(674118) 2015 KH162

Lore & Background

2015 KH162 was first observed on 18 May 2015, in the constellation of Serpens by astronomers at the Mauna Kea Observatories using the Subaru Telescope. The discovery was announced by Scott Sheppard, David Tholen and Chad Trujillo on 23 February 2016. At the time, this minor planet was at a distance of 59.0 AU from the Sun and had a relatively bright magnitude of 21.4 for its enormous distance.

The object orbits the Sun at a distance of 41.5–82.1 AU once every 486 years (177,517 days; semi-major axis of 61.82 AU). Its orbit has an eccentricity of 0.33 and an inclination of 29° with respect to the ecliptic. It is classified as a scattered disc object, or "near-scattered" object in the classification of the Deep Ecliptic Survey, that still gravitationally interacts with Neptune (30.1 AU) due to its relatively low perihelion of 41.5 AU, contrary to the extended-scattered/detached objects and sednoids.

Based on a generic magnitude-to-diameter conversion, 2015 KH162 measures approximately 566 kilometers (350 miles) in diameter, for an assumed albedo of 0.124 and a magnitude of 4.1. As of 2021, no rotational lightcurve for this object has been obtained from photometric observations. The body's rotation period and pole as well as its albedo and surface composition remain unknown.

Reader's Guide

2015 KH162 is notable as one of the most distant known minor planets in the Solar System, currently at about 61.9 AU—twice as far from the Sun as Neptune. Its orbit, with a perihelion of 41.5 AU, places it in the near-scattered disc category, meaning it still gravitationally interacts with Neptune, unlike more detached objects. The object last came to perihelion around 1930 and is moving away from the Sun; it will reach aphelion at 82.1 AU in 2415. The Hubble Space Telescope photographed it on 2 June 2026 during a search for moons around large trans-Neptunian objects, highlighting ongoing interest in its physical nature. Despite its large estimated diameter of about 566 kilometers, its rotation period, pole, albedo, and surface composition remain unknown as of 2021, underscoring the need for further photometric observations. Its discovery by Sheppard, Tholen, and Trujillo using the Subaru Telescope in 2015, and announcement in 2016, contributed to the census of distant Solar System bodies.

Did You Know?

• It is currently about 61.9 AU from the Sun, twice as far as Neptune.
• Its estimated diameter is approximately 566 kilometers, based on an assumed albedo of 0.124.