the solar system eventually coalesced. They represent, they write, “two genetically distinct nebular reservoirs that coexisted and remained spatially separated” during the first few million years of the solar system’s formation.

"The most plausible explanation for their separation, Kruijer and colleagues suggest, is the formation of Jupiter in between them.

"Jupiter is a type of planet known as a gas giant. Its likely formation involved first the accretion of a solid core, followed by the accumulation of thick layers of gases surrounding it.

"Kruijer’s team calculates that the process began very soon after the birth of the solar system, which occurred when part of a giant molecular cloud condensed under the force of its own gravity around 4.6 billion years ago.

"According to the modeling, Jupiter’s inner core grew to the equivalent of about 20 times the mass of the Earth within the first million years. The Sun was still a protostar at this stage, not having become dense enough for hydrogen fusion to begin.

"The growth rate then slowed down, but continued, reaching about 50 times the mass of earth three million years later.

"Thus, Jupiter is the oldest planet of the solar system, and its solid core formed well before the solar nebula gas dissipated,” the team writes.

"Fixing a date for the formation of the largest planet, the scientists conclude, will allow for better analysis of how its presence affected the dynamics of the young solar system.

"Its early development, they suggest, would have heavily influenced the movement of matter, “potentially explaining why our Solar System lacks any super-Earths”."

Comment: Our solar system is most unusual compared to the ones found so far. I feel God evolved it to provide a safe place for life to start. Our galaxy sits in a big void in the universe, which partly protects us from all the dangers the universe presents. Fine tuning.

https://thespacereporter.com/2017/06/scientists-say-milky-way-lives-huge-void/

http://phys.org/news/2016-10-curious-tilt-sun-undiscovered-planet.html

"Planet Nine—the undiscovered planet at the edge of the Solar System that was predicted by the work of Caltech's Konstantin Batygin and Mike Brown in January 2016—appears to be responsible for the unusual tilt of the sun, according to a new study.

"The large and distant planet may be adding a wobble to the solar system, giving the appearance that the sun is tilted slightly.

"'Because Planet Nine is so massive and has an orbit tilted compared to the other planets, the solar system has no choice but to slowly twist out of alignment," says Elizabeth Bailey, a graduate student at Caltech and lead author of a study announcing the discovery.

"All of the planets orbit in a flat plane with respect to the sun, roughly within a couple degrees of each other. That plane, however, rotates at a six-degree tilt with respect to the sun—giving the appearance that the sun itself is cocked off at an angle. Until now, no one had found a compelling explanation to produce such an effect. "

"The tilt of the solar system's orbital plane has long befuddled astronomers because of the way the planets formed: as a spinning cloud slowly collapsing first into a disk and then into objects orbiting a central star.

"Planet Nine's angular momentum is having an outsized impact on the solar system based on its location and size. A planet's angular momentum equals the mass of an object multiplied by its distance from the sun, and corresponds with the force that the planet exerts on the overall system's spin. Because the other planets in the solar system all exist along a flat plane, their angular momentum works to keep the whole disk spinning smoothly.

"Planet Nine's unusual orbit, however, adds a multi-billion-year wobble to that system. Mathematically, given the hypothesized size and distance of Planet Nine, a six-degree tilt fits perfectly, Brown says.

Comment: Planet nine evidence becomes stronger and stronger.