2001 Einstein ( ''prov. designation'': ) is a bright Hungaria asteroid from the innermost region 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 ...

. It was discovered by Swiss astronomer Paul Wild at

Zimmerwald Observatory The Zimmerwald Observatory () is an astronomical observatory owned and operated by the AIUB, the Astronomical Institute of the University of Bern. Built in 1956, it is located at Zimmerwald, 10 kilometers south of Bern, Switzerland. Numerous com ...

near Bern, Switzerland, on 5 March 1973. The

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 ...

(Xe) 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 5.5 hours and measures approximately in diameter. It is named after physicist

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 ...

(1879–1955).

Orbit and classification

''Einstein'' is a member of the Hungaria family, which form the innermost dense concentration of asteroids in the Solar System. It orbits the Sun in the inner main-belt at a distance of 1.7–2.1 AU once every 2 years and 8 months (982 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 0.10 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 23 ° 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 ...

. As no

precoveries In astronomy, precovery (short for pre-discovery recovery) is the process of finding the image of a celestial object in images or photographic plates predating its discovery, typically for the purpose of calculating a more accurate orbit. This ha ...

were taken, 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 in 1973.

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 in honour of the German-born, Swiss–American physicist and Nobelist

(1879–1955). It is considered suitable, that the body discovered at Bern is named after the 1921

Nobel Prize in Physics The Nobel Prize in Physics () is an annual award given by the Royal Swedish Academy of Sciences for those who have made the most outstanding contributions to mankind in the field of physics. It is one of the five Nobel Prizes established by the ...

laureate, since it was the place where he had his golden years while working as a clerk at the Swiss Patent Office in Bern. He is also honored by the lunar crater ''

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 ...

''. 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 ().

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 ...

joked in the postscript of his novel '' 3001: The Final Odyssey'' that he was hoping asteroid 2001 would be named after him, but it was named for Einstein first. Asteroid 3001 was named 3001 Michelangelo. Clarke was later honoured with asteroid 4923 Clarke, named together with 5020 Asimov.

Physical characteristics

The

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 ...

, ''Einstein'' is an

, while 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 ...

, it is an Xe-subtype which transitions from the X-type to the very bright

E-type asteroid E-type (enstatite achondrite–type) asteroids are asteroids thought to have enstatite (MgSiO3) achondrite surfaces. They form a large proportion of asteroids inward of the asteroid belt known as Hungaria asteroids, but rapidly become very ...

Rotation period

Several 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 for this asteroid were obtained from photometric observations. In December 2004, the first lightcurve by American astronomer Brian Warner at his Palmer Divide Observatory (PDS) in Colorado, gave a

of hours with a brightness variation of 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 ...

(). Between 2008 and 2012, three additional lightcurves at the PDS gave an almost identical period of 5.485 hours with an amplitude of 0.67, 0.74 and 1.02, respectively (). Other lightcurves were obtained by Hanuš at the French

CNES CNES () is the French national space agency. Headquartered in central Paris, the agency is overseen by the ministries of the Armed Forces, Economy and Finance and Higher Education, Research and Innovation. It operates from the Toulouse Spac ...

and other institutions, which gave a period of hours (), and by Italian astronomer Federico Manzini at SAS observatory in Novara, Jean Strajnic and Raoul Behrend from December 2012, which rendered a period of hours with an amplitude of 0.66 in magnitude ().

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 space-based

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 ...

(WISE), the asteroid measures 4.0 km in diameter and its surface has an exceptionally high

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 0.81, for which WISE assigns an E-type. The ''Collaborative Asteroid Lightcurve Link'' assumes a lower, yet still high albedo of 0.40 and hence calculates a larger diameter of 5.7 kilometers, as the lower the albedo, the larger the body's diameter for a constant absolute magnitude.

References

External links

*
Lightcurve plot of 2001 Einstein
Palmer Divide Observatory, B. D. Warner (2012)
Lightcurve Database Query
(LCDB), at ''www.minorplanet.info'' {{DEFAULTSORT:Einstein 002001 Discoveries by Paul Wild (Swiss astronomer) Named minor planets

2001 The year's most prominent event was the September 11 attacks against the United States by al-Qaeda, which Casualties of the September 11 attacks, killed 2,977 people and instigated the global war on terror. The United States led a Participan ...

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