Walter Baade
Encyclopedia

Wilhelm Heinrich Walter Baade (March 24, 1893 – June 25, 1960) was a German
Germany
Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...

 astronomer
Astronomer
An astronomer is a scientist who studies celestial bodies such as planets, stars and galaxies.Historically, astronomy was more concerned with the classification and description of phenomena in the sky, while astrophysics attempted to explain these phenomena and the differences between them using...

 who worked in the USA from 1931 to 1959.

Biography

He took advantage of wartime blackout conditions during World War II
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...

, which reduced light pollution
Light pollution
Light pollution, also known as photopollution or luminous pollution, is excessive or obtrusive artificial light.The International Dark-Sky Association defines light pollution as:...

 at Mount Wilson Observatory
Mount Wilson Observatory
The Mount Wilson Observatory is an astronomical observatory in Los Angeles County, California, United States. The MWO is located on Mount Wilson, a 5,715 foot peak in the San Gabriel Mountains near Pasadena, northeast of Los Angeles...

, to resolve stars in the center of the Andromeda galaxy
Andromeda Galaxy
The Andromeda Galaxy is a spiral galaxy approximately 2.5 million light-years from Earth in the constellation Andromeda. It is also known as Messier 31, M31, or NGC 224, and is often referred to as the Great Andromeda Nebula in older texts. Andromeda is the nearest spiral galaxy to the...

 for the first time, which led him to define distinct "populations" for stars (Population I and Population II). The same observations led him to discover that there are two types of Cepheid variable
Cepheid variable
A Cepheid is a member of a class of very luminous variable stars. The strong direct relationship between a Cepheid variable's luminosity and pulsation period, secures for Cepheids their status as important standard candles for establishing the Galactic and extragalactic distance scales.Cepheid...

 stars. This discovery led him to recalculate the size of the known universe, doubling the previous calculation made by Hubble
Hubble
Hubble is a surname and may refer to:* Brian Hubble , American painter and illustrator* Eddie Hubble , American Jazz trombonist* Edwin Hubble , American astronomer* Jack Hubble , English cricketer...

 in 1929. He announced this finding to considerable astonishment at the 1952 meeting of the International Astronomical Union
International Astronomical Union
The International Astronomical Union IAU is a collection of professional astronomers, at the Ph.D. level and beyond, active in professional research and education in astronomy...

 in Rome.

Together with Fritz Zwicky
Fritz Zwicky
Fritz Zwicky was a Swiss astronomer. He worked most of his life at the California Institute of Technology in the United States of America, where he made many important contributions in theoretical and observational astronomy.- Biography :Fritz Zwicky was born in Varna, Bulgaria to a Swiss father....

, he identified supernova
Supernova
A supernova is a stellar explosion that is more energetic than a nova. It is pronounced with the plural supernovae or supernovas. Supernovae are extremely luminous and cause a burst of radiation that often briefly outshines an entire galaxy, before fading from view over several weeks or months...

e as a new category of astronomical objects Zwicky and he also proposed the existence of neutron star
Neutron star
A neutron star is a type of stellar remnant that can result from the gravitational collapse of a massive star during a Type II, Type Ib or Type Ic supernova event. Such stars are composed almost entirely of neutrons, which are subatomic particles without electrical charge and with a slightly larger...

s, and proposed that supernova
Supernova
A supernova is a stellar explosion that is more energetic than a nova. It is pronounced with the plural supernovae or supernovas. Supernovae are extremely luminous and cause a burst of radiation that often briefly outshines an entire galaxy, before fading from view over several weeks or months...

e could create neutron star
Neutron star
A neutron star is a type of stellar remnant that can result from the gravitational collapse of a massive star during a Type II, Type Ib or Type Ic supernova event. Such stars are composed almost entirely of neutrons, which are subatomic particles without electrical charge and with a slightly larger...

s.

Beginning in 1952 he and Rudolph Minkowski
Rudolph Minkowski
Rudolph Minkowski was a German-American astronomer. His father was the physiologist Oskar Minkowski and his uncle was Hermann Minkowski....

 identified the optical counterparts of various radio
Radio astronomy
Radio astronomy is a subfield of astronomy that studies celestial objects at radio frequencies. The initial detection of radio waves from an astronomical object was made in the 1930s, when Karl Jansky observed radiation coming from the Milky Way. Subsequent observations have identified a number of...

 sources. He discovered 10 asteroid
Asteroid
Asteroids are a class of small Solar System bodies in orbit around the Sun. They have also been called planetoids, especially the larger ones...

s, including notably 944 Hidalgo
944 Hidalgo
944 Hidalgo is a small Solar System body with a semi-major axis beyond Jupiter's and an orbital period of 13.77 years. This makes it a centaur, but it was discovered in 1920 and has hence traditionally been considered an asteroid....

 (long orbital period) and the Apollo-class asteroid
Apollo asteroid
The Apollo asteroids are a group of near-Earth asteroids named after 1862 Apollo, the first asteroid of this group to be discovered by Karl Wilhelm Reinmuth...

 1566 Icarus
1566 Icarus
1566 Icarus is an Apollo asteroid that at perihelion comes closer to the Sun than Mercury, i.e. it is a Mercury-crossing asteroid. It is also a Venus and Mars-crosser. It is named after Icarus of Greek mythology, who flew too close to the Sun...

