Jan Oort facts for kids
Quick facts for kids
Jan Oort
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Jan Oort in May 1961
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| Born | 28 April 1900 |
| Died | 5 November 1992 (aged 92) |
| Nationality | Dutch |
| Known for |
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| Awards | Vetlesen Prize (1966) Kyoto Prize (1987) |
| Scientific career | |
| Fields | Astronomy |
| Doctoral advisor | Jacobus Cornelius Kapteyn |
Jan Hendrik Oort (born April 28, 1900 – died November 5, 1992) was a famous Dutch astronomer. He helped us understand our home galaxy, the Milky Way. He was also a leader in a new field called radio astronomy.
Many people called him one of the best astronomers of the 20th century. He made amazing discoveries that changed how we see the Universe. In 1955, he was even named one of the 100 most famous living people!
Oort found out that the Milky Way is always spinning. He also showed that our Sun is not at the very center of the galaxy. In 1932, he thought there might be a mysterious, invisible substance called dark matter. Scientists now believe dark matter makes up most of the matter in the Universe. It helps stars and galaxies clump together.
He also discovered the galactic halo. This is a group of stars that orbit the Milky Way, but they are outside its main flat disk. Oort also taught us a lot about comets. He realized that comets come from a huge area far beyond the planets. This area is now called the Oort cloud.
Because of his important work, the Oort cloud, the Oort constants, and even an asteroid (named 1691 Oort) are named after him.
Contents
Jan Oort: A Star Explorer
Early Life and Learning
Jan Oort was born in a small Dutch town called Franeker on April 28, 1900. His father was a doctor, and his mother's family had many religious leaders.
In 1903, his family moved near Leiden. His father worked at a clinic for people with nervous illnesses. Jan grew up in a nice house surrounded by a small forest. His younger brother, John, later became a professor who studied plant diseases.
Jan went to school in Leiden. In 1917, he started studying physics at Groningen University. He said he became interested in science and astronomy in high school. He thought reading Jules Verne books might have sparked his interest.
He chose Groningen because a famous astronomer, Jacobus Cornelius Kapteyn, taught there. Jan was very inspired by Kapteyn's lessons. He started doing research with Kapteyn early in his studies.
After finishing his exams in 1921, Jan worked as an assistant in Groningen. In 1922, he went to the United States. He worked at Yale and helped Frank Schlesinger at the Yale Observatory. He learned about latitude changes, which helped him later in his career.
Amazing Discoveries in Astronomy
In 1924, Oort came back to the Netherlands. He started working at Leiden University. He became a professor there in 1935. In 1926, he earned his doctorate degree. His paper was about fast-moving stars.
Understanding Our Galaxy's Spin
A Swedish astronomer, Bertil Lindblad, suggested that stars in the outer parts of our galaxy spin slower. Oort realized this was true! He created two formulas that explained how the galaxy rotates. These are now known as "Oort's constants."
Oort showed that the Milky Way does not spin all at once. Instead, stars closer to the center spin faster than those farther out. He also calculated that our Sun is about 30,000 light years from the center of the galaxy. It takes about 225 million years for the Sun to complete one orbit!
These findings changed what scientists thought about the Milky Way. Before Oort, people thought the galaxy was perfectly even around the Sun. Oort showed that the Milky Way spins like a giant pinwheel. He proved that stars move on their own, with different speeds depending on where they are.
Because of this breakthrough, Oort became very famous in astronomy. He was offered jobs at Harvard University and Columbia University. But he decided to stay in Leiden.
Life During World War II
In 1940, Nazi Germany took over the Netherlands. The new rulers fired all Jewish professors from universities. Oort refused to work with the occupiers. He resigned from his jobs and moved his family to a quiet village for the rest of the war. There, he started writing a book about how stars move.
Listening to the Universe with Radio Waves
Even before the war ended, Oort started a new project. He worked with a student, Hendrik van de Hulst. In 1951, they successfully found 21-centimeter radio waves coming from hydrogen gas in space.
Oort and his team were the first to study the center of our galaxy using radio waves. They found a huge amount of matter there, mostly stars. They also saw that a lot of gas in that area was moving quickly away from the center.
