4923 Clarke, provisional designation , is a stony background

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 ...

from the inner regions of the

asteroid belt The asteroid belt is a torus-shaped region in the Solar System, centered on the Sun and roughly spanning the space between the orbits of the planets Jupiter and Mars. It contains a great many solid, irregularly shaped bodies called asteroids ...

, approximately in diameter. It was discovered on 2 March 1981, by American astronomer

Schelte Bus Schelte John "Bobby" Bus (born 1956) is an American astronomer and discoverer of minor planets at the Institute for Astronomy of the University of Hawaiʻi and deputy director of NASA's Infrared Telescope Facility (IRTF) at the Mauna Kea Obser ...

at the

Siding Spring Observatory Siding Spring Observatory near Coonabarabran, New South Wales, Australia, part of the Research School of Astronomy & Astrophysics (RSAA) at the Australian National University (ANU), incorporates the Anglo-Australian Telescope along with a coll ...

in Australia. The spheroidal

S-type asteroid S-type (stony-type or silicaceous-type) asteroids are asteroids with a spectral type that is indicative of a siliceous (i.e. stony) mineralogical composition, hence the name. They have relatively high density. Approximately 17% of asteroids are ...

has a

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 3.14 hours. It was named after British science fiction writer

Arthur C. Clarke Sir Arthur Charles Clarke (16 December 191719 March 2008) was an English science fiction writer, science writer, futurist, inventor, undersea explorer, and television series host. Clarke co-wrote the screenplay for the 1968 film '' 2001: A ...

. On the same night, Schelte Bus also discovered

5020 Asimov 5 (five) is a number, numeral and digit. It is the natural number, and cardinal number, following 4 and preceding 6, and is a prime number. Humans, and many other animals, have 5 digits on their limbs. Mathematics 5 is a Fermat pri ...

Orbit and classification

''Clarke'' is a non-

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

asteroid from the main belt's background population. It orbits the Sun in the inner main-belt at a distance of 1.7–2.6 AU once every 3 years and 2 months (1,147 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 2.14 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 0.20 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 7 ° 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 ...

. The asteroid was first observed as at

Crimea–Nauchnij The Crimean Astrophysical Observatory (CrAO, List of observatory codes, obs. code: IAU code#095, 095) is located at Nauchnij research campus, near the Central Crimean city of Bakhchysarai, on the Crimean peninsula. CrAO is often called ...

in July 1972. 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 the Siding Spring Observatory two weeks prior to its official discovery observation on 12 February 1981.

Physical characteristics

In the

SMASS 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 ...

, ''Clarke'' is a common, stony

Rotation period

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 of ''Clarke'' have been obtained from photometric observations by the APT Observatory Group in Spain, by astronomers at the

Palomar Transient Factory The Palomar Transient Factory (PTF, obs. code: I41), was an astronomical survey using a wide-field survey camera designed to search for optical transient and variable sources such as variable stars, supernovae, asteroids and comets. The projec ...

in California, and by Czech astronomer

Petr Pravec Petr Pravec (born September 17, 1967) is a Czech astronomer and a discoverer of minor planets, born in Třinec, Czech Republic. Pravec is a prolific discoverer of binary asteroids, expert in photometric observations and rotational lightcurves ...

Ondřejov Observatory The Ondřejov Observatory (; ) is the principal observatory of the Astronomical Institute of the Czech Academy of Sciences. It is located in the municipality of Ondřejov, southeast of Prague, Czech Republic. It has a wide telescope, which i ...

(). Analysis of the best-rated lightcurve gave a

of 3.143 hours with a consolidated brightness amplitude between 0.03 and 0.14

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 ...

, which indicates that the body has a nearly spheroidal, non-elongated shape ().

Diameter and albedo

According to the survey carried out by the

NEOWISE Wide-field Infrared Survey Explorer (WISE, observatory code C51, Explorer 92 and MIDEX-6) was a NASA infrared astronomy space telescope in the Explorers Program launched in December 2009.. . WISE discovered thousands of minor planets and nu ...

mission of NASA's

Wide-field Infrared Survey Explorer Wide-field Infrared Survey Explorer (WISE, List of observatory codes, observatory code C51, Explorer 92 and MIDEX-6) was a NASA infrared astronomy Space observatory, space telescope in the Explorers Program launched in December 2009.. . WISE L ...

, ''Clarke'' measures between 3.367 and 3.532 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 ...

between 0.3259 and 0.366. The ''Collaborative Asteroid Lightcurve Link'' assumes an albedo of 0.20 and calculates a diameter of 4.10 kilometers based on an absolute magnitude of 14.3.

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

science fiction Science fiction (often shortened to sci-fi or abbreviated SF) is a genre of speculative fiction that deals with imaginative and futuristic concepts. These concepts may include information technology and robotics, biological manipulations, space ...

writer

(1917–2008), author of '' 2001: A Space Odyssey''. The official naming citation was prepared with assistance from

Richard Binzel Richard "Rick" P. Binzel (born 1958) is an American astronomer and professor of planetary sciences at the Massachusetts Institute of Technology (MIT). He is a discoverer of minor planets, photometrist and the inventor of the Torino Scale, a meth ...

and 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 3 May 1996 (). The asteroid's name independently suggested by

Duncan Steel Duncan I. Steel (born 1955) is a British space scientist. He has discovered several minor planets and has written four popular science books. He is a member of the International Astronomical Union, and has worked at the Xerra Earth Observat ...

(). In the postscript to his novel '' 3001: The Final Odyssey'', Clarke jokingly expresses disappointment that he did not receive asteroid 2001 as his namesake; instead, it was named for

Albert Einstein Albert Einstein (14 March 187918 April 1955) was a German-born theoretical physicist who is best known for developing the theory of relativity. Einstein also made important contributions to quantum mechanics. His mass–energy equivalence f ...

Notes

References

External links

Asteroid Lightcurve Database (LCDB)
query form

)
Dictionary of Minor Planet Names
Google books

– Minor Planet Center * * {{DEFAULTSORT:Clarke 004923 Discoveries by Schelte J. Bus Named minor planets 4923 Clarke 004923 19810302