- Born:
- November 2, 1885, Nashville, Missouri, U.S.
- Died:
- October 20, 1972, Boulder, Colorado (aged 86)
Harlow Shapley
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Who was Harlow Shapley?
Harlow Shapley (1885–1972) was an American astronomer who determined that the Sun is not at the center of the Milky Way Galaxy but is located approximately 30,000 light-years away within the galaxy's central plane.
Shapley's study of binary star systems led him to propose that Cepheid variables are pulsating stars rather than eclipsing star pairs. At Mount Wilson Observatory, he studied globular clusters, discovering they were concentrated in Sagittarius. Using RR Lyrae variable stars to measure distances, Shapley concluded these clusters orbit a center in Sagittarius, far from the Sun, thus reshaping understanding of the Milky Way's size and structure.
Shapley also studied neighboring galaxies, discovering galaxies tend to occur in clusters, which he called metagalaxies. In 1953, he proposed the "liquid water belt" theory, now known as the habitable zone, suggesting a planet must be a certain distance from its star to support liquid water and life. His son was Nobel Prize-winning economist Lloyd Shapley.
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What field of science did Harlow Shapley work in?
Harlow Shapley was an American astronomer who worked in the field of galactic astronomy. His work led to the first realistic estimate for the actual size of the Milky Way Galaxy.
Shapley's studies of globular clusters and variable stars allowed him to determine the distances to these clusters and map their distribution in space. He deduced that the Sun was not at the center of the Galaxy, but some 30,000 light-years away. Shapley also studied neighboring galaxies and found that galaxies tend to occur in clusters, which he called metagalaxies.
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What is Harlow Shapley known for discovering about our galaxy?
Harlow Shapley, an American astronomer, is renowned for his groundbreaking work in determining the Sun's location within the Milky Way Galaxy. Before Shapley's research, it was believed that the Sun resided near the galaxy's center. However, in 1917, Shapley deduced that the Sun is situated in the central plane of the Milky Way but approximately 30,000 light-years away from the center.
Shapley's findings relied on his study of globular clusters, which are densely packed groups of stars. By analyzing their distribution, particularly the concentration in the constellation Sagittarius, and employing RR Lyrae variable stars to accurately gauge distance, he concluded that these clusters formed a sphere around the Galaxy's center. This led him to correctly estimate the size of the Milky Way Galaxy.
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How did Shapley use globular clusters to learn about the Milky Way?
Harlow Shapley determined that the Sun was not at the center of the Milky Way Galaxy by studying globular clusters. In 1917, Shapley found that these clusters were distributed in a sphere whose center lies in Sagittarius. Assuming that the clusters would gather around the Galaxy's center, he deduced that the Sun was about 50,000 light-years away from it; this number was later corrected to 30,000 light-years. This work led to the first realistic estimate for the actual size of the Galaxy and was a milestone in galactic astronomy.
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What was Harlow Shapley's role in the debate about the size of the universe?
Harlow Shapley played a central role in the early 20th-century debate regarding the size of the universe. In 1917, Shapley challenged the prevailing view, arguing the Milky Way Galaxy was far larger than previously assumed. Through his study of globular clusters, he placed the Sun far from the galaxy's center, about 30,000 light-years away.
Shapley's belief in a large Milky Way led him to incorrectly argue that spiral nebulae were contained within it. He debated Heber Curtis in 1920 on the scale of the universe, with Curtis arguing that spiral nebulae were separate galaxies. Though Shapley was incorrect about the spiral nebulae, his estimation of the Milky Way's size was a milestone in galactic astronomy.
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How did Harlow Shapley's work influence the study of astronomy?
Harlow Shapley's work significantly influenced the study of astronomy by changing the understanding of the Milky Way Galaxy's size and structure.
Before Shapley, it was believed that the Sun was at the center of the Galaxy. In 1917, Shapley's study of globular clusters led him to a different conclusion. He deduced that the center of the globular cluster system lies in the constellation Sagittarius, about 30,000 light-years away from the Sun. He proposed that this center was also the center of the Milky Way Galaxy, which was far larger than previously thought.
Shapley's findings marked a milestone in galactic astronomy, providing the first realistic estimate of the Galaxy's actual size and displacing the Sun from the center of the stellar system.
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Harlow Shapley (born November 2, 1885, Nashville, Missouri, U.S.—died October 20, 1972, Boulder, Colorado) was an American astronomer who deduced that the Sun lies near the central plane of the Milky Way Galaxy and was not at the centre but some 30,000 light-years away.
In 1911 Shapley, working with results given by Henry Norris Russell, began finding the dimensions of stars in a number of binary systems from measurements of their light variation when they eclipse one another. These methods remained the standard procedure for more than 30 years. Shapley also showed that Cepheid variables cannot be star pairs that eclipse each other. He was the first to propose that they are pulsating stars.
Shapley joined the staff of the Mount Wilson Observatory, Pasadena, California, in 1914. Employing the 1.5-metre (60-inch) reflecting telescope at Mount Wilson, he made a study of the distribution of the globular clusters in the Milky Way Galaxy; these clusters are immense, densely packed groups of stars, some containing as many as 1,000,000 members. He found that of the 100 clusters known at the time, one-third lay within the boundary of the constellation Sagittarius. Using the newly developed concept that RR Lyrae variable stars accurately reveal their distance by their period of variation and apparent brightness, he found that the clusters were distributed roughly in a sphere whose centre lay in Sagittarius. Since the clusters assumed a spherical arrangement, it was logical to conclude that they would cluster around the centre of the Galaxy; from this conclusion and his other distance data Shapley deduced that the Sun lies at a distance of about 50,000 light-years from the centre of the Galaxy; the number was later corrected to 30,000 light-years. Before Shapley, the Sun was believed to lie near the centre of the Galaxy. His work, which led to the first realistic estimate for the actual size of the Galaxy, thus was a milestone in galactic astronomy.
At this time, the nature of the spiral nebulae, such as that of Andromeda, was a subject of much debate. On April 26, 1920, Shapley and American astronomer Heber Curtis debated “the scale of the Universe” at a meeting of the National Academy of Sciences in Washington, D.C. Their “Great Debate,” as it came to be called, had no clear winner. Curtis did not believe in Shapley’s size for the Milky Way, but his belief that the spiral nebulae were other galaxies (“island universes”) proved correct. Shapley had correctly appreciated the Galaxy’s great size but posited a universe consisting entirely of the Milky Way with the spiral nebulae as objects like the globular clusters.
In addition to his studies of the Galaxy, Shapley studied the neighbouring galaxies, especially the Magellanic Clouds, and found that galaxies tend to occur in clusters, which he called metagalaxies. In 1953 he proposed the “liquid water belt” theory, which stated that a planet had to be a certain distance from its star to develop an atmosphere and have liquid water, and therefore life. This concept is now called the habitable zone. Shapley became professor of astronomy at Harvard University, later director of Harvard College Observatory (1921–52), and was made director emeritus and Paine Professor of Astronomy at Harvard in 1952. His works include Star Clusters (1930), Flights from Chaos (1930), Galaxies (1943), The Inner Metagalaxy (1957), and Of Stars and Men: The Human Response to an Expanding Universe (1958; film 1962). He was the father of Nobel Prize-winning economist Lloyd Shapley.