 (whose perihelion is closer than that of Mercury
Mercury (planet)
Mercury is the innermost and smallest planet in the Solar System, orbiting the Sun once every 87.969 Earth days. The orbit of Mercury has the highest eccentricity of all the Solar System planets, and it has the smallest axial tilt. It completes three rotations about its axis for every two orbits...

) and the Amor asteroid
Amor asteroid
The Amor asteroids are a group of near-Earth asteroids named after the asteroid 1221 Amor. They approach the orbit of the Earth from beyond, but do not cross it. Most Amors do cross the orbit of Mars...

 1036 Ganymed
1036 Ganymed
1036 Ganymed is the largest Amor asteroid, at about 32 km in diameter. It was discovered by Walter Baade on October 23, 1924, and is named after Ganymede, the Trojan prince turned god whom Zeus designated the cupbearer to the Greek gods...

.

Honors

Awards
  • Gold Medal of the Royal Astronomical Society
    Gold Medal of the Royal Astronomical Society
    -History:In the early years, more than one medal was often awarded in a year, but by 1833 only one medal was being awarded per year. This caused a problem when Neptune was discovered in 1846, because many felt an award should jointly be made to John Couch Adams and Urbain Le Verrier...

     (1954)
  • Bruce Medal
    Bruce Medal
    The Catherine Wolfe Bruce Gold Medal is awarded every year by the Astronomical Society of the Pacific for outstanding lifetime contributions to astronomy. It is named after Catherine Wolfe Bruce, an American patroness of astronomy, and was first awarded in 1898...

     (1955)
  • Henry Norris Russell Lectureship
    Henry Norris Russell Lectureship
    The Henry Norris Russell Lectureship is awarded each year by the American Astronomical Society in recognition of a lifetime of excellence in astronomical research.-Previous lecturers:This list of lecturers is from the American Astronomical Society's website....

     of the American Astronomical Society
    American Astronomical Society
    The American Astronomical Society is an American society of professional astronomers and other interested individuals, headquartered in Washington, DC...

     (1958)

Named after him
  • Asteroid
    Asteroid
    Asteroids are a class of small Solar System bodies in orbit around the Sun. They have also been called planetoids, especially the larger ones...

     1501 Baade
    1501 Baade
    1501 Baade is a main-belt asteroid discovered on October 20, 1938 by Wachmann, A. at Bergedorf.- External links :*...

  • The crater Baade
    Baade (crater)
    Baade is a lunar impact crater that is located near the southwest limb of the Moon on the near side, to the southwest of the enormous Mare Orientale impact basin. The area to the east of this crater forms the junction between the 280-km-long Vallis Bouvard to the north and the narrower,...

     on the Moon
    Moon
    The Moon is Earth's only known natural satellite,There are a number of near-Earth asteroids including 3753 Cruithne that are co-orbital with Earth: their orbits bring them close to Earth for periods of time but then alter in the long term . These are quasi-satellites and not true moons. For more...

  • Vallis Baade
    Vallis Baade
    Vallis Baade is a 203 km long sinuous valley on the Moon running south-southeast from the crater Baade and centered at...

    , a vallis
    Vallis
    Vallis is the Latin word for valley. It is used in planetary geology for the naming of landform features on other planets....

     (valley) on the Moon
  • One of the two Magellan telescope
    Telescope
    A telescope is an instrument that aids in the observation of remote objects by collecting electromagnetic radiation . The first known practical telescopes were invented in the Netherlands at the beginning of the 1600s , using glass lenses...

    s
  • The asteroid 966 Muschi
    966 Muschi
    966 Muschi is a main belt asteroid. It was discovered on November 9, 1921 by the German astronomer Walter Baade out of the Hamburger Sternwarte. Baade named the asteroid after his wife's nickname.-External links:*...

    , after his wife's nickname

See also

  • Baade's Window
    Baade's Window
    Baade's Window is an area of the sky with relatively low amounts of interstellar "dust" along the line of sight from the Earth. This area is considered an observational "window" as the normally obscured Galactic Center of the Milky Way is visible in this direction. It is named for astronomer Walter...

    , an observational area he identified in the 1940's as being relatively free of dust that presents and a view of the Galactic Center
    Galactic Center
    The Galactic Center is the rotational center of the Milky Way galaxy. It is located at a distance of 8.33±0.35 kpc from the Earth in the direction of the constellations Sagittarius, Ophiuchus, and Scorpius where the Milky Way appears brightest...

     in Sagittarius
    Sagittarius (astrology)
    Sagittarius is the ninth astrological sign in the Zodiac, which spans the zodiac between the 240th and 269th degree of celestial longitude...

  • Baade's Star, now known as the Crab Pulsar
    Crab Pulsar
    The Crab Pulsar is a relatively young neutron star. The star is the central star in the Crab Nebula, a remnant of the supernova SN 1054, which was widely observed on Earth in the year 1054...

    , was first identified as being directly associated with the Crab Nebula
    Crab Nebula
    The Crab Nebula  is a supernova remnant and pulsar wind nebula in the constellation of Taurus...

     by him.

External links


Obituaries

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