Finding Long Lost Lexell's Comet: The Fate of the First Discovered Near-Earth Object

TL;DR

This study revisits the fate of Lexell's Comet, using historical observations and dynamical simulations, concluding it likely remains in the Solar System and identifying potential descendants and meteor connections.

Contribution

It provides a new dynamical analysis of Lexell's Comet using historical data, estimating its current status and potential descendants, which was not previously established.

Findings

98% chance Lexell's Comet remains in the Solar System by 2000

Lexell's Comet is likely one of the largest NEAs with a diameter over 10 km

Meteor observations can help constrain the comet's orbit despite it being lost

Abstract

Jupiter-family Comet D/1770 L1 (Lexell) was the first discovered Near-Earth Object (NEO), and passed the Earth on 1770 Jul 1 at a recorded distance of 0.015 au. The comet was subsequently lost due to unfavorable observing circumstances during its next apparition followed by a close encounter with Jupiter in 1779. Since then, the fate of D/Lexell has attracted interest from the scientific community, and now we revisit this long-standing question. We investigate the dynamical evolution of D/Lexell based on a set of orbits recalculated using the observations made by Charles Messier, the comet's discoverer, and find that there is a $98\%$ chance that D/Lexell remains in the Solar System by the year of 2000. This finding remains valid even if a moderate non-gravitational effect is imposed. Messier's observations also suggest that the comet is one of the largest known near-Earth comets, with a nucleus of $\gtrsim 10$ km in diameter. This implies that the comet should have been detected by contemporary NEO surveys regardless of its activity level if it has remained in the inner Solar System. We identify asteroid 2010 JL$_{33}$ as a possible descendant of D/Lexell, with a $0.8\%$ probability of chance alignment, but a direct orbital linkage of the two bodies has not been successfully accomplished. We also use the recalculated orbit to investigate the meteors potentially originating from D/Lexell. While no associated meteors have been unambiguously detected, we show that meteor observations can be used to better constrain the orbit of D/Lexell despite the comet being long lost.