Jan Oort facts for kids
Quick facts for kids
Jan Oort
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Oort in 1970
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| Born |
Jan Hendrik Oort
28 April 1900 |
| Died | 5 November 1992 (aged 92) |
| 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 made huge discoveries about our home galaxy, the Milky Way. He was also a pioneer in using radio astronomy to study space.
Many people consider Oort one of the greatest astronomers of the 20th century. He truly changed how we understand the universe. He figured out that the Milky Way spins and that our Sun is not at its center. Oort also found evidence for "invisible matter" in space, which scientists now call dark matter. This dark matter helps hold galaxies together.
Oort also discovered the galactic halo, a group of stars orbiting the Milky Way outside its main disk. He made important discoveries about comets, realizing that many come from a distant region of our Solar System. This region is now known as the Oort cloud, named after him. Other things named in his honor include the Oort constants, the Oort limit, a crater on Pluto, and the asteroid 1691 Oort.
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Early Life and Learning
Jan Oort was born in Franeker, a small town in the Netherlands, on April 28, 1900. His father, Abraham Hermanus Oort, was a doctor. His mother, Ruth Hannah Faber, came from a family of religious leaders.
In 1903, Jan's family moved to Oegstgeest, near Leiden. His father became the director of a clinic for nervous illnesses. Jan remembered growing up in a lovely small forest around the clinic. His younger brother, John, later became a professor who studied plant diseases.
Jan went to school in Oegstgeest and Leiden. In 1917, he went to Groningen University to study physics. He had become interested in science and astronomy during high school. He thought reading the adventure stories of Jules Verne might have sparked his interest.
He chose Groningen because a well-known astronomer, Jacobus Cornelius Kapteyn, taught there. Oort was very inspired by Professor Kapteyn's teaching. He decided to focus on astronomy and began research with Kapteyn early in his studies. After finishing his exams in 1921, Oort worked as an assistant in Groningen. He then spent a year in the United States at Yale University before returning to the Netherlands.
Amazing Discoveries in Space
In 1924, Oort started working at Leiden University. He quickly became a research assistant and later a professor. In 1926, he earned his doctorate for his work on fast-moving stars.
A year later, another astronomer suggested that stars in the outer parts of our galaxy spin slower than those closer to the center. Oort realized this was true and could be proven by observing the stars. He created two formulas, now called "Oort's constants," to describe how the galaxy rotates.
Oort showed that the Milky Way does not spin as one solid piece. Instead, stars closer to the center move much faster than those farther out. He calculated that our Sun is about 30,000 light-years from the galaxy's center. It takes about 225 million years for the Sun to complete one orbit! These discoveries changed how scientists understood our galaxy. Before Oort, many thought the Sun was at the center of a more symmetrical galaxy.
In the early 1930s, Oort became very famous in astronomy. He received job offers from big universities like Harvard and Columbia University. However, he chose to stay at Leiden. In 1939, he studied the Crab Nebula and concluded it was formed from a huge star explosion called a supernova.
Challenges During Wartime
In 1940, the Netherlands faced a difficult time when the country was taken over. Soon after, professors were unfairly removed from their jobs at Leiden University. Oort was deeply affected by this.
He bravely refused to work with the new rulers. He resigned from his university and observatory positions. Oort took his family to a quiet village called Hulshorst to stay safe during the war. There, he began writing a book about how stars move.
Exploring Space with Radio Waves
Even before the war ended, Oort started an exciting new project. He worked with a student to detect radio waves coming from hydrogen gas in space. In 1951, they succeeded in finding these 21-centimeter radio emissions.
After the war, Oort returned to Leiden and became the director of the Observatory. He led a team that built large radio telescopes in the Netherlands. They used these telescopes and the 21-centimeter radio waves to map the Milky Way. They discovered its large spiral shape, its center, and how gas clouds move within it.
Oort was one of the first astronomers to understand how important radio astronomy would be. He predicted that huge clouds of hydrogen gas existed in the galaxy's spiral arms. He believed these clouds were where new stars are born. His predictions were later proven true by the new radio observatories. Oort's work helped the Netherlands become a leader in space studies after the war.
Comets and the Oort Cloud
Oort also made amazing discoveries about comets. He suggested that our Solar System is surrounded by a massive cloud of billions of comets. This cloud is located far beyond the orbits of Neptune and Pluto. Today, we call this distant region the Oort cloud.
He also realized that giant planets like Jupiter can pull these distant comets into closer orbits. This is how some comets, like Halley's Comet, become "periodic comets" that we see regularly.
Jan Oort had a special connection to Halley's Comet. He was one of the few people to see it twice in his life! He first saw it at age 10 with his father in 1910. Then, 76 years later in 1986, he flew in a plane to see the famous comet once more.
Oort continued his research on the Milky Way and other galaxies until shortly before he passed away at 92. He was known for his ability to explain complex mathematical ideas in simple, understandable ways.
His Life and Legacy
In 1927, Jan Oort married Johanna Maria (Mieke) Graadt van Roggen. They had two sons, Coenraad and Abraham, and a daughter, Marijke. His son Abraham later became a professor of climate science at Princeton University.
Oort was also very interested in art. He loved visiting museums and art exhibitions when he traveled. Colleagues remembered him as a tall, kind, and polite man.
Jan Oort received many awards for his work, including the Vetlesen Prize and the Kyoto Prize. Many things in space are named after him, like the Oort Cloud, an asteroid, and a crater on Pluto. When he died in 1992, another famous astrophysicist, Subrahmanyan Chandrasekhar, said, "The great oak of Astronomy has been felled, and we are lost without its shadow." This shows how much he was respected and how important his work was to the world of astronomy.
Images for kids
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Oort by an image of the galaxy Messier 81.
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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
