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, p ...

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

and discoverer of

comet A comet is an icy, small Solar System body that warms and begins to release gases when passing close to the Sun, a process called outgassing. This produces an extended, gravitationally unbound atmosphere or Coma (cometary), coma surrounding ...

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 (California), Mount Hamilton, in the Diablo Range just east of San Jose, California, United States. The ...

. He was of Finnish ancestry. Wirtanen was born in

Kenosha, Wisconsin Kenosha () is a city in Kenosha County, Wisconsin, United States, and its county seat. It is the List of cities in Wisconsin, fourth-most populous city in Wisconsin, with a population of 99,986 at the 2020 United States census, 2020 census. S ...

. 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 The California Institute of Technology (branded as Caltech) is a private research university in Pasadena, California, United States. The university is responsible for many modern scientific advancements and is among a small group of institutes ...

and worked on ballistics at the

Naval Ordnance Test Station Naval Air Weapons Station (NAWS) China Lake is a large military installation in California that supports the research, testing and evaluation programs of the United States Navy. It is part of Navy Region Southwest under Commander, Navy Install ...

in the

Mojave Desert The Mojave Desert (; ; ) is a desert in the rain shadow of the southern Sierra Nevada mountains and Transverse Ranges in the Southwestern United States. Named for the Indigenous peoples of the Americas, indigenous Mohave people, it is located pr ...

. He returned to Lick Observatory after the war, remaining there until his retirement in 1978. Wirtanen discovered periodic comet 46P/Wirtanen, as well as eight

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 ...

s, including notably the

Apollo asteroid The Apollo asteroids are a group of near-Earth asteroids named after 1862 Apollo, discovered by German astronomer Karl Reinmuth in the 1930s. They are Earth-crossing asteroids that have an orbital semi-major axis greater than that of the Ear ...

(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 ...

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 H ...

. 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 Santa Cruz (Spanish language, Spanish for "Holy Cross") is the largest city and the county seat of Santa Cruz County, California, Santa Cruz County, in Northern California. As of the 2020 United States census, 2020 census, the city population ...

in 1990 following a lengthy illness. His remains were scattered at sea.

References

{{DEFAULTSORT:Wirtanen, Carl 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