is an

asteroid An asteroid is a minor planet—an object larger than a meteoroid that is neither a planet nor an identified comet—that orbits within the Solar System#Inner Solar System, inner Solar System or is co-orbital with Jupiter (Trojan asteroids). As ...

, slow rotator and

tumbler Tumbler may refer to: * Tumbler (firearms), a part of the firing mechanism in older firearms * Tumbler (glass), a type of glassware * Tumbler (pigeon), a pigeon breed * Tumbler (Project Xanadu), a unique identifier of a unit of text or an e ...

, classified as a

near-Earth object A near-Earth object (NEO) is any small Solar System body orbiting the Sun whose closest approach to the Sun ( perihelion) is less than 1.3 times the Earth–Sun distance (astronomical unit, AU). This definition applies to the object's orbit a ...

and

potentially hazardous asteroid A potentially hazardous object (PHO) is a near-Earth object – either an asteroid or a comet – with an orbit that can make close approaches to the Earth and which is large enough to cause significant regional damage in the event of impact. Th ...

(PHA) of the

Apollo group Apollo Education Group, Inc. is an American corporation based in the South Phoenix area of Phoenix, Arizona, with an additional corporate office in Chicago, Illinois. It is privately-owned by a consortium of investors including The Vistria Grou ...

, approximately in diameter, making it the largest PHA known to exist. It was discovered on 13 May 1999, by astronomers of the

Lincoln Near-Earth Asteroid Research The Lincoln Near-Earth Asteroid Research (LINEAR) project is a collaboration of the United States Air Force, NASA, and the Massachusetts Institute of Technology's Lincoln Laboratory for the systematic detection and tracking of near-Earth object ...

at the Lincoln Laboratory's Experimental Test Site near Socorro, New Mexico.

Orbit and classification

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 In geometry, the major axis of an ellipse is its longest diameter: a line segment that runs through the center and both foci, with ends at the two most widely separated points of the perimeter. The semi-major axis (major semiaxis) is the longe ...

of 2.73 AU). Its orbit has an

eccentricity Eccentricity or eccentric may refer to: * Eccentricity (behavior), odd behavior on the part of a person, as opposed to being "normal" Mathematics, science and technology Mathematics * Off-Centre (geometry), center, in geometry * Eccentricity (g ...

of 0.64 and an

inclination Orbital inclination measures the tilt of an object's orbit around a celestial body. It is expressed as the angle between a reference plane and the orbital plane or axis of direction of the orbiting object. For a satellite orbiting the Eart ...

of 14 ° with respect to the

ecliptic The ecliptic or ecliptic plane is the orbital plane of Earth's orbit, Earth around the Sun. It was a central concept in a number of ancient sciences, providing the framework for key measurements in astronomy, astrology and calendar-making. Fr ...

. This makes it also a

Mars-crossing asteroid A Mars-crossing asteroid (MCA, also Mars-crosser, MC) is an asteroid whose orbit crosses that of Mars. Some Mars-crossers Minor planet designation, numbered below 100000 are listed here. They include the two numbered Mars trojans 5261 Eureka and ...

. The body's

observation arc In observational astronomy, the observation arc (or arc length) of a Solar System body is the time period between its earliest and latest observations, used for tracing the body's path. It is usually given in days or years. The term is mostly use ...

begins with its first identification as at

Palomar Observatory The Palomar Observatory is an astronomical research observatory in the Palomar Mountains of San Diego County, California, United States. It is owned and operated by the California Institute of Technology (Caltech). Research time at the observat ...

in April 1990, more than 9 years prior to its official discovery observation at Socorro.

Close approaches

has an Earth

minimum orbital intersection distance Minimum orbit intersection distance (MOID) is a measure used in astronomy to assess potential close approaches and collision risks between astronomical objects. It is defined as the distance between the closest points of the osculating orbits of ...

of 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 and in August 2137 at . For comparison, the planet

Venus Venus is the second planet from the Sun. It is often called Earth's "twin" or "sister" planet for having almost the same size and mass, and the closest orbit to Earth's. While both are rocky planets, Venus has an atmosphere much thicker ...

passed from Earth in 2022.

Physical characteristics

Radar images and computer model of asteroid 1999 JM8

In the SMASS and

Tholen classification An asteroid spectral type is assigned to asteroids based on their reflectance spectrum, color, and sometimes albedo. These types are thought to correspond to an asteroid's surface composition. For small bodies that are not internally different ...

, is an

X-type asteroid The X-group of asteroids collects together several types with similar spectra, but probably quite different compositions. Tholen classification In the Tholen classification, the X-group consists of the following types: * E-type – with high ...

. It has also been characterized as a carbonaceous

C-type asteroid C-type (carbonaceous ) asteroids are the most common variety, forming around 75% of known asteroids. They are volatile-rich and distinguished by a very low albedo because their composition includes a large amount of carbon, in addition to rocks ...

, which seems more likely due to its exceptionally low albedo ''(see below)''. 1999jm8-01

Rotation period

Radar imaging Radar is a system that uses radio waves to determine the distance (''ranging''), direction (geometry), direction (azimuth and elevation angles), and radial velocity of objects relative to the site. It is a radiodetermination method used to det ...

by Goldstone and

Arecibo Arecibo (; ) is a Arecibo barrio-pueblo, city and Municipalities of Puerto Rico, municipality on the northern coast of Puerto Rico, on the shores of the Atlantic Ocean, located north of Utuado, Puerto Rico, Utuado and Ciales, Puerto Rico, Ciale ...

observatories revealed that has an unusually slow and possibly chaotic

rotation period In astronomy, the rotation period or spin period of a celestial object (e.g., star, planet, moon, asteroid) has two definitions. The first one corresponds to the '' sidereal rotation period'' (or ''sidereal day''), i.e., the time that the objec ...

, similar to that of asteroid 4179 Toutatis. In July 1999, a rotational

lightcurve In astronomy, a light curve is a graph (discrete mathematics), graph of the Radiance, light intensity of a celestial object or region as a function of time, typically with the magnitude (astronomy), magnitude of light received on the ''y''-axis ...

of was obtained from photometric observations. It gave a period of hours with a brightness amplitude of 0.7

magnitude Magnitude may refer to: Mathematics *Euclidean vector, a quantity defined by both its magnitude and its direction *Magnitude (mathematics), the relative size of an object *Norm (mathematics), a term for the size or length of a vector *Order of ...

(), and suggested that the body is in a non-principal axis rotation, commonly known as tumbling.

Diameter and albedo

measures between 5 and 7 kilometers in diameter and its surface has an exceptionally low

albedo Albedo ( ; ) is the fraction of sunlight that is Diffuse reflection, diffusely reflected by a body. It is measured on a scale from 0 (corresponding to a black body that absorbs all incident radiation) to 1 (corresponding to a body that reflects ...

of 0.02. 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.

Numbering and naming

This

minor planet According to the International Astronomical Union (IAU), a minor planet is an astronomical object in direct orbit around the Sun that is exclusively classified as neither a planet nor a comet. Before 2006, the IAU officially used the term ''minor ...

was numbered by the

Minor Planet Center The Minor Planet Center (MPC) is the official body for observing and reporting on minor planets under the auspices of the International Astronomical Union (IAU). Founded in 1947, it operates at the Smithsonian Astrophysical Observatory. Funct ...

on 16 February 2003. As of 2018, it has not been named.

References

External links

Asteroid Lightcurve Database (LCDB)
query form

)

– Observatoire de Genève, Raoul Behrend * * * {{DEFAULTSORT:1999 JM 053319 053319 053319 053319 053319 053319 19990513