In the perpetual twilight of our Solar System's outer limits, our Sun shines with merely a feeble, distant fire, and appears to be only an especially large star, swimming in a sea of countless other silvery, sparkling stellar lights. When our Solar System was first forming, about 4.6 billion years ago, strange things were occurring. Newborn planetary building blocks – called planetesimals –migrated from where they originated, and blasted into one another, sometimes merging, but sometimes crashing together catastrophically – shattering one another into fragments. The ice-giant, beautiful, big, banded blue Neptune – the most distant of the eight major planets from our Sun – is known to have exerted an influence on our baby Solar System, as it wandered through this primordial "cosmic shooting gallery . " In April 2017, astronomers announced that they had made a major discovery concerning the mysterious birth and evolution of icy bodies in our Solar System's remote, frozen Kuiper Belt– the home of a myriad of dancing comet nuclei beyond the orbit of Neptune. The astronomers said that they had unlocked unique evidence that Neptune's migration during the era of ancient planet formation, in our young Sun's domain, was a "smooth and calm" journey – and not the rampage of a fierce giant, as had been previously suggested in other studies.
"It's a kinder, gentler Neptune," commented astronomer Meg Schwamb in an April 4, 2017 Gemini Observatory Press Release. Dr. Schwamb continued to explain that the new result leaves little doubt that Neptune's migration through the primeval Solar System was a benevolent and gentle sweep – rather than the violent and catastrophic rampage of a big bully.
The study focused on strange "oddball" duos of loosely bound objects, called planetoids, inhabiting the deep freeze of the dimly lit outer regions of our Solar System. The astronomers propose, in a paper published in the April 4, 2017 issue of the journal Nature Astronomy , that these loosely bound objects were probably shepherded by Neptune's gentle gravitational pushes into their current orbits in the dark and distant Kuiper Belt.
The research team, led by Dr. Wes Frazier of Queen's University in Belfast, UK, studied data obtained from the Gemini North Frederick C. Gillett Telescope and Canada-France-Hawaii Telescope (CFHT). Both telescopes are poised upon the dormant Mauna Kea volcano in Hawaii. The team measured the colors of "oddball" new Cold Classical Kuiper Belt Object (CCKBO) duos as part of the Colors of the Outer Solar System Origins Survey (CoL-OSSOS).
The "oddball" objects are members of a class of mysterious bodies called "blue binaries" , which are intriguing sibling pairs, doing a distant dance in the outer limits. Blue binaries are "odd" because, like other nonconformists, they travel to the beat of a different drum than their neighbors. This is because blue binaries do not display the distinctive red color that characterizes the surfaces of most CCKBOs.
The remote Kuiper Belt is the frozen home of a dancing swarm of icy small planetoids –well beyond the orbit of beautiful, blue Neptune. The planetoids are comet nuclei – the lingering relics of the building blocks (planetesimals) of the quartet of giant, gaseous planets inhabiting the outer Solar System: Jupiter, Saturn, Uranus, and Neptune. Indeed, this distant belt hosts over 1,700 known icy objects.
Many planetary scientists have long suggested that the frozen, left-over planetoids were born in the very heart of the Kuiper Belt. However, Dr. Fraser's new study indicates something else – that the blue binaries actually were born in a region situated much closer to the warmth and heat of our Star, and were then shepherded by Neptune's gravitational nudges into the distant orbits that we see today. This strange migration would have occurred several billions of years ago.
Dancing In The Dark
Distant, dark, and cold, the icy denizens of the Kuiper Belt do their alien ballet in our Solar System's distant suburbs. Here, the ice dwarf planet Pluto and its quintet of moons dwell along with a multitude of others of their weird and frigid kind. This remote domain is so far from Earth that astronomers are only now first beginning to explore it, thanks to the historic voyage to the Pluto system by NASA's New Horizons spacecraft , that arrived there on July 14, 2015. New Horizons is now speedily en route to yet another denizen of the deep freeze, and will discover more and more of the as-yet-unanswered mysteries belonging to this dimly lit domain of frozen small worlds.
Therefore, poor Pluto is just one of a large number of similar icy objects in the Kuiper Belt. Discovered in 1930 by the American astronomer Clyde Tombaugh (1906-1997), Pluto was initially classified as the ninth major planet from our Sun. Alas, for little Pluto, astronomers eventually came to the realization that Pluto is just one of many– very many. For this reason, the International Astronomical Union (IAU) , was forced to define the term "planet" and, as a result, Pluto was demoted from major planet status to dwarf planet status.
