Voyager I may have reached the boundaries of our solar system. But it may yet encounter a heretofore unknown member of our planetary group, originally known as “Planet X.”
Voyager I is now sending signals to Earth from beyond the orbits of Neptune and the dwarf planet Pluto, The media has published estimates of its current position as ranging from 9 to 11 billion miles from the sun.
Voyager I was launched in 1977 to explore the outer solar system. Its main mission was to study the planetary systems of Jupiter and Saturn. Voyager II was launched by NASA about two weeks before Voyager I, but Voyager I moved faster and eventually passed it. After Voyager II made a flyby of Neptune, NASA extended the missions of the two probes to study the outer boundaries of the solar system and beyond.
There is a debate currently going on as to whether Voyager I has passed outside our solar system. Three new papers about the spacecraft were recently published online by the journal Science.
One issue is whether the ship has passed beyond the influence of the sun’s magnetic field and is now subject to the interstellar magnetic field.
Another issue is whether or not the ship has reached the heliosphere and heliosheath.
The heliosphere is a bubble of charged particles in the space surrounding the solar system and marking its outer boundaries. The heliosphere is created by solar wind, a stream of charged particles released from the upper atmosphere of the Sun. These particles can escape the Sun’s gravity because of their high kinetic energy and the high temperature of the sun’s corona. The heliosphere’s outer structure is determined by the interactions between the solar wind and the winds of interstellar space
The heliosheath is the region of the heliosphere in which the solar wind is slowed, compressed and jostled by its interaction with the interstellar medium. At the heliosheath depletion region, particles can escape from the solar system, and cosmic ray particles on the outside can slip inside.
According to NovaNext, in order to determine whether Voyager has left the solar system, scientists must measure the decrease in highly energetic charged particles from inside our heliosphere, the increase in charged particles from outside it, and the change in the strength and direction of the magnetic fields within and without.
But even as Voyager approaches the limits of the solar system, it may encounter another member of our solar family, once known as “Planet-X.”
In 2012, Rodney Gomes, an astronomer from the National Observatory of Brazil in Rio de Janeiro, announced at a meeting of the American Astronomical Society the results of his simulation of a region beyond Pluto known as the “scattered disk.” The simulation suggests the presence of an undiscovered world.
The scattered disk is a region that overlaps with the Kuiper belt, but has a much wider reach. The Kuiper belt extends from the orbit of Neptune, 30 astronomical units, or AU, to 50 AU from the Sun. It is similar to the asteroid belt between Mars and Jupiter but is 20 times as wide. The belt is home to at least three dwarf planets: Pluto, Haumea, and Makemake. Some of the Solar System’s moons, including Neptune’s Triton and Saturn’s Phoebe, are also believed to have originated in the region.
Both the scattered disk region and the Kuiper belt consist of small bodies, remnants from the Solar System’s formation, which are composed of rock and metal. The areas of space also contain frozen volatiles (termed “ices”). Volatiles are a group of chemical elements and chemical compounds that are associated with the crust or atmosphere of planets and moons. Examples of volatiles are nitrogen, water, carbon dioxide, ammonia, hydrogen and methane. Volatiles often comprise large portions of moons and dwarf planets.
The region of scattered disk objects is more sparsely populated than that of the Kuiper Belt. Scattered disk objects have orbits as extreme as 100 AU. One such scatted disk is Sedna, a dwarf planet with a highly elongated orbit. The peculiarities of these orbits suggest the presence of another world beyond Pluto that is four times the size of Earth.
In the late 19th century, Neptune was discovered by studying the perturbations in the orbit of Uranus. But scientists believed that there was another massive planet in the outer solar system causing additional disturbances to Uranus. By 1906, Percival Lowell, the founder of the Lowell Observatory in Flagstaff, Arizona, began a search for what he dubbed “Planet X.” When Pluto was discovered in 1930, the search for Planet X seemed to come to an end.
NASA has acknowledged the possible existence of Planet X, a “mystery object” far beyond the outermost planets. The search for it may resume because of the ramifications of the scattered disk region.
And Voyager I may encounter Planet X before it reaches interstellar space.
By: Tom Ukinski