We thought we had a pretty good idea of the solar system. There were nine planets, and Pluto was a little strange, but it was undoubtedly a planet. Then we discovered more Pluto-like "trans-Neptunian objects" (TNO), and scientists began to overestimate what it means to be a planet. Pluto was lowered, and astronomers focused on the outer directions of the solar system, looking for distant, cold planetoids. Just last year, astronomers from the Carnegie Institute for Science still noticed the outermost dwarf plan called FarOut. Now FarOut can move – FarFarOut is even further.
The first image of FarFarOut comes from Scott Sheppard, a Carnegie Institution astronomer who also saw FarOut last year. FarOut was already quite far from 120 AU (1 AU or astronomical unit is the distance between Earth and Sun), which is almost 20 light hours. FarFarOut's initial observations indicate that it is about 140 AU. Pluto is only 34 AU, and the most distant dwarf planet known as Eris is 96 AU.
Sheppard announced the release of FarFarOut during a lecture last week. The original frame featuring FarFarOut comes from the 8-meter Telescope Subaru in Hawaii, Mauna Kea, which is only powerful enough to be discovered. Based on distance and brightness, Sheppard estimates that the object is a dwarf planet with a diameter of about 400 kilometers.
For several months or years, it will make further observations to determine the exact orbit of FarFarOut. It's so far, one sun year for the shrub planet is over 1000 Earth years. We don't know how it looks – it's technically the top of FarOut's display, but it doesn't matter, because we just guess it. Several researchers will have to confirm the findings before we can even be sure that FarFarOut really is. Only then can we name it – it doesn't even have a small planet yet.
The Carnegie Institution team really surpasses these dwarf planet discoveries, but that's not why it scans the edge of the solar system. Sheppard and colleagues are looking for a larger planet in the outer solar system. This theoretical "Planet Nine" could explain some of the orbital odors seen in TNO. It is also possible that there are no nine on the planet, and the clustering of TNO orbits is simply the result of the cumulative gravity of several objects such as FarFarOut. In any case, the discovery of the dwarf planets is still quite impressive.