Carl Alvar Wirtanen (November 11, 1910 – March 7, 1990) was an

American American(s) may refer to: * American, something of, from, or related to the United States of America, commonly known as the "United States" or "America" ** Americans, citizens and nationals of the United States of America ** American ancestry, pe ...

astronomer An astronomer is a scientist in the field of astronomy who focuses their studies on a specific question or field outside the scope of Earth. They observe astronomical objects such as stars, planets, natural satellite, moons, comets and galaxy, g ...

and discoverer of

comet A comet is an icy, small Solar System body that, when passing close to the Sun, warms and begins to release gases, a process that is called outgassing. This produces a visible atmosphere or coma, and sometimes also a tail. These phenomena ar ...

s and

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 ...

s who worked at

Lick Observatory The Lick Observatory is an astronomical observatory owned and operated by the University of California. It is on the summit of Mount Hamilton, in the Diablo Range just east of San Jose, California, United States. The observatory is managed by th ...

. He was of Finnish ancestry. Wirtanen was born in Kenosha, Wisconsin. After visiting the observatory in Kenosha with his violin teacher at age 12, he started grinding mirrors. Wirtanen joined the staff at Lick Observatory in 1941. During the Second World War, he took a job as a physicist at the California Institute of Technology and worked on ballistics at the Naval Ordnance Test Station in the

Mojave Desert The Mojave Desert ( ; mov, Hayikwiir Mat'aar; es, Desierto de Mojave) is a desert in the rain shadow of the Sierra Nevada mountains in the Southwestern United States. It is named for the indigenous Mojave people. It is located primarily in ...

. He returned to Lick Observatory after the war, remaining there until his retirement in 1978. Wirtanen discovered periodic comet

46P/Wirtanen 46P/Wirtanen is a small short-period comet with a current orbital period of 5.4 years. It was the original target for close investigation by the ''Rosetta'' spacecraft, planned by the European Space Agency, but an inability to meet the launch wi ...

, as well as eight

asteroid An asteroid is a minor planet of the inner Solar System. Sizes and shapes of asteroids vary significantly, ranging from 1-meter rocks to a dwarf planet almost 1000 km in diameter; they are rocky, metallic or icy bodies with no atmosphere. ...

s, including notably the Apollo asteroid

(29075) 1950 DA , provisional designation ', is a risk–listed asteroid, classified as a near-Earth object and potentially hazardous asteroid of the Apollo group, approximately in diameter. It once had the highest known probability of impacting Earth. In 2002 ...

, which may have a non-negligible probability of impacting the Earth in the year 2880. He also discovered two other Apollo asteroids:

1685 Toro 1685 Toro ( ''prov. designation'': ) is an asteroid and near-Earth object of the Apollo group on an eccentric orbit. It was discovered on 17 July 1948, by American astronomer Carl Wirtanen at Lick Observatory on Mount Hamilton, California. The s ...

and

1863 Antinous 1863 Antinous , provisional designation , is a stony asteroid and near-Earth object, approximately 2–3 kilometers in diameter. It was discovered on 7 March 1948 by American astronomer Carl Wirtanen at Lick Observatory on the summit of Mount Ham ...

. Based on the ''Shane–Wirtanen survey'', the Shane Wirtanen Catalogue, a count of galaxies, was his major work published in 1954. The asteroid

2044 Wirt 2044 Wirt, provisional designation , is a binary Phocaea asteroid and Mars-crosser, approximately 6.7 kilometers in diameter. The minor-planet moon has an estimated diameter of 1.89 kilometer. The asteroid was discovered on 8 November 1950, by A ...

, discovered by himself at Lick Observatory in 1950, was named in his honor in on 1 January 1981 (). The name was proposed by his colleague Arnold Klemola. Wirtanen died in Santa Cruz, California in 1990 following a lengthy illness. His remains were scattered at sea.

References

1910 births 1990 deaths 20th-century American astronomers American people of Finnish descent Discoverers of asteroids Discoverers of comets * Lick Observatory People from Kenosha, Wisconsin {{US-astronomer-stub