After the war, Oort became the director of the Leiden Observatory. He led a group that built radio telescopes in the Netherlands. These telescopes helped them map the Milky Way using the 21-centimeter radio waves. They found the galaxy's spiral shape and how gas clouds move.
Oort was one of the first astronomers to see how important radio astronomy would be. He believed that huge clouds of hydrogen gas were in the galaxy's spiral arms. He thought these clouds were where new stars are born. His predictions were later proven right by the new radio observatories.
Uncovering Comet Secrets
Oort also studied comets. He came up with some amazing ideas. He suggested that our Solar System is surrounded by a huge cloud of billions of comets. Many of these "long-period" comets come from this cloud, which is far beyond the orbits of Neptune and Pluto. This cloud is now called the Oort cloud.
He also realized that these comets from far away can get pulled into closer orbits by Jupiter. This can turn them into "periodic comets," like Halley's Comet. Oort was lucky enough to see Halley's Comet twice in his life! Once when he was 10, and again 76 years later from an airplane.
Oort led the Leiden Observatory until 1970. Even after he retired, he kept researching. He wrote about the galactic center and how galaxies are grouped together. He continued to study the Milky Way and other galaxies until he died at age 92.
One of Oort's special skills was explaining difficult math ideas in simple ways. He could take complex theories and turn them into clear physical models.
Personal Life
In 1927, Oort married Johanna Maria (Mieke) Graadt van Roggen. They had two sons, Coenraad and Abraham, and a daughter, Marijke. His son Abraham also became a professor who studied climate.
Oort loved art and knew a lot about it. When he traveled, he always tried to visit museums and art shows.
People who knew him remembered him as a tall, kind, and polite man.
Some of Oort's Discoveries
- In 1924, Oort found the galactic halo. This is a group of stars orbiting the Milky Way outside its main disk.
- In 1927, he figured out that the center of the Milky Way was about 19,200 light years from Earth. It is in the direction of the Sagittarius constellation.
- In 1932, he was the first to find proof of dark matter. He measured how stars moved in the Milky Way. He saw that the galaxy's flat part had more mass than the visible matter.
- He showed that the Milky Way has a mass 100 billion times greater than our Sun.
- In 1950, he suggested that comets come from a shared area of the Solar System. This area is now called the Oort cloud.
- He found that the light from the Crab Nebula was polarized. This meant it was likely made by synchrotron radiation.
Honours
Jan Oort received many awards for his work:
- Bruce Medal (1942)
- Gold Medal of the Royal Astronomical Society (1946)
- Janssen Medal (1946)
- Prix Jules Janssen (1947)
- Henry Norris Russell Lectureship (1951)
- Gouden Ganzenveer (1960)
- Vetlesen Prize (1966)
- Jansky Prize (1967)
- Karl Schwarzschild Medal (1972)
- ADION medal (1978)
- Balzan Prize for Astrophysics (1984)
- Kyoto Prize (1987)
Things named after him:
- 1691 Oort (an asteroid)
- Oort cloud
- Oort limit
- Oort constants
- The Oort building at the Leiden Observatory
He was also a member of many important groups, like the Royal Netherlands Academy of Arts and Sciences.
When he died, a Nobel Prize winner named Subrahmanyan Chandrasekhar said, "The great oak of Astronomy has been felled, and we are lost without its shadow." This shows how important Jan Oort was to the world of science.
Images for kids
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Oort with international astronomy colleagues on horseback exploring the Chilean mountains for a place to build the European Southern Observatory, Cerro El Morado, Andes, Chile, June 1963.
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The single dish Dwingeloo Radio Observatory, the Netherlands, 2007.
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Westerbork Synthesis Radio Telescope, the Netherlands, 2007.
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Oort by an image of the galaxy Messier 81.
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Radio map of the galaxy based on the 21cm emission line by Oort et al. (1958)
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Commemorative plate at the house where Jan Oort was born in Franeker (Zilverstraat 18)
See also
In Spanish: Jan Hendrik Oort para niños
