Assertion: comet | /r/HasProperty | estimated
Facets:
value: due to its long elliptical orbit
type: CAUSE
Source sentences:
text: Due to its long elliptical orbit, it is estimated that Donati's Comet will not be seen passing by Earth again until the 4th millennium: Asten calculated a perihelion date of September 3738 and an orbital period of 1880 years[citation needed], and Hill suggested September 3808 and a period of 1950 years[citation needed].
text: It is estimated that it will return in 2,300 years, in the year 4534!