2867 Šteins (provisional designation ) is an irregular, diamond-shaped 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 4 November 1969 by Soviet astronomer
Nikolai Chernykh at the
Crimean Astrophysical Observatory in Nauchnij on the
Crimea
Crimea ( ) is a peninsula in Eastern Europe, on the northern coast of the Black Sea, almost entirely surrounded by the Black Sea and the smaller Sea of Azov. The Isthmus of Perekop connects the peninsula to Kherson Oblast in mainland Ukrain ...
n peninsula.
In September 2008,
ESA's spacecraft ''
Rosetta'' flew by Šteins, making it one of few
minor planets ever visited by a spacecraft. The bright
E-type asteroid features
23 named craters and has a
rotation period of 6.05 hours.
It was named for Soviet Latvian astronomer
Kārlis Šteins.
Orbit and classification
Šteins 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 asteroid belt at a distance of 2.0–2.7
AU once every 3 years and 8 months (1,327 days;
semi-major axis of 2.36 AU). Its orbit has an
eccentricity of 0.15 and an
inclination of 10
° 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 body's
observation arc begins with a
precovery, taken at the
Palomar Observatory in November 1951, or 18 years prior to its official discovery observation.
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 memory of
Kārlis Šteins (1911–1983), a
Latvia
Latvia, officially the Republic of Latvia, is a country in the Baltic region of Northern Europe. It is one of the three Baltic states, along with Estonia to the north and Lithuania to the south. It borders Russia to the east and Belarus to t ...
n and
Soviet
The Union of Soviet Socialist Republics. (USSR), commonly known as the Soviet Union, was a List of former transcontinental countries#Since 1700, transcontinental country that spanned much of Eurasia from 1922 until Dissolution of the Soviet ...
astronomer. He was a long-time observatory director at the
University of Latvia in Riga and designed astronomical instruments. Šteins is known for his work on cometary
cosmogony and the study of
Earth's rotation
Earth's rotation or Earth's spin is the rotation of planet Earth around its own Rotation around a fixed axis, axis, as well as changes in the orientation (geometry), orientation of the rotation axis in space. Earth rotates eastward, in progra ...
.
The official naming citation was published by the
Minor Planet Center on 18 September 1986 ().
Features on Šteins
On 11 May 2012, IAU's
Working Group for Planetary System Nomenclature announced a naming system for geographical features on Šteins.
Inspired by the asteroid's
gem-like shape, its
crater are given the English-language names of precious stones, with the largest being named
Diamond crater ''(see below)''.
Except for the
montes of
Mercury and the
lunar maria (and proposed for
2 Pallas and
7 Iris), the
craters of Šteins are the only features in the
Solar System
The Solar SystemCapitalization of the name varies. The International Astronomical Union, the authoritative body regarding astronomical nomenclature, specifies capitalizing the names of all individual astronomical objects but uses mixed "Sola ...
whose names are not derived from proper nouns.
In addition, a distinct region on the asteroid has been named Chernykh Regio after the discoverer,
Nikolai Chernykh.
Physical characteristics
A study published in 2006 by astronomers at the
European Southern Observatory showed that Šteins is an
E-type asteroid with a diameter of approximately 4.6 kilometers.
After the Rosetta flyby, the ESA described Šteins as a "diamond in the sky", as it has a wide body that tapers into a point. The wide section is dominated by the large
Diamond crater with a diameter of 2.1 kilometers, which surprised scientists, who were at first amazed the asteroid survived such an impact,
while later it turned out that the crater-to-body diameter ratio of 0.79 is in fact not abnormally large as it follows an already established trend.
Besides its irregular in shape, it does not have any
moon
The Moon is Earth's only natural satellite. It Orbit of the Moon, orbits around Earth at Lunar distance, an average distance of (; about 30 times Earth diameter, Earth's diameter). The Moon rotation, rotates, with a rotation period (lunar ...
s.
Diameter and albedo
According to the survey carried out by the
NEOWISE mission of
NASA
The National Aeronautics and Space Administration (NASA ) is an independent agencies of the United States government, independent agency of the federal government of the United States, US federal government responsible for the United States ...
's
Wide-field Infrared Survey Explorer and observations by the
Spitzer Space Telescope, Šteins measures 5.16 and 4.92 kilometers in diameter and its surface has an
albedo of 0.30 and 0.34, respectively.
Its overall Bond albedo is 0.24 ± 0.01.
In 2012, the photographs of Šteins taken by ''Rosetta'' using stereophotoclinometry allowed scientists to determine that the asteroid's dimensions are kilometers, which equates to a mean diameter in volume of 5.26 km.
(Asteroid was later named for the scientist using this 3D-method.) The ''Collaborative Asteroid Lightcurve Link'' adopts an albedo of 0.34 and a diameter of 4.9 kilometers with an
absolute magnitude of 13.36.
Lightcurves and poles
Studying the asteroid with
Rosetta space probe onboard OSIRIS cameras shortly before its flyby showed via a
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 ...
analysis that Šteins has a
rotation period of hours.
The results of the rotational lightcurve agree with ground-based
photometric observations of Šteins with a period of 6.049 hours and a brightness amplitude between 0.18 and 0.31
magnitude ().
A
lightcurve inversion also modeled a concurring sidereal period of 6.04681 hours and determined a
spin axis at (250.0°, −89.0°) in
ecliptic coordinates (λ, β). The modeling was done by compiling a set of 26 previously obtained visible lightcurves.
Exploration
''Rosetta'' flyby

On 5 September 2008, the Rosetta space probe flew by Šteins at a distance of 800 km and a relatively slow speed of 8.6 km/s. Despite the short duration of this encounter (approximately 7 minutes in total), a great amount of data was obtained by the 15 scientific instruments operating on board the Rosetta spacecraft.
This was the first of two planned asteroid flybys performed by the probe, the second being to the much larger
21 Lutetia in 2010.
The timing of the fly-by meant that the asteroid was illuminated by the sun from the perspective of the spacecraft, making the transmitted images clear. The
European Space Operations Centre streamed a press conference on Šteins later that day.
See also
*
List of craters on minor planets
*
List of minor planets and comets visited by spacecraft
Notes
References
External links
Steins: A diamond in the Sky images, ESA
– Observatoire de Genève, Raoul Behrend
Rosetta's OSIRIS cameras reveal the nature of asteroid Steins ESA, January 2010
Asteroid Lightcurve Database (LCDB) query form
Dictionary of Minor Planet Names Google books
– Minor Planet Center
*
*
{{DEFAULTSORT:Steins
19691104
002867
Discoveries by Nikolai Chernykh
20080905
Named minor planets
2867 Steins