Nicknamed "FarFarOut", the 2018 AG37 is the farthest known object from the sun in the solar system. It is a trans-Neptunian object, meaning it is a planet or dwarf planet further away than Neptune. It was discovered in January 2018 during a search for the hypothetical 'Planet Nine' but was not confirmed until February 2021 in a press release given by astronomers Scott Sheppard, David Tholen, and Chad Trujillo. The choice of nickname emphasises its distance from the sun, which is around 19 billion km (11.8 billion miles). Until the 2018 AG37's discovery, the first object was the 2018 VG18, which was nicknamed "Farout".

The 2018 AG37 was first spotted on 15th January 2018 using the large 8.2-meter Subaru Telescope at Mauna Kea Observatory in Hawaii. The object was reobserved in March 2019 with the 6.5-meter Magellan-Baade telescope at Las Campanas Observatory in Chile. A third and fourth observation was made in May 2019 and January 2020 with the Subaru Telescope. As of 2021, it has been observed nine times.

Based on the 2018 AG37's visibility, it is listed as the 12th intrinsically brightest known scattered disc object in the solar system. Due to its distance, it has not been measured, but scientists estimate its diameter to be between 400 and 600 km (250-370 miles). Scott Sheppard concludes the object must have a highly reflective and ice-rich surface to be seen from telescopes on Earth.

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