All they can see is a pinkish dot of light in the night sky, but that is enough to infer that they are looking at a 300-mile ice ball orbiting more than 11 billion miles from the sun - more than three times as far out as Pluto, and the farthest object ever observed within the solar system.
A frosty world is lurking across a distant part of our solar system, and astronomers believe that there is a yet-unseen Planet X out there that shepherds dwarf planets thousands of billions of kilometres away from Earth. One AU is equivalent to the space between Earth and the sun.
Pluto is now at about 34 AU, making 2018 VG18 more than three-and-a-half times more distant than the solar system'smost-famous dwarf planet.
The Carnegie Institution's Scott Sheppard said the object - designated 2018 VG18 - is so far away and moving so slowly it will take a few years to determine its orbit.
"2018 VG18 is the first object found beyond 100 AU in our Solar System", Sheppard told Gizmodo.
One of the challenges of identifying distant solar system objects like Farout is correctly mapping the paths of their orbits.
Planet X's existence has been inferred because of a pattern of eccentricities seen in the orbits of other objects on the solar system's edge.
Candanosa and Scott S. Sheppard Carnegie Institution for Science
The existence of Planet X was first proposed by this same research team in 2014 when they discovered 2012 VP113, nicknamed Biden, which is now near 84 AU away.
"The orbital similarities shown by numerous known small, distant Solar System bodies was the catalyst for our original assertion that there is a distant, massive planet at several hundred AU (Astronomic Units - the distance between Earth and the Sun) shepherding these smaller objects", said Sheppard.
"I said 'far out!' when I discovered it, and it's a very far out object", said astronomer Scott Shepard from the Carnegie Institution for Science, as quoted by New Scientist. - Scott Sheppard, Carnegie Science Institute.
All that's known about Farout, at the moment, is its distance (120 AU), its size (around 500km across), and its colour (pink!).
"This discovery is truly an worldwide achievement in research using telescopes located in Hawaii and Chile, operated by Japan, as well as by a consortium of research institutions and universities in the United States", concluded Trujillo. In their paper, the two astronomers say that the orbits of these distant dwarf planets are clustered in such a way that it can't be an accident. "With new wide-field digital cameras on some of the world's largest telescopes, we are finally exploring our Solar System's fringes, far beyond Pluto". It took NASA's New Horizons spacecraft nine years to get to Pluto, and Farout is about 3.5 times farther away than Pluto, so it would take about 31 years for a spacecraft to reach Farout. This undiscovered planet is called a super-Neptune.
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