A team of NAOJ researchers has published in the MNRAS the orbits of two outbound comets and determined that these comets could easily be two more alien objects caught passing through our solar system. It is also possible that these are objects from the Oort Cloud that were put on escape trajectories through some kind of an interaction or perturbation. 

This has me thinking. Growing up I, and probably many of you, learned that comet orbits come in basically 4 varieties, short period, long period, parabolic, and hyperbolic, where these latter two kinds of orbits both send comets flying out of our solar system. While 2017s 1I/‘Oumuamua was the first definitively extrasolar object to be observed, what if we’ve been observing comets from other solar systems on a random basis for as many centuries as we’ve been observing comets? The rapid rate that we’ve gone from the discovery of 1I/‘Oumuamua to recognizing multiple objects of possible alien origin makes this question of particular interest and I look forward to seeing how our understanding of the origins of comets changes in the coming years. 

The salt of the comet (Unibe)

In other comet news, and building on last week’s announcement of phosphorus in comet crusts, we are now learning that comets are rich  in ammonia ices that trap nitrogen into hard to measure solids. These results come from the Rosetta mission and a Bernese instrument that sampled the material around the spacecraft to directly measure chemical compositions. Earlier research looking at spectra of Halley’s comet’s coma turned up significantly less nitrogen than expected. Solid ammonia, however, wouldn’t have been measurable in that data from the Giotto mission. This new data gives us one more piece of evidence that impacting comets – and likely asteroids as well – brought with them all the building blocks of life.