When comets come screeching from our Solar System's outer limits, into the inner Solar System's warm, welcoming, melting heat, they make dramatic spectacles of themselves with brilliant tails thrashing – as they flash their mysterious light through the sky. These frozen migrating, alien bodies hold captive – in their icy hearts – the most pristine of primordial ingredients that, long ago, went into the construction of our Sun's family of objects. This very ancient mixture, of the purest material, has been preserved in the deep-freeze of our Solar System's dark, distant, and very cold outer regions. These frozen, alien, and fragile visitors from far away fly into the inner Solar System, where our Earth is located, from their mysterious, murky home beyond Neptune. Because comets hold, in their frozen hearts, the well-preserved ancient elements that made our Solar System, many astronomers think that by identifying these ingredients, they can determine how our Sun and its family came to be.
Comets are similar to the rampaging, relic icy planetesimals that merged together in the ancient Solar System to form the four outer gas giants. Alternatively, the asteroids –that primarily inhabit the Main Asteroid Belt between Mars and Jupiter – are similar to the rocky and metallic planetesimals that bumped into one another and merged to form the quartet of small, inner, rocky planets: Mercury, Venus, Earth, and Mars. Planetesimals– both icy and rocky – blasted into one another in the "shooting gallery" that characterized our baby Solar System. These ancient colliding objects merged to create ever larger and larger bodies.
Many astronomers believe that the "oddball" blue binaries migrated from their birthplace – closer to our Sun's warmth and light – out into the frigid twilight of the distant Kuiper Belt. It is generally proposed that this migration occurred several billion years ago, at a time when profound changes were occurring in the orbits of the quartet of outer, gaseous, giant planets.
"The red CCKBOs are thought to have formed at the location in the outer Solar System where they are currently reside. The blue binaries , on the other hand, are interlopers from closer in hiding out in the Kuiper Belt today," Dr. Schwamb, a coauthor on the study, explained in the April 4, 2017, Gemini Observatory Press Release.
Neptune: Our Solar System's Gentle Giant
Dr. Fraser's study suggests that when Neptune migrated from 20 AU to its present location, at 30 AU, it did so with a gentle, slow, peacefulness – a dignified calm voyage, unlike the invading rampage of a violent bully. One AU (astronomical unit) is equivalent to Earth's average distance from our Sun, which is 93,000,000 miles. This gentle march of the beautiful, blue, and banded ice giant planet, allowed the delicate, fragile, and loosely bound blue binaries to be tenderly nudged out to a similar distance, where they are observed today. This smooth and peaceful migration enabled the blue binaries to make their long journey, into the outer limits, without being torn apart into two separate single objects.
"This research has opened the window to new aspects of understanding the early stages of planet growth. We now have a solid handle on how and where these blue binaries originated," Fraser explained in an April 4, 2017 Queen's University Press Release.
"There has been some evidence around how Neptune moved outwards to 30 AU. Our hypothesis about how these blue binaries came to be where they are requires that Neptune's migration was largely a smooth and calm movement," he added.
Dr. Schwamb also explained in the Queen's University Press Release that "This novel program uses two world-class telescopes: the Gemini-North and Canada-France-Hawaii telescopes, simultaneously. In doing so, we are able to gather comprehensive spectral information spanning the ultra -violet, optical, and near-infrared wavelength ranges. Without this program and the partners involved, this major research breakthrough would not have been possible. "
"Working closely together, Gemini North and the Canada-France-Hawaii telescopes coordinated their movements to observe the Col-OSSOS Kuiper Belt Objects at nearly the same time," Dr. Schwamb added.
The simultaneous observations on Mauna Kea enabled the team of astronomers to measure the light emanating from the same side of the Kuiper Belt Object. This eliminated one of the most perplexing difficulties in studying Solar System bodies that rotate.
Dr. Todd Burdullis, QSO operations specialist at CFHT , who helped to co-ordinate the observations, commented in the April 4, 2017 Queen's University Press Release that "Facilitating the simultaneous observations with the Col-OSSOS team and Gemini Observatory was challenging, but paved the way for a greater understanding of the origins of these blue binaries. In tandem, the two facilities observed all the colors of the outer Solar System for the Col-OSSOS team.