1656 Suomi

1656 Suomi, provisional designation 1942 EC, is a stony Hungaria asteroid and sizable Mars-crosser from the innermost regions of the asteroid belt, approximately 7.9 kilometers in diameter. It was discovered on 11 March 1942, by Finnish astronomer Yrjö Väisälä at Turku Observatory in Southwest Finland.

Suomi is a S-type asteroid and member of the Hungaria family, 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 of 0.12 and an inclination of 25° with respect to the ecliptic. It is also classified as a Mars-crossing asteroid, since its perihelion – 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 begins on the preceding night of its discovery, with an observation taken at Johannesburg Observatory on 10 March 1942.

According to the survey carried out by the Infrared Astronomical Satellite IRAS, Suomi measures 7.86 kilometers in diameter and its surface has an albedo 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 based on an absolute magnitude of 13.146.

Since 1991, a large number of rotational light-curve 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 (U=3).

As with 1453 Fennia, this minor planet is named after Finland (Finnish: Suomi). Naming citation was published before November 1977 (M.P.C. 3932).