enough to explain the low inclination of the NOO ($i\sim23.5$). The perihelion distance remains in the small heliocentric distances ($q\subset(0.14;0.23)$AU) and the summation of angular elements (longitude of perihelion – $\pi$) rises gradually from 210$^\circ$ to $\pi\subset(212;218)^\circ$ after 5000yr integration to the past. Clones derived from the uncertain orbital period did not encounter the Earth but had close flybies within the Hill sphere of Venus ($2\%$) and Mercury ($0.5\%$). This gives a non-zero chance that comet C/1917 F1 Mellish might encounter Venus or Mercury. In fact, this could cause a sudden change in its inclination at least within 5000yr in the past.

We also studied the orbital evolution of the MON and NOO meteors from the SonotaCo database. For a chosen subset of high quality orbits (non-hyperbolic, $a<100$AU), the integration uses a beta parameter representing the solar radiation pressure (@kla04) for each particle ($\beta=2\cdot10^{-5}$) derived from an assumed low bulk density ($\varrho=750\,kg/m^3$) and the typical photometric mass of observed meteors (0.5g) and starts for the epoch and the orbital elements valid for the moment of the meteor observation. The numerical integration computed the orbital evolution for 5000yr to the past (Figure 10 and Figure 11).

Unlike @fox85, perturbed orbits of 