The Solar System


Who is Jan Hendrick Oort?

The Oort Cloud is named for Jan Hendrick Oort (1900–1992), who is widely considered to have been the leading Dutch astronomer of his generation. His scientific research covered a great range of subjects, from the structure of galaxies to the way comets are formed. He was also a pioneer of radio astronomy.

In 1927 Oort investigated the then-revolutionary concept that the Milky Way galaxy is rotating about its center. By studying the motion of stars near the Sun, Oort concluded that our solar system was not at the center of the galaxy, as had previously been believed, but somewhere toward the outer edge. Oort then set out to decipher the structure of the Milky Way, using theoretical models and the tools of radio astronomy.

Oort’s work on the origin of comets led him to propose, in 1950, that a huge, shell-shaped zone of space, well beyond the orbit of Pluto and stretching out trillions of miles beyond the Sun in all directions, contains trillions of slowly orbiting, inactive comets. Those comets remain there until a passing gas cloud or star disturbs the orbit of a comet, sending it toward the Sun and inner solar system in a highly elliptical orbit. Today, this zone of long-period comets bears Jan Oort’s name.


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