Dispersal of Solar System material into interstellar space and the emergence of life in nearby planetary systems: humanity as a cosmic phenomenon

The exchange of material between stellar systems is unlikely because of the vast distances between stars, but it is not impossible [1]. During their formation, stellar systems eject small bodies that initially continue to move along the trajectory of their parent star, but over long timescales their motion in the Galactic potential can be altered, and some of them may eventually become free-floating objects in interstellar space orbiting the center of the Galaxy [2]. These objects may later encounter neighboring stellar systems.

Three such objects confirmed as originating in interstellar space [3, 4, 5] have recently passed through the Solar System. This implies that the opposite scenario may also occur and that Solar System material may approach other stellar systems. An encounter at relatively low velocities would allow the Solar System material to pass through the inner planetary regions of the exoplanetary system and potentially interact with planets in the habitable zone, if such planets are present in the target system. Here, we investigate several candidate stars reported in the recent works [6, 7, 8] for which material exchange with the Solar System has been proposed. This raise the possibility that prebiotic material could be transferred between stellar systems, and in more speculative scenarios, that microorganisms capable of extreme survival might also be transported, potentially contributing to chemical evolution relevant to the emergence of life.  

We examine whether the selected candidate systems provide conditions that could support the preservation or accumulation of prebiotic material rather than its destruction or prevent its formation [9]. We also aim to estimate the probability of Solar System ejecta reaching a planet in the habitable zone. We plan to integrate dynamical delivery pathways with confirmed planetary systems to identify the most viable landing sites for biological precursors originating from our system and we discuss the potential for reciprocal interstellar material exchange.

It, however, should be noted that these estimates are subject to large uncertainties arising from uncertainties in the initial conditions, limitations in the observational characterization of exoplanetary systems, and incomplete knowledge of the processes governing interstellar capture and subsequent penetration into inner planetary systems.

We also present, from a philosophical perspective, the consequences of the potential transport of biological precursors originating from the Solar System into interstellar space. The following considerations should be understood as conceptual reflections on humanity’s place in a broader cosmic context rather than as empirically testable claims.  

If the transfer of solid material—and potentially microorganisms—between stellar systems is considered physically plausible, the panspermia hypothesis provides a broader framework for interpreting the origin and distribution of life, proposing that such material may be exchanged through natural dynamical processes [10–12].

Within this broader context, humanity may be regarded as a cosmic phenomenon arising from physical and chemical processes that extend beyond a single planet or even a single stellar system. A second way of understanding humanity as a cosmic phenomenon is through its technological advancement, which enables its gradual expansion into space beyond its home planet—that is, the transformation of planetary humanity into an interplanetary species. A third, epistemic perspective on humanity as a cosmic phenomenon is linked to the view that conscious life represents a way in which the universe acquires the capacity for self-reflection [13]. This threefold understanding of humanity raises ethical questions about regulating space activities and the possible interference with independent evolutionary processes in other systems, particularly in relation to planetary protection and the risk of irreversible contamination or suppression of indigenous life [14]. On the other hand, if we are part of a broader—and possibly “conscious”—cosmic process, should this in turn affect how we understand our identity? Does it make sense to speak of a “cosmic role” for humanity?

Acknowledgements. This work was supported by VEGA - the Slovak Grant Agency for Science, grants Nos. 2/0041/26 and 1/0089/25

References

[1] Adams, F.C. & Napier, K., 2022, Astrobiology, 22,12, 1429.

[2] Portegies Zwart, S., 2021, A&A, 647, A136.

[3] Meech, K. J., Weryk, R., Micheli, M., et al., 2017, Nature, 552, 378.

[4] Guzik, P., Drahus, M., Rusek, K., et al., 2020, Nat. Astron., 4, 53.

[5] Seligman, D. Z., Micheli, M., Farnocchia, D., et al., 2025, ApJ, 989, L36.

[6] Neslušan, L., Janák, F., Nagy, R., & Hajduková, M., 2026, A&A, 708, A309

[7] Gregg, C. & Wiegert, P., 2025, PSJ, 6, 12, 56

[8] Gregg, C. & Wiegert, P., 2025, PSJ, 6, 12, 309

[9] Cao, D., Plavchan, P., & Summers, M., 2024, ApJ, 971, 160

[10] Hoyle, F. & Wickramasinghe, N. C., 1981, Evolution from Space, London: J. M. Dent & Sons.

[11] Napier, W. M., 2004, MNRAS, 348, 46

[12] Belbruno, E., Moro-Martín, A., & Malhotra, R., 2012, Astrobiology, 12, 754

[13] Sagan, C., 1980, Cosmos, New York: Random House.

[14] McKay, C. P., 2003, P&SS, 51, 1087