1656 Suomi ('' prov. designation:'' ) is a

binary Binary may refer to: Science and technology Mathematics * Binary number, a representation of numbers using only two digits (0 and 1) * Binary function, a function that takes two arguments * Binary operation, a mathematical operation that ta ...

Hungaria asteroid The Hungaria asteroids, also known as the Hungaria group, are a dynamical group of asteroids in the asteroid belt which orbit the Sun with a semi-major axis (longest radius of an ellipse) between 1.78 and 2.00 astronomical units (AU). They are t ...

and sizable

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 ...

from the innermost regions of the

asteroid belt The asteroid belt is a torus-shaped region in the Solar System, located roughly between the orbits of the planets Jupiter and Mars. It contains a great many solid, irregularly shaped bodies, of many sizes, but much smaller than planets, c ...

. It was discovered on 11 March 1942, by Finnish astronomer

Yrjö Väisälä Yrjö Väisälä (; 6 September 1891 – 21 July 1971) was a Finnish astronomer and physicist. His main contributions were in the field of optics. He was also active in geodetics, astronomy and optical metrology. He had an affectionate ni ...

Turku Observatory Turku ( ; ; sv, Åbo, ) is a city and former capital on the southwest coast of Finland at the mouth of the Aura River, in the region of Finland Proper (''Varsinais-Suomi'') and the former Turku and Pori Province (''Turun ja Porin lääni''; ...

in Southwest Finland, who named it "Suomi", the native name of

Finland Finland ( fi, Suomi ; sv, Finland ), officially the Republic of Finland (; ), is a Nordic country in Northern Europe. It shares land borders with Sweden to the northwest, Norway to the north, and Russia to the east, with the Gulf of B ...

. The stony asteroid has a short rotation period of 2.6 hours and measures approximately 7.9 kilometers in diameter. In June 2020, a companion was discovered by Brian Warner,

Robert Stephens Sir Robert Graham Stephens (14 July 193112 November 1995) was a leading English actor in the early years of Britain's Royal National Theatre. He was one of the most respected actors of his generation and was at one time regarded as the natu ...

and Alan Harris. The satellite measures more than 1.98 kilometers in diameter, about 26% of the primary, which it orbits once every 57.9 hours at an average distance of 30 kilometers.

Orbit and classification

''Suomi'' is a member of the

Hungaria family The Hungaria asteroids, also known as the Hungaria group, are a dynamical group of asteroids in the asteroid belt which orbit the Sun with a semi-major axis (longest radius of an ellipse) between 1.78 and 2.00 astronomical units (AU). They are t ...

, which form the innermost dense concentration of asteroids in the Solar System. It orbits the Sun at a distance of 1.6–2.1 AU once every 2 years and 7 months (940 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 0.12 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 25 ° 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 again ...

. It is also classified as a Mars-crossing asteroid, since its

perihelion An apsis (; ) is the farthest or nearest point in the orbit of a planetary body about its primary body. For example, the apsides of the Earth are called the aphelion and perihelion. General description There are two apsides in any elli ...

– the point in its orbit, where it is nearest to the Sun – is less than the average orbital distance of the planet Mars (1.666 AU). ''Suomi''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 on the preceding night of its discovery, with an observation taken at

Johannesburg Observatory Union Observatory also known as Johannesburg Observatory ( 078) is a defunct astronomical observatory in Johannesburg, South Africa that was operated between 1903 and 1971. It is located on Observatory Ridge, the city's highest point at 1,808 met ...

on 10 March 1942.

Naming

As with 1453 Fennia, this minor planet was named after

( fi, Suomi). The official was published by the Minor Planet Center on 20 February 1976 ().

Physical characteristics

In the

Tholen Tholen () is a 25,000 people municipality in the southwest of the Netherlands. The municipality of Tholen takes its name from the town of Tholen, which is the largest population center in the municipality. The municipality consists of two peninsu ...

taxonomy, ''Suomi'' is a stony

S-type asteroid S-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 of this type, making it the secon ...

Diameter and albedo

According to the survey carried out by the Infrared Astronomical Satellite

IRAS The Infrared Astronomical Satellite (Dutch: ''Infrarood Astronomische Satelliet'') (IRAS) was the first space telescope to perform a survey of the entire night sky at infrared wavelengths. Launched on 25 January 1983, its mission lasted ten mo ...

, ''Suomi'' measures 7.86 kilometers 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 refl ...

of 0.156, making it one of the largest Mars crossing asteroid with a known diameter. The ''Collaborative Asteroid Lightcurve Link'' (CALL) agrees with IRAS, and adopts an albedo of 0.157 and a diameter of 7.9 kilometers with 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 13.146.

Rotation period

Since 1991, a large number of 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 ...

s of ''Suomi'' have been obtained from photometric observations ''(also see infobox)''. CALL adopts a rotation period of 2.583 hours with a brightness variation of 0.20

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 ...

().

References

External links

Turun Ursa
(in Finnish)
Photometric Observations of 125 Asteroids
Wisniewski, ''Icarus'', Volume 126, Issue 2, pp. 395–449.
Lightcurve plot of 1656 Suomi
Palmer Divide Observatory, '' B. D. Warner'' (2009)
Asteroid Lightcurve Database (LCDB)
query form

)
Dictionary of Minor Planet Names
Google books

– Observatoire de Genève, Raoul Behrend

– Minor Planet Center * * {{DEFAULTSORT:Suomi 001656 001656 Discoveries by Yrjö Väisälä Named minor planets 001656 001656 19420311