14827 Hypnos ('' prov. designation:'' ) is a highly eccentric, sub-kilometer-sized carbonaceous

asteroid An asteroid is a minor planet of the inner Solar System. Sizes and shapes of asteroids vary significantly, ranging from 1-meter rocks to a dwarf planet almost 1000 km in diameter; they are rocky, metallic or icy bodies with no atmosphere. ...

that is thought to be an

extinct comet An extinct comet is a comet that has expelled most of its volatile ice and has little left to form a tail and coma. In a dormant comet, rather than being depleted, any remaining volatile components have been sealed beneath an inactive surface la ...

. It is classified as

near-Earth object A near-Earth object (NEO) is any small Solar System body whose orbit brings it into proximity with Earth. By convention, a Solar System body is a NEO if its closest approach to the Sun (Apsis, perihelion) is less than 1.3 astronomical unit ...

and potentially hazardous asteroid 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. The company owns and operates several higher-learning institutions, includin ...

. The asteroid was discovered by American astronomer couple

Carolyn Carolyn is a female given name, a variant of Caroline. Other spellings include Karolyn, Carolyne, Carolynn or Carolynne. Caroline itself is one of the feminine forms of Charles. List of Notable People *Carolyn Bennett (born 1950), Canadian po ...

and Eugene Shoemaker at the

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

in California on 5 May 1986. It was named after

Hypnos In Greek mythology, Hypnos (; Ancient Greek: means 'sleep') also spelled Hypnus is the personification of sleep; the Roman equivalent is known as Somnus. His name is the origin of the word hypnosis. Pausanias wrote that Hypnos was a dear ...

, the Greek god of sleep.

Orbit and classification

''Hypnos'' orbits the Sun at a distance of 0.9–4.7 AU once every 4 years and 9 months (1,749 days). Its orbit has a high eccentricity of 0.67 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 Ea ...

of 2 ° with respect to the

ecliptic The ecliptic or ecliptic plane is the orbital plane of the Earth around the Sun. From the perspective of an observer on Earth, the Sun's movement around the celestial sphere over the course of a year traces out a path along the ecliptic agains ...

. It is frequently perturbed by

Jupiter Jupiter is the fifth planet from the Sun and the largest in the Solar System. It is a gas giant with a mass more than two and a half times that of all the other planets in the Solar System combined, but slightly less than one-thousand ...

. 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 at Anderson Mesa Station the night prior to its official discovery observation at Palomar.

Close approaches

As a

and potentially hazardous asteroid ''Hypnos'' 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 o ...

of , which corresponds to 5.7 lunar distances. In 1958, ''Hypnos'' passed less than 0.03 AU from both Earth and Mars. Neither planet has been approached so closely by ''Hypnos'' since the 862 AD pass of Earth, or will be until the 2214 pass of Earth. It is also a

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

Extinct comet

''Hypnos'' may be the

nucleus Nucleus ( : nuclei) is a Latin word for the seed inside a fruit. It most often refers to: * Atomic nucleus, the very dense central region of an atom *Cell nucleus, a central organelle of a eukaryotic cell, containing most of the cell's DNA Nucl ...

of an

that is covered by a crust several centimeters thick that prevents any remaining

volatiles Volatiles are the group of chemical elements and chemical compounds that can be readily vaporized. In contrast with volatiles, elements and compounds that are not readily vaporized are known as refractory substances. On planet Earth, the term ...

from

outgassing Outgassing (sometimes called offgassing, particularly when in reference to indoor air quality) is the release of a gas that was dissolved, trapped, frozen, or absorbed in some material. Outgassing can include sublimation and evaporation (which ...

Physical characteristics

''Hypnos'' is an assumed 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 ...

