(53319) 1999 JM8

Template:Mp is an asteroid, slow rotator and tumbler, classified as a near-Earth object and potentially hazardous asteroid (PHA) of the Apollo group, approximately Template:Convert in diameter, making it the largest PHA known to exist.<ref>Template:Cite web</ref> It was discovered on 13 May 1999, by astronomers of the Lincoln Near-Earth Asteroid Research at the Lincoln Laboratory's Experimental Test Site near Socorro, New Mexico.<ref name="MPC-object" />

Orbit and classification

Template:Mp orbits the Sun at a distance of 1.0–4.5 AU once every 4 years and 6 months (1,644 days; semi-major axis of 2.73 AU). Its orbit has an eccentricity of 0.64 and an inclination of 14° with respect to the ecliptic.<ref name="jpldata" /> This makes it also a Mars-crossing asteroid.

The body's observation arc begins with its first identification as Template:Mp at Palomar Observatory in April 1990, more than 9 years prior to its official discovery observation at Socorro.<ref name="MPC-object" />

Close approaches

Template:Mp has an Earth minimum orbital intersection distance of Template:Convert<ref name="jpldata" /> It passed closer than 0.20 AU to the Earth five times in the last century (0.033 AU in 1990), but its next closest approach in the 21st century will be in 2075 at Template:Convert and in August 2137 at Template:Convert.<ref name="jpldata"/> For comparison, the planet Venus passed Template:Convert from Earth in 2022.

Physical characteristics

Radar images and computer models of Template:Mp

In the SMASS and Tholen classification, Template:Mp is an X-type asteroid.<ref name="jpldata"/><ref name="lcdb" /> It has also been characterized as a carbonaceous C-type asteroid, which seems more likely due to its exceptionally low albedo (see below).<ref name="Carry-2016" />

A radar image of Template:Mp, showing two large craters or basins on its surface

Rotation period

Radar imaging by Goldstone and Arecibo observatories revealed that Template:Mp has an unusually slow and possibly chaotic rotation period, similar to that of asteroid 4179 Toutatis.<ref name="lcdb" /><ref name="Brozovic-2012" />

In July 1999, a rotational lightcurve of Template:Mp was obtained from photometric observations. It gave a period of Template:Val hours with a brightness amplitude of 0.7 magnitude (Template:Small), and suggested that the body is in a non-principal axis rotation, commonly known as tumbling.<ref name="Pravec-2005a" />

Diameter and albedo

Template:Mp measures between 5 and 7 kilometers in diameter and its surface has an exceptionally low albedo of 0.02.<ref name="Benner-2001a" /><ref name="Reddy-2012" /><ref name="Benner-2001c" /><ref name="Benner-2002b" /> The Collaborative Asteroid Lightcurve Link derives an albedo of 0.03 and adopts a diameter of 7 kilometers based on an absolute magnitude of 15.2.<ref name="lcdb" />

Numbering and naming

This minor planet was numbered by the Minor Planet Center on 16 February 2003.<ref name="MPC-Circulars-Archive" /> As of 2018, it has not been named.<ref name="MPC-object" />

External links

• Asteroid Lightcurve Database (LCDB), query form (info Template:Webarchive)
• Asteroids and comets rotation curves, CdR – Observatoire de Genève, Raoul Behrend
• Template:NeoDys
• Template:ESA-SSA
• Template:JPL small body