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OORT ? WHAT IS THIS ?

OORT (Jan Hendrik) : Dutch astronomer (1900-1992)

He made major contributions to knowledge of our galaxy.
He brought to the fore its differential rotation, worked out its weigth
and determined its spiral structure.
Oort studied comets as well. The result of this work was a theory,
now widely accepted, that comets come from a distant cloud of comet-stuff,
situated between 40000 and 100000 astronomical units from the sun
and called the Oort cloud.