2018年6月27日 · Jan Oort was born on April 28, 1900, in the farming village of Franeker in Holland. At the age of 17 he entered the University of Groningen and earned his doctoral degree in 1926. He received the Bachiene Foundation Prize (1920), undertook research at the Leiden Observatory (1924), and lived abroad as a research associate at the Yale University ...

2018年5月11日 · Oort cloud A spherical zone surrounding, but gravitationally bound to the solar system, at distances between 20 000 and 100 000 AU from the Sun, which contains about 10 12 comets. Its existence was first proposed in 1950 by the …

With Christiaan Alexander Muller and Jan Hendrik Oort. “The Spiral Structure of the Outer Part of the Galactic System Derived from the Hydrogen Emission at 21 cm Wavelength.” Bulletin of the Astronomical Institutes of The Netherlands 12 (1954): 117–149. First survey of Galactic atomic hydrogen: full discussion of instrument, observations ...

Years before Kuiper proposed the existence of these objects, Dutch astronomer Jan Oort (1900 – 1992) had noticed that orbital calculations revealed no comets arrived within detection range of Earth from outside the solar system. He also determined that many of them originally came from distances as close as just beyond the orbit of Pluto and ...

2018年5月23日 · Oort cloud — A vast, spherical cloud of some one trillion cometary nuclei that orbit the Sun. The cloud, named after Dutch astronomer Jan Oort who first suggested its existence, extends to a distance of 105 AU from the Sun. Planetesimal — Small, 0.6 mi (1 km) sized objects made of rock and/or ice that accrete to form proto planets.

Discovered in the 1940s by Dutch astronomer Jan Oort, it was named the Oort Cloud in his honor. "The Oort Cloud is the result of a long game of interplanetary pinball," says noted comet hunter David H. Levy. The youthful solar system was filled with comets—in Earth's primordial sky there must have been dozens of bright comets at a time.

Other Soviet astronomers realized this and quickly reported finding polarization. Few astronomers in the west believed the initial claims, but Jan Oort in the Netherlands convinced his friend Greenstein to use the Mount Palomar telescope, the largest optical telescope in the world, to search for polarization, which he found.

Dutch astronomer Jan Hendrik Oort noted in 1950 that the source of new comets was a shell located between 20,000 and 100,000 AU from the Sun. The existence of the Oort cloud is now widely accepted. Astronomers believe that comets in the Oort cloud formed near Uranus and Neptune and were gravitationally scattered by these two planets into their ...

2018年5月29日 · Around this time, Dutch astronomer Jan Oort used a radio telescope to map the spiral structure of the Milky Way galaxy. In 1960, several small but intense radio sources were discovered that did not fit into any previously known classification. They …

Jan Oort (1900–1992) observed in 1950 that the highly elliptical orbits of long-period comets seem to extend outward from the sun in all directions to distances of about 50,000 AU. Oort suggested that the outermost portion of the solar system is a huge spherical cloud of protocomets: small bodies composed of ice and dust left over from the ...