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

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.

• The paper reconstructs Lexell’s comet trajectory by integrating 18th-century observations with modern computational methods.
• It finds a 98% probability that Lexell’s comet remains within the Solar System, suggesting potential detection in current NEO surveys.
• The study uses orbital simulations to assess meteor shower predictions and highlights challenges in linking historical comets to contemporary asteroids.

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

The paper "Finding Long Lost Lexell's Comet: The Fate of the First Discovered Near-Earth Object" presents a comprehensive study of D/1770 L1 (Lexell), believed to be one of the earliest observed Near-Earth Objects (NEOs). The comet, recognized for its close approach to Earth in 1770, vanished from the astronomical records due to observational challenges and gravitational interactions. This work revisits the trajectory and potential current status of the comet using historical observations and advanced computational techniques.

The authors meticulously reconstruct Lexell's trajectory using original observations by Charles Messier, factoring in positional inaccuracies due to reference meridians and time systems of the 18th century. Utilizing modern computational methods, they calculate the probable dynamical evolution of the comet's orbit, integrating orbital elements with perturbations from planetary influences. A significant finding is the 98% probability that Lexell's comet has remained within the Solar System boundaries, a conclusion robust even with the incorporation of moderate non-gravitational forces.

The paper further explores the possibility of Lexell's comet being observed in contemporary NEO surveys as an inactive or dormant object. Given Messier's observations deriving a substantial nucleus diameter, the authors posit that if Lexell's comet remains in the inner Solar System, its size would make it detectable. They analyze modern asteroid records, identifying asteroid 2010 JL$_{33}$ as a candidate for being Lexell's descendant, supported by the low probability (0.8%) of a chance orbital alignment. Despite this statistical corroboration, a definitive dynamic link between 2010 JL$_{33}$ and Lexell’s comet is not achieved, due to the trajectory's sensitivity to historical Jupiter encounters.

Further examination involves simulating potential meteor showers linked to dust ejected by Lexell across its apparitions. The variability in predicted meteor activity, both historical and future, critically depends on the comet's precise trajectory, especially post-1779. The absence of strong historical meteoric records coinciding with simulations suggests either a non-dominant meteoric footprint or an early dormancy/disintegration of the cometary body.

The research holistically underscores the challenges in tracing ancient comets with modern datasets and methodologies. Practically, the findings propel considerations in ongoing NEO monitoring, advocating for comprehensive scans that might capture dormant comets, niches in our current detection frameworks. Theoretically, this study exemplifies the complexities embedded within cometary dynamics and solar system evolution, presenting a case where historical records, modern tools, and cross-disciplinary insights converge.

Future developments in this area could benefit from enhancing algorithmic capabilities for long-term orbital simulations and integrating more robust non-gravitational models. Moreover, continuing efforts in precise meteoric cataloging can assist in constraining the orbital parameters of potential cometary progenitors like D/Lexell, offering pathways to uncovering other lost celestial entities within our cosmic neighborhood.