By
This illustration shows you what the distant object nicknamed “Farfarout” might look like in the outer parts of our solar system. The farthest object ever discovered in our solar system, Farfarout, is 132 astronomical units from the Sun, which is 132 times farther from the Sun than Earth is. Estimated at about 400 kilometers (250 miles), Farfarout is shown at the bottom right, while the sun appears at the top left. The galaxy stretches diagonally across the background. Credit: NOIRLab / NSF / AURA / J. da Silva
Gemini North helps determine the distance and trajectory of the remote object.
Using the International Gemini Observatory, a program from NSF’s NOIRLab, and other telescopes on the ground, astronomers have confirmed that a faint object discovered in 2018 and nicknamed “Farfarout” is indeed the farthest object. which is still found in our solar system. The object has just been named the International Astronomical Union.
Farfarout was first spotted in January 2018 by the Subaru Telescope, located at Maunakea in Hawaii. The discoverers of it could see that it was very far, but they were not sure exactly how far. They needed more observations.
“At the time, we did not know the orbit of the object, as we only had the Subaru discovery observations over 24 hours, but it takes years of observations to find an orbit around the sun,” explains co-discoverer Scott Sheppard of the Carnegie Institution for Science. “All we knew was that the object was very far away at the time of discovery.”
This illustration depicts the farthest object still found in our solar system, nicknamed “Farfarout”, bottom right. At the bottom left, a graph shows the distances of the planets, dwarf planets, candidate dwarf planets and Farfarout from the sun in astronomical units (au). One au is equal to the earth’s average distance from the sun. Farfarout is 132 au from the sun. Credit: NOIRLab / NSF / AURA / J. da Silva
Sheppard and his colleagues, David Tholen of the University of Hawai’i and Chad Trujillo of the University of Northern Arizona, spent the next few years using the Gemini North Telescope (also at Maunakea in Hawaii) and the Carnegie Institution for Science Magellan telescopes in Chile to determine its orbit.[1] They have now confirmed that Farfarout currently lies 132 astronomical units (au) of the sun, which is 132 times farther from the sun than the earth is. (For comparison: Pluto is averaging 39 au from the sun.)
Farfarout is even more remote than the previous record holder of the solar system, which was discovered by the same team and nicknamed ‘Farout’. Preliminarily designated as VG18 2018, Farout is 124 au from the Sun.
This illustration depicts the farthest object still found in our solar system, nicknamed “Farfarout”, bottom right. Along the bottom, different solar system objects are drawn according to their distance from the sun, with the planets and the nearest dwarf planet (Ceres) appearing on the far left, and the farthest objects of the known solar system, including Farfarout, on the far right. Their distances are given in astronomical units (au), with 1 au equal to the earth’s average distance from the sun. Credit: NOIRLab / NSF / AURA / J. da Silva
The orbit of Farfarout, however, is quite elongated, taking it 175 au from the sun at its farthest point and about 27 au at its nearest, which is within the orbit of Neptune. Because its orbit crosses Neptune, Farfarout can provide insights into the history of the outer solar system.
“Farfarout was probably thrown into the outer solar system by getting too close to Neptune in the distant past,” Trujillo said. “Farfarout will probably interact with Neptune again in the future, because their orbit is still crossing.”
This discovery image of Farfarout (2018 AG37) was taken with the Subaru Telescope on the night of January 15, 2018, Universal Time (UT). By comparing this image with one taken the next night, it is possible to see that Farfarout (marked by blue horizontal lines) is moving while the background stars and galaxies are not moving. Credit: S. Sheppard
Farfarout is very faint. Based on its brightness and distance from the sun, the team estimates that it is about 400 kilometers (250 miles) wide, which puts it at the bottom of the list by the International Astronomical Union (IAU) as a dwarf planet.
The IAU’s Minor Planet Center in Massachusetts announced today that it has given Farfarout the provisional designation 2018 AG37. The most famous member of the Solar System will receive an official name after more observations have been collected and the orbit will be further refined in the coming years.
This discovery image of Farfarout (AG37 2018) was taken with the Subaru Telescope on the night of January 16, 2018, Universal Time (UT). By comparing this image with one taken the previous night, it is possible to see that Farfarout (marked by blue horizontal lines) is moving while the background stars and galaxies are not moving. Credit: S. Sheppard
“Farfarout takes a millennium to go around the sun once,” Tholen said. “As a result, it moves very slowly across the sky, requiring several years of observation to accurately determine its trajectory.”
Farfarout’s discoverers are confident that still distant objects will have to be discovered on the outskirts of the solar system, and that the distance record may not last long.
“The discovery of Farfarout shows our increasing ability to map the outer solar system and observe it further and further to the edge of our solar system,” Sheppard said. ‘Only with the progress in the last few years of large digital cameras on very large telescopes, it is possible to discover objects like Farfarout effectively. Although some of these distant objects are quite large – the size of dwarf planets – they are very faint due to their extreme distance from the sun. Farfarout is just the tip of the iceberg of objects in the very distant Solar System. ”
Notes
- The Farfarout Gemini North observations were made on 1 May and 2 May 2019 Universal Time, using Director’s Discretionary Time.
Read “Farfarout” – Astronomers confirm the solar system’s farthest planetoid for more information on this research.