Lightcurves

As of 2018, no rotational

lightcurve In astronomy, a light curve is a graph of light intensity of a celestial object or region as a function of time, typically with the magnitude of light received on the y axis and with time on the x axis. The light is usually in a particular freq ...

of ''Hypnos'' has been obtained from photometric observations. The asteroids

rotation period The rotation period of a celestial object (e.g., star, gas giant, planet, moon, asteroid) may refer to its sidereal rotation period, i.e. the time that the object takes to complete a single revolution around its axis of rotation relative to the ...

and

spin axis Rotation around a fixed axis is a special case of rotational motion. The fixed-axis hypothesis excludes the possibility of an axis changing its orientation and cannot describe such phenomena as wobbling or precession. According to Euler's rota ...

remains unknown. It has a low brightness amplitude of 0.05 magnitude which indicates that the body has a rather

spheroidal A spheroid, also known as an ellipsoid of revolution or rotational ellipsoid, is a quadric surface obtained by rotating an ellipse about one of its principal axes; in other words, an ellipsoid with two equal semi-diameters. A spheroid has circ ...

shape.

Diameter and albedo

According to the NEOSurvey carried out by NASA's

Spitzer Space Telescope The Spitzer Space Telescope, formerly the Space Infrared Telescope Facility (SIRTF), was an infrared space telescope launched in 2003. Operations ended on 30 January 2020. Spitzer was the third space telescope dedicated to infrared astronomy, ...

, ''Hypnos'' measures 520 meters in diameter and its surface has an

albedo Albedo (; ) is the measure of the diffuse reflection of solar radiation out of the total solar radiation and measured on a scale from 0, corresponding to a black body that absorbs all incident radiation, to 1, corresponding to a body that refle ...

of 0.22 based on an

absolute magnitude Absolute magnitude () is a measure of the luminosity of a celestial object on an inverse logarithmic astronomical magnitude scale. An object's absolute magnitude is defined to be equal to the apparent magnitude that the object would have if it ...

of 18.65, while infrared radiometry gave a radar albedo of no more than 0.067 and a diameter of at least 740 meters. The ''Collaborative Asteroid Lightcurve Link'' assumes a standard optical albedo for carbonaceous asteroids 0.057 and derives a diameter of 907 meters with an

of 18.94. The diameter agrees with

Tom Gehrels Anton M.J. "Tom" Gehrels (February 21, 1925 – July 11, 2011) was a Dutch–American astronomer, Professor of Planetary Sciences, and Astronomer at the University of Arizona, Tucson. Biography Youth and education Gehrels was born at H ...

1994-publication ''Hazards due to Comets and Asteroids'' in which he estimated a mean-diameter of 900 meters for ''Hypnos''.

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

from

Greek mythology A major branch of classical mythology, Greek mythology is the body of myths originally told by the ancient Greeks, and a genre of Ancient Greek folklore. These stories concern the origin and nature of the world, the lives and activities o ...

. He is the god of sleep, son of

Nyx Nyx (; , , "Night") is the Greek goddess and personification of night. A shadowy figure, Nyx stood at or near the beginning of creation and mothered other personified deities, such as Hypnos (Sleep) and Thanatos (Death), with Erebus (Darkn ...

and

Erebus In Greek mythology, Erebus (; grc, Ἔρεβος, Érebos, "deep darkness, shadow".), or Erebos, is the personification of darkness and one of the primordial deities. Hesiod's ''Theogony'' identifies him as one of the first five beings in exis ...

and twin brother of

Thanatos In Greek mythology, Thanatos (; grc, Θάνατος, pronounced in "Death", from θνῄσκω ''thnēskō'' "(I) die, am dying") was the personification of death. He was a minor figure in Greek mythology, often referred to but rarely appea ...

. He enters the sleep of mortals and gives them dreams of foolishness or inspiration. The English word "

hypnosis Hypnosis is a human condition involving focused attention (the selective attention/selective inattention hypothesis, SASI), reduced peripheral awareness, and an enhanced capacity to respond to suggestion.In 2015, the American Psychologica ...

" is derived from his name. The official naming citation 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. Function T ...

on 6 January 2003 ().

References

External links

Asteroid Lightcurve Database (LCDB)
query form

)
Dictionary of Minor Planet Names
Google books

– Observatoire de Genève, Raoul Behrend * * * {{DEFAULTSORT:Hypnos 014827 Discoveries by Eugene Merle Shoemaker Discoveries by Carolyn S. Shoemaker Named minor planets 014827 014827 19860505