Lectures on astronomical theories . upations take place before the is to be observed, that, owing to the proximity of theorbits of the first and second satellites to the planet, boththe immersion and emersion of either of them can never be-observed in any single eclipse, the immersion being con-cealed by the body, if the planet be past its opposition, theemersion, if not yet arrived at it. So also of the commencement of the occultation, or the passage ofthe satellite behind the disc, takes place while obscured bythe shadow, before opposition, and its re-emergence af
Lectures on astronomical theories . upations take place before the is to be observed, that, owing to the proximity of theorbits of the first and second satellites to the planet, boththe immersion and emersion of either of them can never be-observed in any single eclipse, the immersion being con-cealed by the body, if the planet be past its opposition, theemersion, if not yet arrived at it. So also of the commencement of the occultation, or the passage ofthe satellite behind the disc, takes place while obscured bythe shadow, before opposition, and its re-emergence these particulars will be easily apparent on mere in-spection of the Figure, Art. 536. It is only during the shorttime that the earh is in the arc G. H., i. e. between the sunand Jupiter, that the cone of the shadow converging (whilethat of the visual rays diverges) behind the planet, permitstheir occultations to be completely observed both at ingressand egress, unobscured, the eclipses being then invisible. LECTURE Tin pencd (solar period) of Ift^ i^mH is yuo (?neo-lif 2i yein) Tke lerrestrial prrio^ u at present reckoned, according to the theory a/cnmetary orhit», at daya. Thii ve eonnder, aceordin.,jo the law of gravitation, npreKenU 3 orbital relurru ^f the co;(m1. Whertfare 2,410, dioiiUA by 3, equaU 803j. But the earlArequtre* 146 days to eompUu the leveTUh (annuo/) orbit, and taking the velocity ^ the comet al an»-haifthat tif the earth, 2,4Hi+a90=J7OO And 2700, divided by 3, eguaU 90G dayt, tohieh ie, therefore, the lolar period.^f- pant Hill teu COMETARY ORBITS IN RELATION TO THE LAW OF GRAVITATION JOHN HARRIS.
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Keywords: ., bookcentury18, bookdecade1870, booksubjectastronomy, bookyear1876
