1981 Midas, provisional designation , is a vestoid

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 ...

, 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, approximately 2 kilometers in diameter. It was discovered on 6 March 1973 by American astronomer Charles Kowal 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 San Diego County, California. It was named after King

Midas Midas (; ) was a king of Phrygia with whom many myths became associated, as well as two later members of the Phrygian royal house. His father was Gordias, and his mother was Cybele. The most famous King Midas is popularly remembered in Greek m ...

from Greek mythology.

Classification and orbit

The moderately bright V-type asteroid is also an Apollo asteroid, as well as a

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 ...

and Mars-crosser. The asteroid orbits the Sun at a distance of 0.6–2.9 AU once every 2 years and 4 months (864 days). 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 0.65 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 40 ° 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 ...

. ''Midas'' has a low

minimum orbit 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 o ...

with Earth of , which corresponds to 1.5 lunar distance (Earth–Moon distance). However, it does not pose an impact risk for the foreseeable future. On 19 March 1947 it passed from Earth. The last notable close approach was on 21 March 2018 passing from Earth and shining at an

apparent magnitude Apparent magnitude () is a measure of the Irradiance, brightness of a star, astronomical object or other celestial objects like artificial satellites. Its value depends on its intrinsic luminosity, its distance, and any extinction (astronomy), ...

of +12.4. The next notable close approach will be on 14 September 2032 passing slightly closer at from Earth. As no precoveries are known, the asteroid'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 discovery observation at Palomar in 1973. With a semi-major axis of 1.78 AU, when 1 AU from the Sun (and passing Earth's orbit) the asteroid is moving at 35.7 km/s with respect to the Sun. For comparison Earth orbits the Sun at 30 km/s.

Physical characteristics

Three 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 ...

s obtained from photometric observations gave a concurring

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 ...

of 5.24 hours with a relatively high brightness variation of 0.65, 0.8 and 0.87 in

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 ...

, respectively (). According to the survey carried out by the Japanese Akari satellite, ''Midas'' measures 1.95 kilometers in diameter and its surface has an

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 0.293, while the ''Collaborative Asteroid Lightcurve Link'' assumes an albedo of 0.266 and calculates an identical diameter of 1.95 kilometers with an absolute magnitude of 15.6. In 1987, ''Midas'' was also detected by radar from

Goldstone Deep Space Communications Complex The Goldstone Deep Space Communications Complex (GDSCC), commonly called the Goldstone Observatory, is a satellite ground station located in Fort Irwin in the U.S. state of California. Operated by NASA's Jet Propulsion Laboratory (JPL), its ...

at a distance of 0.08 AU with a measured maximal

radar cross-section Radar cross-section (RCS), denoted σ, also called radar signature, is a measure of how detectable an object is by radar. A larger RCS indicates that an object is more easily detected. An object reflects a limited amount of radar energy b ...

of 0.1 km².

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 named after the figure from Greek mythology,

, the King of

Phrygia In classical antiquity, Phrygia ( ; , ''Phrygía'') was a kingdom in the west-central part of Anatolia, in what is now Asian Turkey, centered on the Sangarios River. Stories of the heroic age of Greek mythology tell of several legendary Ph ...

, who turned whatever he touched to gold. He received this ability as an award, but soon realized that this gift was a curse when his daughter turned into a statue after he had touched her. Relieved of his power by bathing in the river

Pactolus Pactolus (), also called Chrysorrhoas (Χρυσορρόας), the modern Sart Çayı , is a river near the Aegean coast of Turkey. The river rises from Mount Tmolus, flows through the ruins of the ancient city of Sardis, and empties into the Ged ...

, other accounts also tell his death caused by starvation. The official was published 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 15 October 1977 ().

Notes

References

on YouTube * * * {{DEFAULTSORT:Midas 001981 Discoveries by Charles T. Kowal Named minor planets 001981 001981 001981 19730306

Classification and orbit

Physical characteristics

Naming

Notes

References

External links